BechMeister
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Game Version: 0.2.1.0
Challenge 4: Completed.
My rover Percy on the surface of Duna.Documentation of Challenge completion:
development:
SpoilerI looked at Challenge 4 and 5 and decided to co-design the vehicles - It was quite fun to reinact the Mars Sample Return mission. It meant that I ended up designing 3 vehicles for the mission. A rover, A lander with a assent module, as well as a vehicle that could bring the probe core of the lander home:
Test of Rover and Lander on the Runway of KSC.I am particular proud of the Lander - or Duna Sample Retriever vehicle. I made it so the rover can dock with the lander and transfer its science. Then the lander can pitch up and shoot the probe core into low duna orbit again:
In space the 2 stage assent module will then reconnect with the sample return vehicle - seen here:
Sample Return Vehicle: Top - re-entry module with Sample Retriever Assent module core probe - Bellow: The Ion engine and electricity generation module.All 3 vehicle would be launched together in the next Duna Transfer Window and arrive at Duna together to speed up the mission time. How ever not everything went as planned - therefor I will only complete Challenge 4
Launch of the Vehicles:
I launched the Duna Rover on a 3 stage rocket, consisting of a Reusable 1st stage, Reusable 2nd stage and a Duna transfer capsule.
Stage 1: Launch and Landing
Spoiler
Second Stage: Launch and Landing
Spoiler
The second stage pushed the vehicle well into a Duna transfer trajectory. to then stage separate and burn retrograde - making the vehicle remain inside the Kerbin SOI
Stage separation with the Duna Transfer Capsule.
Then about 2 weeks later it splashed down in the ocean.
Duna Transfer Capsule: Launch and Landing:
Spoiler
The transfer capsule arrives at Duna.
once the final maneuver to hit the target area had been made, the cruise module was dropped.
I wanted to hit this valley specifically.
capsule coasting.
re-entry - the heatshield was set to 0% since its not really needed for a Duna landing.. its just very easy to design around.
Rover and Capsule separation.
chute deployed.
and engines burn for a soft landing.
next day at sunrise
Demonstration of the Rover:
I drove the rover 75km around the Duna north pole to check a few possible landing sites. It was quite good at traversing the terrain - having a top speed of 10 m/s on flat terrain.
With a run up it was able to climb a hill of around 45° as seen here:
The vehicle ended up back with the Duna Sample Retriever vehicle after covering the 75km.
Unfortunately for me - the weak link in my attempt at completing both challenge 4 and 5 in one go would be the sample return vehicle.
even though it showed that it had Δv enough to make it to Duna and back again - it had lost 4/5th of its almost 5kΔv - but spend 5 of its fuel - just leaving Kerbin. I suspect its a hard case of the Δv being miss calculated bug.
But making a better return vehicle is the least of my worries.
For a more in-depth rundown you can read my challenge companion blog here:
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-=Duna Sample Return Mission=-
- Part 2: Survey of Target Area -
Map reconnaissance of four possible sites for settlements.<<<<<<<<<< Foreword >>>>>>>>>>
The challenge description called for the Rover to "cover some distance" - I decided that I would take the opportunity to survey possible landing sites for the manned mission to come. There were a few sites that were interesting to me - for various reasons.
Surveying the 4 sites took a few evenings, listening to podcasts and only playing with half a eye on the screen. It covered 75km and I would say that it qualifies as "covering some distance"
More on that bellow:
<<<<<<<<<< Mission Tasks >>>>>>>>>>
Survey Site A. - Sheltered Canyon - Success
Survey Site B. - Sheltered Valley - Success
Survey Site C. - Small Canyon through the Ice Caps - Success
Survey Site D. - Open flats - Success
<<<<<<<<<< Lessons Learned; Lessons Identified>>>>>>>>>>
The rover taking a sample on site D.The Mission In General:
Since Goal Post A to D has a lot in common - I have decided to write a general section of the Lessons Learned; Lessons Identified (when it comes to the rover) and then a specialized section for each site. (more like flavour posts)
The Rover:
Percy - the rover - performed the task very well.
On flat terrain it could sustain a speed of ~ 10m/s - albeit it is not advisable, for the sole reason that, for unknown reasons it would occasionally act like it hits something invisible and lose control. If it crashes with ~10m/s there is a high risk that pieces will break on it. A battery is bad, since it just have enough power to run the WSRL-01 radiation survey - Some times it would break off a reactor unit... Which definitely would result in the survey site being unsuitable for a manned mission.. but also slow down progression - since the Percy would not have the power generation for continuously driving.
Percy thus performed better at 6 m/s - were the periodically loss of control could be corrected via contra steering.
Its cross country ability is quite good - better than expected! The roughest terrain feature it had to navigate was a 45° slope - it needed a run up to the obstacle - but successfully crossed it in 3rd go as seen here:
Still a lot of Jank: RCW is a must
The rover overall still performed a lot better than my Minmus Rover - I have a feeling it's solely because Duna has more gravity, or the rover is significantly lighter - which gives the vehicle more authority when driving, and less mass and inertia to shift around.
That being said... the vehicle really could use some RCWs. There were several times were - when the vehicle lost control - I had to hit the break and maneuver hard to balance the vehicle on a single wheel.. or have it tumble around and do my best to make it land back on all 6 wheels. The antenna was actually great help, since it made it less likely to land on the back...
Percy driving in the shadow in the Canyon of Site AI know I've said this before in the Minmus blog - I really dont enjoy the wheeled vehicle gameplay..
I think the issue comes from them not having a seperate mechanics for ground based vehicles..? at least it seems to me that it is less based on the positions of the wheels.. and more based the velocity vector made by hitting "direction keys".
The vehicle responds to the prograde, and not the position of the wheels.. which means that you end up drifting if you only look at wheels and not the prograde... the key to driving rovers, seems to be this: Gain momentum - do small adjustments and everything goes fine. But most important! Add Reaction Control Wheels - set them to activate via. a action command to roll and pitch the vehicle it goes wrong. The rovemat part does not have RCWs.. which would be fine if it wasn't for the invisible objects that kick the vehicle off course every once and a while.
Survey Mission:
Estimated path driven on the Survey Mission. - brain fart - ofcourse its only 6 samples.In the end the different places of interest were examined - looking for good spots for a manned base with the following criteria to meet:
- Leveled ground - we dont want the coffee cups rolling off the tables
- Access to sunlight
- Shelter from the environment - storms etc.
- A cool looking backdrop for a manned mission.
The last one being the most important of course
- bellow you will see my assessment of the 4 sites in each their spoiler section:
Survey Site A:
SpoilerSurvey Assessment
The Canyon of Survey Site A is only partially suited for manned mission. Although the location is a great backdrop with black Volcanic sand and rolling glacier hills to either side. The east - west running ridge potentially occludes the canyon for much of the day.
A detailed walkthrough of the survey can be seen below:
The rover leaving its touch down location close to Site D and move towards the canyon of Survey Site A.When I saw the canyons carving through the ice of the Duna North Pole. I thought it could be a cool looking place for a base camp - My biggest worry was that the sun would be occluded by the mountain ridges and the terrain too hilly.
The path to the canyon would take me over the glacier - which gave an opportunity to get a Ice Sample. (to test for suitability to get drinking water of course)
Sample I - Ice Sample from the nearby glacier.After that the path quickly took me down the canyon. Once in the canyon, 2 suitable locations for settlements were found: one at the entrance (Sample II) and later at the fork leading to Site B and C. (sample III)
Percy on top of the glacier, looking down into the canyon
Percy taking Sample IIThe sample II location was leveled grounded and in a rather beautiful valley. However the sun was very close to the glacier ridge, as seen below:
Percy moving on to Sample Site III while admiring the midday sun peaking over the ridge.Not to worry, the canyon was leading to Site B any way, and subsequently would be thoroughly surveyed. - Percy went onwards to Sample Site III:
Percy traversing black volcanic ground in the fork that leads to site B and CThe fork in the canyon splitting towards the high ground depression of Site C and the big valley of Site B was less leveled - but it opened up, meaning a greater area was available for a settlement and the ridge was less dominating.
Percy in the canyon fork.Survey Site B:
SpoilerSurvey Assessment:
Site B is very suited for settlements - the valley has multiple flat hills to the north - meaning that getting access to sunlight during the day is not an issue. - the only issue is possible landing sites for the spaceplane mentioned in challenge 8
Percy arriving at Survey Site B - Ike low in the horizonAs you can see Survey Site B is mostly the same black volcanic sand that dominates the canyon leading to it.
another angle of the Survey Site BThe valley is vast and covers a big area - well suited for confined research. And the Sun would be high in the sky.
Percy performing sample extraction IV
Percy on its way up the glacial slope surrounding the sheltered valley - giving a good view of the location.Survey Site C:
SpoilerSurvey Assessment:
Site C is not at all suitable for base building. Not only is it not at all ice free (as seen on the map viewer) - it is also just a slight depression on the ice, so cratered that you can't really see were the depression is running unless in the map view or zoomed out.
Percy leaving the valley of Site B behind.
Sample V in a crater - what on the map looked like was dry land surrounded by ice
same location in the map viewAfter navigating the hard glacial terrain. I finally reached a ridge - that had a somewhat gentle slope - towards Site D.
Percy looking out to the vast open of Site DSurvey Site D:
SpoilerSurvey Assessment:
Site D has plenty of flat leveled terrain. Its gentle clay formations, well suited for base building. The terrain opening to the south meaning no features will obscure the sun. The only negative as I see it is the area is less sheltered from weather fenomena. But it offers great opportunity for excursions and operations further south.
Percy navigating the gentle slope down site D.
Percy taking Sample VI - with the glacier of Site C in the background.
Percy on its way to the Duna Sample Retriever with all the scienceAfter the 4 sites had been investigated, I concluded that the best site would probably be Site D. It came as no surprise to me - but I wanted to see the other sides first before ruling them out.
Site D wins because it has the best potential of all - since it also provides good flat terrain for landing the space plane of challenge 8 on.
Needless to say - shortly after Site D had been successfully surveyed - The Rover arrived at the Duna Sample Retriever. Finishing its 75km tour.
<<<<<<<<<< Moving Forward >>>>>>>>>>
Next up will be a R&D Post containing the redesign of the Duna Sample Return Vehicle, as well as the base modules for the settlement that need to house the Kerbins in the time for the transfer window back to Kerbin arrives.
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-=Duna Sample Return Mission=-
- Part 1: Destination Duna -
The target area for the Duna Sample Return Mission.<<<<<<<<<<Foreword>>>>>>>>>>
The amount of information that accumulated during this initial mission step... was starting to get to a point were, if I decided the entire completion of the challenge had to be included, the post would become excessively long (even for my standards).
It felt naturally to conclude part 1 with the (to a varying degree) successful arrival of all 3 vehicles to Duna SOI.
I hope you'll all find what I learned, doing this, engaging and interesting to read.
<<<<<<<<<< Mission Tasks >>>>>>>>>>
A. Launch Duna Rover and Duna Sample Retriver into a Duna transfer orbit, and return 1st and 2nd stage - Success
B. Launch Duna Sample Returner into a LKO, and return 1st and 2nd stage - Success
C. Land Duna Rover within the Target Area on Duna - Success
D. Land Duna Sample Retriever within the Target Area on Duna - Success
E. Get Duna Sample Returner into LDO ~60km - with enough Δv for the return trip - Failure
<<<<<<<<<<< Lessons Learned; Lessons Identified>>>>>>>>>>
Goal Post A: Launching the Ground Vehicles
Duna Sample Retriever being launched into orbit - 5 days after the Duna Rovers succesful launchThe launch of the 2x ground vehicle was succesful. I was not too worried about these launches as I had a very good understanding of the behavior of the launch vehicle. I scheduled the launch to coincide with the "optimal transfer maneuver node position" (I decided to wait for KSC to be in the ideal position to launch the rover.)
Normally I always launch the vehicle into LKO first. Then find the optimal place on the vehicles orbit, to do the transfer burn that will take me out of the Kerbin SOI. But I decided that I did not need to take such precaution, and launched the vehicles directly from the pad and into a duna transfer trajectory.
KSCs position in relation to Kerbins orbit around Kerbol.I was however still very conservative. (could have launched later) I wanted to perform the transfer burn around Kerbins retrograde around Kerbol - roughly the area K.G.01 is located on the image (the orbiting object) - because that would push my prograde towards the travel direction of Kerbin - placing me on the outside of its orbit, and towards Duna. (i'm sure you all know what I mean)
1st stage has reached the target velocity and is preparing for stage separation and return to KSCThe 1st stage had no issues pushing the much lighter vehicle into its target suborbit. Normally it is very slow to gain altitude and needs to cut the engines at ~900m/s - But I had ample Δv left to push it up to a 1100-1200m/s before performing stage separation and the flip maneuver. (as mentioned in a previous post - the 1st stage usually launch a much heavier vehicle)
Stage separation and flip maneuver - it would be days before the 2nd stage would make it back to Kerbin.The stage separation was successfully performed and the 1st stage would soon find itself back on the pad - while the 2nd stage would start its climb, to push the Duna Rover Capsule out of the Kerbin SOI - It would then be ~6 days before it would reach AP and start its fall back towards Kerbin. Which coincided with the Duna Rover Capsule escaping Kerbin.
With a buffer of 6 days it felt safe to launch the Duna Sample Retriever. I hoped that 6 days would give me ample of time for the capsules to arrive at Duna in a manner where I could land them both in a short succession. I was some what successful - for more details jump to goal post C
Both 1st stages was successfully returned to KSC - and even on the first go! - see spoiler section for details:
SpoilerLaunch and Landing of the Duna Rover 1st stage:
1st stage successfully landed "on the pad" after toasting a few trees.Launch and landing of the Duna Sample Retriever 1st stage:
1st stage of the Duna Sample Retriever back on the pad in KSC.2nd stage of the Duna Sample performing Duna Transfer Burn.
The 2nd stage would then perform an initial burn - aiming to get its AP into the vicinity of Kerbins retrograde vector. Like I said earlier, I was conservative with the launch window - giving me a coasting phase, and ample time to plan the Duna Transfer Maneuver:
Left: Duna Sample Retriever Transfer Trajectory - Right Duna Rover Transfer Trajectory.After the 2nd stages had performed a majority of the transfer burn to Duna. The stage would separate and burn retrograde to push its PE back within Kerbins SOI. After that it was just a long coasting phase until PE - at which they would perform a maneuver putting the vehicle into a suborbital trajectory, and end up in the oceans on Kerbin again.
The Duna Rover Capsule performing the rest of the Duna Transfer Burn.
Upon stage separation the Duna Rover Capsule and Duna Sample Retriever capsule would spend 428Δv and 403Δv of their total 525 Δv getting a intercept trajectory with Duna.
Once out of Kerbin SOI it was time to do the fine maneuvering, putting the two capsules into a crashing trajectory with Duna - My theory was that If I aimed at the center of the planet, then I would arrive more "centerly" on the planet, and then when I did the final aiming maneuver for the target landing zone - I would get an suborbital ark that would hug the polar atmosphere more tight than if I came in above the poles. Which would result in a PE on the "back side" of Duna, since dipping into the atmosphere would happen after they passed over the target area and subsequently result in a much more equatorial landing. The theory was some what right.. although I probably have to aim south of the southpole to get the effect I was actually looking for. Future missions will tell.
After the succesful transfer burn to Duna there was only one thing left to do. See if the Grid fins on the 2nd stage would be enough to keep the heat shield pointed in the right direction on reentry.
Duna Rover second stage successfully landed in the ocean of Kerbin.The Duna Rover 2nd stage reentered the atmosphere with 400 Δv left (remember it's 400Δv after shedding the weight of the capsule) - making it able to keep the heat shield pointed down. However it did splash down with 15 m/s - meaning it only landed unscathed because it landed in the ocean.
To see if the 2nd stage would go sub 10 m/s if it was empty the Duna Sample Retriever 2nd stage was spending its last Δv making sure to target ocean.
The lost mass from the front, meant that it was no longer able to point prograde - but it survived the angled reentry. How ever it still splashed down at 12 m/s.
Meaning that a re-design has to be made for the stage. I have a feeling that I get better performance from aerobreaks when re-entering. So I'll try change the grid fins for aerobreaks and add more parachutes.
The chances of hitting land is slim.. but it would be annoying to lose a perfectly good engine because of a hard landing... and It is very hard to gauge where you land from the edge of Kerbins SOI
Goal Post B: Launching the Orbitter
The Duna Sample Return vehicle being launched into LKOAccording to the KSP Δv roadmap - the tour- from LKO to LDO is ~1700 Δv. By getting better at finding the optimal launch window for Duna I had cut my Δv consumption on a Duna Transfer from 2000+ Δv to around 1200Δv (observation from the failed duna rover mission.)
The Duna Sample Return vehicle had almost 5000 Δv in total- meaning that I should have 1600 Δv to spare, since the return trip would be a collision trajectory with Kerbin.
It should be no issue to launch it to a LKO and have the vehicle leave the Kerbin SOI on its own power. I wanted to do this to see how many passes around Kerbin it would take to get it on to a Duna transfer trajectory.
Stage separation - the first stage is performing its flip maneuver, engines still glowing hot red.Launching the small ion driven vehicle into orbit was going to be a walk in the park - since the 1st stage, and triple LV-909 "Terrier" engined 2nd stage (as I am sure you know by now) is well understood and tested. - it is the glider without wings after all.
The 1st stage was of course returned safely to the pad. This time I made sure to burn enough Δv that I would end up with the around 300 Δv needed to break the fall and land... not taking any chances that it was a weight issue that caused the leg to break off last time. - look at the spoiler section to see succesful launch and landing of the 1st stage.
Spoiler
1st stage safely at the pad again.
the 2nd stage coasting after releasing the Duna Sample Return vehicle - blinding the camera with its huge solar panels providing the vehicle with 67,76 EC/sThe 2nd stage boosted the vehicle into an elliptical orbit, reserving only a 100 Δv to get it back into a suborbital trajectory. The 7 ion engines of the Duna Sample Return vehicle would then be tested for good, checking how many passes around Kerbin it would take to get enough power to leave Kerbin SOI.
Duna Sample Return vehicle doing the last corrections before coasting to Duna - waving Kerbin goodbyeAmazingly enough it would only take the vehicle 5 orbits to gain enough velocity to escape Kerbins SOI. However.. either the Δv readings for the vehicle is wrong, or I have been super inefficient at doing the transfer burn to Duna. Because once the Duna Transfer Trajectory was set - the fuel reserve was halfed but the Δv readings were ~1/5th.
The Duna Sample Retriever vehicles route to Duna - notice that the vehicle has lost 3707/4852 Δv on the transfer maneuver. But have only halfed its Xenon reserve.The Duna Sample Retriever vehicle were also aimed to arrive at Duna at the second intersection point of the orbit - giving the rover more time to pick up relevant samples from the target area - to be send home for analysis. Checking the site for habitability for future missions.
2nd stage re-entering high above Kerbin.Although the 2nd stage was the last to get into orbit around Kerbin, it would still be the first vehicle to touch down on Kerbin again. It had a soft landing in the desert on the continent west of KSC. The 3 aero breaks proved sufficient at keeping the nose pointed forward - albeit the vehicle were still having a bit of fuel to make the nose heavier.
But were the vehicle had sufficient drag to keep the engines out of the plasma cone. The heatshield did not ample protect the faring disc right underneath it. Resulting in the piece failing on the final stretch, just before sheading velocity enough to not "be safe".
Fortunately Kerbals make their vehicles of sturdy stuff! So even though the heat shield was dumped from the failing farings disk. The loss of the heatshield drastically reduced the speed! the vehicle did not suffer any further failures and landed perfect.
The 2nd stage waiting to be retrieved in the deserts to the west of KSC.An easy solution to this issue will be to move the faring disk Infront of the heat shield, and add a decoupler to drop it once re-entering? or swap places and use it as a form of pre-heat shield? Avoiding further vehicle complexity.
Goal Post C: Landing the Rover
Duna Rover intercept trajectory - running low on fuel.For some reason the Duna Rover's, last adjustment of its trajectory to hit Duna, spend ~100Δv of the ~150Δv (that were left after leaving Kerbin SOI.) Whereas the Duna Sample Retrieve vehicle would successfully do the same maneuver at less than half the same Δv.
Even so, I was not worried - 52 Δv was more than enough to do the final corrections once inside the Duna SOI - provided I did them upon entering the edge of the SOI (if you didnt know, the further away from the body you do your maneuver, the cheaper it is).
Aming the vehicle - so it would land on the target area - would become much more challenging though. Especially if it would be on the night side since its hard to see the terrain features in the dark (and spoiler alert - the target area would be on the night side).
However.. as a stroke of fortune out of missfortune. The Duna Rover were not going to be the first vehicle to arrive at Duna. Even though I had given it a 5 day buffer it had still been overtaken by the Duna Sample Retriever:
Vehicle order from left to right: 1: Duna Sample Returner - 2: Duna Rover - 3: Duna Sample Retriever.This meant that the Duna Sample Retriever capsule - which had 115 Δv to play with, could afford to do path corrections all the way down to Duna, and land on the right spot. And then the Duna Rover Capsule could look at the Duna Sample Retrievers relative position to were it were heading and do relative precise maneuver corrections to the target area from a great distance.
Duna Rover closing in on Duna - Ike visible in the distance.It all paned out great. To make sure I got the right point, I quick saved upon entering the Duna SOI and then allowed the vehicle fly within 200km of the planet. Then I checked where the Duna Sample Retriever were located in relation to the spot of the Duna Rover impact. Quick loaded and adjusted the course onto roughly the spot the Retriever would be in the 2d and 5h it took to get to Duna. The maneuver costed less than 10Δv.
Cruise module separates from the capsule once the final aiming has been done.Once within 100 km of the landing area, I made the last adjustments, decoupled the cruise stage and enjoyed the show. - see section D for capsule performance thoughts
See spoiler section for slideshow of the capsule entering Dunas atmosphere.
Spoiler
The aiming point - notice that I overshoot the target - this is because I know I want the parachute to deploy over the target.
I flipped the capsule as the faring bleed of way more energy than the heatshield, which seems to work more as an speeder.
After the Capsule decoupled from the rover, the rover did have some issues though. The lack of RCW meant that it was rolling uncontrollable on the way down, and would not stabilize before hitting the ground. I could somewhat control the rate, with which the vehicle was falling, by firering the landing engines for the durating the engines were pointing downwards, as seen here:
But as you can see it was not optimal.. luckily the Rover landed "successfully" and by a stroke of luck.. it rolled over, onto the wheels again. I disengaging the decent stage ASAP the wheels were all level with the ground... I was simply afraid the stage was making the rover top heavy and it would fall again.
In the end it all panned out and the Rover landed only 5.7km away from the Duna Sample Retriever. - Mission Success!
Kerbol dawning on Sol 1 of the Duna Rover mission.Goal Post D: Hitting the Target Area.
Duna Sample Retriever after the final course corrections - all the Δv spend.As mentioned in Goal Post C, the Duna Sample Retriever were the first to reach Duna. Once inside the SOI I saw that it would take it 2d and 5 hours to hit the surface. I looked at the position of the Challenge 2 lander to the target area, and tried to roughly aim were I thought the place would be within 2d. and 5h. - I really wish the game had a tool that allowed us to see future rotation when planning a maneuver.
Then periodically on the way down I would fine tune the landing site. Until I was only 200km from the surface. At which point I believed I could do the fine tuning of the landing and ditch the Cruise Stage.
After that it was all about figuring out how the capsule would perform on the way down.
The Duna Sample Retriever Capsule after ditching the cruise stage.The capsule performed well, although, just like the Challenge 2 Lander, It accelerated for a long time. In the end I had to perform a flip maneuver to break the fall - It seems the heat shield work a lot more like a speeder than a break. One should think that the blunt shape of the heatshield would make it break more.. compared to the pointy farings. But It may just be me thinking too much of Dunas thin atmosphere.
See spoiler section for the hot reentry:
Spoiler
The faring sustained the final speed drop facing forward and were jettisoned:
Duna Sample Retriever dropping the capsule and preparing for landing.I had some issues were the ditching of the faring, within the atmosphere, would severely warp the assent stages. It made me re-do the landing several times as I was sure it was the issue were if you time warp with the vehicle SAS set to point to a direction (like prograde) it can warp the vehicle (same bug mentioned in the CommNet satelite deployment).
I tried disable all RCWs on the accent stage, so It could not bend the stage into a wrong shape during time warp. Then made multiple Quick Saves - always dropping the faring afterwards to check if the vehicle had warped - before quick loading and proceeding the landing.
I got all the way to re-entry.. were I noticed the warp happened from the decoupling within the atmosphere. To combat it I made the vehicle flip one last time before decoupling, and decoupled as the ascent stage was pointing roughly prograde. It warped a tiny bit.. but not so much that it clipped into the launching ramp (which it did before, and i was sure would result in a catastrophic failure)
Lessons Learned; Lessons Identified - use struts. I am sure its a bug.. but since struts break when placed across a decoupler.. I can always strut the pieces in place.
After that drama, it was all about deploying the chute and prepare the landing.
Duna Sample Retriever performing landing burn.The lander touched down no issues - I turned off the lights and then waited for the sun to come up before deploying the solar panels. I had to put the stage into hibernation as it does not have enough battery power to make it through the Duna Night. I dont see it as an issue - since the challenge does not state that the vehicle needs to be able to last a Duna Day. It can launch the accent stage during the day time once the time for that arrives.
Duna Sample Retriever - safe on Dunas Surface, generating power.After a short test that the accend stage could launch without failing, I saved and uttered a sigh of relief - The hard part was done - The Lander had hit the target area without circularising its orbit first and without breaking. Soon the rover would join it.. and then it was just waiting for the Return Vehicle to get into a LDO before concluding Challenge 5 and 6.
Goal Post E: So close and yet so far
Duna Sample Return vehicle circularising its orbit.The experienced KSP player will have guessed that this is as far as the journey went for the retriever. I know I said I allowed it to get its rendezvous with Duna on its second cross of its path. the II: symbol on the maneuver node. But I waited the time and pretend that I performed the survey of the valley in the mean while. I had to know if the returner would have enough Δv to finish the mission. Or if a sample return had to be postponed another 4 years. Alas the latter was the case.
I made 2 important lessons though:
Lesson A: Capture Burn
I learned i was right about taking a path that brought my PE high into Dunas SOI. I tried to break and stay within Duna on a trajectory that brought me close to the planet ~100km altitude. I did not have enough Δv to circularise the orbit. I could reverse my orbit, but not circularize it.
So I remained far out:
Duna Sample Returner capture maneuverAs you can see it would take a majority of my Δv to capture Duna. If any one has any council on how to perform this part at a Δv discount, I am all ears. - and before you say aerobreak, I dont think Dunas atmosphere is thick enough that it will break the vehicle to not break out of the SOI again.
Lesson B: Solar panel effectiveness.
Around Kerbin - the two SP-XXL "Colossus" produces a total of 66.76 EC/s. But around Duna the two sails only produce 31,56 EC/s - more than a half in reduction. I did not expect the effect to drop that much - Duna is not that much further from Kerbol than Kerbin.
The result was that the vehicle could only use 3½ of its 7 ion engines around Duna. In other words over half the engines were dead weight this far out.
Maneuver to LDO:
Even though the vehicle had arrived at Duna with no means to complete the mission, I still spend the time to find out what was the optimal way to lower my orbit. I arrived at the conclusion that the cheapest way to lower my orbit was this:
A. Lower the PE to the target distance of ~60km:
- 3 burns at AP - duration: 3 min
B. Lower the AP to the target distance of ~60km:
- 5 burns at PE - duration: 3 min - 1.100km altitude
- 4 burns at PE - duration: 6 min - 150km altitude
- 1 burn at PE - duration: 4 min - 91km altitude
- 1 burn at PE - duration: unknown - ~60km altitude.
If any one have any better solutions to get the orbit down cheaper - I am all ears.
The Duna Sample Return vehicle in LDOIn the end the vehicle successfully lowered its orbit from the edge of the Duna SOI to a ~60km circular LDO.
However, as is evident from the screenshot. It completed this leg with far to little Δv to bring the sample back to Kerbin. - After I had learned what there was to learn, I spend the last 173 Δv to de-orbit the lander.
<<<<<<<<<< Moving Forward >>>>>>>>>>
The Ground Vehicles were succesful in their designs and execution - the retriever needs more work. How ever I have already redesigned the vehicle from the LL;LI in Goal Post E. - Reduced the number of engines and increased the fuel capacity.
As the post is already really long, I will be pushing that update into the Part 2 of this mission.
Next post will be the challenge completion of Challenge 5. I will take samples in the target valley - to determine if it's ideal for a science outpost to continue further excursions.
Stay inquisitive, stay engineous - until next time!
Final landing places of the Duna Rover, and the Duna Sample Retriever. -
-=R&D_UPDATE=-
Duna Sample Return MissionOooh Do I have a great update for you guys! I am really proud of these vehicles!
So I looked more into the Mars Sample Return mission. Even though I was quite familiar with it (I really rute for all the aspects to be completed.. But I understand why the scientific world find there are better ways to spend the funding it needs). Still it's a really awesome mission.. and the more I looked into it in detail, the more I wanted to "replicate" it.
Like I said I knew about the role of the Perseverance Rover - as well as the idea of how to return the samples to Low Mars Orbit and then fly it back to Earth. But I never looked into what rocket launched Percy actually. But looking for inspiration I learned it was the Atlas 5 rocket that got the rover to Mars, as well as the transfer stages.
I decided to keep the rover from the unlaunched Challenge 6 design, and then start by designing the Lander. From there I would design the Vehicle that would bring the sample from Duna to Low Duna Orbit first, then the vehicle that would bring it from Low Duna Orbit to Kerbin. And from there, the rockets that would bring all 3 vehicles to space and to Duna.
So without further ado, lets get through the design process:
The Sample Return Lander:
It all started with me seeing this concept for the Mars Sample Retrival vehicle:
Early Conceptual drawing of a Mars Sample Retrieval Lander. (Image credit: NASA) - I believe they wanna toss the rocket into the air now rather than launch it from a tube.There were 2 key features I noticed that I really really thought was clever:
- The "warhead" of the rocket can be loaded directly by the rover.
- The rocket is lying down - meaning a flat, compact design.
Since the challenge 6 rover had a xs docking port in the center. I could build a lander with a tiny 2 stage rocket, Lie it down and have the rover "load" it with the Science Data it would pick up by docking to another sx docking port. Since science data is transferred from vehicle to vehicle.. It meant that the stage broad home could be as little as a probe core.
And if you remember the challenge description:
On 5/10/2024 at 4:44 PM, BechMeister said:If the Lander is multi-stage, the stage with Probe Core must be returned. Otherwise the requirements are the same as in Challenge 4
That's exactly what we are doing.
So I build a relative flat design with a rocket ramp and a 2 stage rocket with enough Δv to get into DLO. I used some inspiration ques from the lander from Challenge 4 and made the landing engines the landing legs. I used the bigger Ox-10c solar panels - because that looked more like the ones on the MSRL concept. The final design looked like this:
The rover from the challenge 6 vehicle and the new lander inspired by the NASA concept.Now I just had to make sure I could have the rover connect to it. It was possible by setting the two front sets of wheels on max spring setting, and the rear wheels on min - just like when docking to the overengineered challenge 6 rocket I showed last design round.
Its not a perfect fit - but good enough if you ask me.
Now the next problem to solve was how to launch the rocket. At first I contemplated doing the toss maneuver: have some small rockets throw the rocket into the air and then engage the rocket engine and fly up.
How ever If I could angle the rocket up, I could build a holder for the parachute to slow down the lander. At first I tried landing legs with different variation in spring strength and or size. But it was not enough, or was really clunky and ugly.
I cursed for a while because we really lack parts that allow us to actuate pieces. but then remembered that Aerobreaks can vary in pitch.. I figured if i put one bellow it and some legs on the end of the ramp I could build a tripod and use the aero break to angle the lander up! And it worked flawless - you just need to manually adjust the angle, because it's moving to fast on its own... This is the feature I am most satisfied with
After that It was just a matter of testing if the rocket would break free no issues, and spoiler alert. It did 
I thought it looked cool on the NASA concept with the 4 fuel tanks - but I did not need that much fuel to stick the landing and send the rocket off - so I decided to load the rocket on without fuel - to save the kilos. The lander has enough fuel to fill the rocket and land at the same time. - It takes a little more than ½ the total fuel reserve to fill the rocket... So there should be more than enough to stick the landing.
Sample Accent Stage:
1st Stage - 48-7S "Spark" engine - 748 Δv
2nd Stage - LV-1 "Aant" engine - 685ΔvTotal: 1433 Δv
Weight:
The lander total: 1.91t
Sample Accent Stage: 0.79t
Sample case (probe core): 0.33tNow that the lander was made I felt the next natural step was to design the vehicle that has to bring the probe core home from Duna to Kerbin.
If you wanna see the staging of the rocket in detail, see spoiler section bellow:
Spoiler
The rocket takes off. - some times the lander breaks in the process, but at this point its done its job.
another angle.
stage separation. - 2nd stage has no chance on Kerbin.
the probe core by itself - test for parachute.
chute deployed.
chute deployed - the probe core falls at a pleasant ~6 m/s
Sample Return Vehicle:
The sample return vehicleSo - Because the vehicle that will bring back the sample from the real MSR mission uses Ion engines - I decided to make a Ion engine vehicle. Surfice to say... I did not enjoy the slowness of the vehicles with ion engine.. So I decided to pack as many Ion engines I could on a vehicle and still power it. With 2x SP-XXL "Colossus" solar panels I could power 6 Ion engines at 100% thrust, and 1 engine at 75% - giving me as high a thrust to weight ratio as possible.. I will still have to take multiple boosts around Kerbin before I will leave its SOI.
The vehicle consist of 2 sails, a z200 battery of 200U a RC-00S1 core 2x PB-x150 fuel tanks - giving the rocket 4852 Δv. Most importantly, the vehicle has the "sample deorbit module" - a heat shield for the return deorbit.
Bellow - Sample Return Vehicle - Above: Sample Deorbit Module and Sample Case(probe core).It should give me ample of Δv to get to Duna and back again. I do wonder though If I should go for a very high Duna Capture orbit - where the velocity will be low... Since I will otherwise fear that I wont have time to break the orbit. The rover that skimmed the surface at 4km was getting up to 2500 m/s - I doubt the Ion engine will have time to de-accelerate those speeds? - Not that It would survive going so low any way.
We will see.
Now I had my rover, I had my lander and I had my sample return vehicle. Time to find out how to get it all into orbit.
Launch Vehicles:
The Sample Return Vehicle:
Since the Sample Return Vehicle only clocked in at 3.24t. - I figured a reworked 2nd stage for the glider rocket would be ideal:
1st, 2nd and the sample return vehicle.The new 2nd stage has enough fuel to get the probe into orbit, and then de-orbit itself. has a heat shield as well as parachutes. Because the engines are very heavy, the vehicle is a bit problematic in case of center of mass being to close to the rear of the vehicle. I hope that adding 3 breaks will help me steer the vehicle.. But experience tells me otherwise. We will see though - I dont mind to be wrong in this regard.
This Kerbin to LKO vehicle is not that exciting. So moving on to the next.
Rover and Lander:
I saw this nice picture of Perseverance rover and its capsule:
From bottom: Heat shield - Rover + Decent Stage + Back Shell - Cruise stage.I know I said I had decided not to use heat shields - since they were very heavy for how little protection was needed to go through the atmosphere. But It is just very difficult to designe a nice blunt shape without them. So I decided to add the heat shield any way, but turn the oblateness all the way down to 0%. Then I build the back shell with a faring and because you can't add stuff on top of farings, I added the cruise stage below the heat shield:
Left: Vehicle Capsule and Cruise Module separated - Right: Vehicle capsule and Cruise Module assembled. - Notice the launch vehicle in the background.I think the design is very satisfying to look at. The stage has 539Δv - enough to make course correction and solar panels to keep it powered. It's hard to believe - but the two capsules actually have the same total weight - I had to share a screenshot to prove it:
I did not intent for this - but its really cool i think.To get the capsules out of Kerbin SOI - I decided to take the 1st stage for my Heavy Fuel Vehicle again and build a 2nd stage that had enough power to get the capsules to the edge of Kerbin SOI - to then fall back down and splash into the ocean.
The result was this:
The 1st stage has enough Δv to launch the 2nd stage into a sub orbital trajectory of 1000 m/s - The 2nd stage with the SC-TT "Labradoodle" engine has 2049Δv - enough to get the capsule to the edge of Kerbin SOI - and then about 500 Δv to aim the decent.
Coming in from the edge it's going to be going very fast. - like the 2nd stage for the Sample Return Vehicle - this also has issues with its center of mass. I hope that the 6 large grid fins will help it fall through the sky with the heat shield front.
<<<<<<<<<< Moving Forward >>>>>>>>>>
I am really happy with these designs and I am really looking forward to give it ago. Its kind of cool to emulate a real mission.. And I actually really enjoyed "building small" specialized vehicles.
I actually dont feel a need to attempt flying the vehicle I originally designed for challenge 6 - If people really want to see me launch it I will do it.. but if it has no interest - I'll just put it in the R&D bin.
Stay tuned for more!
Next up - a triple launch... and the answer to the question if I have the patience for Ion Engines.
-
Challenge 3 completed:
Here is a screenshot of my tiny lander on the surface of Duna:
Challenge 3 complete
Version: 0.2.1.0
It was quite a fun challenge to make a lander that would fit within the small cargo hold of my glider:
The vehicle made its way to Duna - I was a little bit challenged by passing through Ike's SOI - but I still managed to get a path with a PE of 4km - I was affraid that a PE hitting the planet would be dangerous as I did not know how well you Aerobreak in Dunas surface - And I didnt want to deploy the farings and chute before the vehicle was slow enough that it didnt have flames traling of it.
Here the "capsule" enters the atmosphere and the transfer stage is decoupled.
once slowed down the faring was decoupled.
I had a drogue chute to help steer the lander down, and 4 tiny engines to break the fall - they also double as landing legs.
et vois la!
-
-=MISSION EXECUTION=-
Murphy Strikes
The rover being launched into LKO.<<<<<<<<<< FOREWORD >>>>>>>>>>
So! That was an odd launch - Everything went wrong - but not so wrong that the next leg of the mission couldn't proceed. Until the lander touched the Duna surface that is. I decided to just roll with it.. but in the end it became kind of comical how this update would only have a single suffesful task - namely getting the probe to Duna
Any way, I learned something with every failure. - More on that bellow:
<<<<<<<<<< MISSION_TASKS >>>>>>>>>>
A. Deploy the probe with the SDG and return the SDG system to KSC. - Failure
B. Perform transfer burn of the Rover Probe to Duna - Success
C. Land rover on the surface of Duna - Failure.
<<<<<<<<<< Lessons Learned; Lessons Identified >>>>>>>>
Goal post A:
1st stage collapsed on the landing pad.I dont know if i jinxed myself last mission post - by writing business as usual. Because even if I tried to get the landing to stick twice I failed twice. I decided to just roll with it... Even spaceX still tumbles a rocket every once and a while.
I am still not sure why I had such a hard time landing it - I had more Δv than I usually have. Maybe it made me more slobby? or maybe the weight of the rocket was the issue? In any case, on the 1st attempt I had lateral movement over the pad. Which meant that the rocket tumbled on the landing. I always try to come into the pad on an ark. I find that it is easier to kill lateral movement by coming on on an ark and slowly controlling the decent by burning retrograde until the lander is pointing straight up - with no lateral movement - and then controlling the de-acceleration for a soft touch down. I find if I, on the decent phase, fall "straight" down I end up getting lateral movement when doing the fine aiming for the pad.
On the second failure a leg broke off on touch down. I had a hard time timing the de-acceleration. I wonder if the extra weight of the excess Δv caused my timing to be off? Any way.. the result was the same. Maybe I should do some testing to see if having too much fuel coming down means the legs can't handle the weight.
Any way - back to the glider:
The SDG deploying the probe.The glider made it to orbit and deployed the probe. The glider also had an excess of Δv. So I figured deorbiting would be easier than ever. I had overshot the runway the past too launches.. (still making it though) - So I did the decent burn earlier. But too much earlier. - The early burn plus excess Δv meant that It soon became evident that I would not make it to the runway by a longshot.
Finding a good landing spot was "alfa omega" - the glide efficiency is not great on the glider... you really need to time the flare maneuver right to bleed off speed and stick the landing. Too soon and you will pankage into the runway, too late and you will not be able to keep the nose pointing upwards, and the vehicle will break in two- and thats on a completely flat surface. Which meant that I could probably not land uphill.
I found a nice even looking patch of land and managed to land the vehicle on a small hill, devoid of trees (almost)
The glider touching down - notice the sharp angle the trails are taking - it was not a soft landing.Lessons Learned: The glider can make an emergency landing if the landing site is carefully chosen.
For detailed walkthrough of the mission leg - see spoiler section:
Spoiler
the rocket blasting off.
Stage separation - I found that I burned my monopropellant tanks on hot staging - So I have moved them further down. Before they were situated right below the 3 split plate.
Returning to KSC.
aiming for the pad.
breaking through the thick clouds (made it hard to aim) - a Hud element you could toggle on/off that shows the pads and landing strip in the dark or heavy clouds would be nice.
a leg broke on the landing, and when it tumbled it rolled off all the grid fins and broke the top off.
back in space:
The glider finish its orbital insertion burn.
probe deployed.
performing deorbit burn over the southern cost of the western desert
controlling the decent. Since I was sure I was not going to overshoot this time - I just took a flat 40° AoA.
here from another angle.
Here the airspeed was dropping rapidly - and it was evident that I would never reach KSC.
I decided to break left as it looked rather flat.
I decided to go for this ridge as it looked relatively flat - and easier to land on than in the depressions on either side of it.
landing gear out. losing airspeed rapidly.
Now it's just hoping that the landing gear holds.
And safely landed.. Now it just have to be picked up.. we're just a tiny bit off.
relativly speaking x)
Goal Post B:
The probe arriving at Duna.I saw a smart trick on the internet - since the ideal transfer window to Duna is 44,4°. You can take a a piece of paper and fold it so it shows 45° and place that pointing on Kerbol and when Duna and Kerbin is visible from the paper - you have ~45° (which is close to 44,4°): see spoiler section for reference:
Spoiler
When I did this I was surprised how much off I had been - gauging the degree's with my mk.1 eyeball. Because the image with ideal transfer windows - in degree's, had been simplified (all the orbits have the same distance to each other) - placing Duna in continuation of the position of Kerbin meant I was several degree's off. Its obvious I know..
Any way, getting a better transfer window meant that I came to Duna spending much less Δv: Screenshot for reference
The probe arrived at Duna no problems.
Goal Post C:
the conclusion of this ill fated mission. A rover in pieces on the surface of Duna.I had two problems coming in to this mission. First problem was that I was going too fast. If I just allowed the heatshield to be pointed forward the probe would just shoot straight through the atmosphere - Even if I spend all my remaining Δv breaking - the capsule would still accelerate to 2000+ m/s before being low enough for the atmosphere to do something. All I could do then was just wave Duna goodbye and have the probe be lost in space until Duna would line up again.. some time in the far far future.
Desperate times means desperate measures - I found that if I flew the probe backwards I would break:
Duna Lander entering the atmosphereDepending which way I pointed the probe I could even lower or raise the PE. giving some controllability..
The Second Problem was that the lander was too heavy and hit the ground with ~14 m/s and broke into pieces. 1 parachute was not going to cut it - it need breaking engines.
But two important lessons were made:
- Heat shield's are more of a hindrance on Duna - they turn the probe into a bullet and is just weight not spend. I got confirmation that the fairings can take the re-entry heat and will be building re-entry capsules for Duna with farings.
- Duna's atmosphere is so thin that you cannot rely on parachutes only. Unless you put on a lot of chutes.
for detailed walkthrough of the landing - see spoiler section bellow:
Spoiler
spending the last Δv on breaking before releasing the transfer stage.
The burn lasted well into the atmosphere - the Δv was spend shortly before the engine burned off (lucky) - I then decoupled and as the capsule push away the lighter transfer stage. - now accelerating again.
Here from another angle.
I notice that the capsule is just building speed.
the capsule has flipped to break.
the farings are dropped.
Parachute deployed.
we are breaking.
but not enough
<<<<<<<<<< Moving Forward >>>>>>>>>>
Now - this blunder offers an opportunity to give Challenge 5 and 6 a new go. I have looked into the Mars Sample Return mission - that may be launched... And I actually really think its some nifty small vehicles ESA and NASA has planned for it. So I may design an actual lander that can work with a rover - and make a return vehicle with ION engines? They seem a bit gimmicky to me in KSP2 - I guess they are gimmicky in real life too... but their low thrust makes me think they take quite the patience to use.
We'll see - Except a R&D post next - then I can launch all 3 rockets in the next duna transfer window.
Stay tuned in for more!
-
-=R&D_UPDATE=-
Rovers and Mars Sample Return Mission:So I just went through a lot of convoluted R&D to complete Challenge 6 - just to realize that I read the challenge wrong when I read it. I thought the requirement was to get a rover back and forth from Duna - Not a Lander.. (which does make the mission a lot simpler). I think that I, in my head, focused too much on perseverance as being part of NASA and ESAs real Mars Sample Return mission - without realizing that challenge 5 "is" the perseverance mission - that I build both challenges into 1.
Needless to say - Now I've build it - with 12 stages and all... to get it there and back again... So I'm going to do it!
The challenges are as follows:
On 2/28/2023 at 9:15 PM, OJT said:5. Desolation Road
Design an Unmanned Rover, send it to Duna and demonstrate its functionality by covering some distance in it. Rover must have an antenna that can reach the Relay satellites, means to generate electricity and at least 3 wheels
6. Bring It Home
Design an Unmanned Lander that can land on Duna and then subsequently return it intact to Kerbin. If the Lander is multi-stage, the stage with Probe Core must be returned. Otherwise the requirements are the same as in Challenge 4
Challenge 5 Rover:
Updated Lander making a survey test near the Runway 1Since the rover was going to be mobile. It made sense to replace the solar panels with a "Multi-Mission Radioisotope Thermoelectric Generator"(MMRTG) (NASA sure like their acronyms). In game it is known as the PB-NUK power plant.
Instead of a tiny drogue chute I gave it small MK16-r parachute - The drogue chute was almost enough to land the lander. So I hope that the small parachute will do and I can skip the engines... as I had trouble figuring out how to give it fuel and place rockets on it.
Challenge 6 rover and Sample Return Vehicle:
Since the challenge 6 required a vehicle that was big enough to get to Duna and back again, I knew it would not be able to launch it from the SDG. It gave an opportunity to develop a new and bigger rover. I wanted to cram as much science out of the vehicle as possible - and one of the most challenging things to get on it would be a WSRL-01 radiation survey. Which seems like a good thing to survey before a manned mission x)
Now making the rover was not going to be the hard part... Making a vehicle that could deploy and retract a rover would be. The fact we dont have any crane parts meant that the rover had to somehow be able to drive in and out of the lander vehicle... or the vehicle would have to be able to lower a port that allowed it to dock to it again.
It took 2 attempts to develop such a vehicle:
Attempt 1:
a test of the vehicle on Runway 1 - notice the landing legs is placed to give stability and prevent the vehicle from falling on uneven surfaces.The idea behind prototype 1 was that rover could drive in and out the bottom of the decent and accent stage. It would put a limit on the size of the rover - but the medium size would still be more than enough room for a rover with all the science equipment.
The Accent and decent stage looked like this broken up in its parts:
From bottom up:
- Duna Decent Heat Shield - with deorbit engines.
- Rover Carrier and Kerbin decent stage
- Service Stage for Duna Kerbin transfer.
The landing procedure would be this: The Duna Sample Return Vehicle (DSRV) would decouple from the Kerbin-Duna Tour Retour Stage (KDTRS) and the tiny fuel load on the heat shield would deorbit the lander. Once through the thick of the atmosphere the heat shield would be dropped to save weight. and the stage would land via engines and chutes.
Then the rover would drive out and do science, once ready it would redock with the lander and ascent again. Once into the vacuum the farrings would be blown off and the docking port would be ready to dock back with the KDTRS.
When back at Kerbin, the DSRV would then decouple from the KDTRS - again - and deorbit. Once de-accelerated (no more flames) it would also drop the heat shield and deploy a second pair of parachutes for a soft touch down..
However - theory and reality did not align. Once I had made sure the vehicle could land itself I was going to test if the Rover could drive back in. The fact that the engine plate is as tall as it is made me worry that it would not be able to drive over the step. I tried to replace the engine plate with other flat medium sized parts - but in the end it would be just as tall because of the engines.
Radially deploying the engines were not an option - since having the exhaust next to a surface drastically reduces thrust - and It was not possible to place them Infront of the doors (aesthetically it felt wrong to me.. if movable things clip through things it feel like cheating)
My worry was well funded - but not only that I couldn't drive back in - For some reason the rover couldn't even drive off the engine plate.
Left: even if the engine plate did not have landing legs or engines the rover could not get in again.
Right: It's a bit hard to see - but the wheels are just spinning.
Another way to make the vehicle had to be done. I remembered how I made my dropships for Minmus. And I decided to do something similar - see spoiler section for reference If you have not read my Overengineered Minmus Mission:
SpoilerOn 2/10/2024 at 8:59 PM, BechMeister said:B. Designing a Dropship:
Attempt Two:
I decided to make a stage that would lie flat on the ground, and then by adjusting how much the cargo bay doors open, I could adjust the angle of the docking port - and by breaking and accelerating the rover. Or increasing spring strength on the front wheels and reduce on there rear wheels, I could make the rover pitch up and "catch" the docking port. I made a small mock up as a prof of concept:
For a more thorough test of the landing of the proof of concept.See spoiler section:
Spoiler
Next was finding the way to get it back into space again. I developed a 2 stage system. A 1st stage with 1320Δv, just shy of being capable getting into DLO - and then add a little bit a fuel and 4x LV-1R "Spiders" to the "Proof of concept" 2nd stage giving it 357Δv. Which should be enough, and then some, to give it the last kick into orbit and rendezvousing with the KDTRS.
Left Top: 2nd stage - Left Bellow: 1st stage - Right: the Duna Lander Module.Next up was making a way to get it through the Duna Atmosphere. Now - since the Heat shield on challenge 4 did not take any damage - I decided to try do away with it on this build. Instead I build an aerodynamic faring and applied grid fins to help steer it down. The Duna reentry "vehicle" could then have a heat weak medium docking port as its "decoupler" - meaning that there is cohesion with the 2nd stage when it returns to the KDTRS.
The reentry vehicle is pretty simple. Its purpose is to just shield the vehicle from being scorched by the plasma, then blow off and allow the sample return vehicle to land.
It looks like this:
Launch Vehicle and KDTRS:
Last thing to do was to develop the vehicle that would bring this monster from LKO to Duna and back again. The easiest thing to do was to look at something I had build before and already flown a lot. I took the 1st stage for my Heavy Refuel Vehicle to K.G.01 (my space fuel station in LKO) as seen here:
On 12/20/2023 at 9:43 AM, BechMeister said:
The final version, and fully certified H.T.V. - 2nd stage and 1st stage.The 1st stage is designed to push. The Tanker Vehicle of 119.62t to ~900 m/s or 25-30km - before returning and landing at KSC again. So it has not trouble pushing the KDTRS + DSRV at only 79.08t into LKO if the stage is wasted.
Final design of 1st stage and KDTRSThe KDTRS has a total of ~3.439Δv after giving itself a tiny boost into LKO. That should theoretically be enough... When going to Duna I tend to use shy of ~2000Δv - the DSRV weighs 13.21t going to Duna - and less than 4.76t when it returns (depending on the fuel level upon docking). So I hope that 1.439 Δv will be ~2000 Δv. I could do the rocket equation.. But my gutfeel says it will be enough to go there and back again.
If not I guess we will have a rescue mission to launch.
<<<<<<<<<< Moving Forward >>>>>>>>>>
I expect the launch Challenge 5 tomorrow - and then write the update Sunday? (we'll see how it goes - plans only last until contact with the enemy after all)
Stay Tuned - Until next post!
-
-=MISSION EXECUTION=-
The transfer stage bleeding off energy before deploying near the polar cap of Duna.<<<<<<<<<<FOREWORD>>>>>>>>>>
I have decided that, even in the event that this is the end of KSP2(we dont know yet). I'll still continue to grind the content I can out of this game. I am at least aware of the most prolific bugs now, and know how to design around them... and I have only just left Kerbin.. There is so much more to get out of this sandbox still... The KSP2 engagement seem to be on the low end though.. and while I do enjoy making these long detailed blog posts about my progress. Not knowing if any one reads them, is killing my motivation to write them.
I will be finishing the Duna Mastery Challenge though! But I had planned to do the same rundown on Eve next.. But we'll see if that will be something I'll write about. I think that depends on what level the engagement with the game is like, at that point.
Any way.. This challenge went alright.. I must admit though that I was surprised with how thin Duna's atmosphere actually is (even though I knew it was). More on that bellow:
<<<<<<<<<<MISSION_TASKS>>>>>>>>>>
A. Launch probe into LKO and return 1st stage and SDG to KSC - Success
B. Perform Transfer Maneuver to Duna - Success
C. Land the Lander near the Polar Regions - Success.
<<<<<<<<<<Lessons Learned; Lessons Identified>>>>>>>>>>
Goal Post A:
The SDG launching the Probe into LKO.This leg was pretty much business as usual - Although I did learn that the SF-125 will be burned up by the exhaust from the 3x Lv-909 "terrier's" - That did not bother me too much. It looks a lot better to see the exhaust plumes to "clip" through an part that is open, rather than clip through a closed cylinder.
where as it feel redundant to wish for something to be added to the game in these times... I still wish we could hot stage rings in the game.
The launch went without incident and the probe was successfully deployed (being a lot shorter made it very easy, it flew out of the cargo bay on its own RCS power.
For detailed walkthrough of the launch See spoler section bellow:
Spoiler
Lift off! I kind of wish that the tower parts we use to hold the rockets.. were actual attachement points to the launch towers.
Blasting off into space.
Clean stage separation - 1/3 SF-125 burned away. - the other two would fall off.
burn back to KSC.
As you can see the two surviving SF-125 broke off on the way down - but I always liked the look of the 3 split piece without the extenders.
Lining up the pad.
And touch down - all routine now.
the glider is burning itself into an ~90.000m x 90.000m orbit. - I am not being precise this time.
close to the point of the reentry burn the cargo bay door slides open to reveal the probe to the vacuum of space.
Probe is deployed and the SDG is creating distance, as to not fry the satelite with its exhaust.
The probe is ready! Now it's time to land the glider. The fact that I did not try to be precise with hitting 90.000m x 90.000m, and that it was half the weight of the CommNet carrier, meant that the glider had ample of fuel for its deorbit burn.
The longer deorbit burn meant for a gentle reentry - the flames never got bigger than this.
I still managed to overshoot the runway, and had to do a hard break. before spiraling down:
by following the 45° angle from straight down, I made a really narrow spiral dive. Getting down quickly, while maintaining airspeed. It's kind of crazy that its terminal velocity is not much higher than 148,9 m/s
It lead us to come up perfect to the runway.
and touch down.
Goal Post B:
Duna Lander Probe - making transfer burn to Duna.Because I had the CommNet around Duna now, I decided to just put on a small antenna on the vehicle - with a range of 200 Mm. I figured the vehicle would only need trajectory when leaving Kerbin and approaching Duna... How ever I was surprised of how "short" 200Mm was in reality - not extending that far away from the Kerbin SOI. It meant I had to do a little quick load.. you see I had decided to do the approach of burning out of the Kerbin SOI, then make the maneuver for Duna at a optimal point.
However - The optimal point was way outside CommNet range. So I decided to do a more expensive burn and then just make sure that the Duna PE would be a few KM above the surface. I would not have Δv enough to circularize around Duna.. but I didn't need to since I could just be Aerobraking.
the maneuver that got the Lander Probe to Duna.The most important thing for me would be to bring the probe over the North Pole - Final adjustment would be made once in the Duna SOI. - The probe was allowed to coast all the way to the Duna SOI without any signal - a bit harrowing... For a sec I thought that the CommNet wasn't able to relay signal.. but it was just because the signal was only reaquired after the timewarp stopped.
The probe had successfully arrived at Duna SOI
Goal Post C:
Lander safely on the ground, taking its first sample.Once inside the Duna SOI it showed that my my path would take me directly through Ike's SOI - which made aiming quite difficult actually - since Ike naturally gave me a high ark to Duna.
The probe zipping past Ike on its way to Duna.Fortunately there were plenty Δv left to push the PE down once I was through Ike's SOI. For RPG reasons I was interested in testing the soil near the poles of Duna - Seeing the canyons between the poles I figured that would be a cool landing site - so I aimed for this place:
After finding a point to aim at I, then raised the PE to 4km above surface - to make sure that the vehicle didn't pancake into the ground, if the atmosphere wouldn't break me as much as I hoped it would...
The last Δv was spend aiming the trajectory for the canyon - or general area.
The transfer stage being ditched - and the landing stage burning through the atmosphere.once the atmosphere started to heat up, the transfer stage was dropped and the lander stage just flew through the atmosphere like a bullet. It bled of the energy.. albeit much slower than I anticipated - the lander would drift quite far before the speeds were dropped to a level were I felt comfortable the lander would not have been torn apart (at least in our world - In the world of Kerbals they have the alloy Kerbalium . And that is most sturdy) the fairing was dropped, and the scute deployed soon after.
lander drops fairing - creating a lot more drag.After that it was just a question of dropping the heat shield - I dont know if its a bug? or if Duna's atmosphere is just so light it does not need heatshields... At least it had not spend any of its ablative propperties
.
The scute was deployed and the 4 engines put it gentle down to the ground.
The lander breaking for a gentle touch down.The lander would touch down a generally flat place, on the other side of the ice sheet I was aiming fore.. but at least in one piece. We are still taking a sample of the Duna Polar Soil, which can lay the foundation to find the ideal place for future manned Duna Missions.
The probes final resting place.The battery power is a bit light - the lander goes all the way down to EC 70U before sunrise. If all unnecessary power usage has been eliminated. Of course the lander could go into hibernation mode in the night.. but I dont know if that is considered "cheating" in relation to the goal post stating that the vehicle should "have means to generate electricity" - I guess it has the means in the daylight.. but If we go by the Martian Landers and Rovers of our world.. power is spend in the cold nights, making sure mission critical hardware is not killed by the cold. I guess that is of OJT to judge.. where ever he is now days.
For picture slide show - see bellow:
Spoiler
The lander after having performed a Anti- Normal burn to adjust for planet rotation.
Saying goodbye to the transfer stage - here the lack off effect on the heatshield is clearly visible.
the big canyon with the two white peaks in were the spot that I aimed for.
here flying over it - still in high speeds.
the last glow desapating. stage separation would happen just as the hot plasma would extinguish.
The protective faring separating from the craft.
Dropping the heat shield (no longer needed, and deploying the Drogue Chute - to ensure propper stage separation.
Drogue chute doing its thing.
As the sun sets the vehicle is closing in on the ground.
Touchdown!
The craft gets the last bit of sunlight be fore hanging in tight for the night.
The next day it was ready to do science.
<<<<<<<<<< MOVING FORWARD >>>>>>>>>>
with that being a - Challenge Success! - it is time to move forward.Since the parameters of the next challenge is pretty much the same - at least if I just put wheels on the lander. I have decided to compile the R&D post for Challenge 5 and 6. Otherwise the R&D post for challenge 5 will be very short. Since I will mostly be able to use the same vehicles.
See you in the next one!
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Thank you for a nice read - also what a sleek looking plane
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-=R&D_UPDATE=-
Tiny LanderGood day! Here we are again, soldiering on while pretending everything is fine...
I guess it's all one can do at this point... I think I've come to the conclusion that if this was really the end of KSP2. I'll play the content that is there, and then take what I've learned and go my way into the ether. Any way, todays post will be short.
After successfully establishing the CommNetwork around Duna. It is now time to go dig in the ground and figure out what the soil has to offer. The challenge is as follows:
On 2/28/2023 at 9:15 PM, OJT said:4. First Landing
Launch an Unmanned Lander (like Viking) and land it intact on Duna. Lander must have an antenna that can reach the Relay satellites, means to generate electricity and some sort of landing legs. Whether you choose to use already provided lander legs or make some of your own from structural parts is up to you
when I initially started to make builds for this challenge I thought it was going to be a walk in the park. But I was surprised how big even the small parts actually are. Also even though the the challenge does not ask for science parts - it just felt wrong to launch a lander that could not take samples from the ground. I mean, the Viking Probe mentioned as an inspiration has means to dig in the dirt:
Painting of the Viking Lander taking samples on the Martian Surface.So science parts had to be there, now that they are here!
Designing a Lander:
Lander being tested on the Runway of KSC.It is not easy to build this small. I knew my glider would only take vehicles that were - at maximum, somewhere between Small and Medium. medium would already be too big.. since the vehicle would not be able to leave the bay. So I had to build it out of the Extra Small parts:
Lander from the "front" and bellow.The lander is basically constructed by taking a M-Beam 650, flanked by XS reaction wheels and strapping on 4 TMP-XS (the tiny 6 way connector) where I could add the 4 LV-1 "Ant's". Giving the vehicle a total of 70 Δv. (the fuel tank is mostly left empty) The engines also doubles as landing legs.. Since even the smallest leg were huge on this thing.
The biggest issue were fitting the sample arm, (which is rather big actually) and not having it clip into the drogue chute.
I added 2 solar panels and a z-400 battery - together with the tiny probe core it gives the vehicle EC of 405U. Lastly I added a ASCM-B "Little Sniffer" just because it looks like there is a camera on it.
Considering how much the cameras on the rovers give them personality.. I think its weird that we don't have a rover part with camera etc. on it.
The lander totalled at .79t with fuel and .77t dry.
Now we just need to get it to Duna!
Duna Lander Transfer Stage:
From Bottom up: 1. Duna Transfer Stage 2. Duna reentry stage 3. lander.So.. The lander is a little bit wider than the Small heat shield - I figured I could put in a faring that has a cone shape and put a small heatshield at the end. Hopefully the conical shape of the faring will mean that it takes less heat on the way down? and the heatshield will take the brunt of it.
The lander is connected via a decoupler on its side to it. Which is fitting any way since my plan is to get my PE just barely over the surface of the planet - to bleed of as much speed while flying horizontal - so I don't just Pancake into the ground (if the atmosphere is weaker than I expect). So it will be pointing in the correct orientation when deploying.
The Transfer stage has 1967 Δv which should be enough to get a "impact" path to Duna - it is going to be quite interesting how much the atmosphere does? because even when sending missions to mars in real life we use heatshields right?
The Staging Plan is as follows:
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Once the lander enters the atmosphere, stage separate the Transfer Stage from the Re-entry stage, and point the heatshield prograde. - The transfer stage will burn up.
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Once the lander has bleed off enough speed to not rip the lander a part or melt it - drop the faring.
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Engage the drogue shoot - to ensure the lander separates from the heatshield - and stage separate the heatshield off.
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gently touch down with the aid of engines.
The vehicle comes in at (with the lander attached to it) 4.30t total - meaning almost half as light as the CommNetwork Probe launched previously. So getting it into LKO should be a walk in the park.
Speaking of getting into LKO:
Hot Staging:
To help the SDG separate from the 1st stage - I have tried to use 3x CT-S-1 instead of the 3x SF-125 as it looks closer to something that could enable hot staging - I don't know if the game will register it like that? or if the part will survive the heat - We'll see.. if they burn off I guess it does not matter much anyway. As long as the SDG flies clean off upon stage separation.
SDG with the Duna Lander vehicle attached in the cargo bay
<<<<<<<<<< Moving Forward >>>>>>>>>>Next up is launch - Which I think I'll get done pretty quick. We'll see if the little thing does well - I guess with a lander like this, making sure you land on a flat surface is also alpha omega.
Any way - see you in the next update.
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Challenge 2:
Probe arriving at Duna.I completed challenge 2 and 3 in one go - If that is considered cheating I'll just lunch 3 new satellites.
Done in v.0.2.1.0
Proof of Orbit:
See spoiler for detailed walkthrough:
Spoiler
launched probe in my 2 stage glider.
Stage separation, Stage 1 returns to KSC. Stage 2 gets into LKO.
Satelite deployed to LKO
Glider deorbitting.
the clouds are really nice, even on low graphics.
Glider back at KSC. Back in space - the probe burns for Duna.
Break burn at Duna. Orbit achived.Challenge 3:
The probe from Challenge 2 functioned as a probe carrier for the CommNetwork mentioned in challenge 3.
Proof of CommNet around Duna:
3x long range antenna Molniya Satelites.
6x Short range antenna cube satelites + the drone carrier:
See spoiler for detailed walkthrough of this leg:
Spoiler
First Molniya Satelite seperating from the drone carrier and burning to a 100.000m circular orbit.
Drone carrier succesfully deploying 3 Molniya Satelites into a 100.000m circular orbit with ~120° between them.
Probes perform a 60° inclination burn - Using Ike as the reference point for the degrees
First of 3 satelites to reach the correct orbit. Soon the 3 others would be in their ideal orbit - and it was time to launch the cube sats.
First cube sat launched
after 4 more launches - it was time to launch the last:
I then proceeded to burn the drone carrier into a ~200.000m circular orbit - so it would not interfere with the other satelites:
If it is considered cheating to launch Challenge 3 with Challenge 2 - I'll just launch 2 more satelites.
For the very detailed walkthrough - See here:
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2 hours ago, Poppa Wheelie said:
I did this landing from Duna Low Orbit. Fuel tanks can make it without heat shields, but reaction wheels cannot.
I see. Probably as weak as a engine plate then - they burn up if they exceed 700 m/s on Kerbin.
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7 minutes ago, astrobond said:
Yes you are right, you now need big solar panels or Nuclear Reactor if you go far away of Kerbol
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23 minutes ago, Poppa Wheelie said:
I have not needed or used heat shields for other Duna landings I've done in the game so far. So I didn't really consider them. I built version 1 of my 300t payload without heatshields, tested reentry and landing, and it worked. Including heat shields as part of the 300t payload from the beginning would have been the safer bet. Lesson learned.
Nah it seems that if you deorbit from a DLO - you can do it without any precaution.. since orbit speed is only like what.. 700-800 m/s? I dont remember.. So far Ive only been to Duna twice
But I imagine that if you come in directly from Kerbin.. that's when heat shields are needed?
- I'll find out more once I get on with the Duna Mastery Challenge.
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10 minutes ago, astrobond said:
Lol, hopefully, Jeb seems to be ok, and btw, don't forget to put solar panels on your grand tour ship because the PB-NUK is not as patient as Jeb.....
I always put a Nuclear Reactor on vehicles that uses the atomic engine - It seems weird to me not to do that. A part of me feel it should be a requirement.. just like Ion engines needs power.
That being said.. I have only ever left Kerbin SOI succesful twice. But yeah.. Solar panels. It feels like one of the previous post severely nerfed solar panels? - I had vehicles with 2 of the smallest solar panels I had not used for a while that had no problem generating power.. to suddenly not being able to recharge fast enough.
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17 minutes ago, astrobond said:
the total mission time was almost 40 years... xD
Jeb is a patient man.. but then.. He went into the history books.
I wonder what the life span is for a Kerbal at this point. xD
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That is one insane rocket - Did you wait for an optimal launch window? or did you just wait between each leg of the mission?
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Yay! A mission report that isn't just a video!
On 3/27/2024 at 10:02 PM, Poppa Wheelie said:
it just looks great when the boosters separate like that.
On 3/27/2024 at 10:02 PM, Poppa Wheelie said:My biggest engineering mistake came to light during the first landing attempt. I had already test landed an earlier version of this 300t payload. But the final version had 5 large reaction wheels on the bottom of each stack, facing into the Duna wind during atmospheric entry. During landing attempt 1, all 5 of those reaction wheels overheated and exploded. I still had over 300t of payload, but without reaction wheels I couldn't land in enough of an upright position to keep the payload intact.
Did you drop the idea of having heatshields to save the mass? Or was it to aid in landing (its a lot of weight after all) - I myself have started to have drop the heatshield once through the dangerous parts of the atmosphere.
On 3/27/2024 at 10:02 PM, Poppa Wheelie said:By the way, I landed 20.2km from the landing location of my first Duna mission.
nice x)
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I just wanted to say That I "succesfully" made a "Molniya" orbit thx to you guys - The timing is a bit off I think.. but the period is correct at least x) I posted some pictures and gifs of the process in this blog:
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-=MISSION EXECUTION=-
KSP2 and the Three Body Problem.
KSC on a beautiful morning - right before launch.<<<<<<<<<< Foreword >>>>>>>>>>
It feels a bit weird to keep doing this with what's in the news atm. I feel like mission reports are not that important as of now.. especially not when the games future is in question.. I dont know what I feel and think right now. We will see what happens once the vail is being lifted. The thought of KSP2 having the plug pulled before reaching its full potential sadness me.. I had looked forward to the colony part, and resource gathering.. but most of all the multiplayer.
Any way.. here is the Mission Update that answers if the R&D was well funded.. or a waste of time. I can tell you all the vehicles worked flawless, albeit some tweaks in the future can be made. The title of the blog? - Three Body Problem..? heh lets just say its my terrible humor.. but true too.
More on that bellow:
<<<<<<<<<<MISSION_TASKS>>>>>>>>>>
A. Launch Probe into LKO and return SDG to KSC. - Success.
B. Transfer Probe to Duna. - Success.
C. Deploy Molniya Satelites - Success.
D. Deploy Cube Satelites - Success.
<<<<<<<<<<Lessons Learned; Lessons Learned>>>>>>>>>>
Goal Post A:
Drone Carrier with CommNetwork being deployed to LKO.As I expected this step went without issues. One tiny thing was identified though as a possible improvement.Upon stage separation the 1st stage is pushing the SDG, making stage separation difficult. I have decided to experiment with replacing the tubes between the 1st stage and the SDG with the small gitter tubes - I am going to try hot staging to aid the separation. - We'll see next mission how it goes.
Because this step was going to be a walk in the park - I decided to use the step to practice my precise deployment. Although it expended more Δv than if I had just got it into the ballpark orbit, It still had plenty of Δv to get down again.
By adjusting the RSC thrusters down to 1% and the engines to 1% I managed to hit a perfect 90km circular orbit:
The SDG right after 90.000m AP has been achieved, notice that it burned 45° to the Prograde - Not very efficient. HUD cropped into top corner: The achieved 90.000m x 90.000m orbit.One thing that the practice run(to achieve a precise orbit) showed, was the importance of having an engine with the appropriate power. if 1% thrust is not low enough for fine maneuvering - I would consider putting a weaker engine on.. or make sure the RCS is propper balanced - The glider has 3 thrusters for reverse and 2 for front - which actually was too much power even at 1 percent. Actually I would like to have sub 1% to work with.
The deployment of the probe was possible - even without using the time warp hack:
The SDG deploying the probe.When I performed the stage separation I could wiggle it 45° degrees - It was kind of stuck from there.. but by using the RCS thrusters on 10% I was able to slowly fly it out - The decoupler, which was supposed to be staying inside the glider broke off though and was left as space trash. Also I never checked to see if the engine clipped through the back of the glider.. but hey.. the probe got out.
That being said I did encounter an annoying bug - When ever I timewarped with SAS set to Prograde/Retrograde - Radial in/out or Target. The probe would bend out of shape:
QuoteI will attach a bug report here once approved - With the current situation with Intercept Games, I assumed bug hunting effort is on hold until further notice? So I have not bothered reporting the bug yet- Normally I wait for my bug reports to be approved before posting the blog... but I wanted the update out now
Any way - the counter to the bug is to make sure you have locked your orientation, or are pointed towards something that does not move while in time warp (Like a maneuver node)
Before we move on to Goal Post B - Of course the SDG and 1st stage was safely returned back to KSC.
See spoiler section below for detailed walkthrough of the Mission Step:
Spoiler
The SDG blasting off the pad. It was a beautiful morning with light cloud cover. The volumetric clouds just looks awesome... SO.. I may have taken an excess amount of screenshots.
I really think the way the clouds simulate light is impressive.
right before engine cut.
Engine cut - flip and burn back maneuver.
flip and coasting before engine reignition.
Controlled deacceleration. As mentioned previously - the engine plate will not survive speeds exceeding 700 m/s
aiming the rocket for the pad.
breaking the fall.
touchdown.
Back in space.
the glider pushing the AP to 90km
engine cut - the chrome just look so good.
Opening the cargo bay doors:
There it is in all its glory.
Probe deployed and the glider is ready for the back burn.
Deorbiting the glider.
The glider did not have as much Δv for the deorbit maneuver as usual because I had been practicing the precise maneuvering. Fortunately the glide distance can easily be altered by banking left and right. - here the glider is starting to cut a blazing trail, still 50km up.
I never get tired of watching the gliders de-orbit.
Here adjusting the last range of the glide before continuing leveled flight at 40° AoA
bleeding of the final velocity - the blue and orange has always looked amazing together - notice that the bodyflap is not deployed at this moment.
the glider has entered the atmosphere - even though the glide distance had been shortened with the left right left banks - it still managed to extend the glide again while in "leveled flight"
It was nothing a steep spiral down couldn't remedy.
here the glider is "spiraling down" - in reality it's as close as a controlled dive you can get.
one of the last twist of the spirals before the glider is enough down to level the flight. - I am doing my best to conserve energy for the final flare.
lining up the runway and enjoying the look of the clouds and the chrome mirroring the blue sky.
coming through. still very high, its a good thing the runway is so long.
final flare up before touch down.
and now just coasting to the VAB.
and parked outside the VAB
Goal Post B: The Three Body Problem
Probe Carrier in LKO - getting the final telemetry from KSC before performing the 1st og 3 maneuvers that will bring it to a DLOThis step was almost breaking me and the Mission. I kept trying make plans that got me directly from a Low Kerbin Orbit to a Low Duna Orbit. But even if I did it with all the artistry in the world: Not just burning prograde, making sure Duna was in its ideal transfer window etc.(as well as you can when you need to use a protractor on the screen) I was plagued by issues.
The vehicle kept not following the path the maneuver node said it would, It needed to have huge adjustments made once out of Kerbin SOI and I kept arriving at Duna with less than 100-200Δ after the break burn to get into orbit. Which was never enough to finish the mission.
After 2 tries I was about to throw the towel in ring when I remembered that getting vehicles back from The Mun to K.G.01 was never feasibly to go directly from The Mun. It was always more cost effective to burn out of The Mun SOI and then do the fine tuning in Kerbin SOI.
It seems to me that KSP2, as of now, can only really handle a maneuver made within the SOI your already in? - if you your maneuver crosses more than one.. you will have a very hard time getting the path right... And my maneuver was bridging three SOI.. or three bodies: Kerbin SOI, Kerbol SOI and Duna SOI.
Once I decided to split the entire transfer into 3:
- Get the probe out of Kerbin SOI - while in front of Kerbin (so I dont have to burn through the SOI again) and with an AP leaning towards Duna.
- Make a maneuver within Kerbol SOI that, as efficiently as possible, would intercept Duna at ~0 inclination (its hard to judge as you only get the numbers once in the bodies SOI) and with a PE of ~100km (the further you are from the object you want to intercept, the cheaper adjustments are.)
- Once in Duna SOI, perform break burn and target 109.916km AP.
See spoiler section below for detailed walkthrough of maneuvers: but be warned, it's a bit of a mess
SpoilerDirect Transfer from LKO to Duna.
First maneuver node with direct transfer to Duna.Notice how much Δv the maneuver node said it would use - in the end the maneuver ended up taking a ~100 more Δv to complete, and there were a huge discrepancy between the path I ended with and the path the node said i would end with.
In the end the transfer burn to Duna would spend 1313 Δv. And even though I would have less Δv on my 3 split maneuver - for some reason less Δv got me further. Even with 778 Δv - I could only just break to orbit Duna - and not even close to the desired orbits.
Maneuver from LKO to Duna split in 3:
First Maneuver to leave Kerbin SOI. - Notice I try to be more efficient with my burn by making sure I cross my Prograde ~½ way through the burn.
After end burn - notice the discrepancy between the maneuver node and the actual maneuver.
I made the second maneuver for the Duna Transfer by pulling on the prograde until the path crossed Duna's orbit - then I moved the node on my orbit until I had a good intercept. Notice how much further from the optimal transfer window I had to be to get a "cheap" maneuver.
I ended up with this path after end maneuver and 558 Δv -interestingly I had less Δv left compared to the single maneuver + correction. But there is a huge speed difference. The final adjustment was made with RCS thrusters.
Once inside Duna SOI i performed the last burn:
Notice that the screenshot was taken mid-burn.
I ended up around Duna with 157Δv to adjust the orbit to a perfect 100km PE - 190.916m AP
Looking at the screenshots now - I do not understand why I could perform the complete maneuver this way - when it seems I had 220 Δv more from the direct burn - but then I had trouble breaking and staying within Duna. I dont know if the velocity is the coulprit. In the 1 maneuver way, my exit speed ot Kerbin was 10245,3 m/s vs 9543,4 m/s = 701,9 m/s in difference. Maybe in the end, it was just because doing it in 3 burns, meant I could be more precise with my PE arriving at Duna? Meaning I would need to do less maneuvers within Duna SOI?
Maybe someone with a lot of experience in KSP can tell me what I do wrong.. if not - I guess the further missions to Duna will tell me.
After 2 tries at a direct Transfer to Duna - I cut the transfer burn into 2 and finally arrived with enough Δv to continue the mission.
Drone Carrier leaving Kerbin.
Drone Carrier arriving at Duna.
correct resonant orbit achieved to deploy CommSat Network.I arrived at Duna with 157Δv to adjust the orbit to a perfect 100km PE - 190.916m AP
To see a detailed walkthrough of the mission step - see spoiler section bellow:
Spoiler
Carrier performing burn to leave Kerbin SOI
Drone Carrier performing second burn (outside of Kerbin SOI) to intercept Duna.
Breaking burn to orbit Duna.
here we see the probe burning at 1% to precisely tune the orbit for deploying the satelites.
Goal Post C:
First Molniya Drone burning away from the mothership to its 100km flat orbit.Getting the molniya satelites into their orbits did not pose as a significant issue as I had feared going into the project, and all in all the theory worked in "real life". I have split this into a section surrounding each phase of the deployment.
Phase 1: space the satelites 120° apart.
My biggest issue here was that the 48-7S "Spark" engines were too powerful for the task. Something that would not cause Issues in phase 1 and 2 - but later in phase 3 meant a lot of back and forth burning.
I ended up using Ike to find ~0° inclination to Duna - I really think KSP should have tools vanilla to give you the inclinations to the body you orbit. Any way - the drone carrier set to 1% engine power was really easy to control the orbit, and making sure the satelites were evenly spaced.
all 3 Molniya satelites deployed at ~120° apart. 100km flat orbit.See slideshow bellow:
Spoiler
1st Molniya satelite deployed.
Second molniya satelite breaking away from the carrier. - no pictures of the third.
Once the carrier had completed all deployments and arrived back at the Molniya Satelite 01 - this was the margin of error between them.
Phase 2: burn to a 60° inclination
Inclination burned.I tried to get all 3 satelites to burn to their 60° inclination at the same time, by using pause etc. However the game would not allow it.
instead I had to burn one satelite at the time, meaning that they were probably not a perfect 120° degree separation between them. But it still look close enough to me. - the inclination burn shifted the orbit away from a perfect 100x100km orbit - but since all the satelites were pretty much still timed, I figured it would be easier to deal with in Phase 3.
Phased 3: Burn the satelites to their AP of 6700km
first satelite in its correct orbit.I was quite nervous about this part - the whole point of the Molniya Orbit is that at least 1 satelite will be over the pole at All times, and moving slow enough that a simple antenna can track it. There were a few factors that would make it difficult, and a few unknowns that you can probably solve with math - but that I decided to just eyeball.
Getting into the correct orbit.
One of the factors that made it difficult was the in ability to mark the most southern part of the orbit. Which meant I had to eyeball when to burn prograde to raise the AP to the North. Fortunately the engines were easy enough to get the AP to 6700km - the problems arose once at AP.
At AP I had to correct the wrong PE to a perfect 100km. The problem was that the engines even at 1% were too powerful - I kept flipping the satelite, burning prograde then retrograde trying to hit 100.000m flat. but instead jumping between 99.998 and 100.002m - In the end I got them all down to the correct orbit.
A lessons learned lessons identified for the future is either to downgrade the engine power, or give the satelite a little bit of RCS (assuming the RCS at 1% is less powerful than the Spark engine - something that I've come to doubt)
Timing:
I was not sure how to time the satelites propper - and looking back with hindsight. I probably started out with something that would work better with a 4 ship orbit, rather than a 3.
How I solved the timing was by burning Molniya satelite 01 to its 6700km AP. while the Molniya Satelite 01 was at AP. I burned Molniya Satelite 02 to its AP. This meant I now had 2 satelites that would be at each their end of the orbit at all times. After that I figured that if i burned Molniya Satelite 03 to its 6700km AP while 01 was on its way down, and 02 on its way up - to cover the gab that would come between them.
In the future I think it is better to:
- Burn Molniya Satelite 01 into its 6700km orbit.
- When that sat is on its way down (2/3) of the way in its orbit - burn the Molniya Satelite 02 to its AP
- Once Molniya Satelite 02 is 2/3 done with its orbit. Burn Molniya Satelite 03.
I dont know if this will be a better approach. But looking at orbits speed up:
Molniya Orbit in action.It looks like the timing is slightly off? all 3 satelites stays up together at one point in the orbit, and then just barely having 1 satelite over the poles another point of the orbit - I think with a 4th sat this orbital constilation would have been "perfect'er". (I guess 1/4th is always easier to guesstimate than 1/3)
Goal Post C:
The RCS thrusters on these cube satelites gave a lot of trouble - they were way to overpowered even with 1% thrust. I could not, for the love of god, get them to a 100x100km orbit. They kept dancing between 99.999m and 100.002m just flipping numbers. In the end I gave up getting them into a perfect 100x100 orbit and decided that they had enough monopropellant to correct orbits for a long while.
I tried to allow the satelite constellation to run for 3 more years without guidance, just to see the drift. Only 1 out of 6 cube satelites had drifted in its orbit.. and after docking and undocking K.G.01 a lot - I know exactly how to correct orbits for drifted satelites.
Asume a orbit either a few km higher or lower than the target orbit (slow down - speed up). once you're right above/below your target orbit.. rendezvous with your it by lowering your orbit again.
Example of almost hitting 100x100km flat - and having to give up.After "successfully" deploying all 6 cube satelites in their orbit. I decided to burn the carrier into a ~200x200km orbit, to make sure it was out of the way. The satelite still have 264Δv left - I wonder if there is any better use I can make of it now. Either I include it somehow to the constellation - or I deorbit it.
Cube satelite constellation in action.for slide show see spoiler section bellow:
Spoiler
first CubeSat being launched.
Second CubeSat being launched.
4th CubeSat being launched.
Final CubeSat being launched - making the probe carrier seem awful disproportionate
<<<<<<<<<< Moving Forward >>>>>>>>>>
Challenge 2 and 3 complete - and even with flying colours if you ask me.
I always wanted to establish a CommSat Network - now I finally got around to do it
before going on to Challenge 4 - Does anyone have any good ideas of how to use the Drone Carrier? It has 264 Δv left. So its very limited what kind of orbits it can achieve. But if any one have any suggestions on how to better utilize it, I am all ears.
Stay Tuned in for More! Next up - R&D for Challenge 4.
-
6 hours ago, K^2 said:
The reason to put in the units anyways is basically a self-check. If you made a mistake in the formula, you'll either get strange units out or an error. For example, if you were to forget to square the period, you'd end up with (m3/s)1/3 = m/s1/3, and because cube root of seconds (s1/3) isn't a physical unit, you'd get some form of an error. Which is preferable, in my opinion, to getting a number that's completely wrong, using it without realizing, and ending up having to scrap the mission.
thank you all. I think I finaly understand it.. to a user level. Its funny how KSP has been a better math teacher than my math teacher. I always just assumed I was dumb when it comes to math. But when people take the time to sit down and answer my questions. I get along in the end x)
1 hour ago, FleshJeb said:My SX could do this in 1994. There’s a shortcut on the keyboard for the units menu.
This quote reminds me of when my father talk about how he prefere win95 xl to the new one - he says it makes some errors that 95 xl didnt.. I always just shrug - I dont ever think I asked xl to do anything advanced enough to figure out x)
But man.. people bantering about calculators is why I love this forum. -
-=R&D_UPDATE=-
CommNet - Satelites and the Molniya OrbitI figured a good way to continue with this blog - would be to alternate between a R&D post and a Mission Execution Post. Where all the theorycrafting on "how to solve the challenge", will be poured into a post first, and then I follow that up with a Mission Execution Post. I have a feeling that a lot of good discussion can come from making a theory and testing if it worked... at least it will give people a chance to say how wrong I am in my calculations and theories - and stop me before I do something really silly
Or better yet.. give people something amusing to read.
Any way - Without further ado - here is next challenges
On 2/28/2023 at 9:15 PM, OJT said:2. Otherworldly Connection
Build an Unmanned Satellite and enter Duna orbit. Satellite must have an antenna strong enough to reach Kerbin and have means to generate power. Take Ike's SOI into consideration when you plan the orbit!
3. Transmitting Live From Duna
Set up a Relay Satellite constellation in Duna's orbit. There must be at least 3 satellites in the constellation. Each Satellite must have a Relay antenna strong enough to reach Kerbin and have means to generate power. You can either launch new satellites or add some to the one you've sent in Challenge 2, as long as the Satellite from Challenge 2 satisfies the aforementioned requirements
Before we talk about the 2nd challenge I am going to ignore it for a little while, and focus on the 3rd challenge first = 3 CommNet Satelites in Orbit around Duna - To me that screams for a Molniya or Tundra orbit. - Something I've been wanting to try out for a while now.
If you dont know what a Molniya or Tundra orbit is - See spoiler section bellow:
SpoilerThe Molniya Orbit:
Example of a Molniya Orbit with 4 satelites.The Molniya and, its cousin, the Tundra orbit are both very elliptical orbits. with orbits that, respectivly, have a period of ½ and a whole sidereal day and at a very specific inclination to the body they orbit (63.4° around Earth) . The Inclination needs to be this specific in order to cancel out the "pull" from the equatorial bulge - that otherwise slowly alters the orbit. (the "Fat Earth Theory").
Inclination:
You see, the fact that earth bulge at the equator means that it will pull a satelites inclination down towards the equator over time. But at 63,4° - the effect is canceled out. In KSP this is not an issue since all bodies are perfect spheres.. So we can orbit perfectly at any inclination.
Orbital Period:
The other interesting thing about the Tundra and Molniya orbit is the period with which they orbit -namely a Half and A complete Sidereal day.
A Sidereal day uses the stars in the background as its point of reference, where a Solar Day uses the stars as reference. So roughly speaking - A sidereal day is how long it takes the body to rotate so that distant stars appear in the same location from the night before.
Why this orbit:
The point of the Molniya and Tundra orbit is to give coverage to the polar regions, that do not have line of sight to geostationary communication satelites. The Polar Region will always be able to see at least 1 satelite in a Molniya or Tundra Orbit.
A vehicle in a Tundra orbit will orbit over the same spot once every revolution, and the Molniya every second revolution.
There are 2 reasons why I am thinking about a Molniya Orbit:
- A Geostationary orbit will not have Line of Sight to the poles of the planet - and It would make sense for future settlements to be near the poles were there is water ice. So a Tundra and Molniya orbit is necessary for such an settlement to be able to communicate with KSC. (Roleplaying)
- Since the orbit is highly elliptical, it will be more likely that none of the satelites are hidden behind Duna - which should be able to have reliable coms with KSC with fewer satelites and that there are no signal loss to KSC. (except when Kerbol is in the way)
Now how do I propose to make a Molniya constellation around Duna you ask? My plan is this:
- Get 3 long range satelites to Duna and space them 120° from each other around the planet, 0° inclination.
- Get them to burn to a 60° inclination to Duna while maintaining ~120° separation. (hopefully the burn will be quick.)
- Have them raise their Apoapsis to 6700km. (half a sidereal day - see vehicle design section to see how the AP is calculated)
Now to complete this task - the Molniya satelites needs a carrier with an antenna strong enough to get signal from Kerbin. If you guessed that this will be the satelite from challenge 2 you are correct.
My crazy idea is to make a Satelite Carrier - deploy it to Duna and put it in an orbit where I can space out the 3 Molniya Satelites in a 100km orbit - Then perform the 3 steps to deploy them at their correct molniya orbit (Pe: 100km Ap: 6700km) . After this the satelite carrier will deploy the 6 small cube satelites evenly on the 100km orbit - which will provide signal around the equator. Once that is done - we will see how much Δv it has left on the Satelite Carrier and find a good plan for that.
If this sounds like it's going to be difficult... I agree... This will be a test of my patience and precision.
Resonant Orbit Planning:
Now I thought I would have to sit and actually use my brain to calculate the correct orbit periods etc for launching the satelites to get their space even across the orbit - however I was gifted this great tool that does it for you. Use this to plan the spacing of satelites.
When I plot in 6 satelites orbiting at 100km I get these ranges:
The smart thing about planning around 6 satelites LOS is that it resonates with the 3 Molniya satelites - which will be deployed on every second orbit instead of every orbit.
If you - the reader - sees that I have made some terrible error.. please enlighten me
Now the parameters of the mission has been planned. Now it is all about designing the vehicles.
<<<<<<<<<<Designing the Vehicles>>>>>>>>>>
The CommNet Satelites:
Left: Cube Satelite - Right: Molniya Satelite.Molniya Satelite: 1064 Δv
Cube Satelite: unknown (25kg of Monopropellant and 2 RCS thrusters. - more than enough Δv)
Now for the communication satelites the Molniya Satelites are the ones that will be most demanding. They will have to burn from a 0° inclination to a 60° inclination - then raise its apoapsis to match ½ a sidereal day... Now.. How to calculate this number was lost on me. Even though I could find the equation online multiple places I could not get google to calculate it propper. So I asked for help on the forum, and help was received. Thanks to @K^2 and others for helping me wrap my head around this.
To aid others (and myself in the future) I have decided to save the process here:
How to find the AP:
To find the AP for your desired Molniya Orbit you need to first find the Semi major axis of your orbital period - you do that with this equation:
Quotea = (μ*T2/(2π))1/3
a = Semi Major Axis.
μ= Standard Gravitational Parameter - See KSP Wiki
T= ½ a Sidereal rotation Period - See KSP Wiki.If you punch that into google so it looks like this:
Quote(3.0136321E11m^3/s^2 * (32758.93s)^2 / (2 * pi))^(1/3)
Google is smart enough to understand the values Meter and Second and how they relate to each other.
You should get this number: 3,719.831km - which is the Semi Major Axis for a ½ a Duna Sidereal Rotation Period.
Now this number is the distance between Apoapsis and Periapsis - you may think "but that is an oddly big number" - at least that is what I was thinking. But that was because I "forgot" that there is a planet in between, and that the distance we are shown is taken from the "sea level" of the planet/body. We there for have to subtract the planets diameter. (or radius*2)
Now - I have decided that I want a PE of 100km above Dunas Surface - So to find the AP you have to use this formula:
QuoteAP = 2*a - 2*R - PE.
a = Semi-major axis
R = Radius
PE = Periapsis2 * 3,719.831km - 2 * 320km - 100km
This should give you a distance of 6,699.662km - which I have rounded up to 6700 km - With 1064 Δv I hope we have enough Δv to finish both maneuvers. (it seems like it should be enough?)
QuoteNote: should your AP be outside the Body's Sphere of Influence you can shorten the Semi-Major Axis by increasing the number of orbits by lowering the Fraction in the formula for the semi major axis:
(3.0136321E11m^3/s^2 * (32758.93s)^2 / (2 * pi))^(1/3)
By lower the fraction, (Like 1/4, 1/5 etc.) you increase how many orbits the vehicle should take before it is going to be over the same point on the planet again.
This formula is "plug and play" so to speech - you can go to the wiki and lift the numbers, pick your PE and find the AP for any body you want.
If you want to know more read here:
The Cube Satelite:
If we look at the Resonant Orbit Calculator numbers: See spoiler section bellow:
Spoiler
we can see it only requires 40.4 Δv to lower the AP to 100km - I therefore decided that it would be more cost effective to just give the small satelite 25kg of monopropellant and 2x RCS thrusters to decrease the AP.
This makes the satelite much lighter than if it had actual engines - and I can carry much less fuel - thus making the satelites much lighter.
The Satelite Carrier:
Satelite Carrier with 6 cube satelites and 3 molniya satelites.Carrier: 2091Δv
The carrier will have 2091 Δv which should be ample since it's going to be launched from LKO: 80km and the Δv map shows it only requires 1690 - 1700 to transit to Duna Low Orbit.
See spoiler section below for reference:
Spoiler
Now - one does not need to look at this monstrosity of a satelite twice to see it wont fit in the small cargo bay for the SDG... So My "promise" to make everything fit within the small cargo bay only lasted until the next challenge... *Teehee*because - of course this was the only excuse I had for a glider re-redesign - It wouldn't be me without it.
The SDGv2:
Left: SDGv2 - Right - SDGv1.When I first flew the SDG on Challenge 1 - there were 1 obvious thing that struck me. It does not need the docking array. The vehicle is not meant to dock with K.G.01, like the Multi Fuel Gliders are. So I can do away with that and get more cargo space already - without changing the center of mass and drag a lot.. - how ever.. the satelite is still too long...
But I figured I could add a bit of Tube in the end where the vertical stabilizers are and sort of have the satelite twist itself out of the glider... That being said.. I can easily see things go "wrong" though here... namely:
A theoretical comparison of me getting the satelite out of the cargo bay.Nothing has ever gone wrong from banging sensitive electronics out of the box... *cough cough* - Luckily Kerbal tech is sturdy tech...
Here are the two cargo spaces clearly visible - The SDGv1 still loaded with the probe that was send for the Duna Fly By of Challenge 1.
and here a side by side comparison. Luckily the weight savings of ditching the docking port means that even though the Satelite Carrier is pretty heavy at 8.06t - double the payload of its cusin, the Multi Fuel Glider - it only increases weight by 2.22t. Something I am confident that the 1st stage will not have any issues getting into orbit.
Weight distribution across platforms:
Multi Fuel Glider:.............................................................25.34t
SDGv1:................................................................................22.28t
SDGv2:................................................................................27.56t
<<<<<<<<<<CONCLUSION>>>>>>>>>>
The plan has been made, Math has been calculated and vehicles designed accordingly.
Stay tuned in to see if the plan survives first contact with reality.
See you in the next one.
-
Since I am European I actually never had to do that.. as far as I recall, its been a few years now since I had science classes x) But we used meters etc. already - if we did it, its only been for the novelty of doing it.. and it did not stick with me.
I think i've only ever done it when going from grams to liters (with stuff that isn't liquids of course) in physics maybe? but its for far in the past that I can remember...
Any way.. Now I just wonder why the equation works with and without the m³/s²?
-
41 minutes ago, mikegarrison said:
In the equation you are discussing, you can't really ignore the dimensions like seconds even though you don't plug them into the calculator. You still have to make sure that they match up on both sides of the equation.
Okay - is this what @K^2 talks about when he mentions that this has been done for us in the numbers the Wiki provides us here:
On 5/1/2024 at 4:00 AM, K^2 said:Here, a is the semi-major axis of the orbit and μ = GM is the gravitational parameter. You can look up gravitational constant G (which is the same as real world) and mass of the planet M separately, but KSP wiki lists the μ directly, which for Duna is 3.0136321×1011m3/s2
But I still don't understand what the S i underlined substitutes: (3.0136321E11m^3/s^2 * (32758.93s)^2 / (2 * pi))^(1/3) - Because It is my understanding that letters in equations always substitutes some number, or equation? I guess my problem in my head is that I see that part as being divided by a (to me) unknown number.. I have a feeling its something very obvious - like how I did not understand that I should subtract the planets diameter to the semi major axis
Because the equation collapses if I remove the s right? (3.0136321E11 * (32758.93)^2 / (2 * pi))^(1/3) - oh wait it does not... - I got the same result hah argh.
Okay.. So the m³/s² is literally just to show that Its square meter pr. second cubed... So we know what the number is.. its for us not the calculator.
Well even though I answer my own questions I'll still post this in case some one else sees it and have the same questions.
Thank you all.
- bellow you will see my assessment of the 4 sites in each their spoiler section:
.
- I'll find out more once I get on with the Duna Mastery Challenge.
Duna Mastery Challenge - companion report.
in Mission Reports
Posted · Edited by BechMeister
clarification.
-= R&D_Update =-
- Duna Settlement and fixing the Sample Return Vehicle -
Duna Base Element being tested on runway 1
- Boots on the Ground -
With challenge 6 about to be bagged - it is time to prepare for challenge 7:
Now... I know Jeb is more than willing to sit in his suite for 8 odd years - he is made of sturdy stuff indeed. But It has always felt a bit "wrong to me" that you dont need base elements for prolonged stays at an area.
Aaand let's face it - after launching a mission to Duna in the ideal Kerbin - Duna Transfer window, you have to wait ca. 2y and 24 days for the next Duna - Kerbin transfer window to happen. (judging from me sitting with a goniometer on the screen and counting days) - I used this for the angle references:
Now, of those 2y and 24 days, ~300 days is the travel time - So a settlement "just" need to support the crew for 1y and 98 days? (if my math is correct)
- In any case... I think it will be nice to spend that year in a HAB module, rather than a lander. (and please correct me if i'm wrong... about the timings)
So it is time to build a temporary science outpost:
- Designing the HAB Modules -
In my Overengineered Minmus Mission I experimented a little with making HABs - It was a "pretty big base" (or at least a high parts count) consisting of 4 HAB modules, a rover and 2 landers. That could house and service a 10 Kerbal crew. It looked like this:
Base Camp One on the surface of Minmus.
Building and shipping the base for Minmus taught me a lot of things about "base building" - but most importantly that its very easy to build things that gets a parts counter that kills the frame rate! My framerate around Base Camp One would be something like 5 fps. Now I still dread the 3 fps I had during my Minmus Mission (when the base was still docked to the vehicle flying it to Minmus), so I knew I wanted a smaller base for less Kerbals... and send it piece meal.
I really liked the design of the temporary hab modules in the Martian -which had these proportions:
Screenshot from The Martian - seeing their base from above
As you can see it consist of the big dome, a small hab module on the side, as well as a few entrance modules and a solar panel farm - I really wanted to build a dome myself... but the big MK3-L "wanderer" capsule offered a chance to build it while keeping the parts counter down. I wanted to have the asymmetry, and tried to make the entrances with the small crew tubes - but the only way to get doors is to use the lander modules. Which limited a lot in how I could design it.
So to keep the parts counter down, and make sure all worked - the complete base ended up looking like this:
Duna HAB module and Rover being tested on the runway.
It consist of 3 modules: a LAB module, a Living Quarter module and a Solar Panel Farm. All the modules are equipped with wheels - so I can connect them once landed - as well as legs to give the base a firm placement on the ground. - LL;LI from the Minmus mission was that the landinglegs helped if the ports were not perfectly aligned... Also it is a potential means to correct inclination in the HAB. (1 year and 98 days on an angled floor would drive me nuts
)
To support the mission the Crew will also have 2 Duna Rovers.
In the spoiler sections below you will see a rundown of each module:
Laboratory Module:
The LAB module is were all the samples will be processed, as well as mission control and communication between base crew and vehicle crew out on expeditions. - It also works as the centerpiece of the HAB - connecting all the modules.
Note: on this image the module used 4 small parachutes to land, as well as a 0-10 "puff" engine for a soft landing - on the final model the 4 chutes is replaced by one large as seen here:
Living Quarter:
Crew Quarters - containing bunkbeds for the 6 kerbals and a small kitchen section and housing the primary communication disc.
Solar Panel Farm:
The solar panel farm! because of the position on the northern hemisphere of Duna I decided to angle it 45°. The panels need to be placed so it faces south. The two SP-4w panels can will be able to swivel and some what gain solar energy through the day.
Duna Rover:
The LL;LI from the Minmus mission was that the rover from that mission had enough battery power to get from south of the equator and to the Minmus monument - yes I was insane enough that I drove that distance
Which was lucky, because that only had a single OX-STAT-XL panel to recharge the batteries - facing up. I quickly found that it was not ideal for power generation - which means that this design now has a single vertical panel that can rotate.
The rover on Minmus used rocket engines to load itself into the dropships again, which meant It also needed a docking port to be able to refuel the methalox for flying. While the engines also proved very useful on Minmus to navigate steep terrain. The Duna rover does not have engines - so It does not need a docking port. Which also means that it relies solely on power regeneration from its solar panel.
The vehicle is a 8x8 and steers of 3/4 axles: Axle 1, 2 and 4 - The Minmus Rover showed that was the best - the single axle without steering would help keep momentum, when turning at slow speeds in reverse. (for some reason the game always insist on going forward when turning)
- Cruise Stage -
After designing the base modules it was time to find a way to get them to Duna. On my Minmus mission I had these elaborate dropships for "dropping" the base module and returning back to the "mothership" or ICV (Inter Celestial Vehicle). see spoiler section bellow for images:
drop ships has undocked from the mothership and are landing.
breaking for landing
all the ships has landed
The dropships drop the base modules.
After base assembly the 4 dropships returned to the mothership.
But I now know that dropships add a lot of complexity the ICV, that has to bring the modules and vehicles to and from the destination.
On Duna they also had to be a lot more powerful, than on Minmus, to be able to bring the HAB modules to and from LDO to the surface and back again. The added complexity would also bring up the part count significantly... and I want it to be pretty yes.. but please faster than 3 fps
I decided that it would be better to just put the HAB modules in capsules that could survive reentry on Duna and then just stack the capsules in the order I want them dropped and decouple them in order, then land them one at the time.
The Stack ended up looking like this, and weights ~55t (rounded up):
The Stack - with and without fairings.
These stacks would fit well with a much simpler ICV I developed right after being fed up with my Minmus Mission - let me present the Cruise Stage - ICV Hermes:
The ICV - Hermes
The cruise stage was designed with a crew transfer module in mind, and has been lying in my VAB gathering dust for a while.
The Crew Transfer Module consisting of two foldable crew structures that can rotate to create gravity on the tour (the entire craft has to rotate, not ideal I know.. but we gotta work with what we got). As well as two DAVs (Duna Ascent Vehicles).
The crew module weighs 45,6t - going to Duna. and 30,8t going back to Kerbin. The Stack weighs 55t - and that gives the cruise stage 6.290 Δv - which should be plenty. especially considering that it will be unloaded on the way home. (which gives me a chance to see if it needs more fuel to make the tour with the crew module)
- See spoiler section bellow for a walkthrough of the Crew Transfer Module:
ICV Hermes - Crew Transfer Module:
The crew transfer module is designed with 2 crew pods that can house the Kerbalnauts for the ~300 days it takes to get to Duna from Kerbin.
It has two modes:
It is not ideal that the hab modules are arranged horizontal (as it will mean more G's on the button floor than the top) - but it kept the parts down, and meant it folded neatly behind the heat shield.
The capsule connecting the HAB module can also separate from the main arm and re-enter and deploy chutes in case of an emergency.
The vehicle also hold the two DAVs - which is going to bring the crew safely to and from the surface of Duna.
Duna Ascent Vehicle(DAV):
The DAV consist of 3 stages:
- Testing the Stack -
Since the stack was quite complicated I decided to test it above Kerbin to make sure I would not get to Duna and only half the base modules would work... but first things first - we need to get the stack into LKO.
As of now, my go to solution of getting overly complicated structures into space, is strapping on big solid rocket motors to it until it works... If it was good enough for the shuttle program, it's good enough for me.
The solid rocket boosters work as the stacks 1st stage and looks like this:
the full stack
I added a 2nd stage with a LV-2000 "Trumpet" engine to get the stack into its final orbit. It has just enough Δv to get it done - I had 13 Δv left when I was in a stable orbit. Once the stack had been fully dropped, the 13 Δv turned into a few 100 Δv - more than enough for a deorbit of the engine. (the margin is still a little too tight, so I will be adding fuel for the final launch)
Testing the Stack: Getting into Orbit
Getting the rocket into orbit was a simple discipline - if not for the tight Δv margins.
Once orbit was achieved. It was time to test if the modules reentry capsules worked as intended.
Note: In an attempt at keeping the update "short" *cough cough* I have put the individual performances in spoiler sections - Issues found will be discussed after the individual sections.
LAB Module:
The Lab Module was the first to be launched. To make the XL part fit on top the L part I had to make an droppable adapter:
The stack launches the first stage for deorbit - notice the adapter.
I hoped the 4 x 24-77 "twich" engines could deorbit the capsule sufficiently to put the adapter within the atmosphere before dropping them. But the engines had no effect while occluded by the adapter. I had to ditch the adapter prematurely and proceed with the test.
Adapter plate successfully ditched - how ever it is now space trash.
After that it was a simple matter of having the Twitch engines lower the PE.
The capsule re-enter sequence.
The capsule re-entered flawlessly. The only thing I was thinking about changing was swapping the 4x small chutes for a single big one - I just needed to find a good way to get rid of the chute once landed, since would preferer if the windows were not obscured. - see section about final fixes for reference.
Successful splash down.
Living Quarters:
The Living Quater Capsule decoupling from the stack
Since the LAB Capsules Adaptor Plate connected directly to the heat shield of the Living Quarter Capsule - it meant that the twitch engines were not occluded and had no issues de-orbiting the capsule.
The Living Quater Capsule performing deorbit burn.
How ever I quickly found out that the living quarters energy capacity was only that of the MK1 "Explorer" (which functioned as a doorway to the module) - and the re-entry capsule was vastly inadequately powered for the re-entry sequence...
SAS had been turned off - or all the power would run out even before the capsule run through the upper atmosphere - which makes it hard to deploy the chutes.
Fortunately the craft proved to be very stable on the way down. So even without SAS it kept the heatshield pointed in the right direction. I wonder if it's the conical shape at the back that gives it drag.
Any way, it meant the craft re-entered while maintaining enough EC to drop the capsule and deploy the chutes.
The re-entry of sequence of the living sequence.
When I designed this module I thought 4 RCS thrusters would be adequate to break the fall - looking at the velocity with which it drops on Kerbin, I have now assessed that that's too optimistic.
I decided to replace the 4 thrusters with 1x 0-10 "puff" engine - just to be sure I had a high enough TWR on Duna.
Living Quarter Module safely on the surface of Kerbin.
Duna Rovers:
Duna Rover 01 detaching from the stack
The Duna Rovers were not going to be an issue either, since it consisted of two modules that did not have their twitch engines covered by adapters. Deorbit was done with no issues.
Re-entry sequence of the Rover Capsule.
The Δv pool on the rovers are quite small - which meant that the re-entry was so gentle that it hardly lit any flames on the way down. Bleeding off most of the speed by bouncing off the upper atmosphere.
Once through the atmosphere and the chute had deployed it was just a question of waiting until the engines had to "break the fall" (the chute was more than adequate on Kerbin).
The rover landing itself.
After that it was just a question of detaching the rocket motors and have them fly off.
Rover ready for action on the Surface of Kerbin.
Duna Rover 02: See spoiler section - only images
Solar Panel Farm:
The Solar Panel Farm capsule detaching from the 2nd stage
The last module of the stack was the Solar Panel Farm. It undocked from the 2nd stage - just like it is going to undock from the Cruise Stage on Duna.
Like the LAB Capsule before it, the adaptor plate obscured the thrust so much that It had to be ditched in space as space liter for the test to continue.
The adaptor plate being left behind in space.
After that it was just a matter of de-orbiting and see how stable it was on the way down:
the deorbit and landing sequence
Even though this module is super light - it still landed with 3-5 or so m/s on Kerbin - which meant that I felt like I had to add some monoprop tanks and a few RCS thrusters - just in case that the thin atmosphere on Duna is found wanting.
Engine de-orbit:
The last thing to test, was if the Trumpet engine could be safely de-orbited and "reused". This little slide show will proof that my parachute placement was rather poor.. as it touched down on the engine and broke it.
Besides that It worked flawless.. and it should be a simple matter of just moving the chutes further down on the body.
Final Fixes from LL;LI from the test:
In the end everything worked except for 2 main issues that needed further testing after fixing. Namely a change on the LAB modules parachute, and the parachute placement on the 2nd stage - as to make it not land on the engine and denting it...
Then there were some minor issues that can be resolved by adding more batteries and making sure the The Stack is on a sub orbital path when decoupling a stage (where after the ICV will bring itself into a stable orbit again)
Change of parachute on Lab Module:
I thought I could put a big chute on the module and detach it via a decoupler once on the ground.. How ever I forgot that the game does not simulate wind. So I could detach it all I want, it would always land on the top and rest on the roof, like if it had never been detached. Something else had to be done.
The solution was solid rocket engines... the solution is always solid rocket engines.
Parachute update on 2nd stage:
The fix to the parachutes on the engine was just a silly oversight - I had placed the parachutes near the top of the rocket.. meaning that I would keep the heavy engine pointing down. By moving the chutes to the bottom of the vehicle, the issue was resolved. I still did a test however - incase the engine was so heavy it would still land facing down.
But nope it worked - the vehicle was certified for launch!
- Updating the Duna Sample Return vehicle -
Last but not least, an update to the failed Duna Sample Return Vehicle. Since I only had power to run 3 Ion engines at Duna, I decided to reduce the engines from 7 to 3.
This meant the vehicle lost about 1t in weight. After that i bumped the xenon reserve up quite a bit, so it now shows a Δv counter of 9.187Δv. I hope the game is not lying to me this time.. but even if it is only half of 9.187Δv - it should be enough to go there and back again.
<<<<<<<<<< Moving Forward >>>>>>>>>>
Next Duna Transfer Window will be another double launch: The HAB stack and the Sample Return vehicle.
it should leave time enough for both vehicles to come back to Kerbin before the next launch to Duna. So the ICV Hermes can be refited for the crewed mission. And the Sample Return Vehicle can land the sample on Kerbin for analasys.
Hopefully it will give the Kerbals some weeks to check the samples for anything dangerous - before sending 6 brave souls.
Im sure they will make it... Or they can send a "dont touch the stones" memo via datalink once air born.
Science must be made! and any kerbal would give their left hand - touching radioactive stones - if it propels the race into a further scientific understanding.
Stay Tuned for more! Next update is the launch update!