Iridium, Cosmos collision (APOD 2009 Feb 18)

[aristarchusinexile]

But there were probably lots of astronomers who wished Cosmic harm towards Iridium 33:

But only Iridium 33 was steerable. That would imply someone deliberately crashed it.

On the wild possibility side of things .. how about a hacker crashing satellites just for fun and games and chaos?

[Doum]

Hmmm, may be the russian one was still steerable and we have to strike back at them for that attack.

It's a joke here dont strike yet.

[NoelC]

Without using "The Force" I'm not sure the computer could hit it...

"You must unlearn what you have learned."

-Noel

[bhrobards]

I was under the impression Russian satellites are manueverable. If so, how do you know it was out of fuel? I woundn't discount the possibility of either side making a statement.

[bhrobards]

Also the point of collision is very well covered by both countries radar suites.

[Chris Peterson]

I was under the impression Russian satellites are manueverable. If so, how do you know it was out of fuel? I woundn't discount the possibility of either side making a statement.

The radar systems used by both countries for monitoring the majority of orbiting material are not accurate enough to be used for routine orbit corrections when near misses (or hits!) are predicted. So while both systems were maneuverable (assuming there was fuel), it's doubtful that either operator had enough information to actually justify repositioning their equipment.

The Cosmos satellite may or may not have had some remaining control ability, but was apparently out of operation for the last 14 years, so it seem likely that it was uncontrolled. The Iridium satellite was certainly under control, but didn't have good enough data to avoid the accident.

[bhrobards]

I was under the impression Russian satellites are manueverable. If so, how do you know it was out of fuel? I woundn't discount the possibility of either side making a statement.

The radar systems used by both countries for monitoring the majority of orbiting material are not accurate enough to be used for routine orbit corrections when near misses (or hits!) are predicted. So while both systems were maneuverable (assuming there was fuel), it's doubtful that either operator had enough information to actually justify repositioning their equipment.

The Cosmos satellite may or may not have had some remaining control ability, but was apparently out of operation for the last 14 years, so it seem likely that it was uncontrolled. The Iridium satellite was certainly under control, but didn't have good enough data to avoid the accident.

T

The SBX X band ABM fire-control radar is stationed in Adak, it can track an object "the size of a baseball over San Francisco from the Chesapeak Bay." No reason to believe the Russians are too far behind.

[Chris Peterson]

The SBX X band ABM fire-control radar is stationed in Adak, it can track an object "the size of a baseball over San Francisco from the Chesapeak Bay." No reason to believe the Russians are too far behind.

Size isn't the factor, but rather accuracy. And the radar fence system used to maintain the orbiting object catalog isn't generally going to give absolute position to better than a kilometer or so. Certainly, our government and others track critical assets with much higher precision. But there's no way they are tracking everything that accurately. Iridium is privately owned, and who knows exactly how the dead Russian communications satellite fit into their system. My point was that there's really no reason to think that either of these objects were being monitored by anything other than routine tracking systems.

[iamlucky13]

I was under the impression Russian satellites are manueverable. If so, how do you know it was out of fuel? I woundn't discount the possibility of either side making a statement.

The satellite has been out of commission since 1995. That doesn't necessarily mean it couldn't be maneuvered, but that is assumed to be the case.

Without using "The Force" I'm not sure the computer could hit it...

"You must unlearn what you have learned."

-Noel

This is a subtly astute observation. I read elsewhere that Iridium stated they were aware these satellites would be in proximity, but tracking suggested with acceptable confidence they would miss. Things like exact position in space are probabilistic, and when you're working with probability, there's always a chance things won't work out quite like your predictions suggest they should. You can have three sigma confidence in something, but about 0.3% of the time you will be wrong.

Anyway, I don't buy any conspiracy theories on this one, except perhaps insurance fraud, but illegal dealings are lousy way to run major company in the long run, especially since this event probably raised their insurance rates (both because of additional debris in that orbit, and because they have one less spare, so the risk of losing more affecting their financial viability is greater).

Realistically, they couldn't have guided them into a collision confidently.

Follow up twisted quote:

"Cosmos 2251, you've switched off your targeting computer. Are you ok?"

[Doum]

Hey i said it was a joke. I dont think it was premedited to collide. It's just an accident. Geeee..

[bhrobards]

The SBX X band ABM fire-control radar is stationed in Adak, it can track an object "the size of a baseball over San Francisco from the Chesapeak Bay." No reason to believe the Russians are too far behind.

Size isn't the factor, but rather accuracy. And the radar fence system used to maintain the orbiting object catalog isn't generally going to give absolute position to better than a kilometer or so. Certainly, our government and others track critical assets with much higher precision. But there's no way they are tracking everything that accurately. Iridium is privately owned, and who knows exactly how the dead Russian communications satellite fit into their system. My point was that there's really no reason to think that either of these objects were being monitored by anything other than routine tracking systems.

Just a point of information about SBX accuracy it is fire control system designed to guide kinetic kill weapons to multimach warheads. It is exactly what you would use for a satellite intercept. I'm not saying it was, just that it can.

[Jyrki]

Just a point of information about SBX accuracy it is fire control system designed to guide kinetic kill weapons to multimach warheads. It is exactly what you would use for a satellite intercept. I'm not saying it was, just that it can.

In that case I hope that they have fixed the bug that nearly caused the DC area to be annihilated in one Tom Clancy novel :-> Don't remember the title? The bug was about the kill weapon logic being based on seeking the source of heat. Consequently it was zeroing in on the exhaust flames. Not the right thing to do at ballistic speeds, because the targeted missile was easily outrunning the cloud of explosions.

[iamlucky13]

The SBX X band ABM fire-control radar is stationed in Adak, it can track an object "the size of a baseball over San Francisco from the Chesapeak Bay." No reason to believe the Russians are too far behind.

Size isn't the factor, but rather accuracy. And the radar fence system used to maintain the orbiting object catalog isn't generally going to give absolute position to better than a kilometer or so. Certainly, our government and others track critical assets with much higher precision. But there's no way they are tracking everything that accurately. Iridium is privately owned, and who knows exactly how the dead Russian communications satellite fit into their system. My point was that there's really no reason to think that either of these objects were being monitored by anything other than routine tracking systems.

Just a point of information about SBX accuracy it is fire control system designed to guide kinetic kill weapons to multimach warheads. It is exactly what you would use for a satellite intercept. I'm not saying it was, just that it can.

I believe the Ground Based Interceptor ABM missile uses the SBX, but it uses a terminal guidance system in the form of an infrared tracker built into the kill vehicle. SBX gets it in the vicinity, the seeker head finishes the job. I don't know the limits of the system, but the Air Force isn't relying on the accuracy of x-band alone.

Either way, Iridium wagered that the best option was to do nothing.

[Chris Peterson]

Either way, Iridium wagered that the best option was to do nothing.

It sounds like they had no real choice. With dozens of near misses each week in the same sort of uncertainty range, they pretty much have to respond to all, or to none. And if it was all, that means they'd rapidly run out of propellant (which is mainly there for functional mobility- moving their birds into orbit for replacements, out when they die, and generally maintaining the necessary orbital constellation.