Why Shoot Down a Satellite? Analyzing an Analysis 238
A reader, name withheld by request, writes "Writing in the IEEE Spectrum, James Oberg analyzes whether there was, in fact a significant risk to humans from the satellite which the US military shot down on 21 February, purportedly 'to head off the possibility of its splashing a half ton of toxic hydrazine fuel somewhere on Earth.' Previous experts had 'scoffed' at the rationale put forth, pointing out that there was trivial possibility that any significant amount of toxic fuel would make it to the ground intact. Oberg's analysis, titled 'the inside story,' purports to debunk this, and claims that indeed it's possible, and even likely, that there could be a danger to the ground. Unfortunately, the analysis is full of flaws and lack of rigor — indeed, lacking any sort of numerical reasoning. It seems to be too much repeating official 'spin,' and could have used a hefty dose of skepticism — and could also use a little bit of actual analysis using numbers, rather than handwaving." Read on for the rest of an interesting analysis of a topic that suddenly seems more complex.
The submitter continues:
"Here's the first number that Oberg should have quoted: 32 Megajoules per kilogram. That's orbital energy, which is how much energy has to be removed by ablation or otherwise dissipated for the hydrazine tank to enter the atmosphere and hit the ground undamaged. For reference, TNT holds about 4.6 MJ/kg.
Oberg quotes 'Hydrazine requires a tremendous amount of energy to go from solid to liquid.' This energy is known as the heat of fusion, and for hydrazine it is just a little under 400 kJ/kg. That's about 1% of the energy released by entry heating. Hardly a 'tremendous' amount of energy, compared to the entry energy that's nearly a hundred times greater.
Oberg goes on to quote 'There is a widespread notion that meteorites falling to Earth arrive red hot.' He is correct here. In fact, meteorites falling through the atmosphere typically explode, shattering into dozens or hundreds of pieces; something that occurs at the point when the dynamic pressure on the leading face exceeds the yield stress of the material. This occurs for meteoroids of all compositions, including nickle-iron meteorites that are far more robust than hydrazine tanks. If the atmospheric entry of meteorites is relevant, it hardly bolsters the case that a tank will enter intact (and if it's not relevent, why did Oberg bring it up?)
Furthermore, if you look at a typical nickle-iron meteorite, you'll see a surface pitted and mottled with holes ranging from the size of golf balls up to pits the size of baseballs. These are known as regmaglypts; they are the areas ablated away by the entry plasma. Even a single such ablation pit would, of course, destroy a hydrazine tank.
The second number Oberg should have quoted is a number called ballistic coefficient, the mass divided by the area of the tank. Basically, the smaller the ballistic coefficient, the less stressful the entry will be. Unfortunately, a full hydrazine tank has a very high ballistic coefficient. It is an empty tank, not a full one, that is likely to enter intact. Talking about empty film canisters, or even empty fuel tanks, making it intact through atmospheric entry is really about as relevant as talking about dropping a piece of paper on the floor.
The article contains a quote from Andrew Higgins, with a link to (purportedly) the research done that contains the quote. Unfortunately the link does not actually contain the quote used in the article; in fact, it seems to be mostly a discussion of a side issue. Let me emphasize this: Higgins did not say what he is quoted as saying in the place he was reported as saying it. This may merely be sloppy journalism — maybe he said it somewhere else — but I am again left with the question: if I can't even trust the simplest things he says that can be easily checked, why should I trust anything else?
In short, Oberg's article is poorly thought out, avoids even simple back-of-the-envelope calculations, and accepts uncritically information that should have been aggressively questioned. He concludes that a well-defined and thoroughly researched technological hazard assessment — of a kind that someday, for better or worse, will be needed again — has wound up buried in obscurity and obfuscation. This may be true, but no well defined nor thoroughly researched technological hazard assessment was anywhere in evidence. The analysis he gives in the article is buried in obscurity and obfuscation.
(apologies for posting as Anonymous Coward. I work in the field.)"
We all know it was an excuse (Score:2, Insightful)
To test our new weapons and show the Chinese how we roll.
Re:We all know it was an excuse (Score:5, Interesting)
To test our new weapons and show the Chinese how we roll.
That's half of it. While there was a possibility of hydrazine rain, I think we also have to consider that this was state of the art spy satellite which was part of a much larger network of spy satellites. If this thing were to make it to the ground even partially intact, it would be a treasure trove of information concerning the US spy satellite ability and could possibly show a way to counter the shiny new spy network we spent so much money deploying.
Re: (Score:3, Insightful)
If that is the case, we only have to recall how large of an operation it was to track down the Blackbox (because of its comm equipment) on the Columbia in 2003. How this differs from stealing the comm equipment from an F-16 crashing in a warzone or a comm-soldier in a battle, I'm unsure. I seem to recall footage on CNN of the National Guard being deployed in full force. Its obviously pre-planned if such an event occurs or was a tour-de-force should a similar a more serious event (like spy-satellite crash) o
Re:We all know it was an excuse (Score:5, Insightful)
I doubt much more was going on than the testing of space weaponry in plain sight.
But why aren't we more upset about that? Is it really just OK that our government is openly defying the treaties that prevent the weaponization of space?
This is why conspiracies bug me so much. People believe the government lies and thus focus their attentions on grandiose and outlandish possible lies and cover-ups, rather than pay attention to all of the 100% verifiable medium-sized lies that the government tells day in and day out. Rather than fabricate an entire false narrative, the way to do it these days seems to be admit to 80% of what really happened, lie your pants off even if people will call you on it, and wait for the news cycle to pass on by the 20% that didn't add up.
Seriously, we've all but caught our government in an act that is very formally (as in, it would piss off thomas jefferson and not just moveon.org) against the principles of our democracy. What more conspiracy do we need?
IEEE Spectrum is not a government source (Score:4, Informative)
Re:IEEE Spectrum is not a government source (Score:5, Insightful)
Except that James Oberg [jamesoberg.com] is an expert [jamesoberg.com] (or at least damn close to one, read the resumes linked off the second link.) - having been a mission controller for NASA and a professional space engineer, analyst, writer, and journalist for decades. Synchronicity at work - as part of a research project I'm working on, Jim's 1982 book Mission to Mars sits right beside my coffee cup even as I type this...
That being said - the debunking is full of errors as well. The AC provides us with a wonderful handwaving smoke and mirrors show, but fails to acknowledge the role of the structure of the tank itself (which is insulated and has to be accounted for before the Hydrazine starts to vaporize). He also fails to acknowledge the role the structure of the satellite plays, as it too will act as shielding (and a drag brake!) for the tank. (I know Jim is aware of these factors because I've discussed them with him.)
In short, what the AC claims is a debunking is actually closer to being a partial rationale for conducting the shootdown.
I don't know what 'field' the AC works in, but to this knowledgeable non expert he doesn't sound like an expert at all - but rather sounds like someone with an axe to grind. If he is an expert, he has allowed bias to supplant analysis.
Re:IEEE Spectrum is not a government source (Score:5, Informative)
There's a number of good papers out there on how this is analyzed, if someone is seriously interested I'll post some citations, I'm away from the office today.
Re: (Score:3, Interesting)
I'm posting AC and I can't say who for obvious reasons, but I know someone involved in the project and I said to them "sooo hydrazine eh?" and they laughed.
All of this analysis is unneeded the reality is they did it whether it was needed or not, because it allowed them to show that they could and it allowed them to do it in a much safer way that did not result in a debris cloud in orbit.
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Re: (Score:3, Informative)
You misunderstand the reports then - they survived a portion of the reentry (the early, least stressful portion) with the capsule oriented improperly. Long before max heating proper orientation was restored.
Which is amply supported by histor
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You can consider myself corrected.
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I don't know either. Didn't an almost intact hydrazine tank from the Columbia survive? Of course the ballistics.
Oops... (Score:5, Informative)
Nice try on the anonymity, but there's your name on the Related Stories list with the original Firehose posting...
Re:Oops... (Score:5, Funny)
That wins the award 'Epic Fail of the Week'.
And a cookie.
Re: (Score:2)
Re: (Score:2, Funny)
Re:Oops... (Score:5, Informative)
Actually, looks like /. code epic failed. He clicked the "withhold my name" button on the submission but it didn't withhold his name from the firehose section.
Min
Poor Geoffrey A. Landis (Score:2, Funny)
http://www.sff.net/people/geoffrey.landis/ [sff.net]
http://mit.edu/aeroastro/www/people/landis/landis.html [mit.edu]
You're at the Massachusetts Institute for Technology and can not practice simple internet privacy.
elle oh elle to you, good sir.
Re:Poor Geoffrey A. Landis (Score:4, Insightful)
And you cannot practice simple human courtesy. WTF compels you to post that?
Re: (Score:3, Insightful)
You must be new here. Slashdot routinely posts people's addresses and telephone/fax numbers (both home and work).
Re: (Score:2, Interesting)
I'm sure the submitter had a reason to want to post this anonymously. He made a mistake, but his intention was clear. There was no reason to be an asshole and repost his name here, just in case it's removed by one of the editors.
Also, it's interesting that all the people posting his name here are posting as AC. Perhaps they weren't quite as sure about this as they claim.
Re: (Score:2)
At least the labeling is accurate:
"scientist and science-fiction writer" ;)
Re: (Score:2)
Should you ever have something of value to post that you don't want your name attached to, you'll know how to do it. Great.
Not everybody spends his entire day here and knows exactly what shows up where. This is a major goof by the editor who posted this, who you can expect to know that, and who should have done something to prevent it. But blaming somebody who posts actual, original content (which happens here maybe once a year) for a small mistake is childish.
The real reason (Score:2)
Some US General wanted to see if the word 'IMPRESSIVE' would be emblazoned across the sky when they hit it.
Stupid Question... (Score:5, Insightful)
What was the risk of shooting it down? It seems close to "none." The missile used would surely have a mechanism to self-destruct in the event of a miss, and even if it didn't, I don't see how its falling could be any more dangerous than the hydrazine. Plus, it was probably a useful training exercise, should they ever need to shoot down a "really" dangerous satellite.
Of course, since it was done months ago, it's all hypothetical anyway.
Re:Stupid Question... (Score:5, Interesting)
The risk of shooting it down and, at least the way I see it, our big reason for having to justify it was that we had so recently criticized the Chinese for shooting down one of theirs.
Of course, the technology we used was wildly different than the technology that the Chinese used. And we didn't clutter up useful orbit space with a bunch of debris when we were done. But these things don't always matter to people just looking for a reason to US bash. There are a lot of folks out there that were calling the US hypocrites for shooting down their satellite after bashing the Chinese for doing "the same thing".
scuse my ignorance (Score:2)
we didn't clutter up useful orbit space with a bunch of debris when we were done
Just how was that achieved?
Re: (Score:2)
we didn't clutter up useful orbit space with a bunch of debris when we were done
Just how was that achieved?
When we (the US) shot ours down [wikipedia.org], it was in a rapidly decaying orbit and it fell into the atmosphere after being blasted. The Chinese satellite, however, was still in a maintained orbit and when they took it out [wikipedia.org], it was the "largest recorded creation of space debris in history with at least 2317 pieces of trackable size (golf ball size and larger), thereby increasing the total number of currently tracked objects in earth orbit by more than 22%.." Source. [nytimes.com]
Re:Stupid Question... (Score:5, Insightful)
The end result is exactly the same and has nothing to do with US bashing.
The end result of the Chinese shot is a huge amount of space-junk cluttering up an otherwise useful orbit. The end result of the US shot was the relatively tidy destruction of a spy satellite with no risk of accidentally allowing sensitive components to be recovered.
I fail to understand how these are "exactly the same".
Re: (Score:2)
OP has collateral damage blindness.
Re:Stupid Question... (Score:4, Insightful)
Well, you're 100% correct if the only thing that matters is the ostensibly intended consequences.
However, if we are talking about unintended, but foreseeable consequences, as the GP is, you are missing the point.
I'm inclined to agree with the GPs framing of this issue. Satellites have a limited lifespan, and political statements even shorter lifespans. The space junk in question will be up there a long time after the political statement is forgotten.
Re:Stupid Question... (Score:5, Insightful)
The end result was a non-functional satellite.
In the US shot [wikipedia.org], they converted a non-functional satellite into basically nothing. In the Chinese test [wikipedia.org], they converted a (presumably) functional satellite into 2317 trackable pieces of space debris and increased the number of trackable pieces of space junk in Earth orbit by more than 22%. So the consequences of these two shots aren't even roughly equivalent because the end results are vastly different. If the only side you're looking at is the potential arms race, then sure, we both shot down satellites. But China made a huge mess while they were showing off while we did it pretty cleanly. And the US didn't even really need to flex its satellite killing power, since we already did that back in 1985 [wikipedia.org].
So I really don't see any correlation with your "cheating on your wife with a single woman = cheating on your wife with a married woman" analogy. This, to me, seems like cheating on your wife and spreading gonorrhea all over town vs burying your wife after she's passed away.
I swear, sometimes it seems like people try to be dense.
You have no idea how well that's coming across.
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We (citizens of the rest of the world) weren't annoyed about space junk; frankly most of us couldn't care less about orbitting [sic] debris.
That should piss you off. You're obviously looking much more toward short term military/political goals than long term planet-usability.
But by all means put it down to "US bashing". After all, why should the US have to live up to the same standards as everyone else when it can go around bullying everyone, right?
The US proved its ASAT ability in 1985 and hasn't touched it since. It wanted to protect national secrets and used this hazmat fuel as an excuse. Saber-rattling? Maybe, but the US proved competence in this arena long ago and used anti-ICMB tech rather than ASAT tech like the Chinese. Nobody who knows anything about the subject would compare the two (although I admit th
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Not really.
1. China was demonstrating that they had a working and deployed anti-satellite weapon system.
2. The satellite was destroyed in a high active orbit creating a huge amount of very dangerous space junk. That will remain in orbit for many years.
The US modified an anti-ballistic missile system to take out a satellite that was in a decaying orbit. Just a few weeks after the impact the debris reentered the atmosphere and where no longer a threat. After the shoot down the modifications where publicly rem
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Re:Stupid Question... (Score:5, Funny)
If we did not shoot it down we would lose one of our missile sites or one of our 6 cities!
Loss of a city is not bad, but loss of the center missile site can make life a bitch as that satellite comes by..
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Yeah. But if the missile misses you only have to shoot two more up - one for the satellite and one for the missile. Face it, someone in Washington wanted to play "Missile Command" which they miss from playing in the arcades or on their Atari. They didn't want to run a MAME emulator. Meh, what's the difference with the real thing? Last time somebody did that they thought "Global Thermonuclear Warfare" was a fun game to play.
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Aside from the fact they didn't shoot it down, just blast it into more little bits of high-speed space debris whizzing about in orbit, which pose a considerable hazard to useful satellites and anything else we want up in orbit (shuttles and space stations, for example).
Re:Stupid Question... (Score:4, Interesting)
Wait, are you talking about the Chinese shot or the US shot? The debris field from the US shot was centered around 130 miles up (209 Km) in a rapidly decaying orbit, where the Chinese shot was about 500 miles up (804 Km) in a stable polar orbit (IIRC). The US debris field has disappeared, burned up in the atmosphere, while the Chinese debris field is still out there and will remain so for many, many years.
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"he missile used would surely have a mechanism to self-destruct in the event of a miss, and even if it didn't, I don't see how its falling could be any more dangerous than the hydrazine."
It probably did but if it did miss then it would have fallen into the ocean. That is one of the reasons that they took the shot out in the middle of the ocean.
This was a weapons demonstration, nothing more... (Score:5, Informative)
Re:This was a weapons demonstration, nothing more. (Score:5, Interesting)
That may be partially true, but the Chinese shot was way more difficult (albeit messy) than ours. We, of course, had no reason to get nearly as fancy as the Chinese did when they took theirs out and it would have been silly to even try (unless we just had a fancy satellite-killer that we just wanted to try). But, to the eyes of most of the world, I'd imagine you're right. They showed that they could do it, so we did too. Despite the fact that they were radically different shots and circumstances.
Re: (Score:2, Interesting)
I don't see how you can claim that the Chinese shot was more difficult since the shot that the Chinese made was at a target at a greater distance, and a slower velocity. Also the point of the matter is that the United States used a mobile platform to launch. To me this would be a test to prove that we could shoot down an ICBM in route to a destination at a low orbit. Correct me if I am wrong but it seems to me that the farther the distance you have and the slower the velocity of the projectile, there is g
Re:This was a weapons demonstration, nothing more. (Score:4, Informative)
Shooting down objects in high orbit requires a 2-stage attack - They're too difficult to hit directly in spite of your greater correction time. First, a carrier rocket is sent up to get as close as practical to the target. It then launches a kill-vehicle that will track and destroy the satellite.
The US did not require that much sophistication. Since the satellite was on its way down, the attack was more akin to shooting down an ICBM when its location and velocity are both known well in advance.
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Well if shooting down ICBM's was so fucking simple we'd already have a fully functional Star Wars implementation by now.
Shooting down ICBMs would be a helluva lot easier if we had as much notice about their intended positions and velocities as we had with USA-193. If only we would require ~1-month advanced notice before anyone lights one off.
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Wasting taxpayer money, Fanning ego, puffing out nationalist chest, and generally being seen as barbarians had nothing to do with it?
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I think it was for the same sort of reason that Bush announced the plans to go to Mars when China said they were doing manned Moon missions, even though the US has ignored that kind of thing for decades.
Aside from anything else, a Moon base would be the best place to launch a Mars bound rocket from.
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There are several advantages to launching from the moon.
Earth's Gravity well is pretty big. A spacecraft of any size capable of carrying a decently equipped mission, or even just some of the stuff needed, would be quite large. Getting it into space from the Surface of the Earth in one go would be prohibitively hard.
Launching it into low earth orbit a bit at a time sounds good, but then the assembled spacecraft still has to achieve 10.9km/sec to escape Earth's Gravity.
From the Moon escape velocity is just 2.
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That's one symptom of total blindness to what is really going on causing great suffering. I love the "we had to defend our country in Vietnam"..... sure, follow the money, but that's a secret.
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I tend to agree but would also add (speculatively of course) that the satellite was carrying highly sensitive equipment that couldn't be risked being discovered. Protecting people was a convenient excuse.
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That would be bad.
Why so hard? (Score:2)
Why are they making this out to be so hard to work out?
It's not like it's rocket science.... ....oh, wait...
Re:Why so hard? (Score:5, Funny)
so write to the editor (Score:4, Interesting)
[1] choose your conspiracy, there are plenty to go around - you're probably closer to the truth than this article, but you already knew that.
buncha crap, the danger was spy equipment (Score:2)
the amount of hydrazine in there would have made a good substitute for a little suitcase neutron bomb. say, a half square mile or so.
no, Uncle just didn't want his special chips on eBay.
Complex? (Score:2)
Yeah, lets talk about numbers and credibility (Score:4, Insightful)
From the link about why the satellite was no threat:
"The hydrazine tank is a 1-meter sphere containing about 400 liters of hydrazine. The stated hazard area is about 2 hectares, something like 1/10,000,000,000 of the area under the orbit," he adds. The potential for actual harm in unbelievably small. Which means the hydrazine rationale just doesn't hold up, literally not within orders of magnitude."
That's it for any analysis - the rest of the article was devoted to analyzing the political and military reasons why the explanation was bogus. And most of the analysis seemed to be delivered with substantial chips of the speakers shoulders. As for the numbers, while they may be *statistically* insignificant, that is pretty irrelevant next to the political consequences to a military that says "Yeah, we could have shot it down, but the odds were so small it wasn't worth the money. Our bad."
Then the "analysis" with the post - sounds good, until you get to the end: "Posted anonymously". Sorry, but that's a fail right there. He could be a 13year old in his Mom's basement, or Feynman blogging from the grave, but without attribution I just can't take it seriously.
Re:Yeah, lets talk about numbers and credibility (Score:5, Insightful)
What I find so amusing is that people on Slashdot take one look at the qualifications of the author or the IEEE spectrum article which is.
"James Oberg is a veteran NASA mission-control engineer living in Houston. He is now a news consultant, lecturer, author, and occasional tour guide of Russian space centers."
Then decide some bozo posting on Slashdot is more creditable.
Re: (Score:3, Insightful)
The anonymity of this author doesn't mean anything. All of his arguments stand on their own, and are supported by trivially verifiable math. Rather than complain about the authenticity, spend 3 minutes reproducing the results and you'll see that he's right.
Re:Yeah, lets talk about numbers and credibility (Score:5, Interesting)
I for one will admit to not being an expert on hypersonic aerodynamic heating and reentry dynamics but the AC is only included on bit of math.
"32 Megajoules per kilogram. That's orbital energy, which is how much energy has to be removed by ablation or otherwise dissipated for the hydrazine tank to enter the atmosphere and hit the ground undamaged."
This would hold true of the fuel tank was reentering by it's self.
But that fuel tank was inside a rather large satellite. Now you have to take in account all the energy of that would be absorbed by destroying the rest of the satellite around the fuel tank. Then of course there is the simple fact that no transfer of energy is 100% efficient. Not all 32 MJ per KG will be transferred as heat into the fuel tank. Some of it will be transferred into the atmosphere and some of it will be radiated away from the tank as it reenters.
So the AC post is at best a very simple High School physics look at the problem. It assumes a 100% energy transfer to the fuel tank and totally ignores the rest of the structure surrounding the fuel tank. So should I put more value in the qualified author in a subject that I have only a limited knowledge of or some AC on Slashdot's overly simplistic criticism? Frankly after seeing what survived breakup of Columbia I think that the AC is probably just as I said. Some Bozo on Slashdot.
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Not at all I am the Ubergeek. I admitted to not being an expert yet I still comment on the subject.
My card is intact to say the least.
Heck this might earn me an upgrade the Unobtainum Geek card.
Re:Yeah, lets talk about numbers and credibility (Score:5, Insightful)
What "math"? There is no math in the rebuttal, besides a number for orbital energy. No equations, no calculated results, no nothing. I truly hope that Dr. Landis is not the person who submitted the story, because if so my respect for him has taken a hit. A real scientist knows better.
Tell you what. Why don't you post the complete mathematical analysis that proves Oberg wrong? It should take you 3 minutes to complete, and maybe 15 minutes to post. And while you're at it, provide some math to explain why hazardous debris from COSMOS 954 and the shuttle Columbia somehow did reach the ground, despite their obviously comparable ballistic coefficients.
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From wikipedia:
Geoffrey A. Landis works as a scientist and writer of science fiction.
This just smells of thiotimoline to me...
http://en.wikipedia.org/wiki/Thiotimoline [wikipedia.org]
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If that is who authored the story then it would carry more weight with me. But the name was withheld.
If the related stories link is valid. But that could be an error.
But until a name is assigned and or there is a lot more math to back it up I have give more credit to a known expert than a maybe expert.
Re: (Score:3, Insightful)
Until it kills a bus load of kids in Africa and everyone comes out and says how horrible the US is for not destroying the satellite, that we knew it wouldn't hit the US and didn't care if it killed those poor innocent African children. The fact is 90% of the bleeding hearts would have been all over it if it had hit and killed people and the liability and the bad press would have far exceeded the cost of shooting it down, regardless of how improbable.
Just how valuable is a human life? Once you provide that n
Re: (Score:2)
> Just how valuable is a human life?
Well there's over 6 billion of them, and they're trivially easy to replace. Supply and demand suggests "zero".
> All the conspiracy theorists come out in situations like this and complain that it's a cover-up
Not a cover-up, there's nothing TO cover up. They said they were going to shoot it, and they shot it.
The question is whether or not the offered reason for shooting it is the real reason for shooting it. Don't try to tell me THAT'S a settled question!
Maury
Re: (Score:3, Funny)
Maybe next time they could arrange for the bleeding hearts to be under it.
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For a good discussion of the risk magnitude of the re-entry of USA-193 read the comments on this blog:
http://www.armscontrolwonk.com/1797/usa-193-risk-calculation [armscontrolwonk.com]
The expected ("average") number of people who might be exposed to hydrazine was around 0.035, the probability of anyone being exposed was about 0.01 (that is to say 1%), the risk of a fatality from exposure is considerably less than that (hydrazine is toxic, but it is nothing like a lethal war gas). The cost of the shoot-down though was 60 million
Monday morning quarterbacking the satelites (Score:5, Insightful)
I think they shot it down because they decided it was a good idea. What's the problem? The US is going to get criticized by someone for any choice it could possibly make, including doing nothing. This was probably the choice with the least uncertainty.
Duh... (Score:2, Interesting)
Brand new, state of the art spy satellite stops working. Are you going to risk parts of it falling and being salvageable, or are you going to blow it up?
Older Analysis from Oberg (Score:3, Informative)
Oberg had an earlier analysis (March 2008) on the same topic in The Space Review that covers many of the same points with a little more detail than this article.
http://www.thespacereview.com/article/1073/1 [thespacereview.com]
Dear submitter: (Score:5, Funny)
Thank you for debunking the debunking of the debunking.
Hydrazine conspiracy... (Score:5, Funny)
Actually, if there's a conspiracy, its this whole business of hydrazine being supposedly unsafe. Since I've been using hydrazine scalp cream, I've regained a full head of hair and my private assets have significantly increased in size. It's only because George Bush wants everyone to go bald, that the satellite was shot down.
I'm confused. (Score:3, Funny)
Not so complex... (Score:5, Funny)
Most 8 year olds I know are good at making up a pretext for getting what they want.
A: I really wanna shoot down a satellite!
B: You can't do that, it'll make you look like a violent war provocateur.
A: But! But! But! What if it was a dangerous satellite. Like it was going to kill everyone or something. And we had to shoot it down to save everyone! And it had racing stripes and a turret on top and played the A-Team theme song!
B: Well.... Okay, but only if it's a dangerous satellite.
A: Yay! Mom! Dad says we can shoot down a satellite!
Re: (Score:3, Insightful)
Most 8 year olds I know are good at making up a pretext for getting what they want.
A: I really wanna shoot down a satellite!
B: You can't do that, it'll make you look like a violent war provocateur.
A: But! But! But! What if it was a dangerous satellite. Like it was going to kill everyone or something. And we had to shoot it down to save everyone! And it had racing stripes and a turret on top and played the A-Team theme song!
B: Well.... Okay, but only if it's a dangerous satellite.
A: Yay! Mom! Dad says we can
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Actually, it IS a little more complex than that. Who created Iraq in the first place? Out of what famous European political party did the Ba'ath Party originate? May I suggest reading "Saddam; King of Terror" by Con Coughlin, Harper-Collins, 2002, 0-06-0500541-9, for a detaled accounting of Saddam's rise to power.
Summary Title Anagram (Score:2, Funny)
Ahhh, the joys of being at work on a typically slow Monday with no bosses in the office to catch you reading
Chomsky explained it fine (Score:5, Interesting)
http://www.chomsky.info/talks/20011103.htm [chomsky.info]
Re: (Score:2)
yea, were probably building stealth or some other technology into our satellites that might make them harder to shoot down or blind with ground based lasers.
The U.S. didn't need the test (Score:2, Informative)
There are plenty of good reasons to question the timing and urgency of the U.S. decision to destroy US 193, but the last thing they needed to do was prove to China they could shoot down a satellite. Both the U.S. and Russia proved this capability many times over until they were satisfied they had it down back in the Cold War with the U.S. even shooting down a satellite with an F-15 in 1985 [http://www.spacedebate.org/evidence/1245/] (arguably a way cooler stunt than the sea-based shot).
The U.S. probably fel
You can't satisfy a conspiracy theorist (Score:5, Interesting)
I just love how someone can say "I work in the industry!", post as an AC, toss out a couple of buzzwords with no math to speak of, and scream "we're being lied to!". As the submitter of this story so clearly put it when posting his own "analysis":
Translation: "There is a conspiracy here! Trust no one! We're all being lied to!" If there's one thing I've learned over the years, there is nothing the government can say or do to convince someone who thinks like this.
Personally, I have little doubt that the satellite was shot down for exactly the official reason. We've had plenty of space junk hit the ground in recent years; as I remember, people were specifically warned not to handle debris from the space shuttle Columbia, because of concerns of hydrazine contamination. Clearly the shuttle's high ballistic coefficient didn't prevent that, did it? The hydrazine tank didn't have to reach the ground intact to cause concerns. And just imagine the headlines if nothing had been done, and debris from that spy satellite had eventually reached the ground. Russia still gets flack about the nuclear reactor debris that landed in Canada after the re-entry of COSMOS 954, and that was 30 years ago!
Of course, it was obviously an added bonus that the shoot-down was a nice demo of the military's capabilities. But if the U.S. military really wanted to test its ASAT technology, it would hardly need to hold a press conference beforehand, or issue a press release to China or Russia to inform them afterwards! China and Russia track our satellites the same as we do theirs. If one of our dead satellites conveniently "exploded", they would get the message quite clearly.
We'll have to use the Microsoft test method (Score:2)
Send another one up and see if it happens again.
Oh come on... (Score:5, Interesting)
1) the amount of hydrazine fuel contained was infinitesimal compared to the amount of hydrazine that spills on humans every year. The F-16 uses hydrazine in its EPU, and you can trivially find stories of people practically bathing in it as a result of EPU problems and fuel dumps. The effects are generally less than the horrific outcomes presented in the stories surrounding the shoot-down. The idea that the hydrazine presented any sort of real risk is absolutely bogus, something the articles dance around and just won't address directly.
2) the chance of the debris coming down in a populated area is very close to zero. Although underreported (see http://imca.repetti.net/metinfo/metstruck.html), there are no recorded instances of anyone being killed by anything falling from space. Now of course a 1000 lb fuel tank is much deadlier than a small stone, but 1000 lb objects have fallen from space before, and we didn't bother shooting them down (http://www.space.com/news/spacehistory/dangerous_reentries_000602.html).
3) last time I checked, when heat shields fail the aluminum structure generally fails almost immediately thereafter (http://www.columbiassacrifice.com/$A_reentry.htm). I am not aware of any unprotected structure reaching the ground intact (although that could be ignorance) but I am very much aware of many unprotected structures breaking into small parts under the same conditions. This includes tanks with frozen volatiles inside. The only really large pieces of debris to reach the ground were the insulated tanks from Skylab.
4) A nuclear reactor is MUCH more robust than this fuel tank, yet when Cosmos 954 fell to Earth it's 50 by 35 cm reactor shattered and spewed its contents over 600 km (http://gsc.nrcan.gc.ca/gamma/ml_e.php). Yes, the shaping is critical in terms of shock generation and aerodynamic loading, and it's definitely easier for a sphere to re-enter than a cylinder, but still... bologna.
5) the article Oberg's is based on claims ~8 gee loading. Again, bologna; that's what you get on a carefully controlled re-entry, uncontrolled will cause much greater loadings (again, http://www.columbiassacrifice.com/$A_reentry.htm)
6) The article links to several others that are essentially dismissive of the "publicity" cover-story angle as a conspiracy theory. However, we're talking about an administration who's history shows a well-recorded "shoot first" policy based on extremely inflated data. This case fits the pattern to a T, and I see no reason to believe it differs in any way.
I call BS. Sorry James, but the argument remains specious in my books.
Maury
Re: (Score:2)
Oops, missed a cut-n-paste.
The "frozen volatiles inside" I was referring to was the hydrazine tank from Discovery, of course. It remained protected for a good portion of re-entry, and was, of course, part of a system that broke up.
I think NewScientist put it best. "The Pentagon and NASA figure they might as well take a shot at the satellite... missing the satellite completely or just denting it wouldn't make matters worse"
Why not? seems like the real justification to me.
Maury
Landis fails not only in anonymity: (Score:5, Funny)
Dr. Landis implies that Andrew Higgins didn't say the quoted item.
In fact, it's easily found in the link given.
In the linked text, Higgins gives a hyperlink back to a previous letter which was in The Space Review which contains that very quote and in the context Oberg said.
Landis snipes at Oberg for poor journalism, but apparently can't follow a bloody hyperlink. Why, even Cowboy Neal could do that and on a bad day to boot.
Secondly, Landis is an expert in solar cells and solid state devices. He apparently also works on elements of spacecraft electrical power systems, lander design and operation and writes articles on a variety of subjects. Impressive, but not directly in the area.
On the other hand, Andrew Higgins is a principle investigator and an expert in the behavior of materials under extreme hypersonic conditions and computer simulation of the same. His work on materials and combustion in hypersonic ram accelerators leaves him very well equipped to comment on the dynamics of reentry and the behavior of spacecraft materials and fuels under such extreme conditions.
Landis seems to be using the very sloppy and misleading tactics that he accuses Oberg of. Pot. Kettle. Black.
(Mild disclaimer. Andy Higgins is a friend going back to undergrad days (and believe me, it's been a while). I was mildly nettled that Landis invokes the name of an old friend and then becomes selectively blind when Andy gave the link to the very quoted item in the letter that Landis read.)
Foo' (Score:5, Informative)
Oberg goes on to quote 'There is a widespread notion that meteorites falling to Earth arrive red hot.' He is correct here. In fact, meteorites falling through the atmosphere typically explode, shattering into dozens or hundreds of pieces; something that occurs at the point when the dynamic pressure on the leading face exceeds the yield stress of the material. This occurs for meteoroids of all compositions, including nickle-iron meteorites that are far more robust than hydrazine tanks. If the atmospheric entry of meteorites is relevant, it hardly bolsters the case that a tank will enter intact (and if it's not relevent, why did Oberg bring it up?)
Perhaps he brings it up because that widespread notion is dead wrong. In fact, the parts of meteorites which make it all the way to the ground arrive quite cold, way below 'zero'. That's because of ablation. The outer part of the meteorite gets superheated by friction with the atmosphere, but before any significant portion of that heat can conduct to the inner part, the superheated part loses structural integrity and is torn away from the rest. However, the part torn away has, up until that moment, shielded the inner part from absorbing any direct friction heat.
Rinse and repeat. The end result is that whatever part does make it all the way to the ground is still at substantially the same temperature as it was when it entered the atmosphere.
Incomplete thought from the submitter (Score:5, Informative)
The submitter wrote:
I'm not sure why the submitter seems to have only partially quoted Oberg here (apparently out of context), and ignored the point Oberg was trying to make. Although meteorites entering the atmosphere generate a fireball, there seems to be ample evidence that the objects themselves remain cold even upon impact.
I'll cite a few articles here:
From this NASA page [nasa.gov] titled "Hot Meteors and Cold Meteorites," under the section titled "Meteorites Don't Pop Corn," we have this salient paragraph:
A slightly less assertive article [howstuffworks.com] on Howstuffworks is a little more reserved in its claims:
A more nuanced perspective is provided by this amateur astronomer [meteorobs.org] who specializes in the study of meteors (specifically meteor spectroscopy). It's a short read, but a little too long to block quote here. Suffice it to say, there are numerous factors, including the composition and albedo (reflectivity) of the object, whether it was camping out in the Earth's shadow prior to impact (and for how long), the trajectory and velocity upon entering the atmosphere, etc.
Seems to me that the submitter is conflating two separate thoughts. Oberg brings up meteorites because they can and do impact the Earth while still cold, or only moderately warm. That's as far as the analogy goes -- he apparently wants to make the case that an object can remain cold enough that hydrazine fuel inside the container in question might not vaporize prior to impact. Whether we want to extend the analogy to the question of whether the container will shatter during re-entry is a question best asked of metallurgists or material scientists, and that I suspect depends entirely on the composition and manufacture of the fuel tank. (For that matter, whether a meteorite shatters upon re-entry would seem to be a function of the composition of the object, as well as the stresses it encounters -- and those stresses would be a function of speed and trajectory, as well as shape, would they not?)
Respect (Score:3, Interesting)
Re:Destroying evidence (Score:5, Informative)
Right, because they could have flown the U.S.S. Michelle Obama (a special UFO-technology-based ship that the Evil Republicans have been hiding at Area 51) up to the wrongly-orbited sattelite, and... what? Retrieved the film? Any "domestic spying" done from orbit comes in the form data hauled down to earth... you know, satellite imagery? You're a few decades late for the satellite itself to have evidence of something like that. Anything worth talking about is on disk drives and tapes right here on the ground.
Re: (Score:3, Interesting)
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I know. That's my point. It's been, gosh... at least a few years since we did it that way!
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Interesting theory, but weak.
First, that data would get around, if only at the single agency that *might* be running this supposed domestic spying project. Try as they might, it won't be hidden from an incoming Administration. There will be at least ONE staffer that is either not completely loyal to the offending Administration, or one that knows that data is data, and needs to be preserved.
Second, what gives you the idea that an incoming administration of ANY political persuasion won't use any informatio
Re: (Score:3, Funny)
Nonsense. You guys have got it all wrong, like you can only think one layer deep.
Clearly there is no reason for the US to demonstrate an ability to shoot down satellites, as everyone knows the US can shoot down satellites. And yet, there seems to be little good practical reason to shoot down this particular satellite.
The truth is obvious. This was not a "failed" satellite, but rather a test of a satellite-based anti-missile system. In other words, the launched sat contained countermeasures against exact
The situation is even less simple than you think.. (Score:5, Insightful)
Or, it's probably a combination of factors, and not just a dick-measuring competition.
Consider the following:
1. A very expensive intelligence satellite is stranded in low orbit, useless. Said satellite contains expensive, highly-classefied equipment; there's a finite chance that some of this equipment might reach the surface relatively intact (see Skylab, Columbia). Obviously, certain groups (China and Russia, especially) would love to get hold of anything that survived and analyze it. It would be nice to ensure that this equipment is rendered unusable and worthless.
2. The hydrazine tank mentioned. Yes, I know the odds of it hitting anything were very, very small... but not zero. And the public outcry had it hurt or killed anyone would have been loud and swift. The decision-makers probably figured it would be better to face the inevitable international grumbling by shooting down the satellite than to face the very small (but potentially devastating) risk of impact in a populated area.
3. The Navy ABM system is going operational, and someone realizes it has the capability to shoot down low satellites. Someone probably figured "hell, we have this satellite problem; it's going to reenter soon anyways so it's a nice convenient test target. We might as well try it while we have the chance". Besides, the additional cost is a drop in the proverbial bucket.
4. At the top levels, there probably was a bit of "let's show them" going on. But I suspect it was as much a coincidence as anything else, with #1 above leading the "rational" reasons list. The hydrazine tank story just made for the best PR.
Re:The situation is even less simple than you thin (Score:2)
Re:The situation is even less simple than you thin (Score:3, Funny)
Said satellite contains expensive, highly-classefied equipment
When will the world learn that open source is the way to go ? Security through obscurity really means you don't know exactly how much the enemy knows about you, which of course means you're that much more worried and uptight about it all. If all your cards are out in the open, you might not have the intel advantage, but you also don't have to worry about how much China or Russia knows. You can safely assume they know everything, and you can concentrate on beating them with pure skill and ingenuity. If y
Re: (Score:2)
Something done by the US government is NOT a conspiracy?! That's ludic- oh, I see, your tinfoil hat must have fallen off and the government's secret mind-control rays got to you.