How to solve this escaping orbiting?

[InF3RNo]

Hello, I've been trying a lot of times to coordinate Kerbin's orbit Apoapsis to reach the Mun's orbit, now I achieved it, I ran time a lot of time faster to make the Mun go near when I reach the correct place, but now I have a huge problem, I go into a escape orbit and I don't know how to solve this.

A screenshot will make this easier

How should I solve this, I tried at the last blue point with Mun Encounter to do some Maneuvers with Prograde and Retrograde but the orbit goes crazy, I wasn't able to finish the Fly to the Mun, Part 1 Tutorial, so this could be the same problem.

Thanks for the answer in advance,

InF3RNo.

Edited June 28, 2013 by InF3RNo

[Klingon Admiral]

I would burn retrograde immediately, this should push your Kerbin Apoapsis downwardsand thus increase your height at which you enter the Muns SoI, thus decreasing it's gravitational pull on your ship, this raising your munar pariapsis and thus decreasing the magnitude of it's gravity assist.

By the way, your pressing problem isn't your escape trajectory, your pressing problem will be your ship directly crashing into the Mun.

[bigpapabearxx]

Burn Retrograde a bit. Create a maneuver node and drag the retrograde marker.

[regex]

Try adjusting your radial in/out (blue handles) and then fine-tune the orbit with anti/normal (purple handles). Just looking at that orbit, I'm thinking you want radial out until you have a good insertion altitude, then circularize when you get there.

[GoDores]

Looks to me like your current trajectory will intersect the moon's surface, although I usually use patched conics mode 0 so I may be misreading. In other words you'll crash into the Mun before you get to the Kerbin escape trajectory.

That's not a problem; you can still land from that trajectory if you're okay with landing about where the orbit intersects the surface. If you want to get into orbit first you need to burn a little retrograde (for a retrograde Munar orbit) or a longer prograde burn (for a prograde Munar orbit). In either case you'll need another retrograde burn in the Mun's SOI to circularize and keep from escaping.

[Vanamonde]

From the position in your picture, point your nose 90 degrees to the west of the prograde marker and burn. (What's the technical term? Anti-radial?) That will turn the retrograde-into-impact trajectory in that picture into a low prograde orbital approach. If you want to see what an approach should look like on map view, check out the illustrations in my walkthrough: http://forum.kerbalspaceprogram.com/showthread.php/25029-A-moon-rocket-for-newbies (It's the 8th picture down.)

[MH60AV8R]

As soon as you enter the Mun's sphere of influence, point towards your yellow retrograde marker and burn for a few seconds. You should see your Perigee appear from the surface of the Mun. Get it to rise to an altitude you are happy with, then as you approach the Perigee burn retrograde again to get your Apogee to begin to come down into an orbit. If you don't do that then you will basically use the Mun to slingshot yourself out of orbit. I hope this was easy to understand. No offense to the previous posters but I had a hard time understanding what you all were trying to say (though I do know what you were trying to say).

[MH60AV8R]

You won't have to drop any maneuver nodes anywhere either. A simple retrograde burn will suffice once you are in the Mun's SOI.

[Rickenbacker]

I say do a quick retrograde burn where you are, until you get a periapsis at the Mun (50km or so is good). Then timewarp until you reach that periapsis, and burn retrograde until you're in a stable Mun orbit.

[MR4Y]

I would burn radially. Then you decide if you want to orbit the Mun or return to Kerbin.

[RoboRay]

I don't see a Pe marker, so you are automatically going to fail to reach the escape orbit... by impacting the munar surface.

[InF3RNo]

I would burn radially. Then you decide if you want to orbit the Mun or return to Kerbin.

I only know to burn prograde or retrograde, how to burn radially?

I've been busy, I'll try the retrograde that have been said by lot of people answering my post.

I don't see a Pe marker, so you are automatically going to fail to reach the escape orbit... by impacting the munar surface.

So there's no way to solve this?

[Dkmdlb]

So there's no way to solve this?

A burn in any direction at all will change your course enough to prevent you from impacting the munar surface.

Maybe I'm not understanding this thread.

[purpletarget]

I only know to burn prograde or retrograde, how to burn radially?

Radial can be predicted using the Maneuver node's blue markers. From the screenshot you provided, you can burn inwards, bending your path to the left, until you get a Pe ahead of the Mun, which should not only solve your escape issue, but may also give you a free-return trajectory too. (Slingshot back to Kerbin). Chances are however, you may need to use some normal/Anti-normal (pink triangles) as well to line up on the equator for that to work properly. We can't tell from the screenshot if the current problem is off the Mun's orbital plane, but I suspect it is. (ie: Your escape is slinging you up or down away from the plane that the Mun orbits)

The other radial to the right should give you a Pe behind the Mun as it passes, and that'll probably aggravate your escape slingshot. However if you burn retro at that Pe to get captured by the Mun, it doesn't matter so much.

[InF3RNo]

I burnt radially to the left and I got a returning orbit to Kerbin, so this' saved. Problem is I can't ever get a orbit to the Mun without escaping somewhere else. How can I achieve reaching the Mun without doing an escaping orbit?

I tried to do the fly to the Mun's tutorial and I got again an escaping orbit, I'm doing something wrong, it says something about a 45 degrees of the Mun but I don't understand this.

Regards,

InF3RNo.

Edited June 28, 2013 by InF3RNo

[Tank Buddy]

I actually preform this maneuver very often as a way to dispose of the debris of the trans-munar-injection stage. If you have just finished the injection burn, then you can burn retrograde to slow down. This will put you in a prograde orbit (counter-clockwise).

But if you are too late, it is simple: if you want a prograde (CCW) orbit, while in the Mun's SOI burn at 90 degrees (east) between your prograde and retrograde markers. This will push your orbit out of a collision course and raise your apoapsis. To create a retrograde orbit (CW) do the opposite, burn west (270) between the prograde and retrograde markers. Remember, you want to do this maneuver almost immediately after you enter the Mun's SOI for maximum effect and minimum fuel use.

[Mr Shifty]

I burnt radially to the left and I got a returning orbit to Kerbin, so this' saved. Problem is I can't ever get a orbit to the Mun without escaping somewhere else. How can I achieve reaching the Mun without doing an escaping orbit?

Kerbal's First Law (I made that up) is that unless you use your engines, you will leave a planet or moon's sphere of influence with the same speed you entered it, but in a different direction. Specifically, once you enter the Mun's sphere of influence, you will certainly leave it as well, unless you apply thrust or impact something. The easiest thing to do if you want to achieve orbit is to burn retrograde once you reach periapsis around the Mun. Periapsis is best because of the Oberth effect; your engines have the greatest effect on the size of your orbit when you're going the fastest, which is at periapsis. If you burn retrograde there, you can watch your escape trajectory become an ellipse.

tl;dr Burn retrograde when you reach periapsis around the Mun until your orbit is elliptical.

[Sirrobert]

You will ALWAYS be on an escape trojectory if you enter a moon's or different planet's SOI. (or most of the time)

Just burn retrograde at the periaps to lower the apoapsis to within the body's SOI, and only than will you get a capture

[InF3RNo]

Kerbal's First Law (I made that up) is that unless you use your engines, you will leave a planet or moon's sphere of influence with the same speed you entered it, but in a different direction. Specifically, once you enter the Mun's sphere of influence, you will certainly leave it as well, unless you apply thrust or impact something. The easiest thing to do if you want to achieve orbit is to burn retrograde once you reach periapsis around the Mun. Periapsis is best because of the Oberth effect; your engines have the greatest effect on the size of your orbit when you're going the fastest, which is at periapsis. If you burn retrograde there, you can watch your escape trajectory become an ellipse.

Burn retrograde when you reach periapsis around the Mun until your orbit is elliptical.

Problem is I don't have a periapsis, this is what happens:

Now how I solve this no Periapsis problem?

Also in tutorial it says something about 45 degrees ahead of the Mun's Orbit, I don't understand this, how do I know when it's 45º?

At last I solved it, it seems I needed the Apoapsis go a bit futher than the Mun's Orbit itself, otherwise I'd end exploding into the Mun.

Thanks for all the answers.

Edited June 28, 2013 by InF3RNo
Solved it

[Mr Shifty]

Problem is I don't have a periapsis, this is what happens:

Now how I solve this no Periapsis problem?

Yeah, that trajectory is going to impact the Mun. Ideally, you'd correct this when you're still close to Kerbin as that will save fuel. You want the periapsis to be at least 5 km in altitude. If you've entered the Mun's SOI with this trajectory, you might be able to burn radially to bring the periapsis out, but it's going to use lots of fuel.

Also in tutorial it says something about 45 degrees ahead of the Mun's Orbit, I don't understand this, how do I know when it's 45º?

Orient your map so you're looking down on the Mun's orbit. If you increase your apoapsis until it's at the Mun's altitude, then to achieve intercept, you want to rotate it around until it intersects the Mun's orbit about 45 degrees counter-clockwise from the Mun's current position.

At last I solved it, it seems I needed the Apoapsis go a bit futher than the Mun's Orbit itself, otherwise I'd end exploding into the Mun.

Thanks for all the answers.

Good to know it's working for you. You can also rotate your maneuvering node so that you leave Kerbin's orbit earlier or later and that should keep your periapsis above the Mun's surface.

[TomcatMVD]

Problem is I don't have a periapsis, this is what happens:

Now how I solve this no Periapsis problem?

Happened to me yesterday and I lost my **** until I realized the solution was rather simple. Place a maneuver node anywhere in your projected trajectory and pull one of the radial markers (the blue ones) until you see a Pe appear. Then just wait until you reach it and burn retrograde to create an actual orbit.

[Klingon Admiral]

The first rule in a situation like this: Don't panic! You still have a lot of time to figure out what to do.

Then, the easiest way to solve such a problem is creating a maneuver node and looking what the different options do. In your case, you lack most of the lateral speed required to stay in orbit, so you want to burn either radialy or anti-radialy (the blue markers on your maneuver node). Use the one pointing torwards Kerbin, as you have a bit of lateral motion in that direction and we don't want that to go to waste, don't we? As the Mun has no atmosphere, a pretty low periapsis will suffice, albeit I would keep it above 5km to avoid munar peaks getting in your way.

And 45 degrees? Isn't the "eyeball-y" way to wait until Munrise/Munset and push your Apoapsis out, resulting in an angle of about 90 degrees?

[Scotius]

"Aiming at the Mun rising" while useful, won't help him reach other bodies. IMHO it's better to learn maneuver nodes from the start. Also, you don't really need to cross the Mun's orbit. You just need to get an encounter when you are at AP, or near it. You will move very slowly then, which means your retrograde burn to get into Mun orbit will cost less dV. It's easy to see when your trajectory "jumps" into Mun's SoI - if it's straight (or close to straight line) it means you are moving fast. If it's curving around the Mun already, it means relatively small burn will get you into orbit.