
Russian Satellite Hit by Debris from Chinese Anti-Satellite Test - petrel
http://mashable.com/2013/03/09/russian-satellite/?utm_medium=feed&utm_source=feedburner&utm_campaign=Feed%3A+mashable%2Ftech+%28Mashable+%C2%BB+Tech%29
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mappu
There'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>

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robotmay
I was wondering if someone would mention Planetes. I'd still rank it as one of
my favourite anime series, as it's such a plausible near-future sci-fi. Highly
recommended.

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Ingaz
Funny. The first thing I've remembered was Planetes.

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cmaher
[http://en.wikipedia.org/wiki/2007_Chinese_anti-
satellite_mis...](http://en.wikipedia.org/wiki/2007_Chinese_anti-
satellite_missile_test)

<http://celestrak.com/events/asat.asp>

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

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brownbat
> 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...](http://www.space.com/3415-china-anti-satellite-test-worrisome-
debris-cloud-circles-earth.html)

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."

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brownbat
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.

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qwertzlcoatl
<http://en.wikipedia.org/wiki/Kessler_syndrome>

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brownbat
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/>

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danshapiro
The 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.

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dasil003
Yes, but what are the orbits of the debris and how quickly do they fall into
the atmosphere or deep space?

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fhars
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.dlr.de/en/desktopdefault.aspx/tabid-5170/8702_read-18916/)
, <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.)

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alberich
> 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?

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fhars
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>

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alberich
Oh, I thought it was gravity alone that did the work :) Thanks for explaining
it.

~~~
fhars
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.)

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gngeal
"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"

Actually, it wouldn't, because orbiting a celestial body radiates energy in
form of gravitational waves, but in case of Earth's gravitational field and at
the speed of orbiting satellites, this mode of losing energy is negligible.

~~~
fhars
Yes, but I still think that the tidal deformation of the earth under the
gravitational influence of the steel nut will vastly dominate general
relativistic effects like gravitational waves. You usually use neutron stars
orbiting black holes to produce the latter.

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peripetylabs
When China conducted that test, Russia's Defence Minister called the reporting
of it "exaggerated and abstract." This should make things more concrete.

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

~~~
rzimmerman
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...](http://www.scientificamerican.com/media/multimedia/0212-spacejunk/img/chart-
historical-debris-growth.jpg)).

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.

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

~~~
raintrees
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.

