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Iridium 33 & Cosmos 2251 Collide

by BobG
Tags: 2251, collide, cosmos, iridium
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BobG
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Feb12-09, 01:23 PM
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An Iridium satellite and a dead Russian satellite collided on Feb 10 at 16:56:00 UST.

Debris From Satellites' Collision Said to Pose Small Risk to Space Station

They hit each other at an angle of 102.46 degrees, giving them a closing speed of about 11.65 km/sec (about 26,000 mph). That's going to leave a lot of debris.

It's not the first collision. An old Arianne rocket body hit the French Cerise satellite in 1996, plus there's been two or three suspected collisions between debris and dead satellites (there's a lot more dead satellites still in orbit than active satellites). It probably is the first satellite to satellite collision.

Cosmos 2251, a Strela 2M communications satellite (a really old satellite design - the first was launched in 1970, with the last launched in 1994.):


Iridium 33, a communications satellite:
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Gokul43201
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Feb12-09, 02:33 PM
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Quote Quote by BobG View Post
(there's a lot more dead satellites still in orbit than active satellites)
Perhaps we need a You Only Live Twice style ship (only, it would be a scavenger, not a predator) to clean up the mess.

Wouldn't it be awesome to hear a robotic Japanese voice, saying: "Bling out your dead"?
(and no wiseass remarks about sound propagating through a vacuum, thank you)
BobG
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Feb12-09, 02:35 PM
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How depressing. Now I won't see the Iridium flare on March 25. Looking at old elsets, these have been on a collision course for quite a while. Iridium satellites can maneuver out of the way, given enough warning (it only takes a small orbit adjustment to avoid the collision). Evidently, they don't receive collision avoidance support from anyone.

A view of the orbit trajectories:

http://www.obsat.com/images/Ir33coll_top.gif

(Having a big picture is kind of annoying, so you'll have to link to it if you want to see it.)

chemisttree
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Feb12-09, 02:45 PM
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Iridium 33 & Cosmos 2251 Collide

Wow! The paths intersected at nearly 90 degrees! That's gotta be a million to one shot. (A million-to-one shot, Doc. Million-to-one!)
BobG
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Feb12-09, 03:02 PM
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Quote Quote by Gokul43201 View Post
Perhaps we need a You Only Live Twice style ship (only, it would be a scavenger, not a predator) to clean up the mess.

Wouldn't it be awesome to hear a robotic Japanese voice, saying: "Bling out your dead"?
(and no wiseass remarks about sound propagating through a vacuum, thank you)
A satellite at that altitude is travelling 7400 m/sec. Size varies, but 750 kg isn't a bad estimate for a satellite. That's about 20.5 gigaJoules of energy (about the same as 5 tons of TNT). The only way you're going catch that satellite in a net is if you happen to be in the same orbit so you can get that relative velocity down. Then you have to change orbits to catch the next satellite, etc.

The only way to clean out an orbit is to deorbit the satellite at its end of life. That was actually the plan for the Iridium satellites when their company went bankrupt, but then the government bailed them out with a contract for their service.

Generally, deorbiting a satellite should take as much energy as it took to put it into that orbit in the first place. Fortunately, you don't have to bring it all the way in with satellite thrusters. Once the satellite is low enough, the atmosphere starts to suck energy out of the orbit and it decays on its own.

For higher orbits, deorbiting isn't even feasible (it would take way too much fuel). They put the satellite into a new orbit that's out of the way (supersynching geosynchronous comm satellites, for example).
Astronuc
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Feb12-09, 03:07 PM
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Ahh - so that was the loud bang I heard.

Actually it was more of a 'disturbance in the force'.


That's amazing they hit as chemisttree observed.

Lots more debris to dodge - Crash of US, Russian satellites a threat in space
http://news.yahoo.com/s/ap/20090212/...e_collision_22

http://news.yahoo.com/s/afp/20090212...20090212204433

Ooops!
turbo
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Feb12-09, 03:27 PM
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That collision was like hitting a bullet with a bullet.
LowlyPion
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Feb12-09, 04:04 PM
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Picture of the collision. Edit: oops It's not. It's another incident mentioned in the article.
http://news.nationalgeographic.com/n...ctures_big.jpg

From this article:
http://news.nationalgeographic.com/n...sion-pictures/

Edit: An interesting read even if that picture isn't of the actual collision event.
BobG
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Feb12-09, 04:22 PM
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That's a 1978 photo of Cosmos 954, which, instead of achieving orbit, spread its radioactive fuel over Canada.
signerror
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Feb12-09, 04:28 PM
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Quote Quote by BobG View Post
That's a 1978 photo of Cosmos 954, which, instead of achieving orbit, spread its radioactive fuel over Canada.
Interesting story behind that.

Operation Morning Light - A personal account

They never found the thing. They flew a gamma spectrometer hooked up to a huge DEC for real-time data analysis. And they dropped condoms filled with dyes to mark locations from the air.
signerror
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Feb12-09, 04:39 PM
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Quote Quote by BobG View Post
A satellite at that altitude is travelling 7400 m/sec. Size varies, but 750 kg isn't a bad estimate for a satellite. That's about 20.5 gigaJoules of energy (about the same as 5 tons of TNT). The only way you're going catch that satellite in a net is if you happen to be in the same orbit so you can get that relative velocity down. Then you have to change orbits to catch the next satellite, etc.
I'm sure something could be figured out.

Maybe: send up missiles tipped with pressurized nitrogen tanks, timed to rapidly vent right in front of the debris clouds, at high relative velocity. The diffuse gas cloud could cause enough delta-v to perturb their orbits, pushing them into the upper atmosphere.

Or, nuclear weapons for the same effect. They effectively vaporize themselves, though the ion radiation might present a problem for living satellites.

Or, satellites charged up to extremely high voltages. (How?) They would attract conductive metal debris, accumulating it into a ball.

Or maybe giant electrified nets.

Or space-directed high-power microwave arrays. You could use a phased array to focus a beam on a small region, enough to heat up small projectiles until they vaporize. This is made easier by the insulating properties of a vacuum: the only heat loss mechanism is radiative.
Topher925
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Feb12-09, 04:41 PM
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Those NASA guys certainly do have a lot of fun.
BobG
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Feb12-09, 04:44 PM
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Here's a link to AGI's website: http://www.agi.com/corporate/mediaCe...ridium-cosmos/

They have some simulations, which can be viewed as a movie or by downloading the free AGI viewer. The viewer is pretty cool, since there's some nice STK simulations done for things like the Chinese ASAT test a couple years ago.

The viewer works in power point presentations and provides a really nice touch.
LowlyPion
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Feb12-09, 06:40 PM
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Quote Quote by BobG View Post
That's a 1978 photo of Cosmos 954, which, instead of achieving orbit, spread its radioactive fuel over Canada.
I see. I didn't pick that up when I read it. I thought it was a screen capture of something at the time. Thanks for straightening it out.


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