Entering into a captured orbit?

[xcorps]

How difficult is it to enter a captured orbit from another SOI (ie exit Kerbins SOI and enter Muns SOI with no escape node)

Edited April 12, 2014 by xcorps

[einsteiner]

It is impossible. Your energy is constant if you don't make any maneuvers, and since you enter from outside the Mun's SOI you will have enough energy to exit it.

[Superfluous J]

It is impossible. Your energy is constant if you don't make any maneuvers, and since you enter from outside the Mun's SOI you will have enough energy to exit it.

While that is mathematically true, it's not true in-game. Slight rounding errors make it possible to do this, and if you are at high time warp it's even easier.

But that'd be considered abusing the limitations of the physics engine

[Rakaydos]

Using the mun to capture into kerbin orbit, however, works just fine.

[Crown]

I quite don't understand the question. Do you mean entering from a highly eccentric orbit around Kerbin to a stable eccentric orbit around Mun without doing any burns?

[FenrirWolf]

Reminds me of a 'fundamental rule' I read about on the tutorials board. The rule is that when it comes to SoI's, what goes down must come up.

For example, let's say you enter the Mun's SoI going 40m/s relative to the Mun, and you are not on a collision course with it. You will naturally speed up as gravity accelerates you towards the Mun. But once you pass periapsis and continue along your trajectory, you'll see that your ship starts to lose speed just the same as it was gaining it before. By the time you reach the SoI boundary again, guess what speed you'll be going? That's right, 40m/s!

So basically once you've encountered another body you have to do something to bleed off that excess velocity if you plan to stick around. A burn of the engines, a bit of help from the friendly neighborhood atmosphere (if applicable), or a rare nudge from the Kraken as already stated

Edited April 12, 2014 by FenrirWolf

[Tex_NL]

Getting captured into an orbit without doing anything is in fact pretty easy. Most of us do it all the time; gravity assists and aerocapture. BUT .... it won't be a stable orbit.

Getting captured into a stable orbit is as Einsteiner correctly said impossible (as long as we ignore the rare math errors 5thHorseman mentioned). With an aerocapture obviously you will fall back into the atmosphere again unless you raise your Pe. If you use a gravity assist sooner or later (it could be on your next orbit or it might take several years) you will have an encounter again with a wide variety of possible results.

[SRV Ron]

Getting captured into an orbit without doing anything is in fact pretty easy. Most of us do it all the time; gravity assists and aerocapture. BUT .... it won't be a stable orbit.

Getting captured into a stable orbit is as Einsteiner correctly said impossible (as long as we ignore the rare math errors 5thHorseman mentioned). With an aerocapture obviously you will fall back into the atmosphere again unless you raise your Pe. If you use a gravity assist sooner or later (it could be on your next orbit or it might take several years) you will have an encounter again with a wide variety of possible results.

I have actually seen such a capture show up while setting up a maneuver mode. In reality, it dropped out at the last moment. This is the closest screen shot to that event.

It is possible, but extremely difficult to pull off.

[Sirrobert]

I have actually seen such a capture show up while setting up a maneuver mode. In reality, it dropped out at the last moment. This is the closest screen shot to that event.

http://i.imgur.com/w4jJ1mF.jpg

It is possible, but extremely difficult to pull off.

That is due to the rounding errors.

[Tex_NL]

I have actually seen such a capture show up while setting up a maneuver mode. In reality, it dropped out at the last moment. This is the closest screen shot to that event.

http://i.imgur.com/w4jJ1mF.jpg

It is possible, but extremely difficult to pull off.

That images does not show a capture without input! The blue line is your current orbit. It shows you've entered Layhte's SOI and will be leaving again unless you make that 11.4m/s burn.

I admit: it is close but this is NOT a capture described by xcorps in the first post.

[xcorps]

Thanks for the feedback guys. I was thinking of making a burn right at the capture point to try to save Dv entering into an orbit without having to do a "long" burn to change the new peri to the altitude I wanted.

I didn't think it could happen, but I thought maybe a corrective burn on an ellipsis.

[SRV Ron]

That images does not show a capture without input! The blue line is your current orbit. It shows you've entered Layhte's SOI and will be leaving again unless you make that 11.4m/s burn.

I admit: it is close but this is NOT a capture described by xcorps in the first post.

As I said, I missed getting the screen shot when the Maneuver Mode was showing an actual capture.