AEGIS - Nuking the Mun (Picture Heavy)

[Concentric]

On the importance of only quicksaving at the right times.

Yesterday was launch day. Today, rescue/refuelling missions are being planned.

AEGIS was not an acronym, just a complex nuclear Mun mission in which I underestimated the fuel needed to land twice on the Mun with nuclear engines. It carried a full complement of science equipment, two nuclear landing engines, two Kerbals, and 4.24 tons in two rover and escape system pairs.

First the launch. Straight up for the first two asparagus stages, then beginning gravity turn and dropping the final radial pair on the way up. Circularisation put this up at a 100km orbit, which adjusted inclination in order to transfer to polar Munar orbit.

Staged off the last of the lift stage, which used its RCS to drop into a lower orbit, then later deorbited with the last of its fuel. Then the twist, which performed exactly as in testing, pointing the nuclear engines of the service module to push the assembly for the Mun.

Burn went almost as planned, and slight adjustment on the way out fixed it, taking the periapse under 60km over the Mun on a near-polar orbit.

Adjusted the orbit as it was made to ensure it passed over both the Polar Crater and the Pole itself, then Dozer and Harbus moved into the lander. Patny got the Near Mun crew report and a few space readings with his gravitics gear, then waited as the rest of the team moved down towards the crater.

A nice landing, with the beginnings of the warning signs on fuel that I probably ought to have paid attention to. If here I had transferred fuel out of the escape system and into the main tanks, perhaps... well, it would have been another 30 units of fuel that could have made a crucial difference. Quicksaving before dropping the system-lander pair was a good decision. Later quicksaves, not so much. Took a bunch of readings, took the EVA reports and surface samples, planted the flag, transferred everything to the landing cans and went for a drive.

The drive went well, four RTGs providing the power to the rover wheels. Had to use the brakes to prevent the rover from rolling down the crater. Then went a kilometer or so away. Did a twist in a jump, like so:

Began the drive back, nice and steady. Accelerated, then came across another little ridge.

This time... the twist was not completed. The Russian Judge didn't even bother to give it a score, instead walking out in disgust (though that may have been at his own navigation skills - how do you get lost enough to end up on another celestial body, anyway?).

Smashed off an RTG and a headlight. Mere twisting was insufficient to return to upright. Fortunately, I had installed a SRiMech (been rewatching the old BBC Robot Wars on YouTube recently. It's a Self-Righting Mechanism.) in the form of an LT5 landing leg at the back. It was intended to put the rover onto its wheels from the back on which it is dropped, but the Pegasus ladder on the battery had proven enough when dropped onto a flat surface. I had not removed it because it balanced the front and back of the rover, and perhaps a little foresight.

It took some twisting, some pitching, and a well-timed "lowering" of the leg, but I returned the rover to its wheels, and drove my way back a touch more carefully.

Took off, then went to the Poles. As you can perhaps see, fuel was low. It was coming to the point that I was unsure whether I would have the fuel to land safely, let alone take off again.

But, once I emptied the escape system's fuel tanks and the balancing ballast monopropellant tanks into the main body, a safe landing was just about in reach.

Then I dropped the remaining rover and escape system - which is empty as you can see - took the readings and planted the flag. Then all readings and samples were transferred to a single lander can, Dozer and Harbus got back in, and I made the biggest mistake of the entire mission. F5. Yeah. So, reverting to the crater landing was no longer possible. I made several attempts at orbit, which was a no-go. Also, tried a suborbital rendezvous - very difficult and presently beyond my skill. Then tried getting out and going for it with the thruster pack at apoapse - no go, though I know it to be technically possible.

No small docking port on the lander, so bringing the full MES over to get a little fuel is also not an option. And the rovers are one-seat (clinging to the ladders might be okay for a slow drive, I guess), where the MES needs two or four for balance, not to mention it's a bit of a way and it was late at night. Could just go to the MES on thruster packs and hope it can do it... but really a refuel/rescue mission seems to be what is called for here.

The service module has no chance of landing and refueling the lander, but it has over 300 units of monopropellant and quite a bit of fuel to power its twin nuclear engines, so I don't doubt its ability to catch orbiting Kerbonauts, just to get at suborbital ones in time.

A lesson learned, then. Even nuclear engines need fuel, and don't quicksave too often - specifically, don't quicksave if there's any chance of wanting to return to an earlier point.

Edited March 7, 2014 by Concentric
Missed a picture

[Concentric]

Refuel/Rescue/Return

Last time, Commander Dozer was stuck in the AEGIS nuclear lander with Harbus without the fuel to take off from Mun's north pole and dock with Patny in the orbital service module. I came up with a variety of plans and "plans" to get those Kerbals home, including tipping the lander on its side, then hanging onto the boarding ladders of the rover, jumping into full-power nuclear engine exhaust, then hoping to get orbit and rendezvous with thrusterpacks. Unfortunately, the lander lacked probe cores and could not operate in this fashion without leaving a Kerbal behind. (There wasn't enough fuel to run the engines while getting out, onto the rover and getting a run-up for the jump. You can see why this was a "plan" - Harbus's suggestion.)

Next I looked into the long (82km directly) drive over the mountains to the remaining full escape module in the Polar Crater. I began the drive, deciding to quickload back to being in the lander should something go seriously wrong. Four RTGs provided the power, which was almost enough to just go full acceleration all the way. I drove more carefully than that, Dozer and Harbus clinging to the ladders, but evidently not carefully enough. Several rolls eventually ended up knocking off the all the RTGs and the headlights, so I reverted and began planning a rescue/refuel/return mission.

Built a quick probe with lights, power generation, RCS, reaction wheels, a docking port and a Rockomax X200-16, which should be almost twice the necessary fuel to fill the lander entirely. Then I stuck it onto a copy of Station Aleph's Fuel Tank launcher, from before I got the Mainsail. Plenty of power to get such a small thing to Mun orbit/precision-collision.

The 8-fold symmetry can cause problems when asparagus staging with this launcher, for example a Skipper getting knocked off by the first asparagus stage going. Decided not to revert, staged again to rebalance thrust - dropping two fuel tanks and an engine - then twisted and continued the burn. Burned for a polar transfer, got orbit and adjusted it to pass over the lander at a low point.

Coming in here, slowing with the last of the launcher's fuel before staging off the empty tank and slowing further, moving to dock. Docking onto a landed structure is more difficult than docking in space, I find - but that may just be my relative lack of experience talking. A little fiddling and tilting, and...

Docked. Then I filled the bottom tanks, undocked, and smashed the refueller into the ground a little way away. Ought to have filled the monopropellant tanks from the refueller's stock too, but it didn't make that much of a difference in the end.

Lifted off and made orbit, then adjusted the service module's orbit using RCS so that it was easy to rendezvous with (100km circular). Put the lander at about 50km and made the maneuver node for intercept. Got the rendezvous and orbit-matched using the lander, then switched to the service module (which still had some RCS fuel, unlike the lander) and completed the docking. Then, a fuel, science and crew transfer to the service module, leaving a little fuel in the lander because I wanted to blow it up.

Dozer transferred the science, then Harbus, that dolt, flung himself out into space with a ladder malfunction. Made it back, though, this time boarding without touching the ladder.

Disabled the service module's engines, then fired the still-connected lander retrograde at full power. Undocked and twisted, spun back, reactivated the engines and burnt back up to orbit, leaving the lander on a firey collision course with the ground. Somehow, at this point, RCS fuel was rather low - it might have accidentally been transferred to the lander - or possibly was just used up in the docking maneuvers.

Found a good escape vector, then it was time to aerobrake for landing. This time, I resolved not to physics-warp at all to avoid tragic accidents like being attacked by the colour from outer space. Took a picture while aerobraking of a sunrise, then fired up engines just after periapse to make this a landing pass with an enhanced aerobrake.

Deployed parachutes a little early as the fall was coming in over the mountains, but didn't physics warp. Then, safely home with a little emergency lithobraking - what else are engines and girders for, eh?

And a safe recovery meant 1311 science points, bringing me up to a total of 1450 - just 500 short of finishing the tree. Took Ion Propulsion, Advanced Motors and Large Probes - the Heavy Aerodynamics node can wait, I think.

I think AEGIS has taught me quite a bit - mostly in an interplanetary-preparation manner, but even a little bit of experience towards base-making with that refuelling mission there. Next on the agenda... interplanetary probes perhaps? Who knows.

Edited March 8, 2014 by Concentric
Minor grammatical modifications

[Vanamonde]

This is the most elaborate Mun mission I have seen in quite some time.