What are the chances of...

[Slam_Jones]

So, I've been wondering this for a little while now... what are the chances of an asteroid becoming a new moon without any interference?

Basically, what are the chances that an asteroid will come close enough to Kerbin to aerobrake and get pulled into orbit without striking the planet? I've heard of it occurring naturally (I think), so I'm curious if this has happened to anyone? On one of my career modes, I'm at year 50 or so and it hasn't happened, though I've tracked many many asteroids as they make close passes or impacts. Of course I could fly out, intercept, and drag one into orbit, but I'm not quite skilled enough to manage that yet

[Norpo]

I don't think asteroids simulate aerobraking unless you're actively watching them in-game (as in, you would be controlling it, not from the tracking station), if they aerobroke as well, their periapsis would be inside the atmosphere, and it would just keep aerobraking until it crashed down.

I bet they could get a gravity assist from the mun or something, but I think the chances of that are low, considering the asteroid and the mun are on different planes most of the time.

[Guest]

Not possible in standard KSP. The gravity model is just too simplistic for it to happen. Principia might allow such a thing, though.

[Slam_Jones]

-snip- if they aerobroke as well, their periapsis would be inside the atmosphere, and it would just keep aerobraking until it crashed down. -snip-

Ohhh, totally forgot about that aspect of it. Derp.

So with stock KSP, it's basically impossible. Good to know.​

[Overfloater]

Perfectly possible in stock KSP, take example of my Jool capture, just need to catch Laythe or Tylo at their orbit's edge:

No aerobraking involved.

Only it's very unlikely for an asteroid to get such an encounter xD

[Slam_Jones]

-snip-

Interesting, so aerobraking isn't possible, but it can get pulled in by all the moons.

I've noticed that with anything I send to Jool, it eventually gets ejected from the system due to grav assists. Did that happen eventually to the asteroid? Or did it somehow get a truly stable orbit?

I just love the idea of flying to a new planet or something and having more moons than there should be. Just adds an extra layer or exploration

[Vallius]

It certainly does, but there's nothing science fictional about the number of moons around Jool

Laythe having surface liquid water on the other hand...

In our solar system, most of the gas giants have dozens of moons, some of which are about the size of other planets.

[tutrakan4e]

It's happened to me before, I feel like it spawned inside the SOI

[LABHOUSE]

Happened to me after 20 years physics warp (in game obviously)

[Mitchz95]

It's happened to me before. A class-A got itself stuck in a stable polar orbit around Kerbin.

[GloriousWater]

I had the Mun intercept a Class C that would otherwise crash into Kerbin, and it was in an eccentric retrograde orbit for 3 months. Then the Mun kicked it out again...

Needless to say, I crashed an ion probe into it for SCIENCE!

[*Aqua*]

Not possible in standard KSP. The gravity model is just too simplistic for it to happen. Principia might allow such a thing, though.

QFT

Even if an asteroid is captured, its orbit will be unstable. It will either aerobrake until it crashes down or will be kicked out by a moon (probably the same moon which put the stone on its "stable" orbit).

[magnemoe]

Perfectly possible in stock KSP, take example of my Jool capture, just need to catch Laythe or Tylo at their orbit's edge:

http://i.imgur.com/Vg8K3jg.jpg

No aerobraking involved.

Only it's very unlikely for an asteroid to get such an encounter xD

Yes its possible, I found an asteroid in orbit around Kerbin without touching it.

Its however very rare and the orbit will always be unstable, the orbit of the astroid has to intercept the moons SOI, the next intercept will probably send it out in interplanetary space again.

I was lucky as the orbit was very inclined and the orbital period was long making more Mun intercepts unlikely.

[rodion]

it's awesome that this actually happened to several people, it would really make my game feel alive if such an event happened to randomly happen to me. highly interesting.

[razark]

I wasn't paying attention to asteroids at all, until I noticed that I had something in a near-polar orbit ~400 km x 75,000 km around Kerbin. I'm still in the first year of game-time, as well.

One mission later, and it's now in a 400 x 7,000 km orbit.

[ScriptKitt3h]

I've found smaller class-C and B asteroids in highly eccentric orbits around Kerbin.... normally post-timewarp when I'm either returning from another planet or waiting for something.

However, they're so small and hard to reach that I generally try to ignore them.

[Mitchz95]

Note that it only seems to work if you're tracking the asteroid at the time. Otherwise it'll probably have despawned by the time you notice it, especially if you're running interplanetary missions at the time.

[KerikBalm]

I don't see how it is possible to have it capture into a stable orbit, given KSP's simplistic SOI thing... I don't know if you get get orbital resonances set up (maybe its possible with orbits that only breifly cross into an SOI of one of the moons).

That said, the first asteroid I captured in career mode, was, well, already captured. I didn't see the capture, but I could see that its orbit came very very close to the orbit of Minmus. As near as I can figure, it got a gravity assist from minmus to capture it into a very irregular orbit around Kerbin (which would work similar to what was just shown for capturing into jool with just gravity assist from moons) - however, it was not a stable orbit, its orbit did intersect the orbit of minmus. The orbital periods were different, but eventually it would have re-encountered Minmus, and then its orbit would change.

Of course, I went out there, and redirected it, and gave it a new, more regular, stable orbit around Kerbin.

Aerobraking can capture a roid (if you have it focused), but of course, that orbit won't be stable, and will continue to degrade unless you raise the PE - although in KSP, if the PE is above a certain altitude, you can focus on other craft, and time warp, and that orbit will be "stable", at least until you switch back to the asteroid while it is in the atmosphere.

[magnemoe]

I don't see how it is possible to have it capture into a stable orbit, given KSP's simplistic SOI thing... I don't know if you get get orbital resonances set up (maybe its possible with orbits that only breifly cross into an SOI of one of the moons).

That said, the first asteroid I captured in career mode, was, well, already captured. I didn't see the capture, but I could see that its orbit came very very close to the orbit of Minmus. As near as I can figure, it got a gravity assist from minmus to capture it into a very irregular orbit around Kerbin (which would work similar to what was just shown for capturing into jool with just gravity assist from moons) - however, it was not a stable orbit, its orbit did intersect the orbit of minmus. The orbital periods were different, but eventually it would have re-encountered Minmus, and then its orbit would change.

Of course, I went out there, and redirected it, and gave it a new, more regular, stable orbit around Kerbin.

Aerobraking can capture a roid (if you have it focused), but of course, that orbit won't be stable, and will continue to degrade unless you raise the PE - although in KSP, if the PE is above a certain altitude, you can focus on other craft, and time warp, and that orbit will be "stable", at least until you switch back to the asteroid while it is in the atmosphere.

its not an stable orbit, asteroid enter Kerbin the Mun SOI, mun gravity changes trajectory so asteroid ends in Kerbin orbit. Yes the astroid orbit will intercept Mun orbit however if the orbit is pretty inclined and has an have long orbital period it has low chance for an Mun intercept and can stay a long time.

The low chance event here is the Mun SOI intercept, if dV reqired for capture is low as its for many asteroids its an decent chance for it to be captured. Note if its plane is close to mun plane Mun intercept is more likely but it would also give it an high chance for enter Mun SOI the next orbit and then an high chance to be expelled from orbit.

[Sky_walker]

I had one asteroid that patched conics indicated as entering an orbit around Kerbin - so I send a probe and landed on it. Sadly it didn't work out as patched conics initially indicated - it swinged around Kerbin, left Kerbin SOI - it entered kerbolcentric orbit never coming back again into Kerbin SoI.

[KerikBalm]

Yes, as I said, you can get a capture, but it won't be stable.

I was particularly surprised by the minmus capture, not Mun capture. The longer orbital period and smaller SOI makes that sort of orbit even longer lived than a mun capture.

[JayKay]

I've found that many asteroid trajectories are indicated as orbits around Kerbin on the map view once they are within a certain distance, but the reality is that once they leave Kerbin's SOI they are no longer in its orbit and return to heliocentric orbits.

Edited November 7, 2014 by JayKay

[Guest]

I've found smaller class-C and B asteroids in highly eccentric orbits around Kerbin.... normally post-timewarp when I'm either returning from another planet or waiting for something.

However, they're so small and hard to reach that I generally try to ignore them.

They most likely were not captured, but simply spawned within the SOI. This can happen at times.

[JenBurdoo]

I've gotten a single asteroid into eccentric Kerbin orbit after a lot of timewarping. I had to select and follow a lot of them first, though, and I'm sure more than a few smacked into Kerbin in the meantime.

[Flight]

I may be wrong, but since KSP is not an n-body simulator, doesn't that mean that if an asteroid were aerobraking, wouldn't it necessarily (a) eventually fall to that planet or ( not decelarate enough and escape?

In other words, I think it's impossible for an asteroid to aerobrake and end up on a permanent orbit of that same planet. Is that assumption correct?