Quick: is 4000 Dv enough to land & return from surface of Duna to Kerbin?

[fireblade274]

I plan on tugging a lander to Duna for a rescue mission but I don't go to Duna often.. Is 4000 Dv enough to land from Duna LDO to its surface, back to LDO, and then a burn to intersect with Kerbin? I plan on aerobraking at Kerbin w/heat shield

[Guest]

This might help.

Short answer: Most likely, if you're careful.

[eddiew]

If you can land on chutes and aerobrake at Kerbin, yes I think so. It's not much hotter than returning from Minmus, if you use a gentle transfer.

But can you not refuel from the tug after ascent?

[Guest]

Sounds about right.

I did a Duna return mission with a three-stage design (not counting the launcher which got me into LKO):

• Booster which got me from LKO to an intercept course for Duna, discarded when that was done
• Orbiter which I used for manoeuvring around the Duna system (used aerocapture to get into orbit, no heat shield needed)
• Lander which I used to get to the surface and back

For the return trip, I refueled the lander from the orbiter, left the orbiter on Duna, and burned back for Kerbin with the lander's engines and fuel. 

I didn't have a heatshield for the Kerbin return though; instead I launched a SSTO spaceplane and nabbed it into its cargo hold for deorbit. I didn't do the arithmetic to check if it would've been cheaper to haul the heatshield to Duna and back for aerocapture off Kerbin instead of fuel to get into low enough orbit that I could RV with the return craft. Now that I think about it, it probably would have been at least if you can make the return capsule small enough to use the 1.25 metre shield. (I was using lander cans for crew, so I would've needed the 2.5 metre one, which would've been on the heavy side.)

[Wallygator]

Yes. 

Assuming the rest of your vessel is designed to take the punishment.  

[Snark]

You have 4 km/s of dV, and you're already in low Duna orbit?

Then yes, you have plenty of dV to land, take off, and return home to Kerbin.  In fact, you have over twice the dV you need (assuming that you have a parachute for Duna landing).  If you don't have a parachute for landing and have to do it on engine power the whole way, you still have a 30-40% safety margin.

Heck, with 4000 m/s of dV, you could go from low Kerbin orbit to the surface of Duna and back-- and that's with 1000 m/s safety margin! 

As it happens, basically this exact question just got asked recently-- here's a discussion of the numbers involved which you may find helpful:

 

[Temeter]

Of course everything that has been said can be extended: A good lander, which might be refueled after going back to duna orbit, can save you even more D/V.

15 minutes ago, Snark said:

Heck, with 4000 m/s of dV, you could go from low Kerbin orbit to the surface of Duna and back-- and that's with 1000 m/s safety margin! 

 

Somehow that's how I understood the question.^^'

For 3k you need to aerobrake on kerbin return, tho?

Edited October 8, 2016 by Temeter

[Snark]

1 minute ago, Temeter said:

For 3k you need to aerobrake on kerbin return, tho?

Well, yes.  But,

1. why the dickens wouldn't you ... and,
2. the OP already said:

18 hours ago, fireblade274 said:

I plan on aerobraking at Kerbin w/heat shield

 

[Temeter]

4 minutes ago, Snark said:

Well, yes.  But,

1. why the dickens wouldn't you

Maybe cause muh reusable interplanetary nuclear mothership

Quote

2. the OP already said

 

Details. :^)

[fireblade274]

Haha so first of all it turns out I meant Dres was where I'm trying to go, slight laps of memory and typo lol, thank you for the link to the Dv table @regex, I was having trouble finding it (though I did not look too long tbh )

I have 3.8k of Dv to work with for the landing craft, for it to land on Dres, re orbit, then burn for an intercept of Kerbin. I'm a bit concerned since I've only been to Dres once before, but I built another "booster" craft to get it in Dres orbit first. It has 6k Dv (without being attached to the lander craft payload) so i think it could have some fuel left inside i can use by redocking with the booster after landing on Dres to top off as much fuel as I can, and I think I'll be gravy

I hope I will be since I already set the gears in motion last night by putting the "booster" in LKO and i'm refueling it with my spaceplane till its full, then ill sent up the lander to dock with the booster and send em off

Edited October 8, 2016 by fireblade274