Travelling to Moho?

[Huojin]

I cannot for the life of me manage to get to Moho. Or, for that matter, other bodies where their orbit is off-centre. Any help would be much appreciated, my attempts to decipher other instructions on it have proven utterly futile and tend to end poorly for my kerbalnauts.

[Xeutack]

You can either:

1: Adjust your orbits. You do that by firing 'up'/normal+ in the descending node or 'down'/normal- in the ascending node, which you can see when you target the body. Takes more fuel that the 2nd approach though.

2: Make sure that your rendezvous with the body takes place close to either the ascending or descending node. This is more economical but also a little harder. If you don't wanna do calculations and stuff you, can just blindly see if it can happen. Get into a sun orbit and at a maneuver anywhere, that approximately intersects with Moho's orbit. Set Moho as target. You should now see Moho's and the spaceship's positions at closest approach. Now hold the left mousebutton while clicking on the maneuver star and drag the star around your current orbit to find the place where the closest approach is optimized. You may have to adjust the maneuver a little in all directions as you go to get the encounter just right. Good luck.

[stupid_chris]

Are you setting your maneuver nodes at the right phase angle? It's normal you won't get an intercept right away even if you set it at the right moment if the inclination/eccentricity is high. You're gonna have to do a course correction to get a correct intercept. Moho is by far the hardest to reach in the game.

[MBobrik]

Make sure that your rendezvous with the body takes place close to either the ascending or descending node.

Opposite approach works too. Start when Kerbin is in the ascending/descending node. Just be sure you get the alignment right because, like it happened to me yesterday, even when you get an encounter, you come in thundering at 5km/s excess speed, and most ships don't have spare 5 km/s like mine had.

[stupid_chris]

most ships don't have spare 5 km/s like mine had.

Lithobraking

[Jason Patterson]

Landing on Moho is one of the most challenging missions in the game. It's tiny, requires enormous delta-v, and its orbit is all kinds of messed up. What I've got listed below will get you there, but it's important to note that it is far from being the most energy efficient method.

1. Put your Moho rocket on the launchpad.

2. Find the orbital node between Kerbin and Moho.

- Go to map view and double click the sun.

- Move and zoom your camera so that you're about to see Kerbin's entire orbit on edge.

- Without moving your camera up or down, move it around the sun (along Kerbin's orbit) until you also see Moho's orbit on edge. Both orbits should be lines on your screen now, or as close to lines as you can get them.

- The points where the two orbits cross (which will also line up with the Sun) are the orbital nodes.

3. Time warp until Kerbin is at one of the two nodes.

4. Launch and burn so that your new orbit's periapsis will be at the altitude of Moho's orbit at the orbital node. (You do not need to match orbital inclinations at any point in this process, that's why we picked the orbital node.)

5. Time warp to periapsis and plan a retrograde burn to get your Moho encounter. If you are right at the orbital node you won't need anything other than retrograde, but that's very unlikely. Use the close approach markers to fix it (this will be a sizeable burn, but it will also be slowing you down partially for your landing, so it's not all wasted.)

Moho's SOI is smaller than the distance from Kerbin to the Mun, and it's moving at an incredible pace, so you just have to be patient and keep trying until you get it.

[Huojin]

I think I've gotten manoeuvre nodes to show a Moho intercept, but they're consistently off when I burn them.

Are there no videos of anyone travelling to Moho? Someone should get on that, if not >_>

[stupid_chris]

I think I've gotten manoeuvre nodes to show a Moho intercept, but they're consistently off when I burn them.

Are there no videos of anyone travelling to Moho? Someone should get on that, if not >_>

Getting an intercept directly to Moho from Kerbin is rather hard to get. It's easier to do course corrections halfway to your destination. If you have a close approach, you don't need to have an intercept as soon as you exit Kerbin. Halfway there, just take a few second and play with a maneuver node, you should get an intercept easily. Normal planets usually take less than 50m/s to get that intercept, but Moho is a bit more hungry.

[Johnno]

I think I've gotten manoeuvre nodes to show a Moho intercept, but they're consistently off when I burn them.

You can do course correction burns and then if you burn too long you can adjust your orbit with just RCS. http://alexmoon.github.io/ksp/ is a great tool for helping you get started.

Are there no videos of anyone travelling to Moho? Someone should get on that, if not

I don't know, have you looked? You've already gotten several suggestions on how to deal with getting to Moho. Beyond the delta-v amounts needed and the inclined orbit getting to Moho is just the same as getting to Mün or Minmus. I don't really see how a video would make any difference once you're familiar with orbital mechanics, of which there are plenty of tutorials and videos if you bother looking.

Google or check youtube for 'kerbal interplanetary travel' (or just kerbal interplanetary), I'm sure you'll find plenty.

[Huojin]

I don't know, have you looked? You've already gotten several suggestions on how to deal with getting to Moho. Beyond the delta-v amounts needed and the inclined orbit getting to Moho is just the same as getting to Mün or Minmus. I don't really see how a video would make any difference once you're familiar with orbital mechanics, of which there are plenty of tutorials and videos if you bother looking.

Google or check youtube for 'kerbal interplanetary travel' (or just kerbal interplanetary), I'm sure you'll find plenty.

I've been trying to do mid-course correction burns, but I'm finding it tricky. I've looked for videos on how to get the Moho, but most of the videos I've found seem to deal with getting to Duna or Eve, which are easier. I've been totally unable to find anything that deals with Moho's eccentricity. Hence why I asked.

And I've more or less just confused by some of these instructions. Like I understand, but actually seeing it would go a long way to helping me to understand it better. If it wouldn't be of better help to you, congratulations, but if a particular way works better for me, I'll enquire about it.

[KerbMav]

Just burn them and make corrections as you go.

Might take a bit more fuel, but you cannot align a vessel that exact and keep it that still during burns that you will have absolutely no deviations from your planned course.

Use quicksave at Kerbin if you feel you wont be lucky today, but just give it a go - worked for me so far.

Edit: Im getting slow these days ...

Yes, it is tricky, thats one big part this game is about!

Actually getting anywhere is always the same - the inclination just adds another factor to deal with.

Use all six directions on your maneuver node and try to move them ever so slightly when you are still far away.

It gets more precise as you get closer to your target, but the farer away you are the more you can influence your angle at arrival and how you approach the target body.

Edited July 16, 2013 by KerbMav

[Guest]

I've been trying to do mid-course correction burns, but I'm finding it tricky. I've looked for videos on how to get the Moho, but most of the videos I've found seem to deal with getting to Duna or Eve, which are easier. I've been totally unable to find anything that deals with Moho's eccentricity. Hence why I asked.

And I've more or less just confused by some of these instructions. Like I understand, but actually seeing it would go a long way to helping me to understand it better. If it wouldn't be of better help to you, congratulations, but if a particular way works better for me, I'll enquire about it.

I googled "KSP moho" and found some videos, but the first 5 videos I looked at were either from .17 or were incomplete moho missions or outright failures. There is a good reason for this. Moho is the most difficult mission in the game, requiring something like 11,000 delta-v or more. Putting together videos of a complete moho mission would take many hours of work. Using mechjebs maneuver planner and maneuver editor in conjunction with alexmon's launch window planner and kerbal alarm clock will make planning your mission much easier, but still not easy. I understand if you want to stay with just the stock game however. In this case, try turning on infinite fuel with alt-f12 and using a small simple rocket to just get the feel for transfer windows and delta-v requirements before getting gung-ho.

Finally, I spent 3 weeks, in my spare time putting this together :

http://forum.kerbalspaceprogram.com/showthread.php/40158-To-Eeloo-and-back

Long and boring but it's complete.

Eeloo is similar to moho in that it's not easy. The same fundamentals are needed to get to moho, you're just going in the opposite direction.

[Mr Shifty]

I cannot for the life of me manage to get to Moho. Or, for that matter, other bodies where their orbit is off-centre. Any help would be much appreciated, my attempts to decipher other instructions on it have proven utterly futile and tend to end poorly for my kerbalnauts.

Use alexmun's calculator, as another commentor suggested: http://alexmoon.github.io/ksp/

Here are the results from a plot I generated using the tool:

To use this data, you start from a 100 km circular orbit around Kerbin. Warp to you departure time: day 68 at around 2am. (I use Kerbal Alarm Clock for this.) Set up a maneuver node at 129 degrees to retrograde, which looks like this (excuse the crude MS Paint drawing):

You can see in the image that I was hovering my mouse over the ejection delta-V of 1503 m/s, which shows you the breakdown into prograde and normal components (1501.9 m/s prograde, 53.7 m/s normal.) You can use MechJeb or Improved Maneuver Nodes to enter those values directly, or you can pull the prograde marker until your total delta-V reads 1501.9, then pull the normal marker until it reads 1503 m/s. Zoom out and if you're not at Moho intercept, you should be able to rotate the maneuver node around your orbit until you get one.

1503 m/s can be a long burn, so try to center the burn around the maneuver node. After the burn, you may not be at intercept, but you should be close. Just set up another maneuver node outside Kerbin's SOI to adjust for intercept; should only be a few m/s.

You can also see that insertion into Moho orbit will take at least 3500 m/s, so make sure you have the fuel for that.

Edited July 16, 2013 by Mr Shifty

[DMagic]

I think the problem is that you are probably trying to get to Moho the same way you get to any other planet; wait for an ejection window from LKO, do a correction burn mid flight, then do a single orbital injection burn. This is possible, but it's very tricky to do well with Moho. Even small deviations from an ideal transfer between Kerbin and Moho can lead to very high delta-v requirements for the injection burn (I've seen anything between 2300 and 5000 m/s).

I've been to Moho many, many times, probably more than any other planet. For almost every attempt I completely ignored transfer windows. There are some tricks for dealing with the inclination change that have already been mentioned, like waiting until you are at the ascending or descending node to do the ejection burn. Those help, and can save you some delta-v.

But the most important thing, at least I think so, is to just treat a Moho transfer like an orbital rendezvous. Do your ejection burn in LKO until your solar periapsis crosses Moho's orbit (it's best to do this so that you intercept Moho's orbit near its own solar periapsis). Then do multiple shorter burns at periapsis to bring down your apoapsis down a bit. You might have to make a few orbits around the sun to get a good intercept. But by doing it this way you can insure a near ideal intercept, one where you meet Moho at, or very close to, your own solar periapsis.

Yes, this method means that you don't get much benefit from the Oberth effect; some, or most, of the injection burn is done in solar orbit, far away from Moho. But I can almost guarantee you that you won't get an ideal intercept by setting up the transfer the traditional way. This is especially true if you are using a large lander, or other heavy vehicle, that requires very long burns. This method also means that your final injection burn should be much shorter, which is much easier than trying to deal with a single 4000 m/s burn near Moho.

I use some tricks to deal with the inclination change, some are described in my Moho thread, others have been mentioned here, but those really only save about 500 - 600 m/s of delta-v. Setting up transfers the way I described above I was regularly able to go from LKO to a stable, 100km polar orbit above Moho using under 5000 m/s of delta-v, my record was around 4300 m/s. And this was done using all manner of different vehicles, from relatively small and easily maneuverable crafts, to ridiculously heavy things that took 15 minutes for the ejection burn (and took 5 minutes just to turn around).