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oly720man
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Satellites Collide Over Siberia

Thu Feb 12, 2009 7:54 am

http://news.bbc.co.uk/1/hi/sci/tech/7885051.stm

US and Russian communications satellites have collided in space in the first such reported accident.

A satellite owned by the US company Iridium hit a defunct Russian satellite at high speed nearly 780km (485 miles) over Siberia on Tuesday, Nasa said.


Well, where are all the bits going to end up? And given that a flake of paint can potentially ruin your day in space this could be a nightmare.
 
bennett123
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 9:11 am

Three thoughts spring to mind;

1. Amazing with all that space, they managed to be in the same place at the same time.

2. I thought that large objects are tracked.

3. Would either satellite have the ability to manoevre.
 
connies4ever
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 10:06 am



Quoting Bennett123 (Reply 1):
Three thoughts spring to mind;

1. Amazing with all that space, they managed to be in the same place at the same time.

2. I thought that large objects are tracked.

3. Would either satellite have the ability to manoevre.

1 - It is a low probability, but non-zero.
2 - I believe USAF Aerospace command only tracks from the US and plots orbits. orbits are a funny thing, they keep changing a) due to changes in atmospheric drag - yes, there is an atmosphere up there, and b) non-uniformity in Earth's gravity field
3 - No. In fact the Russian Cosmos had been 'dead' for years.
 
scouseflyer
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 10:35 am

With the Russian bird weighing nearly a tonne and the Irridium one 560 kg - I wonder what was the impact velocity was - that's going to be an enormous amount of energy!
 
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Scooter01
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 11:27 am

The link to this animation from SeeSat-L was published by several Norwegian newspapers:
http://i39.tinypic.com/2vbk75z.gif

Scooter01

[Edited 2009-02-12 03:35:39]
 
bennett123
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 11:54 am

Connies4ever

Perhaps if all operators plotted their "objects" it would help. Surely the US are not unaware of Russian satellites that are "up there"

When I mentioned manoevering, I was primarily thinking about the Iridium.
 
Airboeing
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 4:29 pm

Hello

Quoting Bennett123 (Reply 5):

Bennett, every satellite, during its operational life, can manoeuvre. The problem, when it comes to collision avoidance, is : "is the risk big enough compared to the cost of a manoeuvre ?"

Such risks are not computed for every satellite in operation, and risks are mesured by a probability of collision, which can't be 100% because of the errors made in the orbits computations. Thus, IF a risk is detected, people have to ask if it's worth a manoeuvre (costing propellant, so reducing the length of the mission).

That means that for many private companies, usualy there are no avoidance manoeuvre, even no risk computation, and I think this is the case for Iridium (not sure of that though...). For governement and science satellites, things are different. The Space Station for instance, make avoidance manoeuvres every year.

Quoting Connies4ever (Reply 2):
2 - I believe USAF Aerospace command only tracks from the US and plots orbits

USSTRATCOM tracks every object bigger than 10cm, active satellite or not, US or Russian or Chinese or other, military or not (well, if they are detected once at least). More than 32000 objects are tracked.
But forecasting every collision risk is not done.
 
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Spacepope
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 4:56 pm



Quoting Bennett123 (Reply 5):
When I mentioned manoevering, I was primarily thinking about the Iridium.

The Iridium sattelite seems to be the only part of this equation capable of changing direction. It's more likely that the thing got clobbered by the Cosmos space junk. Did the Iridium sattelite have a defined orbit, or as a coms sattelite was it geostationary?
 
bennett123
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 5:02 pm

Airboeing

Thanks for that.

Hard to see how they make the decision not to manoevre without any assessment of the risk.

Whilst I appreciate that calculations cost money, it does seem somewhat "hit or miss". This decision could prove expensive if a chunk of this collision hits someone. Furthermore, satellites are not cheap.

David
 
kingairta
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 7:38 pm

Neither is getting them up there.
 
gsosbee
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 8:48 pm

Being the devil's advocate, how do we know the incident was an accident?
 
sv7887
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 8:57 pm



Quoting Gsosbee (Reply 10):
Being the devil's advocate, how do we know the incident was an accident?

I was just thinking the same thing lol. I wonder if the Pentagon will want to demonstrate their Anti-Satellite capability again to "prevent" these kinds of things from happening again.
 
Airboeing
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 9:33 pm



Quoting Spacepope (Reply 7):
or as a coms sattelite was it geostationary?

As the sat altitude was about 800km, it can't have been a geo, whixh altitude would have been of 36000km

Quoting Bennett123 (Reply 8):
Hard to see how they make the decision not to manoevre without any assessment of the risk.

One has to understand that when risks are not precisely caracterised (as it is often the case), a manoeuvre could raise (sic) the risk instead of reduce it...
 
nomadd22
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RE: Satellites Collide Over Siberia

Thu Feb 12, 2009 9:40 pm

Iridiums don't have to maintain as precise a position as geostationary bird, but the ones in each orbit do need to keep the exact same orbital period and stay spaced out evenly. So, they would have to shut down if they couldn't maneuver any more. But as close as they are to being out of fuel, they're not going to move one every time there's a one in a thousand chance of collision.
 
connies4ever
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 1:29 am



Quoting Airboeing (Reply 6):
Quoting Connies4ever (Reply 2):
2 - I believe USAF Aerospace command only tracks from the US and plots orbits

USSTRATCOM tracks every object bigger than 10cm, active satellite or not, US or Russian or Chinese or other, military or not (well, if they are detected once at least). More than 32000 objects are tracked.
But forecasting every collision risk is not done.

If I wasn't clear enough: Aerospace Defence Command plots orbits for everything, but my belief is that they take the points on the orbit for any given s/c from within the US.

Quoting Spacepope (Reply 7):
The Iridium sattelite seems to be the only part of this equation capable of changing direction. It's more likely that the thing got clobbered by the Cosmos space junk. Did the Iridium sattelite have a defined orbit, or as a coms sattelite was it geostationary?

Yes, Iridium can manouevre -- my bad -- otherwise how could they move a spare from a parking location to replace the one just lost ?

Can anyone confirm that Cosmos 1133 (?) is the same type sea-surveillance satellite as Cosmos 954 which crashed in our North West Territories in 1978 ?
 
Thorny
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 2:15 am



Quoting Gsosbee (Reply 10):
Being the devil's advocate, how do we know the incident was an accident?

I'm not sure what would be gained by Iridium destroying one of its own satellites by smashing it into a long-dead Russian satellite, or why Russia would have pretended its satellite was dead for the last 10 years, just waiting to destroy one of the 66 easily-replaceable Iridium satellites...

Quoting Sv7887 (Reply 11):
I was just thinking the same thing lol. I wonder if the Pentagon will want to demonstrate their Anti-Satellite capability again to "prevent" these kinds of things from happening again.

That's the kind of altitude China used in its anti-satellite test, an altitude with an orbital lifetime of years or decades. The US anti-satellite demo was at an altitude where the debris de-orbited in a matter of weeks if not days. Doing a test at that altitude creates huge debris clouds that persist a long time, which is why the world was so irate with China, and why the much-lower US test did not create the same outrage.

Quoting Connies4ever (Reply 14):

Can anyone confirm that Cosmos 1133 (?) is the same type sea-surveillance satellite as Cosmos 954 which crashed in our North West Territories in 1978 ?

The satellites in Tuesday's collision were Iridium 33 (launched in 1997 on a Russian Proton rocket) and Cosmos 2251.

Cosmos 2251 was a Strela-2M communications satellite launched in 1993.
 
nomadd22
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 2:30 am

Iridium got lucky. The sat that got hit just happened to be in plane 3, which has 3 working spares last I heard. They can move them between planes, but it takes a while.
 
Thorny
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 4:13 am



Quoting Nomadd22 (Reply 16):
Iridium got lucky. The sat that got hit just happened to be in plane 3,

But there is some concern that the debris cloud might impact other Iridiums in the same plane.
There's not much drag that high up, the debris won't be coming down any time soon. Major hazard to navigation.
 
rwessel
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 5:06 am



Quoting Airboeing (Reply 6):
Bennett, every satellite, during its operational life, can manoeuvre. The problem, when it comes to collision avoidance, is : "is the risk big enough compared to the cost of a manoeuvre ?"

That's far from true. Many satellites do not have any translational ability at all, and many have pretty modest attitude control as well (a little bit of spin and a magnetic torque rod can go a long way at keeping one end of the bird pointed at the earth).

It really depends on the mission. For example probably all geosync birds need translational capability to stay in their assigned spot. As do birds that operationally need to change their orbits.

Hubble, for example, has no translational capability at all, although it has excellent altitude control. Similarly, many civilian earth observation satellites (whether sats, etc.), as in the same boat.

Many, sure. Probably even most. But certainly not "every."
 
4holer
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 6:40 pm



Quoting Thorny (Reply 17):
But there is some concern that the debris cloud might impact other Iridiums in the same plane.
There's not much drag that high up, the debris won't be coming down any time soon. Major hazard to navigation.

More specifically, is the gap once occupied by Iridium 33 in the network able to be reoccupied by a spare considering that the debris cloud is focussed on that location/orbit?
 
nomadd22
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 8:27 pm

Quoting 4holer (Reply 19):
More specifically, is the gap once occupied by Iridium 33 in the network able to be reoccupied by a spare considering that the debris cloud is focussed on that location/orbit?

The debris would only hang around that location because it had no velocity relative to 33s position/orbit. It's not likely to hurt the new one.

[Edited 2009-02-13 12:27:56]
 
bennett123
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 10:01 pm

I think that he is more concerned that the replacement needs to be moved into the Danger Zone.
 
connies4ever
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RE: Satellites Collide Over Siberia

Fri Feb 13, 2009 11:58 pm



Quoting Thorny (Reply 15):
The satellites in Tuesday's collision were Iridium 33 (launched in 1997 on a Russian Proton rocket) and Cosmos 2251.

Cosmos 2251 was a Strela-2M communications satellite launched in 1993.

Thx Thorny. Not sure if the Strela's were nuclear powered or not. Any thoughts ?
 
rwessel
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RE: Satellites Collide Over Siberia

Sat Feb 14, 2009 4:49 am



Quoting Connies4ever (Reply 22):
Not sure if the Strela's were nuclear powered or not.

No, they're not.
 
oly720man
Topic Author
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RE: Satellites Collide Over Siberia

Sat Feb 14, 2009 4:22 pm

Here's one vision of where the debris field spread to, along with all the other stuff already up there.

http://www.newscientist.com/data/ima...s/ns/cms/dn16592/dn16592-5_824.jpg

and there's an animation here

http://bbs.keyhole.com/ubb/ubbthreads.php?ubb=showflat&Number=1199474
 
Oroka
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RE: Satellites Collide Over Siberia

Mon Feb 16, 2009 3:11 am

Im pretty sure I read in an article (on space.com) that NASA knew this was going to happen, just not when. It was only a matter of time.
 
PPVRA
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RE: Satellites Collide Over Siberia

Mon Feb 16, 2009 4:35 am



Quote:
Debris falling in Texas, possibly from satellites

DALLAS (AP) — The Federal Aviation Administration has received numerous reports of falling debris across Texas, which could be related to a recent satellite collision.

Some of the callers around midmorning Sunday reported what looked like a fireball in the sky.

FAA spokesman Roland Herwig says officials suspect the debris could be related to the collision, but that has not been confirmed.

The FAA notified pilots Saturday to be aware of possible debris after a collision Tuesday between U.S. and Russian communication satellites. The chief of Russia's Mission Control says clouds of debris from the collision will circle Earth and threaten numerous satellites.

A spokesman for the Williamson County Sheriff's Office says the department used its helicopter to search for the source of the debris but found nothing.

http://www.google.com/hostednews/ap/...Z5P_PZJnI2vqPuEkhBGJzrS1AD96CB6P00

Some good news, but potentially hazardous too.

I wonder what the Sheriff's Office helicopter could possibly be doing. . .
 
Thorny
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RE: Satellites Collide Over Siberia

Mon Feb 16, 2009 6:46 pm

I'd say it is very unlikely that Sunday's fireball over Texas had anything to do with Tuesday's Iridium/Cosmos collision. It was probably a derelict stage from a rocket launched in the last year or so.

And I wonder what exactly the FAA expects pilots to do with its "space debris" warning. "Pilots: Be on the lookout for something falling out of the sky at any time from any direction..." Yeah, that's helpful...

They do realize that Earth is being continually bombarded by space junk, both man-made and natural, every year, right? I mean, we're talking tons of meteorites every year...

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