I accidentally stranded three Kerbals over Duna.

[Omegagoldfish]

I accidentally ran out of fuel for my Duna craft, and panicked and launched the refueling vehicle in a bad window, what should I do? These are the options I considered.

1: Launch a new rescue craft, and tow the Kerbals back home (no landing)

2: Launch a new rescue craft, and tow the Kerbals back home (after using the lander module once)

3: Wait for my current rescue craft to find a decent spot and refuel the orbiter. (From here, the mission will go as planned)

[Foxster]

I think, after some careful thought, I'd go for...

4: Use the last of the fuel in the craft in Duna orbit to de-orbit it as a kind of viking funeral. Enjoy the show as you plummet your kerbals to their doom. Then launch a better designed craft with more dv as a follow-up mission. 

I say this because I remember doing something like this in my first career game and it cost way more to mount several rescue missions than it would have done to just abandon the first one and do it better a second time. 

[bewing]

The only reason your dilemma would be a problem is if you are in career mode, so: since you have already reached Duna orbit, you are about to get a bunch of tourist contracts to visit Duna. Forget rescue craft. Just have them thumb a ride on the next tourist ship that goes by.

Edited June 30, 2016 by bewing

[Omegagoldfish]

32 minutes ago, Foxster said:

I think, after some careful thought, I'd go for...

4: Use the last of the fuel in the craft in Duna orbit to de-orbit it as a kind of viking funeral. Enjoy the show as you plummet your kerbals to their doom. Then launch a better designed craft with more dv as a follow-up mission. 

I say this because I remember doing something like this in my first career game and it cost way more to mount several rescue missions than it would have done to just abandon the first one and do it better a second time. 

Well, the lander module has some fuel inside of it. The only problem is that it would survive impact with the ground. I'd just be down a Kerbal, and a craft I could re-use.

 

23 minutes ago, bewing said:

The only reason your dilemma would be a problem is if you are in career mode, so: since you have already reached Duna orbit, you are about to get a bunch of tourist contracts to visit Duna. Forget rescue craft. Just have them thumb a ride on the next tourist ship that goes by.

Tourist ship? I don't even do orbit tours, let alone Duna ones. Plus, there's already a rescue craft up there...

[bewing]

Tourist ships are very productive things. A tourist ship can transport crew members, rescuees, and science experiments from some distant location back to KSC (or to rotate new crew members to a distant location)-- and you get paid to do it. So you may want to consider their benefits in a future game.

[Snark]

I'd say, the answer to "what to do" depends a lot on what the orbits look like, what your patience level is (e.g. are you willing to wait a long amount of calendar time to get a good encounter, in order to save dV), etc.

Got any screenshots, stats, etc. to share?

Personally, I tend to be impatient about calendar time, so I'd probably go with option #2.  The main difference between #2 and #3 is that if the existing rescue ship is in a bad orbit, you might need a few orbits to get it to sync up with Duna.  Just how long it would need (and how much dV) would totally depend on what the current orbits look like.

Incidentally, I notice you keep saying "tow" ... why would you need to "tow" the vehicle?  Presumably you originally designed it to go to Duna and return, yes?  In that case, you don't need to "tow" it back-- just give it a fresh load of fuel, leave the (now empty) rescue vehicle behind, and let the original ship fly itself home, yes?

[Omegagoldfish]

19 hours ago, Snark said:

I'd say, the answer to "what to do" depends a lot on what the orbits look like, what your patience level is (e.g. are you willing to wait a long amount of calendar time to get a good encounter, in order to save dV), etc.

Got any screenshots, stats, etc. to share?

Personally, I tend to be impatient about calendar time, so I'd probably go with option #2.  The main difference between #2 and #3 is that if the existing rescue ship is in a bad orbit, you might need a few orbits to get it to sync up with Duna.  Just how long it would need (and how much dV) would totally depend on what the current orbits look like.

Incidentally, I notice you keep saying "tow" ... why would you need to "tow" the vehicle?  Presumably you originally designed it to go to Duna and return, yes?  In that case, you don't need to "tow" it back-- just give it a fresh load of fuel, leave the (now empty) rescue vehicle behind, and let the original ship fly itself home, yes?

By tow, I screwed up. The current rescue vehicle can totally refuel the main orbiter, (possibly with fuel to spare), but I don't know how to provide screenshots here. I will send them when I figure out how.

 

(I took the screenshots, indicating orbits for both craft and fuel for the orbiter. Rescue vehicle fuel is identical to full orbiter, plus 1200 units)

Edited July 1, 2016 by Omegagoldfish

[bewing]

To post screenshots -- you need to get an account on, and use, an image hosting service, such as imgur. Or have your own website, with hotlinking turned on.

[Snark]

4 hours ago, bewing said:

To post screenshots -- you need to get an account on, and use, an image hosting service, such as imgur. Or have your own website, with hotlinking turned on.

Imgur is quick and easy, and no account is required.  You don't have to "sign in" or anything, it's just drag-and-drop.

Discussion here:

 

[Omegagoldfish]

Screenshots:

Spoiler

The Duna craft. UI is present to show fuel situation. The top module is the lander, the middle is the re-entry, and the bottom is the drive. (All mono-propellant is gone, used for attempting to normalize the orbit.)

 

Spoiler

The orbit of the Duna craft. Note the inclination.

 

Spoiler

Finally, the orbit of the rescue craft.

[Omegagoldfish]

After a goat sacrifice to Squad, some Kerbin gravity assists, and a lot of waiting, I managed to rescue the Kerbals.

 

This question is now answered.

[OhioBob]

Based on the orbit of your rescue craft, I don't see any problem getting it to Duna.  You just have to wait for the correct phase angle.  If I'm seeing things correctly, it appears that your rescue craft is currently about 105 degrees ahead of Duna.  The correct phase angle is when you are trailing Duna by about 45 degrees.  This means you have 210 degrees of catch-up to do.  This should take about 500 days.  If you have the patience to wait, I'd just do that.

I see no advantage to launching another rescue craft because the phase angle still isn't right.  You're going to have to wait for either your current rescue craft to get to the correct phase angle, or you're going to have to wait for Kerbin to get to the correct phase angle to launch a new craft.  In either case you have about a 500-day wait, so you might as well just use the craft that you already have.  (The rescue craft will actually catch up to Duna faster than Kerbin because it's orbit is a little smaller.)

The only reason that I'd consider launching a new mission is if you have any concerns about not having enough propellant remaining in the current rescue craft to refuel the return vessel after you get to Duna.  As long as you're sure you have enough propellant, I'd go with option #3.

(edit) Oops, looks like I'm way too late.
 

Edited July 17, 2016 by OhioBob