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I live in Kentucky, and for the last two days we have heard low, loud, and rumbling explosions every couple of hours over several counties. It is supposidly the debris re-entering the atmosphere.
Was wondering if anyone else had experienced this? Even makes you wonder what was on that satellite after two days...( 66.156.138.35 ( talk) 16:45, 14 February 2009 (UTC))
NORAD was moments away from an emergency public broadcast in Canada re debris. I'm not sure why there is mention of 'radioactive' debris in this newspaper article either. Calgary is a major city (pop. 1 million) in the province of Alberta. http://www.calgaryherald.com/entertainment/Calgary+dodges+space+junk/1290211/story.html —Preceding unsigned comment added by 204.191.190.96 ( talk) 05:20, 11 June 2009 (UTC)
Perhaps I'm reading this too literally, but nowhere in the article does it say that this was an accident. I assume it was, but it is entirely possible to read this article and assume that the satellites were forced to collide on purpose, without a reason given. Would it be agreeable to change it to include the words "accidental" or "unexpected?" —Preceding unsigned comment added by 216.54.22.188 ( talk) 19:11, 12 February 2009 (UTC)
I don't know exactly how satellite tracking works, but it may be possible that since it was a defunct Russian satellite that it was only being tracked by Russia, not by NASA (i.e. cold war relic). As these satellites are in relatively low earth orbits, I don't know whether the cumulative effect of the atmosphere on the long lived Russian satellite may have caused this. Or alternatively it is possible (although it appears unlikely) that it was a deliberate attempt to test ways to knock other satellites out of orbit/ destroy them. —Preceding unsigned comment added by 86.131.102.102 ( talk) 20:43, 12 February 2009 (UTC)
BTW, i'm the same guy as the post from IP 146.193.39.206. —Preceding unsigned comment added by 89.152.245.176 ( talk) 00:32, 13 February 2009 (UTC)
There is a war on. As I understand it US and NATO/Coalition partners have been buying pretty much all the commercial satllite time they can get. I can't imagine that running those satellites in unprofitable at the moment - although Iguess the projected withdrawals from Iraq might make it so.
ON the subject of it the orbits could be predicted then why was the Iridum satellite not moved out of the way. Well may it had no maneuvering fuel left. Or maybe it had enough to move it away and not enough to put it back in a useul orbit. IN which case they are better of leaving it where it is an hoping for a miss.
Just a thought. (or two) 219.90.144.59 ( talk) —Preceding undated comment was added at 13:26, 14 February 2009 (UTC).
"Well may it had no maneuvering fuel left." It does. Or at least Iridium claim they could have manoeuvred it.Nasa, whilst they tracked both objects, predicted them to miss each other by a large margin (were talking tens/hundreds of kilometres- i can't remember the exact value). For the record, the cost to maintain one less satellite is effectively zero, since they still have to track the other 71 or so and use them. Your point about the gain from the insurance is valid. I thought the implication was that the company weren't making money, and that a collision with one of there satellites was a way to recoup losses. 86.174.122.122 ( talk) 23:45, 14 February 2009 (UTC)
The USSSN is of course tracking *all* objects it can detect, no matter who launched a particular object. For the reason why no evasive actions were taken, it might probably be that starting evasive maneuvers for every possible close encounter in LEO is simply not feasible: "At the time, Campbell said that Iridium was receiving an average of 400 reports per week of objects coming within 5 km of one of their satellites." and "Using a collision prediction program to perform a retroactive analysis of the satellites' orbits, aerospace analyst T S Kelso found that the Pentagon's public data showed that the two satellites would have missed each other by 584 metres." ( [1]) -- Cruncher ( talk) 04:42, 19 February 2009 (UTC)
presumably this 584 metre prediction is attributable to the Intel Pentium floating point bug? 75.87.134.179 ( talk) 19:00, 20 July 2009 (UTC)
I started this article because the news said it was the first satellite collision, which I thought was noteworthy. If this is not the first such collision, then perhaps this isn't deserving of its own article. I will trust whatever a concensus of editors decides. Grundle2600 ( talk) 02:23, 12 February 2009 (UTC)
The "collisions" between DART and MUBLCOM and between Progress and Mir occured during deliberate attempts to bring two spacecrafts together slowly. So they were very different. The collision of Cerise, however, was quite similar. It too featured a functioning satellite colliding completely accidentally with space debris. The only difference is that in the 2009 event, the other object colliding was an old, "dead" satellite, so we have two real satellites colliding. In 1996 it was a satellite meeting a piece of debris that was not designed to be a functioning satellite. / 129.142.71.166 ( talk) 16:38, 12 February 2009 (UTC)
For whoever is interested here are links to the ground track plots of both satellites at the time of collision, courtesy of Heavens-Above:
84user ( talk) 15:23, 12 February 2009 (UTC)
Damn, that's closer to a head-on collision than I would've imagined! Potatoswatter ( talk) 21:34, 12 February 2009 (UTC)
Are there likely to be any legal claims for compensation arising from this?
It seems like the Russian satellite was a derelict one, while the Iridum one was still operating. Had the russian orbit decayed from its' assigned path, or were they both still following their assigned orbital path? If one of them was off the assigned orbit, it seems like the other could claim damages against them. And probably for a large amount.
Or do such legal considerations even apply in space? What court would have jurisdiction to hear such a case? And what set of laws apply out there? Might be some precedents set here. T-bonham ( talk) 17:21, 12 February 2009 (UTC)
Let the Recent Space Wars and Demolitions begin. -- AaThinker ( talk) 18:27, 12 February 2009 (UTC)
According to the BBC the Russian satellite weighs 950kg (2,094lb). Not 900kg as stated. I haven't changed it, but can someone check which it is and correct it as appropriate
Link: http://news.bbc.co.uk/1/hi/sci/tech/7885051.stm?lss
Gunther says 900 kg and I'd believe him over the numbers-challenged BBC. Also, it was presumably out of fuel and hence weighed less. Potatoswatter ( talk) 21:30, 12 February 2009 (UTC)
Indeed. Apparently all the cosmos satellites weighed 900kg. I suggest we go with that figure. Although that figure doesn't include fuel usage, and more importantly, the Cosmos most likely wasn't out of fuel. 86.174.122.122 ( talk) 23:49, 14 February 2009 (UTC)
The two satellites are said to have been travelling at almost perpendicular paths. This means that we can more or less add their velocities together to get the velocity of the debris. A satellite in a circular orbit (Iridium 33 had a nearly circular one) which gets one single boost, will settle into an elliptical orbit with the height of the original orbit as its lowest point. The danger to spacecraft and satellites should therefore be greater above the Iridium orbit than below. EverGreg ( talk) 19:18, 12 February 2009 (UTC)
How the hell could have this been permitted to happen? Stationkeeping, anyone? Even if the Kosmos was unmanoeuverable, certainly the Iridium could have been raised to a slightly higher orbit? Even if it took many orbits of advance notice, this isn't supposed to be a problem for tracking stations, right? They should be able to tell well in advance that this would happen. —Preceding unsigned comment added by 146.193.39.206 ( talk) 19:40, 12 February 2009 (UTC)
SOCRATESdid not have it's probability listed. Don't know if COMBO did? Problem is TLE's have such large errors in them as state vectors even the computed probabilities at celestrak are really not very accurate. --aajacksoniv 19:42, 19 February 2009 (UTC)
Suppose you were responsible for GLOBALSTAR M045. Would you maneuver to avoid the conjunction with COSMOS 2253 coming up on 2009 Feb 18? There are 3 chances in 1000 of a collision.... What percent of the sat's fuel would you be willing to burn to decrease that probability to 3 chances in 10,000? SThis article would be better if it somehow clued readers in to the idea that Iridium may have faced a decision just like that.... ( sdsds - talk) 15:35, 13 February 2009 (UTC)
And why should someone make the operator take avoidance action? It is the operators satellite - who does it hurt more than the operator if it goes down? And how do we know that the iridium operators didn't try and manourver and that teh Russian sat didn't also manoeuver and hit it on purpose? Or that the Russian's hadn't agreed to maneuver their sat but their maneuver failed. No enough info for real debate amongst s non rocket sceintists. —Preceding unsigned comment added by 219.90.144.59 ( talk) 13:36, 14 February 2009 (UTC)
"absolutely no chance that they wouldn't know this was going to happen" Load of rubbish. Nasa frequently publishes "warnings" of "possible" collisions. Iridium satellites frequently appear in this list, but up till now, haven't actually suffered a collision DESPITE that they haven't manoeuvred their satellite. And the Russian satellite hasn't been operational since 1995. I think it is unlikely that the Russians would have been able to power it up 14 years later just to take out a communications satellite.
"since any actual manoeuvre taken would reduce the risk to zero." No it doesn't. If you make the wrong manoeuvre, you could actually increase the chance of a collision (of course, you might not realise at the time). That's why it's a Probability. And you don't want to be making lots of manoeuvres. It can slow your satellite down, and change it's orbit, increase atmospheric drag and that sort of thing. And what's to say that you don't then run the risk of hitting something else. And all the Iridium satellites are designed to work so that you can always see at least one at any given time. If you keep mucking around with the orbits, they won't be able to do so. —Preceding unsigned comment added by 86.174.122.122 ( talk) 23:58, 14 February 2009 (UTC)
You miss my point. The data that Nasa provide on likely collisions isn't accurate. They don't predict definite "collisions". They predict "potential collisions". Manoeuvres may lower the probability of being hit, but unless you do something drastic (which is obviously a bad idea because you want to keep it in that orbit), it only lowers the probability, not takes it to zero.
I suppose you could class this as 'not trusting you navigators enough', but bearing in mind this is the first incident between a working satellite and another satellite, I'd say they're good enough to risk 'putting the junk up there'. Sure this is a "Since it never happened before, all those warnings were clearly bogus" argument, but ever heard of 'The Boy Who Cried Wolf'? —Preceding unsigned comment added by 86.174.122.122 ( talk) 20:34, 17 February 2009 (UTC)
I think it should be mentioned in this article that the debris will be travelling around 25000 kph relative to the ground, and so if any of it happens to cross paths with another satellite it will cause significant damage. - ARC Gritt TALK 20:31, 12 February 2009 (UTC)
Perhaps, but the speed relative to the ground isn't a particularly great measure when you bear in mind that other satellites are travelling at the same speed. Although it appears that the debris is going to take an orbit that is neither polar nor geostationary/equatorial, which means it is more likely to cause damage to other satellites as it will be going in a different direction. —Preceding unsigned comment added by 86.131.102.102 ( talk) 20:48, 12 February 2009 (UTC)
I would love to see some discussion of the collision mechanics. The Iridium is physically large, with large solar panels. The Kosmos had only 40 W of solar capacity, implying around 1/2 square meter of solar panel. It would be possible the Iridium could be largely in one piece, missing a panel, and spinning (no doubt radar would soon verify this). The near-right-angle hit would not retard its orbital velocity, and would arguably impart some velocity to the right of its original orbit, an impulse leading to an elliptical orbit. However, it would seem to me conservation of momentum must apply. Can the debris cloud overall gain velocity? In the head-on case, bus to bus, I would expect considerable vaporization, and much of the debris would be either robbed of orbital velocity, or directed so vertically as to be almost certain to intercept the atmosphere quickly. Tomligon ( talk) 22:46, 12 February 2009 (UTC)
The result of the proposal was withdrawn, [3] no consensus (non-admin) -- G W … 00:49, 14 February 2009 (UTC)
There is nothing to say in the satellite articles except that they belonged to their respective classes and collided. Are there any objections to redirecting them here? Potatoswatter ( talk) 21:24, 12 February 2009 (UTC)
Hmm, just to justify this a bit.
What makes this major and the others smaller? Kingturtle ( talk) 21:45, 12 February 2009 (UTC)
I am not a huge fan of the current name, 2009 satellite collision. First of all, we are assuming this is going to be the only satellite collision in this year, while although these events are rare, we can't be for sure this will be the case. Second, the name really isn't a good descriptor. Remember that "satellite" doesn't just mean man made satellites, they can also refer to as moons as well. So for example, someone could read the title and think two of Jupiter's moons collided or something of that nature. Because of this, I would like to suggest a new name for the article: something along the lines of Collision of Iridium 33 and Kosmos-2251. Thoughts? Tavix (talk) 04:10, 13 February 2009 (UTC)
The result of the proposal was no consensus to support move. JPG-GR ( talk) 05:33, 20 February 2009 (UTC)
A photo of the Kosmos model should be added. 76.66.196.229 ( talk) 06:28, 13 February 2009 (UTC)
Computing estimated Collision Speed is not a research per se. It is basically using known mathematical formulas and constants (like Mass of the Earth and Gravitational constant) also collision angle is based computing orbits from NORAD TLEs. So I think this section should not be noted as Original Research. —Preceding unsigned comment added by Amoeba000 ( talk • contribs) 22:25, 14 February 2009 (UTC)
Would it be okay to present the English equivalents of the metric measures on this section of the article? -- 68.60.67.149 ( talk) 23:08, 14 February 2009 (UTC)
That would be OK. —Preceding unsigned comment added by 92.55.98.115 ( talk) 10:27, 15 February 2009 (UTC)
Thank you. -- 68.60.67.149 ( talk) 16:39, 15 February 2009 (UTC)
The article now shows Hugh Lewis's calculated collision speed of 42120 km/h which is exactly 11.7 metres per second and probably rounded. However, it is a big improvement on CNN's figure, and I am happy with the current approximation.
Meanwhile, for curiosity's sake, here is the Collision speed computation (removed from the article as Original Research). I have tweaked the numbers and added a few cites.
It assumes both satellite orbits are perfectly circular when they are in fact ellipses. It also assumes the Earth is spherical and homogenous (it's not). The first assumption will under-calculate collision velocities close to perigee. Using a 789 km collision altitude and 102.2 collision angle yields 11.62 km/s. But using 776 km collision altitude (from JSR) and 102.46 collision angle (from a physics forum) I get 11.65 km/s (which verifies BobG's calculation).
The approximate collision speed is based on the velocities of the satellites and the angle at which they collided. Estimated speed of each satellite at an altitude of approximately 789 kilometers above earth was v=7.467 metres per second (26.88 km/h). This is computed by the formula for speed of a satellite in circular orbit which is , where G is the gravitational constant (6.6726 E-11 (N-m2)/kg2), M is the mass of the combined planet/satellite system (Earth's mass is 5.9736 E24 kg), [1] and r is the radius of the orbit measured from the planet's center in our case r=7,149 Km. [2]
The angle at which the satellites collided was measured using Satellite tracking software (Simulation des GPS v2.41), and was approximately 102.2 degrees. Other sources have 102.46 degrees. [3] The input data for the tracking software were from updated NORAD TLE.
The combined collision speed is as follows: , which gives 41,840 kilometres per hour (26,000 mph) (or 11.622 kilometres per second). [3]
The Orlando Sentinel reports the event to have been, "what amounted to a 26,000 mph collision." [4]
They hit each other at an angle of 102.46 degrees, giving them a closing speed of about 11.65 km/sec
84user ( talk) 03:21, 17 February 2009 (UTC)
'Russia has not commented on claims the satellite was out of control.' The term 'out of control' suggests the russian satellite did something unexpected thereby being at fault, causing the accident. If there is no evidence for that unexpected move (reference) this statement should be removed since article&ref contain an unverifiable claim harming NPOV. 82.95.200.104 ( talk) 23:34, 14 February 2009 (UTC)
Perhaps "There is no reason to suspect that any malicous action was involved, since the Russian satellite had been defunct since 1995 (I'll get the reference later). Russia has not commented on whether the satellite was out of control"
Although it's not really neutral, but it is a balance POV. 86.174.122.122 ( talk) 00:04, 15 February 2009 (UTC)
The whole sentence should be removed because it is false. The head of the Russian Space Forces was quoted in the Moscow Times as saying they haven't used it since at least 1995. (An astronautix.com article actually says the Strela-2M's were superceded by a constellation of Strela 3-M's in 1994.) And BTW, orbits are not "completely predictable". There are lots of chaotic forces, gravitational moments, drag, the Moon, magnetic fields, etc. It fact, the Cosmos 2251 was actually INCREASING in altitude at the time of the collision. Rather strange for an unpowered craft, wouldn't you say? --Warren Platts 75.68.200.190 ( talk) 18:31, 19 February 2009 (UTC)
Has it not occured to anyone that the orbit is slightly elliptical, so when it is moving perigee to apogee, it's altitude will increase? 86.150.129.117 ( talk) 22:57, 23 February 2009 (UTC)
It appears that there are a number of inconsistencies in the exact data about the collision at the moment. (My) previous comment about the mass of the Russian satellite is a case and point. The (nice) picture depicting the point of collision claims that the collision was at a different altitude to that in the main article. I suggest that we should decide on a value for it and stick with that. I know this might seem to be nit-picking, but even if we are unsure of the correct value, I think we should at least be consistent. 86.174.122.122 ( talk) 21:23, 15 February 2009 (UTC)
I have since found two sites that agree on a value of 789/790km: http://www.n2yo.com/collision-between-two-satellites.php http://www.space.com/news/090211-satellite-collision.html
I suggest we use this value. —Preceding unsigned comment added by 86.174.122.122 ( talk) 23:16, 15 February 2009 (UTC)
In the interest of consistency, I have to support a title that refers to the actual satellites. If you go to the disambiguation page for satellite collisions: http://en.wikipedia.org/wiki/Satellite_collision. then you'll see the other 'collisions' are labelled by the satellites that collided. 86.150.129.117 ( talk) 21:15, 7 March 2009 (UTC)
There should be something about the impact to the Iridium network, communications, risks, etc 76.66.196.229 ( talk) 07:43, 17 February 2009 (UTC)
This entry doesn't explain *why* they collided. Was there some mistake in calculating the orbits? Did some equipment malfunction? -- 209.203.125.162 ( talk) 19:04, 16 December 2013 (UTC)
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"Space News listed the collision as the fourth biggest fragmentation event in history," - is that the biggest space fragmentation? what is a "fragmentation event"? I can believe this is the fourth biggest space fragmentation event, but surely at least four things in history have fragmented into more pieces...? — Preceding unsigned comment added by 165.225.50.89 ( talk) 23:30, 22 February 2019 (UTC)
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I live in Kentucky, and for the last two days we have heard low, loud, and rumbling explosions every couple of hours over several counties. It is supposidly the debris re-entering the atmosphere.
Was wondering if anyone else had experienced this? Even makes you wonder what was on that satellite after two days...( 66.156.138.35 ( talk) 16:45, 14 February 2009 (UTC))
NORAD was moments away from an emergency public broadcast in Canada re debris. I'm not sure why there is mention of 'radioactive' debris in this newspaper article either. Calgary is a major city (pop. 1 million) in the province of Alberta. http://www.calgaryherald.com/entertainment/Calgary+dodges+space+junk/1290211/story.html —Preceding unsigned comment added by 204.191.190.96 ( talk) 05:20, 11 June 2009 (UTC)
Perhaps I'm reading this too literally, but nowhere in the article does it say that this was an accident. I assume it was, but it is entirely possible to read this article and assume that the satellites were forced to collide on purpose, without a reason given. Would it be agreeable to change it to include the words "accidental" or "unexpected?" —Preceding unsigned comment added by 216.54.22.188 ( talk) 19:11, 12 February 2009 (UTC)
I don't know exactly how satellite tracking works, but it may be possible that since it was a defunct Russian satellite that it was only being tracked by Russia, not by NASA (i.e. cold war relic). As these satellites are in relatively low earth orbits, I don't know whether the cumulative effect of the atmosphere on the long lived Russian satellite may have caused this. Or alternatively it is possible (although it appears unlikely) that it was a deliberate attempt to test ways to knock other satellites out of orbit/ destroy them. —Preceding unsigned comment added by 86.131.102.102 ( talk) 20:43, 12 February 2009 (UTC)
BTW, i'm the same guy as the post from IP 146.193.39.206. —Preceding unsigned comment added by 89.152.245.176 ( talk) 00:32, 13 February 2009 (UTC)
There is a war on. As I understand it US and NATO/Coalition partners have been buying pretty much all the commercial satllite time they can get. I can't imagine that running those satellites in unprofitable at the moment - although Iguess the projected withdrawals from Iraq might make it so.
ON the subject of it the orbits could be predicted then why was the Iridum satellite not moved out of the way. Well may it had no maneuvering fuel left. Or maybe it had enough to move it away and not enough to put it back in a useul orbit. IN which case they are better of leaving it where it is an hoping for a miss.
Just a thought. (or two) 219.90.144.59 ( talk) —Preceding undated comment was added at 13:26, 14 February 2009 (UTC).
"Well may it had no maneuvering fuel left." It does. Or at least Iridium claim they could have manoeuvred it.Nasa, whilst they tracked both objects, predicted them to miss each other by a large margin (were talking tens/hundreds of kilometres- i can't remember the exact value). For the record, the cost to maintain one less satellite is effectively zero, since they still have to track the other 71 or so and use them. Your point about the gain from the insurance is valid. I thought the implication was that the company weren't making money, and that a collision with one of there satellites was a way to recoup losses. 86.174.122.122 ( talk) 23:45, 14 February 2009 (UTC)
The USSSN is of course tracking *all* objects it can detect, no matter who launched a particular object. For the reason why no evasive actions were taken, it might probably be that starting evasive maneuvers for every possible close encounter in LEO is simply not feasible: "At the time, Campbell said that Iridium was receiving an average of 400 reports per week of objects coming within 5 km of one of their satellites." and "Using a collision prediction program to perform a retroactive analysis of the satellites' orbits, aerospace analyst T S Kelso found that the Pentagon's public data showed that the two satellites would have missed each other by 584 metres." ( [1]) -- Cruncher ( talk) 04:42, 19 February 2009 (UTC)
presumably this 584 metre prediction is attributable to the Intel Pentium floating point bug? 75.87.134.179 ( talk) 19:00, 20 July 2009 (UTC)
I started this article because the news said it was the first satellite collision, which I thought was noteworthy. If this is not the first such collision, then perhaps this isn't deserving of its own article. I will trust whatever a concensus of editors decides. Grundle2600 ( talk) 02:23, 12 February 2009 (UTC)
The "collisions" between DART and MUBLCOM and between Progress and Mir occured during deliberate attempts to bring two spacecrafts together slowly. So they were very different. The collision of Cerise, however, was quite similar. It too featured a functioning satellite colliding completely accidentally with space debris. The only difference is that in the 2009 event, the other object colliding was an old, "dead" satellite, so we have two real satellites colliding. In 1996 it was a satellite meeting a piece of debris that was not designed to be a functioning satellite. / 129.142.71.166 ( talk) 16:38, 12 February 2009 (UTC)
For whoever is interested here are links to the ground track plots of both satellites at the time of collision, courtesy of Heavens-Above:
84user ( talk) 15:23, 12 February 2009 (UTC)
Damn, that's closer to a head-on collision than I would've imagined! Potatoswatter ( talk) 21:34, 12 February 2009 (UTC)
Are there likely to be any legal claims for compensation arising from this?
It seems like the Russian satellite was a derelict one, while the Iridum one was still operating. Had the russian orbit decayed from its' assigned path, or were they both still following their assigned orbital path? If one of them was off the assigned orbit, it seems like the other could claim damages against them. And probably for a large amount.
Or do such legal considerations even apply in space? What court would have jurisdiction to hear such a case? And what set of laws apply out there? Might be some precedents set here. T-bonham ( talk) 17:21, 12 February 2009 (UTC)
Let the Recent Space Wars and Demolitions begin. -- AaThinker ( talk) 18:27, 12 February 2009 (UTC)
According to the BBC the Russian satellite weighs 950kg (2,094lb). Not 900kg as stated. I haven't changed it, but can someone check which it is and correct it as appropriate
Link: http://news.bbc.co.uk/1/hi/sci/tech/7885051.stm?lss
Gunther says 900 kg and I'd believe him over the numbers-challenged BBC. Also, it was presumably out of fuel and hence weighed less. Potatoswatter ( talk) 21:30, 12 February 2009 (UTC)
Indeed. Apparently all the cosmos satellites weighed 900kg. I suggest we go with that figure. Although that figure doesn't include fuel usage, and more importantly, the Cosmos most likely wasn't out of fuel. 86.174.122.122 ( talk) 23:49, 14 February 2009 (UTC)
The two satellites are said to have been travelling at almost perpendicular paths. This means that we can more or less add their velocities together to get the velocity of the debris. A satellite in a circular orbit (Iridium 33 had a nearly circular one) which gets one single boost, will settle into an elliptical orbit with the height of the original orbit as its lowest point. The danger to spacecraft and satellites should therefore be greater above the Iridium orbit than below. EverGreg ( talk) 19:18, 12 February 2009 (UTC)
How the hell could have this been permitted to happen? Stationkeeping, anyone? Even if the Kosmos was unmanoeuverable, certainly the Iridium could have been raised to a slightly higher orbit? Even if it took many orbits of advance notice, this isn't supposed to be a problem for tracking stations, right? They should be able to tell well in advance that this would happen. —Preceding unsigned comment added by 146.193.39.206 ( talk) 19:40, 12 February 2009 (UTC)
SOCRATESdid not have it's probability listed. Don't know if COMBO did? Problem is TLE's have such large errors in them as state vectors even the computed probabilities at celestrak are really not very accurate. --aajacksoniv 19:42, 19 February 2009 (UTC)
Suppose you were responsible for GLOBALSTAR M045. Would you maneuver to avoid the conjunction with COSMOS 2253 coming up on 2009 Feb 18? There are 3 chances in 1000 of a collision.... What percent of the sat's fuel would you be willing to burn to decrease that probability to 3 chances in 10,000? SThis article would be better if it somehow clued readers in to the idea that Iridium may have faced a decision just like that.... ( sdsds - talk) 15:35, 13 February 2009 (UTC)
And why should someone make the operator take avoidance action? It is the operators satellite - who does it hurt more than the operator if it goes down? And how do we know that the iridium operators didn't try and manourver and that teh Russian sat didn't also manoeuver and hit it on purpose? Or that the Russian's hadn't agreed to maneuver their sat but their maneuver failed. No enough info for real debate amongst s non rocket sceintists. —Preceding unsigned comment added by 219.90.144.59 ( talk) 13:36, 14 February 2009 (UTC)
"absolutely no chance that they wouldn't know this was going to happen" Load of rubbish. Nasa frequently publishes "warnings" of "possible" collisions. Iridium satellites frequently appear in this list, but up till now, haven't actually suffered a collision DESPITE that they haven't manoeuvred their satellite. And the Russian satellite hasn't been operational since 1995. I think it is unlikely that the Russians would have been able to power it up 14 years later just to take out a communications satellite.
"since any actual manoeuvre taken would reduce the risk to zero." No it doesn't. If you make the wrong manoeuvre, you could actually increase the chance of a collision (of course, you might not realise at the time). That's why it's a Probability. And you don't want to be making lots of manoeuvres. It can slow your satellite down, and change it's orbit, increase atmospheric drag and that sort of thing. And what's to say that you don't then run the risk of hitting something else. And all the Iridium satellites are designed to work so that you can always see at least one at any given time. If you keep mucking around with the orbits, they won't be able to do so. —Preceding unsigned comment added by 86.174.122.122 ( talk) 23:58, 14 February 2009 (UTC)
You miss my point. The data that Nasa provide on likely collisions isn't accurate. They don't predict definite "collisions". They predict "potential collisions". Manoeuvres may lower the probability of being hit, but unless you do something drastic (which is obviously a bad idea because you want to keep it in that orbit), it only lowers the probability, not takes it to zero.
I suppose you could class this as 'not trusting you navigators enough', but bearing in mind this is the first incident between a working satellite and another satellite, I'd say they're good enough to risk 'putting the junk up there'. Sure this is a "Since it never happened before, all those warnings were clearly bogus" argument, but ever heard of 'The Boy Who Cried Wolf'? —Preceding unsigned comment added by 86.174.122.122 ( talk) 20:34, 17 February 2009 (UTC)
I think it should be mentioned in this article that the debris will be travelling around 25000 kph relative to the ground, and so if any of it happens to cross paths with another satellite it will cause significant damage. - ARC Gritt TALK 20:31, 12 February 2009 (UTC)
Perhaps, but the speed relative to the ground isn't a particularly great measure when you bear in mind that other satellites are travelling at the same speed. Although it appears that the debris is going to take an orbit that is neither polar nor geostationary/equatorial, which means it is more likely to cause damage to other satellites as it will be going in a different direction. —Preceding unsigned comment added by 86.131.102.102 ( talk) 20:48, 12 February 2009 (UTC)
I would love to see some discussion of the collision mechanics. The Iridium is physically large, with large solar panels. The Kosmos had only 40 W of solar capacity, implying around 1/2 square meter of solar panel. It would be possible the Iridium could be largely in one piece, missing a panel, and spinning (no doubt radar would soon verify this). The near-right-angle hit would not retard its orbital velocity, and would arguably impart some velocity to the right of its original orbit, an impulse leading to an elliptical orbit. However, it would seem to me conservation of momentum must apply. Can the debris cloud overall gain velocity? In the head-on case, bus to bus, I would expect considerable vaporization, and much of the debris would be either robbed of orbital velocity, or directed so vertically as to be almost certain to intercept the atmosphere quickly. Tomligon ( talk) 22:46, 12 February 2009 (UTC)
The result of the proposal was withdrawn, [3] no consensus (non-admin) -- G W … 00:49, 14 February 2009 (UTC)
There is nothing to say in the satellite articles except that they belonged to their respective classes and collided. Are there any objections to redirecting them here? Potatoswatter ( talk) 21:24, 12 February 2009 (UTC)
Hmm, just to justify this a bit.
What makes this major and the others smaller? Kingturtle ( talk) 21:45, 12 February 2009 (UTC)
I am not a huge fan of the current name, 2009 satellite collision. First of all, we are assuming this is going to be the only satellite collision in this year, while although these events are rare, we can't be for sure this will be the case. Second, the name really isn't a good descriptor. Remember that "satellite" doesn't just mean man made satellites, they can also refer to as moons as well. So for example, someone could read the title and think two of Jupiter's moons collided or something of that nature. Because of this, I would like to suggest a new name for the article: something along the lines of Collision of Iridium 33 and Kosmos-2251. Thoughts? Tavix (talk) 04:10, 13 February 2009 (UTC)
The result of the proposal was no consensus to support move. JPG-GR ( talk) 05:33, 20 February 2009 (UTC)
A photo of the Kosmos model should be added. 76.66.196.229 ( talk) 06:28, 13 February 2009 (UTC)
Computing estimated Collision Speed is not a research per se. It is basically using known mathematical formulas and constants (like Mass of the Earth and Gravitational constant) also collision angle is based computing orbits from NORAD TLEs. So I think this section should not be noted as Original Research. —Preceding unsigned comment added by Amoeba000 ( talk • contribs) 22:25, 14 February 2009 (UTC)
Would it be okay to present the English equivalents of the metric measures on this section of the article? -- 68.60.67.149 ( talk) 23:08, 14 February 2009 (UTC)
That would be OK. —Preceding unsigned comment added by 92.55.98.115 ( talk) 10:27, 15 February 2009 (UTC)
Thank you. -- 68.60.67.149 ( talk) 16:39, 15 February 2009 (UTC)
The article now shows Hugh Lewis's calculated collision speed of 42120 km/h which is exactly 11.7 metres per second and probably rounded. However, it is a big improvement on CNN's figure, and I am happy with the current approximation.
Meanwhile, for curiosity's sake, here is the Collision speed computation (removed from the article as Original Research). I have tweaked the numbers and added a few cites.
It assumes both satellite orbits are perfectly circular when they are in fact ellipses. It also assumes the Earth is spherical and homogenous (it's not). The first assumption will under-calculate collision velocities close to perigee. Using a 789 km collision altitude and 102.2 collision angle yields 11.62 km/s. But using 776 km collision altitude (from JSR) and 102.46 collision angle (from a physics forum) I get 11.65 km/s (which verifies BobG's calculation).
The approximate collision speed is based on the velocities of the satellites and the angle at which they collided. Estimated speed of each satellite at an altitude of approximately 789 kilometers above earth was v=7.467 metres per second (26.88 km/h). This is computed by the formula for speed of a satellite in circular orbit which is , where G is the gravitational constant (6.6726 E-11 (N-m2)/kg2), M is the mass of the combined planet/satellite system (Earth's mass is 5.9736 E24 kg), [1] and r is the radius of the orbit measured from the planet's center in our case r=7,149 Km. [2]
The angle at which the satellites collided was measured using Satellite tracking software (Simulation des GPS v2.41), and was approximately 102.2 degrees. Other sources have 102.46 degrees. [3] The input data for the tracking software were from updated NORAD TLE.
The combined collision speed is as follows: , which gives 41,840 kilometres per hour (26,000 mph) (or 11.622 kilometres per second). [3]
The Orlando Sentinel reports the event to have been, "what amounted to a 26,000 mph collision." [4]
They hit each other at an angle of 102.46 degrees, giving them a closing speed of about 11.65 km/sec
84user ( talk) 03:21, 17 February 2009 (UTC)
'Russia has not commented on claims the satellite was out of control.' The term 'out of control' suggests the russian satellite did something unexpected thereby being at fault, causing the accident. If there is no evidence for that unexpected move (reference) this statement should be removed since article&ref contain an unverifiable claim harming NPOV. 82.95.200.104 ( talk) 23:34, 14 February 2009 (UTC)
Perhaps "There is no reason to suspect that any malicous action was involved, since the Russian satellite had been defunct since 1995 (I'll get the reference later). Russia has not commented on whether the satellite was out of control"
Although it's not really neutral, but it is a balance POV. 86.174.122.122 ( talk) 00:04, 15 February 2009 (UTC)
The whole sentence should be removed because it is false. The head of the Russian Space Forces was quoted in the Moscow Times as saying they haven't used it since at least 1995. (An astronautix.com article actually says the Strela-2M's were superceded by a constellation of Strela 3-M's in 1994.) And BTW, orbits are not "completely predictable". There are lots of chaotic forces, gravitational moments, drag, the Moon, magnetic fields, etc. It fact, the Cosmos 2251 was actually INCREASING in altitude at the time of the collision. Rather strange for an unpowered craft, wouldn't you say? --Warren Platts 75.68.200.190 ( talk) 18:31, 19 February 2009 (UTC)
Has it not occured to anyone that the orbit is slightly elliptical, so when it is moving perigee to apogee, it's altitude will increase? 86.150.129.117 ( talk) 22:57, 23 February 2009 (UTC)
It appears that there are a number of inconsistencies in the exact data about the collision at the moment. (My) previous comment about the mass of the Russian satellite is a case and point. The (nice) picture depicting the point of collision claims that the collision was at a different altitude to that in the main article. I suggest that we should decide on a value for it and stick with that. I know this might seem to be nit-picking, but even if we are unsure of the correct value, I think we should at least be consistent. 86.174.122.122 ( talk) 21:23, 15 February 2009 (UTC)
I have since found two sites that agree on a value of 789/790km: http://www.n2yo.com/collision-between-two-satellites.php http://www.space.com/news/090211-satellite-collision.html
I suggest we use this value. —Preceding unsigned comment added by 86.174.122.122 ( talk) 23:16, 15 February 2009 (UTC)
In the interest of consistency, I have to support a title that refers to the actual satellites. If you go to the disambiguation page for satellite collisions: http://en.wikipedia.org/wiki/Satellite_collision. then you'll see the other 'collisions' are labelled by the satellites that collided. 86.150.129.117 ( talk) 21:15, 7 March 2009 (UTC)
There should be something about the impact to the Iridium network, communications, risks, etc 76.66.196.229 ( talk) 07:43, 17 February 2009 (UTC)
This entry doesn't explain *why* they collided. Was there some mistake in calculating the orbits? Did some equipment malfunction? -- 209.203.125.162 ( talk) 19:04, 16 December 2013 (UTC)
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"Space News listed the collision as the fourth biggest fragmentation event in history," - is that the biggest space fragmentation? what is a "fragmentation event"? I can believe this is the fourth biggest space fragmentation event, but surely at least four things in history have fragmented into more pieces...? — Preceding unsigned comment added by 165.225.50.89 ( talk) 23:30, 22 February 2019 (UTC)