Moonshot / Entering Moon Orbit / Landing on moon from my current stance?

[hallothere]

Hey there guys,

Hope all is good...

I've finally managed to get a ship into a semi-perfect orbit around Kerbin at 310,000m and a velocity of 2000m/s. Currently, I have no idea when to change my heading for the moon, due to unkown movement of the moon and all the rest there is to know.

If I understand correctly, it will be easy to change my trajectory (without to much effort and fuel) once I reach Periapsis (or is it Apoapsis?).

I've read through the tutorials but could not find my current situation (perhaps I read wrong or did not understand completely). I have attached / linked screenshots for all you elite kerbanauts to assist in ideas.

Any feedback or response would be much appreciated

[Fendleton]

For your first go I'd suggest first doing a mission to orbit the Mun, then deciding whether to land or not later. It's what I usually do, because direct landings are a bit hit and miss. Get them wrong and you'll "land" at 500m/s. You also get to check your fuel later to see if you can make it.

First off: Your altitude is a little high for an efficient mission. Generally I try to circularise at 125km or under to save fuel. No big deal though, as long as you've still got enough fuel.

What you need to do now:

1. Wait until the mun rises over sets under the horizon of kerbin. (Thank you Pyre)

2. Point the craft prograde, switch to map view, Immediately burn until your apoapsis is at about the right height. Some time before this, the patched conics SHOULD show you entering the Mun's SOI. If it doesn't, just shut off the engine and timewarp until the mun comes into the right position a billion orbits later.

4. Warp until you get captured by the Mun.

5. Finetune your path according to the orbit you want. A 50km holding orbit is an OK place to start, and requires a 50km (or so) periapsis. A 10km orbit makes landing extremely easy, but you don't get to use timewarp past about X10. My standard holding altitude is between 10 and 12 kilometres for an equatorial orbit.

6. When you get to your desired altitude at periapsis, circularise. You should still be using your main rocket for this, rather than your lander, although that depends on the spacecraft design.

7. Congratulations. You're now in orbit around the Mun. If you have a lander with enough fuel, you'll want to attempt a descent. On the light side, so you can see the shadow of the lander at low altitude and know when you're about to touchdown. Otherwise, you can return to Kerbin by orbiting until the planet rises above the horizon, then burning while pointing to prograde. That will eventually put you on either an elliptical orbit or a direct return trajectory.

8. Landing is fairly simple. Use ASAS to keep steady (or a lot of button mashing) on retrograde the whole way down, and make sure you end up going straight down. Don't let your speed get too low before you're at low altitude: 30-50m/s is my general approach speed between 1 and 2 KM up, higher than that you just want to be going slow enough you can quickly get to a safe speed when you need to (so, 80-100m/s). About 500-1000m above the surface (NOT 500-1000 on the altimeter) reduce speed down to 30m/s or so, check you're going straight down....and aim to slow your speed down in the last 50-100m, slow to under 10m/s, with no horizontal component. Try not to land on steep slopes.

9. To get back, take off, head east into a low altitude orbit as soon as you can. Use the same "burn prograde when the planet rises" trick to get back on a return path, or into an orbit where it's easy to return from. If the planet rises while you're getting INTO orbit, just keep burning and you should get there in one burn.

Keep in mind that flying below 10km over the Mun at orbital speeds makes for some nice landings (and lets you see the surface details that higher orbits do not), but is risky due to terrain clearance (especially since you will not have a perfectly equatorial orbit without extra correction burns).

Edited September 13, 2012 by Fendleton

[Pyre]

Your orbit looks circular enough that where you do your injection burn shouldn't matter too much, however, I noticed that your prograde heading is 270 degrees. That's not really a problem, except that you will need to do your transfer burn when the mun SETS, and you will end up using more fuel to slow down since you will be heading towards then mun head on. Other than that, just follow Fendleton's advice, and you should get there.

[hallothere]

What you need to do now:

Thank you Fendleton.

I actually feel a bit stupid right now.. After I posted this I went to the welcoming forum, and found the Orbital Mechanics 101 :? (Stupid me) which has all the videos needed (but your reply is like all the videos in one )

Your orbit looks circular enough that where you do your injection burn shouldn't matter too much, however, I noticed that your prograde heading is 270 degrees. That's not really a problem, except that you will need to do your transfer burn when the mun SETS, and you will end up using more fuel to slow down since you will be heading towards then mun head on. Other than that, just follow Fendleton's advice, and you should get there.

Thanks, its good to have multiple insights and explanations if you do something other than in the videos.

[Rickenbacker]

Dunno about waiting until the moon sets, I assume you're orbiting to the east? In that case, the time to start the lunar insertion burn is just as the moon peeks up over the eastern horizon, then use the map to see when your trajectory intersects the moons sphere of influence.

Edit: OOps, just noticed that you're orbiting to the west, so ignore the above . ALthough heading east is more efficient, for future missions.