Simulation shows how space junk spreads after a satellite breaks up Whether it's a satellite breaking up or the detritus of a launch, the whole space community agrees that space junk is a huge problem. After all, even a fleck of paint can make a noticeable dent in the International Space Station's windows. Tracking space debris is a lot easier if you know where to look, so US Naval Research …
(It's interesting to observe that the spot where the disintegration starts gets the least amount of debris.)
no.... not really...
At its Facebook page, the NRL says the simulation needed around 24 hours on a 32-core machine to create.
And almost completely useless... as the collision collides with other particles and other crap, making it chaotic in nature and as a result mostly unpredictable.
That part of the article was badly written. In fact the exact origin point of the debris cloud will get a huge amount of debris passing thru it, but a short distance away (except along its orbit) there will be little or no debris-flux to speak of. That's how orbits work. At least until perturbations by the Moon and Sun introduce chaos and mess it all up. Can't guess the 'relaxation time', but it can't be more than a few hundred orbits, I would say.
It's interesting that the origin point is also where most of the secondary collisions among the debris will occur, since that's the densest point of the orbital cloud. However, the impact speeds won't be much higher than the original expansion speed of the debris cloud, for what that's worth.
As a layman.. where does all the energy come from that provides the angular momentum of pieces rising to the higher orbital distances? Is this all provided by the force imparted upon the target object that gave rise to its initial breakup? If it is has a sensitivity analysis been done to confirm the representative form of the 'disassociation pattern' that has been generated here?
On a another, equally lay level, the patterns together with "Anonymous' " comments about the moon and perturbations mentioned by Wilkinson it all starts to look like the earliest stages of the formation of an accretion disk around a spinning initial black hole as extraneous material flies in and starts bumping around and the 'soup' starting to settle out into clusters of matter into its densest parts to form stellar objects which further accrete and sweep to create the arms of a spiral galaxy, and at a fractal level, the planets of their own stellar systems.
Or they could have generated a model following any one of the other dozen or so solution paths at each point in time and place of the calculations and ended up with any one of millions of different forms of galaxies etc etc. Still its always gratifying when you follow the solutions which paint the prettiest pictures. Don't you think?
> "...where does all the energy come from that provides the angular momentum of pieces rising to the higher orbital distances?"
The video states it's a fragmentation event with delta-v's up to 2 kilometers per second, a genuine explosion. That's enough to raise fragments quite high, but they still have to come down and pass thru the fragmentation point.
Other fragments are driven down as well, but due to the steeper gravitational gradient they don't go as far down as the high fragments go up. I think that's why they selected the 900km orbit altitude, so that no part of the pattern actually touches the Earth.
It also states that this sim is confined to the original orbital plane, but in a real event most of the fragments would not remain in the orbital plane. That would be much harder to sim, and I doubt it would really differ that much from the 2-D sim. All the fragments would still return to the event point anyway. Not all at the same time, of course.
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