Stuck in 300km orbit with no fuel. Help!

[Chel]

Hello. Earlier today I tried reaching the Mun. I didn't have enough fuel to land, so I decided to instead fly really close to the surface, take some scientific data, and get back to Kerbin. Unfortunately, I only had like 30 fuel, and used it all up getting my craft in an orbit around Kerbin (otherwise I would be orbiting the sun). So no fuel, Jeb's stranded, and haven't researched enough parts for long distance space travel, let alone experience in rendezvous. Please help! I don't want to cheat because then the debug menu turns off achievements and I want them for my Xbox. 

[Geonovast]

Can you EVA?

EVA fuel is essentially infinite, as in it refills when you re-enter a pod.  You can do this as many times as you'd like.

When you're at your AP, get out and push, literally.  Point your ship retrograde, EVA out, get behind, and push forward until you're down to ~ 1 unit of EVA prop.  Get back in, then back out.  Keep pushing until your PE is 30-35km.  Then get back in and ride it out.

Also, if you were only going to the Mun, how on kerbin would orbiting the sun be a risk?

[steuben]

option 1. learn rendezvous. hard, but worth while.

option 2. get out and have jeb push. get him out, get behind and push the ship retrograde until his eva fuel is mostly exhausted. then climb back in. refuel. lather, rinse, repeat. do this until PE is around 30km. you'll want to do this around AP for best effect. but this will require a roughly similar to rendezvous.

option 3. take the hit on achievements

option 4. ???

option 5. profit!

[GoSlash27]

1 hour ago, Geonovast said:

Also, if you were only going to the Mun, how on kerbin would orbiting the sun be a risk?

Geonovast,

Presumably he couldn't close the munar encounter and wound up in a slingshot.

Best,

-Slashy

[Hunony]

1 hour ago, steuben said:

option 1. learn rendezvous. hard, but worth while.

option 2. get out and have jeb push. get him out, get behind and push the ship retrograde until his eva fuel is mostly exhausted. then climb back in. refuel. lather, rinse, repeat. do this until PE is around 30km. you'll want to do this around AP for best effect. but this will require a roughly similar to rendezvous.

option 3. take the hit on achievements

option 4. ???

option 5. profit!

exactly

[Zhetaan]

1 hour ago, The_Cat_In_Space said:

[...] let alone experience in rendezvous.

Can you guess how most of us were pushed into learning rendezvous?

Seriously, it's not a bad idea.  It is not very difficult (comparatively) to reach and rendezvous with a 300 km orbit; it gives you plenty of room below the orbit to catch up to the stranded vessel.  Besides, the only real difficulty in rendezvousing with a vessel is that it's a small target--but you know something of how to rendezvous already or else you would not have been able to get the Mun encounter that put you into this mess in the first place.

Yes, you can get out and push, but the problem with doing that is that it's tedious and there's little guarantee that you'll be able to push on the correct heading (when Jeb jumps out of a pod, your SAS goes with him).  Additionally, the best time to push is retrograde at the apoapsis, but pushing down from a 300 km orbit with a jetpack will be ...

... Let's just say that your time would likely be better spent learning a vital skill that you will need if you want to work with stations, crew transfers, and the like, rather than holding down the W key for a total of an hour.

[EnderKid2]

All kerballed spacecraft have effectively infinite Delta V, but it is irritating and tedious to access.

[Chel]

6 hours ago, Zhetaan said:

Can you guess how most of us were pushed into learning rendezvous?

Seriously, it's not a bad idea.  It is not very difficult (comparatively) to reach and rendezvous with a 300 km orbit; it gives you plenty of room below the orbit to catch up to the stranded vessel.  Besides, the only real difficulty in rendezvousing with a vessel is that it's a small target--but you know something of how to rendezvous already or else you would not have been able to get the Mun encounter that put you into this mess in the first place.

Yes, you can get out and push, but the problem with doing that is that it's tedious and there's little guarantee that you'll be able to push on the correct heading (when Jeb jumps out of a pod, your SAS goes with him).  Additionally, the best time to push is retrograde at the apoapsis, but pushing down from a 300 km orbit with a jetpack will be ...

... Let's just say that your time would likely be better spent learning a vital skill that you will need if you want to work with stations, crew transfers, and the like, rather than holding down the W key for a total of an hour.

Well I have no fuel, and when Jeb gets out it starts spinning. It's on an orbit that intersects Minmus and flies by the Mun. 

8 hours ago, Geonovast said:

Can you EVA?

EVA fuel is essentially infinite, as in it refills when you re-enter a pod.  You can do this as many times as you'd like.

When you're at your AP, get out and push, literally.  Point your ship retrograde, EVA out, get behind, and push forward until you're down to ~ 1 unit of EVA prop.  Get back in, then back out.  Keep pushing until your PE is 30-35km.  Then get back in and ride it out.

Also, if you were only going to the Mun, how on kerbin would orbiting the sun be a risk?

Yep I can EVA, but when I exit the ship it spins (because it needs a pilot for SAS). And I wanted to get in a Kerbin orbit because travelling around the sun takes forever. I'll try pushing it, but for a 300km orbit it may take some time...

[Geonovast]

4 minutes ago, The_Cat_In_Space said:

but for a 300km orbit it may take some time...

Bah, I did it once for a 9900km x 4900km orbit, only took about 30 trips.

[g00bd0g]

You haven't lived 'till you've pushed a ship out of orbit. As a matter of fact, that would make an awesome kerbal mission.

[GoSlash27]

21 hours ago, The_Cat_In_Space said:

Yep I can EVA, but when I exit the ship it spins (because it needs a pilot for SAS). And I wanted to get in a Kerbin orbit because travelling around the sun takes forever. I'll try pushing it, but for a 300km orbit it may take some time...

If I understand you correctly, your orbit is 47Mm apoapsis and 300km periapsis. If that's the case, lowering the periapsis to 35km is only 8 m/sec DV assuming you do it at apoapsis. That shouldn't take long to do at all... But getting back in the ship afterwards could be difficult.

Best,
-Slashy

[Curveball Anders]

14 minutes ago, GoSlash27 said:

If I understand you correctly, your orbit is 47Mm apoapsis and 300km periapsis. If that's the case, lowering the periapsis to 35km is only 8 m/sec DV assuming you do it at apoapsis. That shouldn't take long to do at all... But getting back in the ship afterwards could be difficult.

Best,
-Slashy

Actually no, since you don't have to get the Pe down to 35. just under 70.

Once under 70 your Ap will drop drastic for each pass.

So you can slowly bring both Ap and Pe down in a controlled fashion to a very nice reentry, while taking some time that is.

[Lego_Prodigy]

On 4/6/2018 at 9:54 AM, Geonovast said:

Can you EVA?

EVA fuel is essentially infinite, as in it refills when you re-enter a pod.  You can do this as many times as you'd like.

When you're at your AP, get out and push, literally.  Point your ship retrograde, EVA out, get behind, and push forward until you're down to ~ 1 unit of EVA prop.  Get back in, then back out.  Keep pushing until your PE is 30-35km.  Then get back in and ride it out.

Also, if you were only going to the Mun, how on kerbin would orbiting the sun be a risk?

How to kill a kerbal 101: reentry heating trying to parachute down. You will need to send a new mission to get as close as possible to the stranded craft, and then use the EVA fuel to get over to the craft, then prepare for reentry.

[GoSlash27]

1 hour ago, Curveball Anders said:

Actually no, since you don't have to get the Pe down to 35. just under 70.

Still... that's less than a 1 m/sec difference. Should be a quick push for either. The trick will be 1) not overdoing it and 2) getting back in once you're done.

Best,
-Slashy

 

[Lego_Prodigy]

For future future flights, get a good feel of about how much fuel you will need to go to and from the Mun, actual calculations are not really necessary.

If you can't do that (i would probably mess that kind of thing up), try his suggestion of nudging the craft with an EVA pilot, then get back in.

[Geonovast]

1 minute ago, Lego_Prodigy said:

How to kill a kerbal 101: reentry heating trying to parachute down. You will need to send a new mission to get as close as possible to the stranded craft, and then use the EVA fuel to get over to the craft, then prepare for reentry.

Absolutely nowhere in my post did I say anything about deorbiting the kerbal by itself.  Did you even read what you quoted?

On 4/6/2018 at 9:54 AM, Geonovast said:

Can you EVA?

EVA fuel is essentially infinite, as in it refills when you re-enter a pod.  You can do this as many times as you'd like.

When you're at your AP, get out and push, literally.  Point your ship retrograde, EVA out, get behind, and push forward until you're down to ~ 1 unit of EVA prop.  Get back in, then back out.  Keep pushing until your PE is 30-35km.  Then get back in and ride it out.

Also, if you were only going to the Mun, how on kerbin would orbiting the sun be a risk?

 

[GoSlash27]

1 hour ago, Lego_Prodigy said:

For future future flights, get a good feel of about how much fuel you will need to go to and from the Mun, actual calculations are not really necessary.

Calculations are only unnecessary when you overengineer your ships so you have a lot more fuel than you actually need, raising costs and lowering payload capacity. If you want your ships to move the most payload for the lowest cost and make absolutely sure your kerbals will make it home every time, then yeah... calculations *are* necessary.

Best,
-Slashy

[bewing]

Stock KSP is a game about learning how to eyeball all your engineering and piloting, for larfs. Even real world craft get a "margin for error" added into everything, after doing the calculations. So basically all craft are overengineered to have a lot more fuel than you actually need. Calculations are only necessary if you are trying to cut your margins razor thin.

 

[GoSlash27]

1 hour ago, bewing said:

Stock KSP is a game about learning how to eyeball all your engineering and piloting, for larfs.

[Citation Needed]

1 hour ago, bewing said:

Even real world craft get a "margin for error" added into everything, after doing the calculations. So basically all craft are overengineered to have a lot more fuel than you actually need.

There's a big difference between "a little more" and "a lot more"

1 hour ago, bewing said:

Calculations are only necessary if you are trying to cut your margins razor thin.

Disagree. Calculations are necessary any time you want to be certain that you are building a cheap, efficient rocket while being certain that it will succeed. Some people enjoy playing that way, and that's fine... It adds all sorts of tension and drama.  But there are others who don't enjoy leaving their kerbals stranded in a 47M x 300k orbit, or wasting cash and launchpad capacity hauling around tonnes of fuel that never gets used.

 Your mileage may (and clearly does) vary

-Slashy

[Chel]

So after reading all these answers, should:

A: Get Jeb out and push the spacecraft

B: Send another rocket to rendezvous and let Jeb board it

C: Give up and terminate the flight from the Tracking Station

D: Use the cheats menu (which disables achievements and makes me feel guilty)

[Mark Kerbin]

I would go with the Jeb pushing method. Safe and easy. Just try not to let the ship rotate too much

 

[bewing]

And you can cheat just a teensy bit and use momentary timewarps to stop any rotation.

 

[GoSlash27]

Normally I'd recommend a rendezvous rescue, since it's the safest and most reliable course of action (plus rendezvous is a skill you should have). Unfortunately, you're on an orbit that crosses the Mun and (potentially) Minmus, which could eject you into solar orbit or worse if not dealt with. Therefore, I have to suggest GOAP. I concur with bewing's recommendation to use time warp to halt rotation.

I wouldn't terminate the flight under any circumstances. Bring Jeb home alive!

Good luck,
-Slashy

Edited April 8, 2018 by GoSlash27

[Geonovast]

36 minutes ago, GoSlash27 said:

I have to suggest GOAP.

He could GOAP at PE and until it's a safer orbit, then do the rescue mission.

[GoSlash27]

1 hour ago, Geonovast said:

He could GOAP at PE and until it's a safer orbit, then do the rescue mission.

True, but that's 74 m/sec DV to accomplish as opposed to 8. As long as he's going to GOAP, why not just do a little push and come straight home?

Best,
-Slashy

Edited April 8, 2018 by GoSlash27