My first interplanetary mission, heading to Jool

[UH60guy]

Well, after the main mission’s fleet left for Jool, some other transfer windows opened up.

I took this opportunity to send the same probe launcher craft to Duna, Moho, and Eloo. I also sent a version of the LLAMA (with landing struts instead of floats) and the KRASH to Duna to see if I could learn to fly them and how to aerobrake properly before arriving at Jool.

First up, I learned the importance of a mid-course correction to fine tune my approach. The LLAMA and cruise stage needed nearly 3000 m/s in delta V upon arrival since I was only skimming the outskirts of the Duna system at about a 20 degree angle to Duna. Thankfully I had the fuel to spare since I was flying something designed for a longer trip, but it took a 20 minute burn to get pointed in the right direction. At least the aerobraking went OK.

I immediately went and set up mid-course correction appointments with the Jool fleet so they’ll hopefully come up behind Jool more gradually- or at least closer. Unfortunately that was the only refuel tanker I brought along on the Duna test, so we’ll see if the gas from it, the probe launcher, the ascent stage, and the KRASH can be combined to get everyone home.

Next, the probe launcher arrived. I did find one fatal flaw in the design when I launched the first probe- the RTG power sources on the probes were not placed symmetrically. Heck, I probably didn’t need them anyway. However, they’re stuck on there and the rockets can only fire about 5 seconds at a time before going out of control due to the asymmetric center of mass. With some patience at Jool, I might be able to limp them into position to make it work- it’s just going to be a lot of shift-X-shift-X etc. to keep them on target to all the moons. I may reserve the other four probes here at Duna to keep enough fuel on board to use the probe launcher as a backup tanker. It’s already served its purpose as a mission test.

Edited September 3, 2013 by UH60guy

[UH60guy]

OK! The mission framework test on Duna is going well. Again- I sent duplicates of my Jool craft to Duna to test them out before they arrive at Jool. Long story short, I am excited about the main mission, and I now have confidence it will succeed. The supporting mission, the Jool moon probes, has a serious design flaw that may cause it to fail.

First up, the base: The only change from the LLAMA that I sent to Jool is that I slapped some landing struts on in place of the floats. Since Duna’s atmosphere is thinner, I could use the braking thrusters to find a more interesting spot to land and still have plenty of fuel to break atmo later. I found a huge crater around 15 degrees north, 85 west, and set down there. I used all the lower stage/base fuel and part of the ascent stage fuel on the inclination change, but still had plenty left. It performed exactly as it should, landed with parachute assist, and only needed minimal braking thrusters at the bottom to soften the impact. Bob was pretty proud of his landing. Here he is mugging for the camera after I had him repack all the parachutes:

The ascent went pretty well. Although, since I had used most of the fuel in the ascent stage’s lower stage, it separated pretty early and nearly wiped out the base and the two Kerbalnauts left behind. That’s a good lesson for the Laythe landing: I need some horizontal distance before staging! Bob went to check out the debris following the close call. He's so happy to be alive, he hasn't yet noticed that damaged and probably leaking radioactive generator behind him.

The ascent stage made orbit perfectly, and docked with the original fuel ship. It was joined later by the KRASH (return vehicle), and all docked in orbit. I’m debating leaving the fuel ship behind as it’s in a good parking orbit around Duna (100 km, 2 degree inclination) that future missions can use it. I’ll probably just top off the KRASH and send just that home at the next window. Here's the ascent stage on its way to orbital rendezvous with the interplanetary cruise stage and KRASH:

Now that I think about it- it has fuel and parachutes, and can reach Duna orbit with just this stage- it may be good to leave behind as a rescue vehicle after I top off its fuel tanks.

The probe mission fared less well. I didn’t throw any RCS thrusters on the probes (no real need after separation from the probe ship), but I also didn’t include any reaction wheels to give it some more oompf other than the basic probe core. Unfortunately, due to the placement of the RTG, that means it loses directional control after about 2-3 seconds of thrust. I was able to limp one into a 2880 km synchronous orbit (which now I see is the same distance as Ike), but it may be difficult to transfer the others to Ike or into polar orbits. I’ll have to try, since I’ll be tied to flying these once arriving at Jool- except then I’ll have 10 probes and 5 moons to contend with.

Since Duna only has one moon, I didn’t send a second probe ship- I slapped together a rover and managed to land it about 10 km from the base. That was the biggest help of anything. It performed flawlessly- it tops out around 22 m/s, it's stable, has two seats, and can keep a steady charge. It linked up with the crew, and they were able to check out an interesting anomalous feature about 35 km from where they landed:

http://i.imgur.com/Ao8wNAE.jpg

I saw how useful that was, being able to traverse the terrain like that, so I think I’ll design and send a boat to the Laythe colony if everything works out. Unfortunately the rover still needs some work- the skycrane performed well on Duna, but only due to parachutes. When the duplicate I sent to Moho got there, I found problems. I was able to get into a stable orbit, but the rocket placement on the skycrane caused it to spin out of control on landing and impact the surface. When the (again duplicate) probe ship gets there, it may suffer the same fate due to the probes' inability to sustain thrust. If the main ship can brake enough to get the probes into a stable orbit, again, they may be able to limp to the proper inclinations (0, 30, 60, 90, and a spare).

Edited September 5, 2013 by UH60guy

[UH60guy]

Kerbin Kerman, having returned from the dead twice (failed LLAMA test and reentry minus spacecraft), took up residence in the tracking center. The powers that be put him on the task of monitoring orbital debris. After a failed rover launch test, where the upper stage exploded in low Kerbin orbit, Mr. Kerman pulled up his map and set the filter to only show debris. He wondered if he would need to put the 80 km orbit off limits for a little while.

While munching silently on snacks, he noticed a few crumbs on the DRADIS screen. After brushing most off, one lone dot remained in a strange location outside Duna’s orbit. It turned out it was no snacky cake crumb: it was a piece of debris on an intercept orbit to Jool. Fearing something broke loose from one of the Jool convoy ships, he placed a long distance call to the crew of the Kobyashi Maru flying the return stage.

Sonwin: Hello?

Kerbin: Um, hey there Sonwin. Is everything OK?

Sonwin: Sure, though nothing’s been going on for the past two months. We’re just waiting on our mid-course correction burn in about 20 days.

Kerbin: Would you mind running a system check?

Sonwin: Sure. All systems appear nominal, fuel is looking good for Jool orbit insertion and Laythe transfer. Why do you ask?

Kerbin: No reason! <click>

Sonwin: Odd. Pass the snacks, Dergun.

He placed another long distance call to the Event Horizon, carrying the Laythe Landing and Ascent Module Assembly (LLAMA):

Kerbin: Jeb, come in Jeb.

Jeb: (munch, munch) Hi Kerbin. Didn’t I throw you out an airlock during reentry?

Kerbin: Never mind that, can you run a systems check before your mid-course correction? I have you still a few weeks out from it, but we want to make sure everything is going well.

Jeb: Sure. Staging sequence is set, monopropellant tanks topped off. Parachutes look good from what I can see out the window. Fuel is… wait, fuel looks a little strange. We have about a third remaining but the readout says capacity is 28,080 instead of the design 32,400. That’s odd, I thought the Jool transfer burn went better than that, though Herman was a little heavy-handed on the controls.

Operator: You have two minutes remaining on this call. To continue, please deposit $8,500.

Kerbin: Piloting shouldn't be the problem, since we're looking at a capacity discrepancy rather than supply level being too low. How do you feel about doing an exterior check? You can set a record for the first deep space EVA. While you’re out there I’ll go look for some quarters.

Jeb: Um, OK.

Once on EVA, Jeb gave the LLAMA a through inspection.

Jeb: Heat shield looks great, all parachutes in place. Lights work well (stop playing with them Herman). Science package intact, power source looks good. I’m moving to the Interplanetary Cruise Stage now.

Kerbin: Roger.

Jeb: Docking port clamped, lights operational. Fuel mounts look… oh.

Kerbin: Oh?

Jeb: Kerbin, we’ve had a problem. It looks like the main tank- the central one that they all feed to- has broken free. I don’t see it anywhere. We’re down to two nuclear rockets and four skippers.

Kerbin: Uh-oh. That central tank would have been completely full too. How do the others look?

Jeb: According to the exterior gauges, the four tanks with the skippers are depleted as was planned during Jool transfer burn. The other two look mostly full. The tank must have broken off sometime after the burn was completed, while we experienced that weird wibbly-wobbly timey-wimey acceleration where time passed really fast.

Kerbin: Come on back inside Jeb, we’ll work some options for you. At least now we know what we’re up against. <click>

Kerbin hung up the phone and began listing off options, none of them good. What are our resources?

Four Kerbals are on the damaged Event Horizon/LLAMA. The LLAMA is intact, but only carries enough fuel to descend from orbit and can barely maneuver when the landing stage is attached. The upper stage is very maneuverable and carries enough fuel for about 3000 m/s delta V, but only carries two crewmembers- using that as an escape pod would mean abandoning Genester and Billy-Bobbery without the possibility of recovery or chancing a long ride holding the ladder. The Event Horizon’s cruise stage carries fuel, but its structure is compromised by an unknown amount.

In a converging orbit, we have the Kobyashi Maru with three Kerbals aboard the KRASH vehicle. It has seats for all seven and can manage about 3500 m/s in delta V when separated from the cruise stage. It could rescue everyone, but adjusting for an intercept short of Jool would deplete about 2000 m/s, which makes orbit insertion or rendezvous with one of the refuelers after the rescue tricky. Its cruise stage is in good condition with about 60% fuel, but it is difficult to fly as the rendezvous-er, instead of the usual rendezvous-ee. It was designed to do that, but in Laythe orbit where the changes in velocity would have been a lot easier to manage.

I have two probe launchers on the way, but they’re a long way off and will arrive at Jool pretty late. They have a lot of fuel on their cruise stages, but they’re pretty unwieldy to maneuver for an intercept- they take about a minute or so to turn retrograde from prograde. The probes are expendable- orbital testing after mission launch shows their mission is a likely failure- but I can transfer their fuel to the cruise stage before abandoning them to at least help a little..

Plan A: Abandon a probe package and divert a probe ship’s cruise stage to meet the Kobyashi Maru before reaching Jool orbit. That’s an expensive burn and requires some difficult orbital ballet as the ship is unwieldy to maneuver in close proximity. They’re also a lot farther out, so it may not even be possible. But, if it can get there, we would have an intact cruise stage that we could move the LLAMA to, and take all the remaining fuel from the disabled Event Horizon. The LLAMA only carries 80 units of monopropellant, so the transfer between docking ports will need to be extremely precise. If we pull it off, this will allow us to meet the main mission objective.

Plan B: Undock the KRASH from the Kobyashi Maru and use it as it was designed- as a crew rescue vehicle. Fly the light and maneuverable vehicle to the LLAMA, but expend most of its fuel getting there. It can refuel from the Event Horizon’s tanks before reaching the Jool orbit burn. Put all the crew onboard and hope to make Jool orbit safely. This will leave the Event Horizon to fly the LLAMA through remote control, but depending how much fuel is transferred to the KRASH, it may not make orbit and cause the mission to fail (but the crew will at least be saved).

Plan C: Continue as planned, but park the LLAMA in Jool orbit awaiting refuel to transfer to Laythe. This plan relies on praying to the Lords of Kerbol that the cruise stage holds together during orbit insertion. Aerobraking is probably out of the question, as the structural integrity is a complete unknown. They’d have to wait for the Kobyashi Maru to arrive and refuel, but that was always part of the redundancy built into the plan. We can meet the mission objective this way, but it’s the riskiest option.

Kerbin set off to compute some orbits and run the numbers. He'll try to come up with a way to test out the integrity of the Kobyashi Maru as well- though firing the engines for the mid-course correction may put it out of reach of the rescue ships. The tanks are mounted to a thrust plate at the forward end, connected by I-beams. That part's pretty sturdy. He's worried that without the central tank that the side tanks were heavily strutted to present, the whole thing may turn into a wind chime and explode if thrust or rotation is applied. More to follow as the situation develops!

Edited September 11, 2013 by UH60guy

[UH60guy]

Here's the orbital situation. The crippled Event Horizon is on the far right, then the Kobyashi Maru KRASH/return stage), then the Nostromo and Sulaco probe vessels. The other two at left are doomed probe and rover ships en route to Eloo (see earlier posts for how I know they're not going to work on site).

We're committing to Plan A. The Nostromo, the closer of the two probe vessels, transferred all the fuel from the probes an abandoned them in Kerbol orbit.

Next, the cruise stage made a 1500 m/s burn for intercept.

More on the situation as it develops.

[UH60guy]

Captured! The Nostromo docked the Event Horizon and transferred all fuel aboard.

Next, the LLAMA transferred between the cruise stages, and is set up to ride the Nostromo to Jool.

MechJeb reports 3151 m/s delta available, but it may be inaccurate due to the new staging setup. However, we now have a fighting chance to make the mission happen at Jool! They just have to make orbit, and everything else should be fine. Mid-course correction in two days, Jool intercept in 195 days.

I think I'll count that as both a Kerbol SOI rendezvous and rescue!

Edit- maybe I should only count it as a rescue if they reach Jool orbit safely.

Edited September 12, 2013 by UH60guy

[UH60guy]

OK, this weekend was spent learning to fly/maneuver the ships before arrival at Jool. With every transfer window that opened while the convoy is headed to Jool (boy, that's taking a long time...), I've sent to each planet probe carriers and a test rover design for a follow-up mission to Jool. Just for fun, I sent a manned capsule to Gilly and Dres as well, though that's more a lesson on launching to rendezvous from another world and EVA than on flying the exact same ship.

The rover's since landed successfully on Duna and Eve, where it's performed amazingly well. The parachutes and skycrane give it a real easy landing. Laythe should be no problem, if I can hit a landmass near where the Laythe base splashes down. I'm having some issues with meeting delta V requirements for landing without aerobraking though- I've already smashed two into Moho after running out of gas. Though that may have dire implications for a Tylo rover attempt, I'll still send a fleet of these rovers during the next Jool transfer window. I'll see if I can add another stage to help slow it down in orbit at least.

The probes may not be as bad off as I feared. From my probe carrier at Duna, I was able to test out the max thrust allowable on the probes before the torque can no longer maintain control. As long as I keep thrust under the first big notch beside the nav ball- I think that's about 33%- it can fly straight. Ike was an easy target, but I was able to get two probes there, one in equatorial orbit, and one into a polar orbit. Same went with the Eve probes- I was able to get them into polar orbit at Eve, and even transferred to the inclined Gilly in a polar orbit. Plenty of fuel to spare, but I just had to be patient with the thrust.

I learned another technique at Moho with the probes. I came screaming into the system, and the launcher was about 300 m/s short of being able to make a capture orbit. I could have launched each probe at that time, but due to the velocities and the difficulty of trying to make orbit with five probes in just a few minutes, I opted for a different approach. I transferred all the fuel from the central probe to the probe launcher, letting the launcher enter an elliptical orbit. That then gave me a stable orbital platform to transfer some fuel back and launch each probe at my leisure. The elliptical capture orbit even made it easier to change inclination and achieve a polar orbit. It's a shame I had to abandon four probes to save the crew of the Event Horizon earlier, but I'm now beginning to think the probe mission at Jool just might work.

Finally, onto the lessons learned with the manned landers. The Dres module hasn't arrived yet, but I'm beginning to doubt it has enough fuel to make the return trio. We'll see. I was however, able to land at Gilly with a single crew capsule. Landing was easy, but I quickly learned the importance of putting probe cores on all subcomponents of my ships in the future... After undocking the top portion to land, and making a successful near-zero G EVA on a mountain side (I didn't like Gilly that much!), Shepfrod Kerman had a panicked moment when he went to launch- the main body of the ship, not having a probe core, was identified as debris and would not show up on the map! Thankfully there was not much else in orbit other than a probe, so that was the only piece of debris to be found when the view was zoomed way out. A double click could set it as a target, but not view the orbit. I had to rely on MechJeb to plot the rendezvous instead of doing it myself, but it worked eventually.

[UH60guy]

An alarm went off in the KSC tracking center- Kerbin Kerman looked over and saw that finally, after the better part of a year in transit, the first interplanetary mission ever was entering the Jool sphere of influence. Sure, many interim missions to test the equipment had been run in the mean time, but wow- this one was the first! Well, first to launch, last to arrive. They were still reeling over the loss of Bob Kerman in a 1000 m/s "landing" on Dres in an under-fueled ship, and had to hope this would go better.

First transmitted image of Jool:

Kerbin: KSC to Interplanetary Modular Vessel Nostromo, come in Nostromo.

Jeb: Huh? Oh yeah, IMV Nostromo here.

Kerbin: Hey, the tracking center shows you entering Jool’s sphere of influence. I need you to go EVA and make sure everything looks good on both the LLAMA and ICS before making for course adjustments.

Jeb: Oh… About that… I kinda already did all that.

Kerbin: You mean you forgot the whole ordeal with a busted cruise stage, a harrowing deep space rescue, and flying an untested machine with unknown fuel quantities, and you just made your orbit burns?

Jeb: Yep, that’s about the size of it. It’s been so long, and well, there you go. We are now set up at 1.5 degrees inclination with a Jool periapsis of 117 km. That should set us up for Laythe intercept following aerobraking, you know, if we don’t all explode and die.

Kerbin: OK, well before Jool atmosphere interface, can you check out the craft? EVA and IVA?

Jeb: No-can-do on the EVA. Not enough time with the amount of snacks we need to eat first. Inside, well, we’re all fouled up. Somewhere between the software patch you sent us to 0.22 and our ICS transfer, our staging display is all over the place. I can’t make heads or tails of what any button will do. Even worse, Herman spilled his drink, and everything’s sticky. I do show seven fueled and activated engines, though they're in three different stages now.

Kerbin: Roger. Don’t touch any more buttons, we’ll sort out staging after the aerobrake. That’s part of the LLAMA pre-launch checklist anyway. You shouldn’t need to stage on the way to Laythe anyway.

Jeb: Sounds good. Engaging snack time mode at this time and we’ll call you following Jool orbit interface.

...later...

Jeb: YEEEHAW! She's holding up! (hear me baby, hold together).

Jeb: Kerbin, aerobrake is successful! We made it through just as Laythe was rising ahead of us, beautiful sight. Aerobrake wasn't completely nominal; our map shows apoapsis just inside the orbit of Vall, not on intercept to Laythe.

Jeb: All's not lost, that'll give us time to raise the periapsis above the atmosphere for just a little delta V, and let us get a good phasing orbit for transfer.

Kerbin: That's good news! Now when you get close to apoapsis, we need you to go EVA and do a vehicle checkout. Just don't do it too close to Jool, unless you like high radiation levels.

Jeb: Understood. Apoapsis in four hours. Initiating nap mode in 3-2-1-mark. Zzzzzzz.....