I need help to figure out how to land on the Mun.

[Fl4shbang]

Im pretty new at this, but im starting to understand more and more of how things work.

Quick runtrought of what i know how to do sofar.

Build a rocket that works.

Make it out in orbit around kerbal.

Change the size of my orbit.

Intercept the Mun orbit.

Now to what i do not know how to do yet.

How to actualy get into a path to land on the Mun. Everytime i get close, i dont have enogh fuel to slow down enough i think. Ending up in a orbit around the sun.

Short overview of what i need to know. What direction do i need to come from? Towards the direction of the mun's orbit? Or the back folowing the mun's orbit. Wil the mun gravity pull me towards it? Is there any trick to get close without having to use so much fuel? I usualy end up running out, before i can actualy think about doing a landing. I tried adding more fuel tanks, but it gets to heavy, and i end up the same way either way. My basic rocket is as follows. Comandpod, decupler, advanced sas, 3liquid fuel, engine, decupler, 4 fueltanks, engine. Around the botom stage i added 6 long solid fuelboosters to get it off the ground. I know there is no way to land this rocket on the mun. But i want to learn how to get in the right path before i add the parts i need to make it land. Lets just call it a test mission:) And please, i do not know many technical terms yet, so to prevent a whole bunch of questions from me to figure out what every word meen, please keep it as simple as posible:)

[Nibb31]

1) When you intercept the Mun's SOI, the first thing to do is to raise or lower your Pe so that you orbit at something between 50 to 80km. You can orbit the Mun prograde or retrograde, it doesn't matter.

2) When you reach your Pe, burn retrograde to circularize your orbit around the Mun.

3) When you are ready land, burn retrograde to deorbit.

4) Between 15-20000m, start burning to shed off your speed. You should have enough thrust and fuel to do this of course. You can make a good lander with only one fuel tank and the small engine. If your lander is too heavy, then you won't have enough thrust to lose your velocity.

5) As you are descending, watch your retrograde marker on the navball. On the final landing, it should be vertical (0 lateral speed) and so should your ship.

Edited October 8, 2012 by Nibb31

[Fl4shbang]

Raise lower Pe? What is Pe? So i need to make a orbit around the mun between 15-20000m from the mun before actualy trying to land? Thats where i tend to sqrew up. Becouse i dont understand witch way to point the ship to make the orbit. I think i have tried every direction without making any change to my path as i can see. Turning my flight into a one way ticket around the sun. I guess prograde or retrograde meen toward the path and with the path of the mun.

[BillWiskins]

Just in case, since you mentioned not knowing a lot of technical terms, 'burn retrograde' is just turning your craft around, so that the engine is aimed at the direction you are moving - so you're travelling backwards - and throttling up. It has the opposite effect of burning prograde, obviously, so rather than accelerate, you'll slow down. On the navigation ball in the bottom centre of the screen, there is a yellow marker. That's your forward direction - prograde - and there is also one on the opposite side of the ball as you rotate, which shows your retrograde vector. That one has a cross through it.

Nibb refers to adjusting your Pe - that's marked on the map, so you'll have seen it already. It's your closest point in an orbit to the body you're in orbit of. It's short for 'periapsis', and the opposite is 'apoapsis', Ap in game, and the furthest point of your orbit.

When you burn to intercept the Mun, you'll see the orbital projection change in the map view. There will now be a new 'Pe' marker - referring to your approach to the Mun - and this you can alter from as far away as low Kerbin orbit. Basically you'll want to adjust it (by speeding up or slowing down using pro and retrograde burns) as soon as possible, so try to do it as soon as the map screen shows the encounter. It's more fuel efficient that way.

[EndlessWaves]

The essentials are:

1. Extend your orbit at the correct time so your intercept the mun when you get to the apoapsis.

2. When your orbit has intercepted the Mun's sphere of influence (i.e. gold line turns blue) shed your excess energy by burning retrograde until your orbit line intersects the Mun. If your first burn was well timed there may not be any burn here.

#2 may or may not put you in orbit around the Mun (it depends on the original course), if it does the continuing to burn retrograde will put the PE inside the Mun so you're on a collision course.

3. You're now falling towards the Mun. When to start to slow down depends on your thrust to weight ratio and how fast you're travelling and could be anything from 200km to 20km. It's better to start early on lower thrust as it's easy to reduce thrust but impossible to increase it higher than maximum. Your rocket sounds fairly powerful so I'd try somewhere around 80km.

Save a few hundred kilometres out so you can try a couple of times as it's easy to misjudge stuff here. Be aware that the altimeter is also useless under ~5km as it only reflects mean surface level not your height above ground.

If you run out of fuel doing this then you basically need to build a rocket with more range (either bigger or more efficient).

[Nibb31]

Well, it looks like you need to learn how to orbit first. Practice raising and lowering your orbits around Kerbin before going for the Mun. Pe is Periapsis (you can see it on the Map) and Ap is Apoapsis.

Prograde and Retrograde are the direction of your orbit. Prograde is forward (to accelerate and therefore raise your orbit), Retrograde is backward (to decelerate and therefore lower your orbit). The two yellow/green markers on youyr navball indicate precisely you prograde and retrograde heading.

[EndlessWaves]

Well, it looks like you need to learn how to orbit first.

Nope, I never bother to orbit when going to The Mun

Retrograde and Prograde are the directions of travel and apply equally to orbits and paths that aren't orbits.

Likewise Apoapsis/Periapsis are the furthest and closest approaches to a body and also apply to flybys as well as orbits.

[Nibb31]

Nope, I never bother to orbit when going to The Mun

Retrograde and Prograde are the directions of travel and apply equally to orbits and paths that aren't orbits.

Likewise Apoapsis/Periapsis are the furthest and closest approaches to a body and also apply to flybys as well as orbits.

Pedantic post is pedantic. On a Munar flight, you are always orbiting something, so any trajectory is technically orbiting around something. And there is no Apoapsis on a flyby trajectory

I suggest orbiting the Mun before landing because it is easier. It gives you more time to slow down (you actually slow down in two steps) which requires less thrust. It also allows you to take your time to choose your landing site.

[Leonov]

All of my Secessful landing have been right before the sun reaches KSC launch get a nice circular orbit, intercept mun, Make the orbit line point at the surface, usually the side facing the sun and slowly make a landing approach, if you do it wrong you crash into mun at about 3000-5000m/s

[pebble_garden]

Perhaps this 6-part Mun mission tutorial will be of help. Or this tutorial on Orbital Mechanics.

[Fl4shbang]

Alot of helpful info here:) thanks alot guys, i wil go trough them all and hopefully i wil make it to the mun surface with all my kerbals alive by the end of this week:)