Jool-5 Challenge: Go Big and Get Back Home

[bobcook]

This is a mission report for my attempt at the Jool-5 Challenge and is by far the most ambitious project I've ever attempted in KSP. I'm not even sure its going to work. I have no idea how large of a ship I can create before my computer (a recent MacBook Pro Retina) slows only a few frames per second. Follow along as I try to make this work.

My project is titled "Go Big and Get Back Home" and I'm going for the Jebediah level. I'm not trying to do this efficiently. I figure any government which hires my space agency will have to open up the bank and spend everything it has (mostly on fuel). Like most governement-funded projects, this also means I have likely over-committed on what can be achieved, and have only a vague idea how to achieve any of it. And I probably lack the talent to do it really well.

Some things I've established for my project:

• 6 Kerbals will journey to Jool and return safely after landing on all five moons
  
• Four hitchhiker modules are necessary to have enough space for everyone to be comfortable
  
• Use a different lander for each moon (five separate landers)
  
• Each lander will carry two Kerbals to the surface of each moon
  
• Each lander has a science package of two SC-9001 Science Jr, two Mystery Goo canisters, and two of each sensor type (plus a sensor nose cone for Laythe)
  
• Each lander's science package has to land back to Kerbin (no transmissions allowed)
  
• I will need to bring along a heck of a lot of fuel to compensate for the eventual poor planning that will undoubtably occur
  

When I began this project there were 89 Kerbin days until the next Jool launch window.

I'm using KSP 0.23.5 with the Kerbal Alarm Clock, MechJeb (for informational displays) and RealChutes. I'm using the ARM parts (I need those huge fuel tanks). I dropped Kerbal Engineer, it wasn't performing very well.

Wish me luck in what will be either a huge achievement, or a strong lesson for others to learn what not to do.

Edited May 24, 2014 by bobcook
Now using MechJeb for informational displays instead of Kerbal Engineer.

[bobcook]

The first step is to launch the "carrier vehicle" (the central core that will haul the landers to and from Jool).

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[bobcook]

Started bringing up the landers. In this series I launch and dock two of the three "BVP style" landers (identical landers for Bop, Vall, and Pol).

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[SSSPutnik]

Nice work! I hit severe lag around 1050 parts...

Lander designs look good.

[bobcook]

Nice work! I hit severe lag around 1050 parts...

Lander designs look good.

Thank you! This is certainly a gigantic challenge and I've got a long way to go...

[bobcook]

I brought up the Laythe lander and docked it to the core vehicle. After docking I adjusted the amount of fuel to approximately match the mass of the two other landers. This is a feeble attempt to avoid being too far out of balance. No idea if it will work but figure its not going to hurt.

With the fuel truck still attached its currently at 475 parts and 494.75 tons. Two more landers to go. The final BVP lander will attach to the fourth docking port and the Tylo lander will take the place of the fuel truck.

79 days until the Jool launch window, plenty of time.

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Edited May 15, 2014 by bobcook

[bobcook]

Tonight's work brought the final BVP lander up to the core vehicle that will haul the landers to and from the Jool system. 78 days until the launch window opens, should be easy to meet that schedule.

Including the fuel truck, 558 parts and 513.4 tons. Slight bit of lag now and then, but not really hindering things. I tested the ability to rotate the ship to get it aligned for the burn out of the Kerbin system. Large degrees of rotation takes a long, long time. Have to remember this when planning maneuvers.

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[bobcook]

We've reached a moment of crisis in this project. Not quite "brown pants" level panic, but there is serious concern at mission headquarters. Seems like this "seat of your pants" approach has a flaw or two.

Without the Tylo lander, the core vehicle is currently at 495 parts and 470.33 tons. But only ~5.3k of delta V. Seriously insufficient, I figure I'll need at least that much once I reach Jool. Considering scraping the entire core vehicle and rebuilding it.

[bobcook]

I've started to prototype a new "core" and mocked up the entire ship with landers in the VAB. Theoretically I'll get 14k delta V in this configuration. There are 75 days to go until the Jool launch window, so there is still enough time to do some more prototyping.

[bobcook]

Having a new design in the VAB isn't the same as having it built in orbit. I can't launch anything like this to orbit all at once, so its going to be broken down into modules and launched separately. The first two parts are the "core stage one" (the front part) and the Tylo lander that makes up the middle section of the cruise vehicle.

The new cruise vehicle assembly (the front part plus Tylo lander) is 220 parts, 181.56 tons. But the lander isn't fully fuelled yet, so its lower mass than it should be.

I also switched to MechJeb instead of Kerbal Engineer for delta V calculations as well as flight performance displays. Seemed like Kerbal Engineer would freak out periodically and hide its display. Sometimes the display would return and sometimes, unpredictably, it just stayed hidden. Frustrating.

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[bobcook]

The engine and fuel tank module is now in orbit. There was a mishap during the ascent where two engines from the second stage fell off during separation. No idea what happened but they definitely fell off. Fortunately the loss was symmetrical e.g. the vehicle still flew straight. It was a bit rough getting to orbit but eventually did make it. Due to the size and bulky shape of the module I ended up bringing it to orbit with empty fuel tanks. I've got a lot of work ahead of me to bring up enough fuel to fill the ~24 empty tanks.

73 days until the Jool transfer window.

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Edited May 18, 2014 by bobcook

[bobcook]

The new fuel tanks and engine module is in orbit but needs a lot of fuel. My fuel truck design allowed me to bring nearly 7 full large tanks of fuel up at once. This means four trips required to fill up. Along the way I messed up and accidentally deorbited the small tender with MechJeb that I'd had attached to the core engine vehicle. It really wasn't an accident of course, it was just something I didn't pay attention to. So I put up a different type of temporary tender module with MJ so I can manoeuvre this massive vehicle and raise it to the orbit where it can start meeting up with other components.

66 days to the Jool launch window.

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[bobcook]

Now that the two parts of the core vehicle are in orbit its time to connect them together for the trip to the Jool system.

389 parts, 1982.87 tons. 136,080 LF in the big fuel tanks. 11k m/s delta-v. 64 days to go until the transfer window to Jool.

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[bobcook]

The final assembly is now complete with its five landers, four hitchhiker cans, six crew members, and lots of scientific equipment. And snacks, I'm sure.

The crew: Jeb, Derfen, Bob, Sonny, Rodlong, Bill

The vehicle: 728 parts, 2217.72 tons

Its 55 days until the Jool launch window. Soon it will be time to fire up the engines and escape out of the Kerbin gravity well.

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[bobcook]

On the way! Now that construction is complete, the crew is prepared, and we have packed all the snacks, its time to leave the Kerbin system for a voyage to the Jool system. At the time of departure there was 55 days to the transfer window.

First thing I discovered was that I had to disable all of the reaction wheels in the landers and the forward control pod. If I didn't, the front section would start to twist like a pretzel when trying to change orientation.

Next, found that it didn't fly straight. Turns out there was still some lander fuel tanks that were empty, which made the vehicle unbalanced. I think there is a mod for this, but too late now. I poked around until I found an empty one, then rechecked everything. Also pulled some fuel out of the Laythe lander to get it closer in mass to the BVP lander, and it worked to keep everything balanced.

Then it was time to turn up the engines. Acceleration was a pitiful 880 mm per second squared - yes, millimetres. Burn time was an hour and twenty minutes (real time), used 891 m/s delta-v, consumed 235.961 tons of fuel. Jeb is happy, the rest of the crew is relaxed.

18 days until we reach the point of escape, which should leave us around 37 days in Kerbol orbit to set up the required maneuvers to reach Jool.

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Edited May 25, 2014 by bobcook
fix acceleration units

[bobcook]

The the burn to set up the Hohmann transfer from Kerbin's orbit to Jool's orbit is now complete and the crew has 2 years 265 days to wait until intercept. Of course there will be some tuning of the approach, to set up the aerobrake maneuver, but that won't be necessary for a while.

The burn took a little more than 2 and half hours in real time, using 2,778 m/s delta-v consuming 561 tons of fuel. My first stage of "drop tanks" was expended during this burn, reducing the overall mass by 124 tons (dry). Boosted the remaining delta-v quite a bit. The vehicle is now 1,291.46 tons, 656 parts. Its still laggy but manageable.

The crew appears to be happy and comfortable, the four hitchhiker pods give plenty of space to stretch their legs. Not much to do but play cards, eat snacks, and practice landings with the simulators.

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[bobcook]

Arrival at the Jool system! The happy crew have traveled nearly three years to reach this stage, and is very happy to get to work. First thing that is needed is to get the aerobrake maneuver set up. The aerobrake should have brought the orbit to somewhere between Laythe and Tylo, and I was hoping it would be close to one of those orbits. Sadly it wasn't, so had to pick one or the other. I chose Tylo which meant expending a bunch of fuel to raise the orbit and then get captured by the target moon.

Did some science along the way, accumulating 917 points so far just in the space near Jool and high Jool orbit.

At the conclusion of these operations I have established a safe orbit around Tylo at 1.4 million meters. The plan is to disassemble the core vehicle to pull out the Tylo lander and ferry it down to a tighter orbit then start surface operations. The mission isn't going exactly as I'd planned at this point, but I think its still within the envelope of success.

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[bobcook]

Tylo operations have been completed, more or less successfully. It didn't go exactly as planned. Actually, very little of it worked as designed, but at least the crew managed to pull off a successful landing with lots of new science gathered.

After extracting the Tylo lander the plan was to use one of the other landers as a "fuel tank" and lower the orbit to ~100km. Ended up at ~91km, and burned way more fuel than expected. This meant either ferry more fuel back and forth, or bring the core vehicle down. Ended up separating the core and left the crew quarters plus other landers up at the 1.4 million meter orbit, and brought the engine/fuel module down. Ok now have enough fuel, time to deorbit and land!

The Tylo landing simulations done back at KSC showed we needed to start the deorbit burn at 60km and burn the first stage at half throttle. Once done, burn through the second stage at half throttle until within a thousand meters of the surface. Then ramp up the throttle and commence landing. Nice theory but it didn't go as expected this time. Found that I needed to increase throttle on the second stage quite a bit. The fourth attempt nailed it very well, with more delta-v remaining than expected.

After Jeb and Bob completed the surface operations it was time to leave. The ascent was a bit of a mess. Ended up with a goofy orbit that required bringing the core vehicle up to a 420km orbit. That is where it sits, joined up with the remains of the Tylo lander.

I've now found a huge problem in my design. When the Tylo lander was part of the structure of the core vehicle it had docking ports at both ends. Now it doesn't, and I don't have any spare ports (4 ports, 5 landers). Not entirely sure how to save this mission at this point. Might end up seeing if I can get the Tylo lander back to Kerbin by itself. Or might have to do some crazy sort of ferry scheme, when its time to leave the Jool system. For now, it will probably stay in high orbit around Tylo.

My "F9" count is now at 5: one in Kerbin orbit due to unbalanced fuel tanks that made it impossible to steer, three failed Tylo landings, and one more due to "rag doll" syndrome for the two crew on the surface of Tylo after a successful landing. That was really annoying.

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[bobcook]

Once operations at Tylo were completed the crew began to think about how to get the Laythe operations underway. This meant escaping from Tylo high orbit (1.4 million meters) then transfer down to the orbit of Laythe. Fortunately the atmosphere of Laythe can give an aerobrake boost and help cut fuel consumption a bit.

The Tylo lander was piloted by Jeb and Bob. This time Jeb stayed with the rest of the crew and its Bob and Bill on the Laythe expedition. After reaching Laythe the on-board computer was able to show the landing spot as the crew adjusted velocity. No sense landing in the ocean, but the margin for error was small. The entire operation was successful and captured in the album below. 5,534 science points accumulated so far (assuming safe return to Kerbin).

Two moons completed, three to go. Val is up next. Still haven't sorted out the problem of 5 landers but only 4 docking ports. My "F9" count remains unchanged, at five. Due to the wizardry of MJ's ability to predict the landing spot even in an atmospheric descent, I didn't need a dozen guess-and-reload cycles. I did do the entire landing manually, just used the MJ landing predictor functionality.

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Edited June 8, 2014 by bobcook
Include my "F9" count

[bobcook]

The next phase of this mission is to land on Vall and conduct lots of science. Rodlong Kerman has the Vall lander in high Tylo orbit, with the rest of the core crew module and other landers. Meanwhile Bob and Bill are in Laythe orbit with the core fuel and engine module. Basically, the plan was for Rodlong to meet Bob and Bill in Vall orbit. Then Bob and Rodlong would conduct the rest of the mission to land on Vall, get some science points, and return to orbit.

A problem quickly revealed itself during the landing preparations: the lander's orbit was nearly exactly on the terminator between day and night, meaning the landing will be in twighlight or more likely darkness. Given the high mountains it likely be a tricky landing.

Considering I'd never practiced landing at Vall it seemed to go pretty well. The lander design worked very well, had plenty of delta-v remaining to rendezvous with the core module. At the conclusion of this phase Bill is in the Laythe lander by himself in Vall orbit, and Bob and Rodlong are with the Vall lander + core fuel and engine module also in Vall orbit. Jeb and the rest of the crew are back in high Tylo orbit with the other landers plus the core crew module. Only two more moons to go (Pol and Bop) but I've got to get all the ships back together again.

Assuming I can get all the ships back to land safely at Kerbin, I've accumulated 7,613 science points so far. The next Jool-to-Kerbin transfer window is more than 200 days away so we are in really good shape.

My "F9" count took a hit, and is now at a total of eight. The three new events included: coming out of time warp on a trajectory to collide with the center of Vall (no idea what happened there), a redo of the transfer from Laythe due to very poor planning, and one launch from Vall in the opposite orbit than the core module. Oops.

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[bobcook]

Rendezvous at 100 million meters. At least that is the plan. At the start of this phase of the mission the crew were someone scattered around the Jool system. Bob and Rodlong were in one ship in Vall orbit. Bill was in the Laythe lander in Vall orbit. Jeb, Sonney, and Derfen remained in high Tylo orbit with the crew module and other landers. Time to get everyone together again.

This phase went pretty smoothly. First Bill established himself in an orbit around Jool at 100 million meters, roughly corresponding to the periapsis of Bop's orbit. Next Jeb and crew left Tylo and performed a rendezvous maneuver (requiring several orbits to get sorted out) to meet up with Bill. Lastly Bob and Rodlong left Vall orbit and also rendezvoused with the rest of the crew.

After resting, refuelling, and packing more snacks, the crew split up again to send a lander off to Bop and another to Pol. Time at the Jool system is getting short, so these missions need to happen in parallel. My "solution" to the lack of enough docking ports to bring all the landers back together is to have Rodlong pilot one of the landers back to Kerbin independently. This should work. Hopefully.

Approximately 90 days remain until the transfer window from Jool to Kerbin. Still have plenty of fuel. I think I might have overestimated the amount of fuel required for this mission. But that is better than the alternative. My "F9" count increased by one to nine, when I had an inadvertent encounter with Tylo again which would have destroyed the landers with Jeb and crew. Drat.

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Edited June 18, 2014 by bobcook

[bobcook]

Bob and Sonney successfully conducted operations at Bop.

After departing the rest of the crew they managed to get an intercept with a simple inclination change. This brought them to an orbital trajectory that also forced an immediate landing. Turns out Bop is quite mountainous. After successfully conducting lots of science experiments they returned to orbit and will rejoin the core cruise vehicle and Bill in orbit around Jool. Assuming the crew can return all science to Kerbin we are currently at 9,692 science points.

It's going to take longer than 80 days to join Bill, retrieve Jeb and Derfen from Pol, and exit Jool's SOI. This means the crew will miss the next optimal transfer window to Kerbin. Fortunately there is plenty of fuel remaining so we might be able to reach Kerbin directly without waiting for another window.

Four moons complete, one to go. Then we'll worry about how to get back to Kerbin. My "F9" count remains at nine, landing at Bop was straightforward after getting this far.

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[bobcook]

Time for operations at Pol. Jeb and Derfen crewed the Pol lander after separating from the rest of the crew, and successfully plotted an intercept course. After achieving orbit, the crew descended to the surface while conducting the science experiments available. Once landed, more science was conducted and a few obligatory photos taken. Afterwards it was time to get back to orbit and rendezvous with their crew mates.

This phase of the mission now concludes the landing operations on all five moons. Assuming a successful return to Kerbin, the crew has accumulated 11,771 science points. My "F9" count remains unchanged at nine.

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[bobcook]

Home! After more than eight years away the brave crew has returned from a very successful mission to the Jool system. The first step required that the crew rejoin Bill in the core cruise vehicle and then plot a course back to Kerbin orbit. Their return journey was not without a few incidents though.

As mentioned back in Tylo orbit, the core vehicle didn't have enough docking ports for all five landers, due to a serious deficiency in design and planning. Very Kerbal. So Rodlong was assigned to pilot a lander back to Kerbin by himself. The lander didn't have sufficient delta-v for the trip. Which mean the rest of the crew had to meet him on the way back to Kerbin for a refuelling operation. Instead of refuelling though Sonney took a single lander on to Kerbin himself and allowed Rodlong to rejoin the rest of the crew.

The second "minor incident" happened when attempting to drop the final four fuel tanks from the core vehicle. Turns out the various times when using those tanks to fuel other landers the crew messed up and didn't correctly drain the same amount from each tank. So one tank kept running its engine when the other three drained, which meant the vehicle took off in a very strange direction. Upon tank separation that rogue tank flew off in a crazy direction and everyone was very lucky to avoid any incidental damage.

Finally though the crew managed to reach Kerbin orbit, then in turn each lander descended to Kerbin and was recovered for its science. Then Bill brought back the crew module and also landed safely. Total of 12,435 science points were earned on this mission.

My "F9" count finished at ten, the last incident happened while performing an aerobrake maneuver around Kerbin. The core vehicle had a periapsis of 30km but this was much too low and resulted in a suborbital trajectory that was pretty messy. Aerobraking seems hard to predict without some experience, a periapsis of 40km was much better and although it was not a perfectly circular orbit it worked out ok.

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Edited June 25, 2014 by bobcook