My Toughest Rescue (yet)

[Gryphon]

I just completed my toughest rescue in KSP.

I am very proud of managing to get this screenshot with Bill alive and well on the surface of Kerbin:

Here's how he got there:

I started a new Hard career mode game for the new version of KSP, 0.25. I am using multiple mods including, but not limited to:

TAC Life Support

Deadly Reentry

Remote Tech 2

FAR

Kerbal Engineer Redux

No Mechjeb

So, I sent Bill Kerman on the first mission to the Mun. It's early, so I don't have solar panels or fuel cells, but I do have batteries, so I packed a bunch on his ship. My mistake was counting on using the rocket engine to charge the battery each time I burned. I overestimated how much it would charge. A lot. I believe I needed about 3X the battery capacity on board.

So there I am, with Bill 90% of the way to the Mun, and that's when I figure out that I won't be able to charge the batteries enough with the remaining fuel to do the mission. The ship was close to a free return trajectory, but then I figured out that it would take far too long to get back home that way. So, I refigured for a direct abort. It would be close, but Bill would go about an hour and a half without power, reenter, land, and recover with a few minutes to spare.

On the way back, I burned all the fuel, both to return faster and to build up charge to keep the heater running. Then I ran into another problem. I realized the trajectory was not deep enough in the atmosphere to slow him down enough to reenter in a single pass. Normally, this would be OK; the trajectory would just take him around one orbit and drop back down, so he could just go around and reenter successfully the second time.

In this case, though, he would have been out of power for over two hours and be dead.

OOPS!

The good news was that his flight path would pass over KSP before he would run out of time.

RESCUE MISSION!

I quickly modified an existing ship with a probe core and an antenna, and launched it to rendezvous with Bill's dead ship. Of course, I needed to make rendezvous while the rescue ship still had line of sight to KSC, since I don't have any relay satellites yet.

(As Bill's time ran down, I may have sent Bill on an EVA to make sure he would survive, since it appears that TACLS has a different countdown for power loss when you go EVA, even from a ship that is without power.)

I launched, made several quick orbital adjustments, and I made the rendezvous, just as the rescue ship went over the horizon from KSC. (Using RemoteTech, remember?) Bill transferred over, and all was well...OR WAS IT?

(I realized a little too late that Bill didn't grab the science data when leaving the dead ship. As I maneuvered the rescue ship for another rendezvous, both ships started reentering the atmosphere and were losing altitude pretty quickly, so I dropped that plan.)

As Bill's rescue ship was heating up on reentry, I realized another problem known as NO PARACHUTE!!

See, the ship I had QUICKLY modified had a nosecone parachute, which I removed to place the Stayputnik (the only probe core I have available). When I removed the parachute, I hadn't added a replacement.

Bill wasn't doomed yet, though. I set up the rescue ship with both a high TWR and a lot of delta V, to ensure it could make orbit and the rendezvous quickly and sloppily if necessary. At this point, it still had a fair amount of fuel left.

So, I just waited out the heat, let air resistance slow down the ship as much as I dared, then I started burning to kill the last 200 m/s of delta v.

and...

BILL MADE IT!

It was a clean landing and nothing broke.

What I didn't realize until AFTER he landed was that the ship had juuust a smidge of fuel left when he set down; just 38 m/s of delta v.

So, that's what made this my Toughest Rescue.

Edited October 13, 2014 by Gryphon

[Wallygator]

Nicely done!

I learned that same lesson about batteries also. Now in early career flights, I tend to turn off SAS and RCS system while coasting to the Mun or Minmus. Using that approach, I've been able to get the boys back using only the electric charge in the command pod and the normal charging via engine burns.

Regardless, you accomplished a nice feat!

[Starman4308]

Congratulations! That must've been a very tricky rendezvous. Must've been a bit difficult to manage reentry without frying your engine as well: usually, for me, I ditch anything except the command pod, parachute, maybe science payload, and the heatshield before reentry.