What happens to wreckage after two satellites collide head-on in the same orbit?

[Himal kharel]

when two identical satellites of same cicular orbit around the Earth but in opposite direction. assuming that an inelastic collision takes place what happens to the wreckage.

 

[berkeman]

when two identical satellites of same cicular orbit around the Earth but in opposite direction. assuming that an inelastic collision takes place what happens to the wreckage.

What do you think? Which equations would apply?

 

[chrisbaird]

If they are the same mass, their total angular momentum is zero before so it will zero afterwards. If inelastic, they essentially stick together as one giant mass of wreckage that has zero velocity, and therefore falls straight down.

By the way, this would be very hard to do in practice, because 3D space is so huge. You would have to have some sort of dynamic tracking and locking system for two satellites to meet while in orbit. Simply shooting them off into perfectly opposite orbits would be near impossible.

 

[pallidin]

Are we talking about 2 satellites in opposite but impact orbit each moving at 17,000 mph?
That's an extraordinarily serious impact, inelastic or not.

 

[Drakkith]

Is this supposed to be a realistic question? At the velocity they will impact at, you won't have any wreckage to find hardly.

 

[pallidin]

Is this supposed to be a realistic question? At the velocity they will impact at, you won't have any wreckage to find hardly.

Yeah, and here is a small example:

 

[nesp]

We don't have much experimental data of impact at those hypervelocities. What we do have are observations of actual impacts, though not of exactly opposite directions as you state. In 2009 we observed a collision at approximately 11 km/sec, and in 2007 we had a Chinese ASAT with impact velocity around 8 km/sec. In both cases the collisions produced thousands of pieces of debris ejected roughly in the direction of the flight vectors. The debris whose velocities nearly canceled out re-entered quickly, but there were significant amounts of small debris that were scattered along the orbital planes due to shock waves generated by the vaporized remants of the hypervelocity collision.

You can't really get a pure inelastic collision at those velocities with net velocities going to zero. At those velocities the heat generated quickly vaporizes the material, and the resulting shock waves explode and scatter the pieces before they can close on each other.

 

[Drakkith]

Isn't an inelastic collision the one where some of the energy is converted into other forms? Seeing this on wikipedia: http://en.wikipedia.org/wiki/Collision#Types_of_collisions

 

[nesp]

Yes, an inelastic collision is one in which at least part of the kinetic energy is converted into a different form, such as heat. In satellite collisions you don't get perfect elastic or inelastic collisions, you get a mix, with momentum conserved but not kinetic energy. So much of the kinetic energy is converting to heat, vaporizing the materials and exploding them into shrapnel that blows fragments along orbits fanning out from the original orbit. Basically, it's a real mess that stays in orbit for many years.

 

[Drakkith]

I'm only going off the explanations from wikipedia, but it seems to me that it MUST be one or the other. Either the collision converts no energy into other forms, or it does. What am I missing here? Is it more complicated than merely one or the other?

 

[BruceW]

I think what nesp means by perfectly inelastic is if all the KE were turned into energy of some other kind.
And perfectly elastic just means elastic, that total KE stays the same.
And any other type of collision will be inelastic (i.e. KE doesn't stay the same)

 

[Drakkith]

Ahh, I can see that.