Mun Landing help

[Anrui]

How much delta V do you recommend for landing on the mun and landing back on Kerbin?

[Geschosskopf]

Starting at KSC:

1. Getting into LKO: ~3600

2. Transfer to Mun: ~900

3. Establish low Munar orbit: ~250

4. Land on Mun: ~600-700 depending on how you do it.

5. Take off from Mun back to low Mun orbit: ~600

6. Transfer burn to hit Kerbin's atmosphere: ~250

7. Post-aerobrake fiddling with Kerbin Ap and Pe: Budget 500 for this just to be safe. Assumes multple aerobraking passes.

8. Deorbit in LKO to land where you want to: ~300

[Gaarst]

Starting at KSC:

1. Getting into LKO: ~3600

2. Transfer to Mun: ~900

3. Establish low Munar orbit: ~250

4. Land on Mun: ~600-700 depending on how you do it.

5. Take off from Mun back to low Mun orbit: ~600

6. Transfer burn to hit Kerbin's atmosphere: ~250

7. Post-aerobrake fiddling with Kerbin Ap and Pe: Budget 500 for this just to be safe. Assumes multple aerobraking passes.

8. Deorbit in LKO to land where you want to: ~300

9. Realizing you forgot chutes: Priceless

Sorry, couldn't resist

[Anrui]

Starting at KSC:

1. Getting into LKO: ~3600

2. Transfer to Mun: ~900

3. Establish low Munar orbit: ~250

4. Land on Mun: ~600-700 depending on how you do it.

5. Take off from Mun back to low Mun orbit: ~600

6. Transfer burn to hit Kerbin's atmosphere: ~250

7. Post-aerobrake fiddling with Kerbin Ap and Pe: Budget 500 for this just to be safe. Assumes multple aerobraking passes.

8. Deorbit in LKO to land where you want to: ~300

I haven't unlocked Aerobraking in the tech tree yet. So do you think I should plan my approach and rentry so that I 'skim' the atmosphere in order to slow down instead? Or bring some more dv with me to help myself slow down?

[SanderB]

you can aerobrake with any vessel, aerobrakes worthy of the name just allow you to radically increase how much drag your vessel experiences. If you time your return from the mun, you can return close to KSC without going to LKO first. Kerbin rotates in 6 hours, so if KSC is 90° degrees behind your periapsis your vessel needs to hit it in x number of days (can be any number of days) plus 1h and 30m because kerbin rotates 90° in that time frame, which means you'll be flying over KSC at that periapsis altitude. If your reduce peri to 12km and stick it right above where KSC should be according to the time frame of Kerbin's rotation then you'll be landing very close to it. You can increase or decrease the time it takes for you to reach kerbin without influencing your peri too much by burning directly toward or away from Kerbin.

[Arkalius]

Don't confused the activity of "aerobraking" and the part called "airbrakes". Aerobraking is just the process of dipping into a planet's atmosphere to slow down. It can be used to bleed off a lot of energy without having consume any reaction mass, but it is very difficult to use precisely.

Airbrakes are just large control surfaces designed to generate a lot of drag.

[Anrui]

Don't confused the activity of "aerobraking" and the part called "airbrakes". Aerobraking is just the process of dipping into a planet's atmosphere to slow down. It can be used to bleed off a lot of energy without having consume any reaction mass, but it is very difficult to use precisely.

Airbrakes are just large control surfaces designed to generate a lot of drag.

Thanks a lot for this explanation. I thought that "aerobraking" was something only done with aerobrakes. I've done this maneuver before but didn't know that it was aerobraking.

[Snark]

Assuming you don't care much about where you come down (typically the case unless you're flying a spaceplane and need solid, flat land), you need pretty much zero dV for steps 7 and 8 in Geschosskopf's excellent summary. Just set your periapsis to around 35 km in step 6. You'll aerobrake and head down to landing without a hitch, as long as your ship has reasonable heat tolerance.

[jwenting]

do make sure your chutes aren't going to deploy automatically though, put them in their own stage. If you don't they'll burn off...

[Snark]

do make sure your chutes aren't going to deploy automatically though, put them in their own stage. If you don't they'll burn off...

A handy precaution for that is to raise their minimum deployment pressure to 0.5 atmospheres, ideally at build time in the VAB so you can't forget about it later.

[davidpsummers]

How much delta V do you recommend for landing on the mun and landing back on Kerbin?

The landing on the Mun is theoretically 580 m/s. You won't be able to do it with that amount because you aren't infinitely fast. When I do a landing, my best is about 1.5x theoretical. My worst is about 3x. I often take 2x.

Otherwise, you need about 3300 m/s to get to orbit. About 860 to get to the Mun. (Then you land as above). You need about 580 to get off the surface back to Mun orbit. You need about 310 to Leave Mun orbit. Once out of moon orbit, you just lower your periapsis of the resulting Kerbin oribt so it intersects Kerbal or is in the atmosphere and, when you get there, pop off the capsule and reenter it. (To limit rentry heating, I would have a periapsis that just grazed the surface).

- - - Updated - - -

Thanks a lot for this explanation. I thought that "aerobraking" was something only done with aerobrakes. I've done this maneuver before but didn't know that it was aerobraking.

I would, however, make sure I have a heat shield. :-)