http://en.wikipedia.org/wiki/2007_Chinese_anti-satellite_mis...
http://celestrak.com/events/asat.asp
The mentioned Chinese test is single-handedly responsible for the vast majority of space debris.
Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
11–20 of 34 posts
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#12The scary bit is that each collision generates a new debris field, which can in turn generate more new collisions, so the safety of orbit starts decreasing geometrically.
Yes, but what are the orbits of the debris and how quickly do they fall into the atmosphere or deep space?
It depends on the height. At the height of the ISS, is it about a year or less, at the height of the Chinese test is seems to be a few decades or maybe one or two centuries and at 1000km the lifetime of space debris starts to be measured in millennia. (Combining some numbers from http://www.dlr.de/en/desktopdefault.aspx/tabid-5170/8702_rea... , http://www.spaceacademy.net.au/watch/debris/sdfacts.htm and http://en.wikipedia.org/wiki/Space_debris . http://www.orbitaldebris.jsc.nasa.gov/faqs.html#12 gives numbers that are about a factor of ten smaller, and it also depends on the type of debris, a sheet of mylar experiences a higher drag than a steel nut of the same weight.)
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#13Earlier quoted context omitted.
Yes, but what are the orbits of the debris and how quickly do they fall into the atmosphere or deep space?
It depends on the height. At the height of the ISS, is it about a year or less, at the height of the Chinese test is seems to be a few decades or maybe one or two centuries and at 1000km the lifetime of space debris starts to be measured in millennia. (Combining some numbers from http://www.dlr.de/en/desktopdefault.aspx/tabid-5170/8702_rea... , http://www.spaceacademy.net.au/watch/debris/sdfacts.htm and http://en.wik…
> a sheet of mylar experiences a higher drag than a steel nut of the same weight.
Drag in space? At what altitude, more precisely, does the objects start to experiment drag or the lack of it therefore?
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#14I am wondering why the debris was not from US Anti-Satellite test? After all, US has done much more such tests secretly.
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#15Earlier quoted context omitted.
It depends on the height. At the height of the ISS, is it about a year or less, at the height of the Chinese test is seems to be a few decades or maybe one or two centuries and at 1000km the lifetime of space debris starts to be measured in millennia. (Combining some numbers from http://www.dlr.de/en/desktopdefault.aspx/tabid-5170/8702_rea... , http://www.spaceacademy.net.au/watch/debris/sdfacts.htm and http://en.wik…
> a sheet of mylar experiences a higher drag than a steel nut of the same weight. Drag in space? At what altitude, more precisely, does the objects start to experiment drag or the lack of it therefore?
Yes, of course. That is the only mechanism that can remove debris from orbit (apart from flying up there and shooting lasers at it and other untested fantastic ideas). And debris in higher orbits survives longer exactly because the earth's atmosphere gets thinner and thinner the further you are from the surface. The upper boundary of the atmosphere is somewhere above 100000km (62000 miles) http://en.wikipedia.org/wiki/Exosphere#Upper_boundary
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#16I am wondering why the debris was not from US Anti-Satellite test? After all, US has done much more such tests secretly.
It's kind of hard to blow up a satellite secretly (as in, no one noticed).
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#17I am wondering why the debris was not from US Anti-Satellite test? After all, US has done much more such tests secretly.
The last US "test" was in 2008 to destroy a defunct spy satellite. Spy satellites have very low orbits (around 100km) and an overwhelming majority of the debris from that test reentered the atmosphere and burned up within weeks or months. Previous ASAT tests were done in the 80s and were also all at low altitude where debris burns up within a few months. The Chinese ASAT test was at around 1000km and much of that debris will be there for tens or hundreds of years. It basically undid all the work the international community had done on reducing debris over the past decade (http://www.scientificamerican.com/media/multimedia/0212-spac...).
It is possible, but highly unlikely that the US does ASAT tests in secret. It's unlikely mainly because any unannounced rocket launch looks suspiciously like an ICBM (and is easily detectable), so it is in everyone's best interest to announce launches ahead of time. If the US has done secret ASAT tests, they would continue to do them at lower orbits out of concern for debris.
The US tracks all objects in low Earth orbit that are about 10cm or greater in diameter using a large network of radar stations. The Russians have similar capabilities, though not on the same scale. As a result, they actually can tell where most of the debris came from. However in this article it was not clear if it was just conjecture or actual tracking data from the Chinese ASAT debris that led them to that conclusion.
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#18http://en.wikipedia.org/wiki/2007_Chinese_anti-satellite_mis... http://celestrak.com/events/asat.asp The mentioned Chinese test is single-handedly responsible for the vast majority of space debris.
I'm sure that's all just anti-PRC propaganda. I'm waiting for the PRC state workers to astroturf that on in the comments.
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#19Earlier quoted context omitted.
> a sheet of mylar experiences a higher drag than a steel nut of the same weight. Drag in space? At what altitude, more precisely, does the objects start to experiment drag or the lack of it therefore?
Yes, of course. That is the only mechanism that can remove debris from orbit (apart from flying up there and shooting lasers at it and other untested fantastic ideas). And debris in higher orbits survives longer exactly because the earth's atmosphere gets thinner and thinner the further you are from the surface. The upper boundary of the atmosphere is somewhere above 100000km (62000 miles) http://en.wikipedia.org/wik…
Oh, I thought it was gravity alone that did the work :)
Thanks for explaining it.
Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test
#20There's a very good 2003 sci-fi anime called Planetes[1] that explores the problem of space debris in some detail, and how humanity might deal with it in the future. Highly recommended if you're interested in these issues. 1. http://myanimelist.net/anime/329/Planetes
Ah! Wonderful :) This is, in fact, a hard science fiction!
http://en.wikipedia.org/wiki/Planetes
"Unlike many other anime and science fiction productions, special care was given in Planetes for a very realistic depiction of space and space travel."
"The Japanese space agency JAXA served as a technical consultant to the series. The US version of the DVDs featured interviews with two scientists from NASA's Orbital Debris Section."