space debris

[palinbook]

Regarding the latest near miss by debris on the ISS,does all debris rotate the same way or is it even more dangerous than we think with all sorts of stuff all over the place.if this is the case there will have to be some craft in the future collecting rubbish in orbit.

[jdbenner]

There is more than one orbit.  So while there is more debris near popular orbits, the space junk is more or less orbiting in different directions.

[DonPMitchell]

Not very much is put into orbit in the anti-earthwise direction, because that takes a lot of energy.  But the angles and eccentricities of orbits vary a lot.  An object is not likely to hit you at 16 km/sec, in other words.  But it might hit you at 0.5 km/sec, and that would still be bad.

I'm skeptical about the collection of the Soviet and American satellites a few months ago.  But I'm not sure how to calculate the collision cross section.  And of course, there is a "birthday paradox" effect, given N objects in orbit, the chances of any two colliding is much bigger than the chances that one particular object will hit another particular object.

[ijuin]

Israel is known for launching its satellites westward (i.e. anti-earthwise), primarily because to launch eastward would result in the spent first stage being dropped onto somebody else's national territory (e.g. Iran).

[DonPMitchell]

Russia angles its launches north to avoid China.  Baikonur is at 46 degree latitude, but most Russian spacecraft are put into orbits with an inclination of about 65 degrees.

With regard to satellite collisions, the question is, did Russia nudge a satellite as a test?  If we assume a satellite has a cross section on the order of a square meter, the question is what is the proper phase space to consider this problem, and what volume does each satellite randomly occupy in that space?

[jdbenner]

There is a greater chance of a collision with a fragmented satellite, verses the collision probability with an intact satellite.  However the fragments orbits will decay faster, than the intact satellite (at least in the case of low orbits).  You can throw a pillow farther than a pile of feathers.