33

What's the best way to return a Kerbal back to Kerbin if they're in orbit around Kerbin. I have my best pilot, Jebediah, stuck in orbit without fuel. I'm quite fond of him so I would like to mount a rescue mission to return him back home.

I'm not really sure how to mount a rescue mission, what type of rocket should I build to get Jebediah back?

  • 1
    If you're in full career mode you'll end up doing this a lot--Kerbals are very good at getting themselves stranded in orbit and you'll get plenty of contracts to go get them--and you get a free Kerbal out of it also. – Loren Pechtel Mar 23 '16 at 4:13
58

Get out and push!

Yes, I am serious. It works.

Go on an EVA, activate the jetpack, and fly against the prograde-facing side of the capsule. When you are nearly out of EVA fuel (right-click on the astronaut to check how much you have left), get back into the capsule and leave it again to refill. You can do this as often as you want.

It doesn't do much, but each time you bump against the capsule, you bump it back a bit reducing its velocity. With enough patience you can get the capsules trajectory sub-orbital. You only need to get the periapsis below 70km. Atmosphere friction will then do the rest and deorbit your craft. Then you just have to activate your parachute and recover the craft.

...you do have a parachute on the craft, don't you?

No? Well, then all you can do is:

Do a rescue mission.

In order to rescue a kerbonaut you will need to perform an orbital rendezvous. This is an advanced maneuver to pull off, and it is even more difficult when you haven't unlocked maneuver nodes yet. But learning it is very important because it is the prerequisite for docking which opens countless new opportunities.

Build a more powerful ship than the one you built before, especially with much more fuel on the upper stage. Then add a probe core, some batteries and solar panels so it can fly unmanned. When you play career and don't have the technology yet, you can also just stack two command pods on top of each other. It looks quite ugly, but it works. Before you launch the vehicle, go to the crew-tab in the vehicle building and make sure the pod for Jebediah is empty.

Launch the rescue vehicle a few minutes before Jeb passes over the KSP to make sure you get close to it.

During and after the launch try to get on an orbit which is almost the same as the one of the ship you want to meet. When you timed the launch right you will end up quite close to the target, but it is quite unlikely that you will get it perfectly right, especially on the first try. Likely you will end up a few degree in front or behind the target.

When the target is in front of you, go on a lower orbit. When it is behind you, go on a higher orbit. The vessel on the lower orbit will catch up to the one on the higher orbit. When you are within 5km of the target, you can boost directly into the direction to close the distance. When the ships are below 100m apart and have no relative speed towards each other, you can use an EVA to transfer Jeb to the rescue ship.

  • And remember to match inclination of orbits! Nothing more annoying than getting within 5kms only to find that you're already passing your target way off to the left. – SevenSidedDie Mar 13 '15 at 16:40
  • If your rocket is heavy enough, take a look at this video for an idea. – oldmud0 Mar 14 '15 at 18:56
  • "You can do this as often as you want." IIRC, the pods also contain an amount of monoprop that depletes as the kerbonauts refill their EVA suits. So it's not unlimited like it used to be. Unless that functionality was part of a mod I'm now not remembering. – Flater Apr 27 '15 at 14:25
  • @Flater AFAIK the "mono-propellant" carried by most command modules and the "EVA fuel" the cerbonauts use are two separate resources. – Philipp Apr 27 '15 at 14:31
  • Unless it was changed, the EVA resource is labeled "Monoprop", just like the RCS resource. The reason pods now contain monoprop (they didn't before) is specifically because EVA suits require it. When EVA suits had unlimited resources, monoprop wasn't part of the pods yet. Pedantically speaking, it's not strictly a fuel because it's not consumed in a chemical reaction ;) – Flater Apr 27 '15 at 14:35
29

If the pod has a parachute, you can perform a Manley manoeuvre:

  1. Orient your pod so it points retrograde. This is not strictly necessary, but makes things a lot easier.
  2. EVA from the pod and position yourself behind it, and begin pushing.
  3. Push the pod retrograde until its periapsis is below 60 km (anything below 70 will do, but lower is faster). If you are near running out of EVA fuel, get in the pod and get back out, which will refuel your EVA pack.
  4. If you're feeling up to it, lowering the periapsis more will bring you home faster, just be careful that you don't descend into the atmosphere with Jeb still outside the capsule, or he might not be able to get back in, due to wind.

If the pod does not have a parachute, things get a bit more sticky, but there are a couple of options:

  1. Standard rocket in any configuration; just make sure you bring a free seat.
  2. Grabber rocket with lots of fuel, refuelling the ship in orbit.
  • You are fastest at the periapsis and slowest at the apoapsis, so wouldn't actually pushing at the apoapsis decrease your periapsis the quickest? – Murch Mar 16 '15 at 23:47
  • @Murch Right, you push at apoapsis to lower your periapsis, standard maneuver stuff. – Williham Totland Mar 16 '15 at 23:55
  • You seem to be suggesting pushing at the periapsis in (4), otherwise, why would you be close to the atmosphere, considering you are trying to save a stranded ship. ;) – Murch Mar 17 '15 at 0:09
  • @Murch: Not specifically at periapsis. Just not at apoapsis. Depending on the orbit, OP might be at about the halfway point between Ap/Pe, which may already be inside the atmosphere. It's just a general precaution to take current altitude into mind when EVA'ing. – Flater Apr 27 '15 at 14:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.