Russian Satellite Hit by Debris from Chinese Anti-Satellite Test • Hacker News Board

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#21

Post by fhars » Sun, Mar 10, 2013, 5:15 PM UTC

alberich wrote: post #19

fhars wrote: post #15

Earlier quoted context omitted.

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.

Gravity doesn't do anything on its own, in the absence of other forces, the orbit of a steel nut around the earth would be stable (that's also why we haven't yet crashed into the sun even after being in its gravitational field for billions of years). (Well, you would get some instability because neither the earth nor the nut are perfect spheres or perfectly rigid, but those effects would take billions of years to become noticeable.)

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#22

Post by ars » Sun, Mar 10, 2013, 5:27 PM UTC

cmaher wrote: post #11

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.

I wonder if Russia can demand compensation from China.

It's not like China wasn't warned - I remember tons of criticism of them before they launched, yet they did it anyway.

If you deliberately cause damage, you should be liable.

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#23

Post by ars » Sun, Mar 10, 2013, 5:27 PM UTC

alberich wrote: post #13

fhars wrote: post #12

Earlier 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?

> At what altitude, more precisely, does the objects start to experiment drag or the lack of it therefore?

There is no cutoff. It just gets less and less the higher you go, but there is no point where you can say "zero".

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#24

Post by sultezdukes » Sun, Mar 10, 2013, 6:19 PM UTC

darkarmani wrote: post #18

cmaher wrote: post #11

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.

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.

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.

Well, there ya go right below you :)

http://news.ycombinator.com/item?id=5352254

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#25

Post by brownbat » Sun, Mar 10, 2013, 6:50 PM UTC

qwertzlcoatl wrote: post #4

http://en.wikipedia.org/wiki/Kessler_syndrome

To save the click through:

As the chance of collision is influenced by the number of objects in space, there is a critical density where the creation of new debris occurs faster than the various natural forces remove them. Beyond this point a runaway chain reaction may occur that pulverizes everything in orbit.

There was a fun idea for a while to use a powerful laser to shoot at the front end of space debris. The resulting ablation would turn the little nuts and bolts into tiny rockets using their own material as fuel. http://en.wikipedia.org/wiki/Laser_ablation

See also: xkcd What If? on using laser ablation to propel the moon away from the Earth: http://what-if.xkcd.com/13/

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#26

Post by raintrees » Sun, Mar 10, 2013, 7:01 PM UTC

antihero wrote: post #8

The Chinese are pretty minted, can they not buy the Russians a new one?

I don't see anything in the post claiming the purpose of the satellite, or if it was still operational.

So I would surmise the main point here is to highlight the increasing danger of space debris, and that the danger is going to be exponential, rather than linear in growth.

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#27

Post by InclinedPlane » Sun, Mar 10, 2013, 7:03 PM UTC

longcheng wrote: post #14

I am wondering why the debris was not from US Anti-Satellite test? After all, US has done much more such tests secretly.

The US performed its anti-satellite tests against targets in low Earth orbit, so that the orbits of the debris decayed quickly. That was not the case for the Chinese test, which was in a relatively high orbit and generated a huge amount of long-lived debris.

More so, the idea of "secret" anti-satellite tests is a bit rich, satellites are tracked by RADAR from multiple countries, you can't hide a satellite blowing up.

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#28

Post by samstave » Sun, Mar 10, 2013, 7:45 PM UTC

fhars wrote: post #12

dasil003 wrote: post #10

Earlier 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…

This is something I have been wondering for a while; assuming we could detect it, space debris around a body could be a serious indication of life on a planet, could it not?

Especially if it could stay around for so long. Though this assumes that the population of that planet is not nearly as trashy as our own.

I wish there were a requirement for all space-faring nations to clean up space debris.

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#29

Post by brownbat » Sun, Mar 10, 2013, 7:57 PM UTC

cmaher wrote: post #11

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.

> The mentioned Chinese test is single-handedly responsible for the vast majority of space debris.

It was widely considered the most prolific single source of debris, but I don't think it's responsible for the majority of space debris.

NASA catalogged 900 or so pieces of space debris from the test exceeding 10 cm, expecting the number to climb to about 950 such pieces. [1]

In total, NASA tracks about 21,000 pieces of debris over 10 cm. [2]

Is largest single source getting confused with majority, or was more debris discovered after the fact?

1. http://www.space.com/3415-china-anti-satellite-test-worrisom...

2. http://orbitaldebris.jsc.nasa.gov/faqs.html#3

PS - Not trying to play 50 cent army here, "largest single source" is still definitely bad, just not the same as "vast majority."

Re: Russian Satellite Hit by Debris from Chinese Anti-Satellite Test

#30

Post by brownbat » Sun, Mar 10, 2013, 8:13 PM UTC

brownbat wrote: post #29

cmaher wrote: post #11

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.

> The mentioned Chinese test is single-handedly responsible for the vast majority of space debris. It was widely considered the most prolific single source of debris, but I don't think it's responsible for the majority of space debris. NASA catalogged 900 or so pieces of space debris from the test exceeding 10 cm, expecting the number to climb to about 950 such pieces. [1] In total, NASA tracks about 21,000 pieces of…

Ah, I see now that my parent's sources list it as "largest debris-generating event" (celestrak) and "The test is the largest recorded creation of space debris in history with at least 2,317 pieces of trackable size (golf ball size and larger) and an estimated 150,000 debris particles." (wikipedia).

That tracks with what I saw, so take this as just a minor tweak to GP's phrasing.

Don't skip that post because of the oversight. The celestrak link offers an incredible HD video simulating the debris cloud and the path of the ISS... it's like an action movie. Great find, so I upvoted.