Achieving Munar Orbit

[Radsoc]

The most common technique to reach the moon is to use the 'Trans Munar Injection', i.e. you orbit Kerbin early on. A drawback is that it may create more space junk around the planet than necessary.

I\'ve been doing it differently, I just keep going straight on up until the trajectory maximum reaches 11400km which is the Munar orbit radius. Consumed steps will fall back to Kerbin as no orbit exists at that stage. Ideally the moon waits for you there (at this point the fuel consumption should be equal to the Trans Munar one), but otherwise you have to accelerate in the opposite direction of the moon and align with its orbit. A good thing is that you never miss it.

[Kosmo-not]

You can always drop a stage so it reenters the atmosphere or crashes into the mun surface. The fuel consumption of orbiting Kerbin first vs. going straight up depends on how much thrust to weight you have available. A low thrust to weight is going to use a lot more fuel going straight up due to gravity.

[Radsoc]

Alright, that\'s probably doable, so by orbiting Kerbin you get to accelerate perpendicularly towards the gravitational field and reach higher speeds before you finally 'exit' than you would get by going straight up? That\'s the idea behind the higher fuel efficiency?

[Kosmo-not]

By burning straight up, you\'re losing fuel to gravity drag. A good way to demonstrate this is to burn your engines at a low enough thrust that you leave the launchpad very slowly. Obviously, you\'re going to have to use up a ton of fuel to get to orbit (if it\'s even possible like that). By burning towards the horizon, you add orbital energy without any of it being eaten up by gravity drag.

I just did the calculations...

Starting at 100km, the velocity required to go straight up to 11,400km is 3077m/s.

The velocity required to get to the same altitude with a horizontal vector is 3087m/s.

The question is: which way can you get to that velocity while burning the least amount of fuel.

[Volt]

Launch over the sea to a \'parking\' altitude. That\'s anywhere outside the atmosphere, 70,000m or 1 million metres, it doesn\'t matter. Depends how much fuel you want to waste. (lower is better, obviously.)

Make sure you get an orbit - it doesn\'t have to be particularly circular, just within reason and the Apses (Ap, Pe) should be above 70,000m (150,000 for 50x warp). Then go into time warp, making sure if your rocket\'s attitude is somewhat close to your prograde vector. (Green circle with 3 lines coming off it and NO X inside, this should only be an issue if you have a fairly large or hard to control rocket like my standard Mun rocket).

Watch while in time warp (I advise no higher than 50x) until the Mun has appeared over the curve of Kerbin, then burn at the prograde vector I mentioned earlier. Your Apoapsis (Ap) will begin to move, across and up. It should settle at around 70-90 degrees ahead of the Mun. Burn until you have an Ap of 11,000,000 to 12,000,000. You\'ll then be on an intercept course.

If your intercept is successful, your sphere of influence will change to the Mun, indicated by a rapid shift in all instrument data. On the orbital map, you should now have a green line, a parabolic orbit, going towards the Mun. Ideally, if you have a periapsis, wait until here then burn retrograde (the same icon as Prograde but with an X) Until you get an Apoapsis and lower that down to your intended orbit. There you go, a Mun orbit.

If any of this is inaccurate/doesn\'t make sense, please let me know.

Proof that this method works:

I just used this method to get to the Mun; this is the only method I ever use. Also, the probe here is excellent for landing practice. I had an NP mid-length 1m tank and the medium power NP 1m engine under it, decoupled at about 5m/s and 1500m alt. Don\'t expect to return home in it, though.

It\'s worth noting that using this method, you sometimes end up with an orbit that intersects the Mun. This means you\'re going to go boom if you keep going on it. My solution to that is to point at the triad with the dot on the navball (retrograde vector to KSC I think), turn 90 degrees, then burn across. This gave me a Pe in a few seconds.

[Xivios]

Yeah, the Horizon method is very good and always works. You can, with some experience, learn to 'tweak' the parabolic orbit by shifting the apoapsis, but it\'s not really necessary.

As soon as you enter the muns SOI, it\'s very easy to enter an eastbound or westbound munar orbit by watching the map view and burning either east or west until the periapsis appears on the desired side - just because the mun is a fairly small dot doesn\'t mean the navball artificial horizon/compass doesn\'t work - east, west, north and south still have a lot of meaning even when the ground is so far away. Incidentally Kerbin will be to the east from your position, which is why KSC pro and retrograde marks also work at this stage. It doesn\'t take much fuel to do s as long as your far away from the mun when you do it, ideally, it would be done by a proper timing of the initial injection burn, but it\'s much easier to see with the map view when you enter the muns SOI and at that point you\'re still far enough away to correct it how you orbit the mun without burning much fuel. A mid-course north or south burn can even help to reduce the inclination off the equator, but you probably won\'t fix it entirely until your in munar orbit.

I\'ve also noted that a fresh persistance file will allow a fairly direct ascent with no Kerbin orbit if you pitch over about 30 degrees east and hold it there until apoapsis is at munar orbit. But that only works for your first launch, or a demo launch.

[Volt]

My main issue with Munar transfer right now is indeed being off the ecliptic by a LOT. My inclination if I burn using the horizon method tends to be screwed up because I always end up in a direct descent and have to burn perpendicular. Without any autopilot or an orbital plane indicator, it\'s almost impossible to keep that 0 degree inclination. That\'s my main worry when it comes to my Munar missions - I\'m planning 1 more landing mission with the pod I posted before I land a third then attempt to rendezvous with a manned mission; Surveyor 3 and X craft (<--- gold star to the first person to work out which craft X craft is.) Not being able to change my plane is going to make rendezvous using a large lander quite difficult.

Edit:

Ooh, it seems ROUGH plane change maneuvers are quite easy once you work out where your Normal+ and Normal- are. I just managed to get Surveyor II to tap Surveyor I after landing 8km to the south. Might be a bit more difficult with a Manned Lander because there\'ll only really be one direction of thrust instead of the 6 made available by RCS. In fact, with my flying skill it might be impossible...

Note that you should probably avoid landing at night at all costs. The whole process of landing and rendezvous was made much more nerve-wracking by the total lack of sunlight... so much that I took this picture after a whole half-orbit of darkness just to signify the blessing that the return of the sun was to me...

[SmiteZero]

I\'ve put a base on the Mun using a 4-stage rocket with payload fairings with zero orbital debris. It\'s not difficult.

First stage: Achieve a a sub-orbital trajectory with an apoapsis of your desired orbit altitude. Dump first stage and payload fairings here after leaving atmo.

Second stage: Kerbin orbital insertion, trans-munar injection, munar orbital insertion and finally braking enough around the Mun so you can dump this stage and it will impact the surface.

Final stages for descent. Anything dropped here will also impact the surface and not be left as junk in space.

Just needs some thought.

I still havn\'t figured out how to launch a satellite without leaving a trailing tank and motor, though. S:|

[Volt]

Retro thrusters would have done in previous versions. Sadly, ActivatesEvenIfDisconnected = True is now defunct despite still being just as useful ingame.

[Roblox]

Thank you Alot for this! Now i can make a moon base!