Jebs stuck in an elliptical ? orbit

[Kerbal007]

Jebs stuck in an elliptical ? orbit:(

Help Jeb ran out of gas power and I don't know how to burn to intercept him and save the day :/ I have not unlocked mechjeb yet..

http://cloud-4.steamusercontent.com/ugc/541896836996283294/CAC4FB7CE855037386126FE61E713C9A4008FBC6/

[Deutherius]

If the active ship is the rescue vessel and the target is Jeb, then you got this pretty much covered, the encounter looks good enough. Just follow this simle procedure:

1) Wait until you are close to the orange marker (~1 minute, depending on your TWR)

2) Click on the velocity display on the navball until you are in a "target" mode (it usually does this automatically when you are close to your target, but better safe than sorry)

3) Turn your ship to the displayed retrograde and burn until velocity reads close to zero or zero

4) Turn towards your target and burn a little

5) Wait until you are closer to your target. If you are too far, repeat steps 3 and 4. If you are comfortably close, just do step 3

Congratulations, you are now parking right next to Jeb's ship with the option to transfer him by EVA/dock and refuel/whatever you wish

[jarmund]

It seems one of your close passes is pretty close already. I recommend getting to that orange point and then click the speed-indicator on your navball to make it show your speed relative to your target (that's a trick i didn't learn about until after months of playing). When yyou're at the closest, burn retrograde until you speed reads close to 0, and then work from there.

[Kerbal007]

Thanks lads, somehow a restart placed the affected ship into a normal alignment so the panels could get light, and I was able to make it home, however in a previous attempt I got a hell of a lot closer, around 200m, I think i was rushing whereas if im right I can adjust over several orbits?

[impyre]

Thanks lads, somehow a restart placed the affected ship into a normal alignment so the panels could get light, and I was able to make it home, however in a previous attempt I got a hell of a lot closer, around 200m, I think i was rushing whereas if im right I can adjust over several orbits?

This depends a lot on how the two orbits relate to each other. If you want to use the "multiple-orbit" method to get a closer intercept, I can share what I've done. I get an orbit that's similarly shaped and inclined with a single intersection point, get to that intersection point, then burn pro-retrograde until I will get a close encounter on the next pass. If you have the target set, you can watch the target position marker move as you burn.

[celem]

I think i was rushing whereas if im right I can adjust over several orbits?

Not so much really... at least not always.

You got a nice fairly close intercept displayed on that first pass. If you had tried to adjust over multiple orbits then you would find that Jeb would not be at the point where your orbits crossed on the next lap around Kerbin, his orbit is wider than that of the rescue ship and therefore his orbital period is a chunk longer. On the next lap Jeb would have been still on his way out to the intercept point when the rescue ship passed it. Given enough time then eventually he would come back round again to another close approach, but it could be many orbits down the road.

As impyre alludes to, adjusting over multiple orbits works best if the two orbits are very similar to begin with (therefore similar periods). It can also work if the orbits are different but they need to be a bit more specific. For instance if Jeb had an orbital period exactly twice that of the rescue ship then the second orbit would result in Jeb being at opposition (furthest away) at the intercept, but the next orbit again would bring back the nice close approach. This is whats referred to as Phasing Orbits and is a useful trick to learn when you start moving on to docking and orbital assembly. (its why you build stations in a pretty high orbit. I like to build at 150km so that launches from kerbin can set up a phasing orbit beneath them. If you built at 70km then future launches would have to launch higher still to be able to phase correctly. This is also one of the reasons ISS sits up at 300km in our world, to make space for phasing orbits below it (and to avoid atmospheric drag which in reality doesnt have a sharp cutoff))

[mrclucks]

If jeb is in a dead ship on an elliptical orbit, all you need to do is Eva and have jeb push the ship retrograde when at apoapsis. If you haven't made it to the atmosphere when you're almost out of fuel you just hop back in, hop back out and repeat. Eva fuel goes back up when you get back in BTW. Then once youre in a degrading orbit, you just wait it out till you don't get out of the atmosphere anymore. Hope you packed enough 'chutes

[Warzouz]

If you have RCS, you can prepare your orbit for rescue. I was out of fuel twice in my Joolian 5 mission. I managed to get back to Laythe Orbit (where my station was) but not able to circularize. RCS to change the inclination to 0 and set the correct periaps. Then I sent a Tug to cache it. It was quite easy (MJ can help a lot with that).

If you have a docking ring you can simply refuel (a simple drone mission with little fuel will do). If you don't, you have to send a ship with an empty seat.