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Space

NASA's Odds For Iridium De-Orbit Casualties 174

Posted by timothy from the numerology dept.
Super_Frosty sighted (and cited) this story running on Yahoo! which says, in part, "U.S. space scientists put the odds at nearly 1 in 250 that debris from the proposed burn-up of the world's first global satellite telephone mesh would hit someone on Earth. The prospects of a casualty from the now-averted mass 'de-orbiting' of the system known as Iridium were spelled out in a previously secret study by the National Aeronautics and Space Administration." Isn't it nice that this has been put off for a little while? (Oh, and what were your favorite Lotto numbers again?)
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NASA's Odds For Iridium De-Orbit Casualties More

NASA's Odds For Iridium De-Orbit Casualties

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  • Government bails out its stupid corporate citizens (Score:4)

    by alienmole ( 15522 ) on Sunday December 10, 2000 @09:02PM (#568079)
    This has become quite an interesting situation. Motorola (basically) creates this huge white elephant and finances it by selling shares and bonds during an economic boom. Unfortunately, they did a really bad job , making enough mistakes of both a business and technical nature to prove their collective incompetence beyond a doubt.

    Now their space junk is about to come crashing down on Earth, potentially landing on countries with which the U.S. already has difficult diplomatic relations. I mean, accidentally blowing up a Chinese Embassy during a "war" because a CIA Rolodex is out of date is one thing, but crashing a satellite into Beijing would be a completely different story.

    If NASA's odds are at all close to reality, is it any wonder that the Department of Defense has stepped in? The next question may be what assurances will need to be in place the next time some company decides it wants to blanket the earth with flying diplomatic disasters. Motorola and its cohorts may have done a great disservice to the cause of commercial space exploitation.

    BTW, I should mention that I'm all for ambitious ventures involving science, space, and/or technology. I just wish that the people with the bucks weren't so catastrophically dumb sometimes!

  • Don't worry, but the time it reaches earth, it will be no larger than a chihuahua's head :)
  • This is a joke on a Yahoo! television commercial that was broadcast earlier this year. A guy living in a trailer in Quasi sees the report on television, and orders a bunch of pillows from Yahoo to protect himself. Not the most hilarious thing I've ever seen, but it just irks me when people don't understand that something is a joke.
  • Everybody puts in money on who they think will get hit by an iridium satellite. Everyone who bets correctly gets to split the money from the pool. Ok I'll start off, I'm putting in 5 dollars on cmdrtaco.

    -Stype
  • very funny.

    If the odds of anyone being hit are 1/250, and there are 5 billion people equally likely to be hit, then chances of any particular person being hit are then 1 in 1.25 trillion. This is about as good as the chances that OJ is innocent of his wife's murder.

    If there are only 25 million Iridium customers, we have 25E6/5E9 * 1/1.25E12 of a chance of them being hit. This is about as good as the chances of the Florida Supreme court interpreting Roe vrs. Wade retroacitly as meaing that Al Gore's mom must have aborted her son.

    The chances of anyone being his may be exadurated to begin with, and the chances of any particular person being hit may vary with location and shielding. I've got my umbrella up, just in case. Stranger things have happened.

  • I tried to explain this to my mother once when we were at a campsite waiting for another family to show up.

    The probability does not change just because the particular event in question actually happens in a given place and time. The factors involved in computing the probability are not related at all to the way anything eventually happens...that's why it's called probability...it is a prediction of the likelihood of some event.

    This probably still doesn't explain it all that well...oh well...my mom never got it either.

  • Did you ever think for a moment that the gentleman had epilepsy and a tendency for Grand Mal Seizures?

  • >If you read Chomsky's stuff you know that a 1:250
    >chance that someone will die from iridium debris
    >is nothing compared to the huge atrocities that
    >go on all around the world.

    True, true.

    But that being said, I rather there be no chance I'll get hit by a falling Iridium satellite.
  • Yo, that was 72lbs, not 27.

    Whups, you're right. It's even worse than I first stated. I should have dug up that link [animatedsoftware.com] before posting.

    Yep, putting 72 pounds of plutonium on top of a rocket that blew up twice out of 25 launches is not my idea of a smart move. Not that most slashdotters were very sympathetic [slashdot.org] to such concerns.

    And yep, it is worrisome that there is so much plutonium still in orbit. I don't what else to say about that, except that it sucks.

  • No the odds of someone getting hit is then divided by the number of people on the planet for the chance of a personal interraction. But even that produces a number way too high unless you're sailing in the Pacific or Atlantic ignoring shipping advisories.

    Realistically the odds of you getting hit personally is probably somewhere in the region of one in several thousands of billions. You'd be wiser to worry about encounters with natural meteors, and even wiser to forget the whole thing and pay more attention the next time you have to walk across the road.
  • I thought the guys who did the launch math were fired for putting a negative sign in the wrong place. Perhaps they were given the option to resign...
  • I'm pretty impressed that the DOD was able to get basically unlimited access for 20,000 phones for $150/month each (this is less than Iridium had planned on charging). They're basically commanding a $5.5B system for $36M/year.

    Pretty impressive in light of the $500 hammer stories.

    Michael
  • If there's a 1 in 250 chance that the falling objects will hit someone. The odds are, there's going to be a few ear-bursting near misses, and a small amount of structural damage.

    In any event, if you use simple kiddy math, there's a 1 in 1500000000000 chance that a bit will hit YOU. And if you look at all the millions of things that could kill you, this ends up somewhere near the 'insignificant' end of the scale.

    --
    I will be late for work; a falling star hit my leg and it broke.
    Glen Murphy

  • Re:Am I missing something? (Score:3)

    by Znork ( 31774 ) on Monday December 11, 2000 @12:16AM (#568092)
    Well, the basic problem is that the guys who did the launch math have quit, so the guys who did the buisness plan math are in charge.

    The latter have been known to make errors.
  • If the DoD can step in and prevent them from falling back to earth, can't they just give 'em a little boost and send them hurtling out away from Earth? Why is this option not discussed? Am I wrong that this is possible?
    • The article states that there is a 1 in 250 chance a piece of debris will hit somebody. This means that any one person has a 1 in 250 * 6 billion = 1.5 trillion chance of getting nailed.

    The beauty of it is, assuming that there were about 100 engineers working on the design of the satellite, it's only a 1 in 15 billion chance that one of them gets hit in the head by the debris that they created! :)

    ...unfortunately, the chances are still pretty slim that we can get rid of Bush :(

  • Sorry for the off topic post. A while ago someone posted a crack for the Infoseek Quickseek bar, i.e., how to change it so it searches a different engine. I'd be much obliged if someone could post that again. Thanks! Oh, *ahem* Linux rules, Microsoft drools!
  • If it falls the impact itself may not kill someone but it may indirectly cause someone death. Down power lines, explosions, ..etc you get the picture. Alot of deaths happen after a hurricane not only during.
  • ... that what goes up must come down. Somewhere.
  • "Iridium-Flares" have nothing to do with solar reflections. They are directly related to the satelites brodcast frequencies. They frequencies chosen for communication are near to the ones used for radio telescopes. The satelites aren't always on the mark, so their signals bleed into the images that astronmers are taking of outerspace.
  • I don't have the Earth escape velocity handy, but suffice to say that with the amount of extra fuel these things carry, all you'd do is move the satellites into a higher orbit. When they deorbit satellites like this, all they're doing is nudging it into a lower orbit, within earth's atmosphere, and then let the air resistance do the rest.
  • The DOD picked up the tab on the system for quite a few reasons. the most public being:

    A U.S. interagency group led by the Justice Department feared that this ``might create widespread anxiety and lead to a public outcry for ill-considered government action,'' the Pentagon paper said.

    But also as the aritcle has said the DOD (collectivly) uses about 3000 of these phones. The deal they struck fall to the tune of 3-million-a month for unlimited airtime for 20000+ users.

    To me this seems to be a good deal as they plan to use it so supplment thier current communications infrastructure:

    Iridium ``will provide a commercial alternative to our purely military systems,'' said Dave Oliver, principal deputy under secretary of defense for acquisitions, technology and logistics. The Navy, for example, needed more than twice as much such point-to-point secure communications capability as was available, the Pentagon said.

    Now 3 mil a month as we all know is MUCH cheaper than say putting more sattlites into space to meet the holes that the DOD has in thier system. This seems to be a cost effective solution that will not only save money but not lay waste to the first world wide communications sattlite system.

    Besides I would miss those schweet flares! Ignore the sig
  • Imagine a beowolf cluster of these falling out of the sky! :)
  • .. will the satellites come down in any specific areas or can we expect total global coverage?
  • "The prospects of a casualty from the now-averted mass 'de-orbiting' of the system known as Iridium were spelled out in a previously secret study by the National Aeronautics and Space Administration."

    Hello? Doesn't anybody find it strange that the study detailing the dangers was kept secret until after the danger had passed? As far as I'm concerned, this is the end of NASA's credibility and trustworthiness regarding saftey issues. Why the hell were they hiding this report?

    Kind of makes those predictions of doom regarding the Cassini probe seem a little less overblown after all. Personally, I was never that comfortable with the idea of putting 27 pounds of plutonium on top of a rocket design that has been known to explode on two separate occasions (once before the Cassini launch and once after). But hey, I guess I'm just a technophobe!

  • RUN AWAY!!!! (Score:4)

    by Unknown Poltroon ( 31628 ) <unknown_poltroon1sp@myahoo.com> on Sunday December 10, 2000 @08:38PM (#568104)
    The sky is falling!!!!
    Really.
    I'm serious this time.

  • here's the commercial for those interested. It's in .QT format.

    Pervert.

  • The important question is what are the odds of it hitting someone in a region where people are likely to sue (obviously if it hits some tribe in the middle of the Congo - chances are less than if it dropped on someone in Australia, the UK or North America).

    Of course, if Iridium is technically owned/financed by the US government at this time (see the earlier Slashdot story this week) then I'm sure they'll just kill you or your family before you can make a public scene.
    ---
    seumas.com

  • Yeah, I think 1:250 is a really huge risk, and I have a _very_ hard time understanding this could be correct. Yahoo gives very little details on how it was derived. Perhaps they forgot a few zeros? 1:250000 would be more like it.

    If, indeed the chance is 1:250, then I think the DoD spending is justified.


  • (Oh, and what were your favorite Lotto numbers again?)

    Yeah. I'd never win the lottery, so I don't bother.

    But *this*, yeah, I stand a very good chance of "winning" these odds.

    My 1976 Dodge Ram will be sitting in my driveway, looking pretty, its chrome heliographing in the sun, the fresh paint sparkling. It's survived 24 years on the road in the Toronto area, over 200,000km, an errant Toyota Camry whose driver had to be extracted from the wreckage of his car with the jaws of life, and more recently a voltage regulator failure that sent my electrical system to the possible world record of 26 volts while I was driving home but didn't do any more damage than blowing out my left headlight.

    And then, clear out of the blue, there will come an Iridium satellite.

    I know it. I can feel it.

    I'm building a bunker.

  • There is a phenomena known as "Iridium-Flares" by which one can see the very bright sun reflections off of the iridium satellites.

    Damn, there I was thinking they were the latest in retro-70's fashion.

  • It has to be said at least once (Score:4)

    by Chester K ( 145560 ) on Sunday December 10, 2000 @08:40PM (#568110) Homepage
    ...there is no danger, however, as the satellites are now expected to land in Quasi, an uninhabited part of the Australian outback.
  • Actually, I think we can thank NASA on this one. By keeping the report secret until after the DoD buyout happened, they kept the urgency down and thus the price low. As other posters have pointed out, the DoD only paid $72 million for the satellites, which is less than 1% of the total cost of building them in the first place. The only people who really got shafted in the whole Iridium debacle were the investors and venture capitalists who put up the money in the first place. And well, who gives a shit about them? They've got money to burn anyway, so let 'em burn it!


  • You just watch. If G. W. Shrub gets elected, as soon as he starts pitching the ABM pork project the lobbiests are telling him to promote, he'll cite this iridium threat as a reason why we need an anti ballistic missle program.


    If it were up to me, and clearly it's not, I'd leverage this threat to fund a hunter-killer satellite system. Not that I'm really a proponent of interrupting other people's communications, I just would like to see some of that battle-bots tv stuff taken to the next level. Obviously if we had hunter-killer satellites, they could fly around flinging these iridium satellites out into space.



    Seth
  • Actually, like you suggested, the chances are pretty low. Most of China's landmass is very sparsely inhabited. Amazes me, but its true. Ah well, if you can fit 300 million into Indonesia, nothing should suprise me.
  • Is that the chances that YOU personally will get hit by one of the satellites is about 1.5 trillion to 1. You're much more likely to win the lottery.....even if you DON'T buy a ticket. :)

    -Restil

  • I wonder how much of their infrastructure this will knock out... ;)

    -- Pete.
  • 6.5 mps (miles per second) is escape velocity
    IANAP (I am not a physicist), I remember reading about this in one of asimov's essays (asimov on numbers, physics, cheese-pants. whatever).

    I have no respect for people who put me down with their larger knowledge of trivia, but if you're in a field where this knowledge is crucial, and you ever come to Hawaii, I'll teach you how to surf. (people who launch things into space are cool)

    Surfing is religion

    you are silly
  • It's a bird! It's a plane! It's....*thunk*. Iridium smacking into my head.
  • The basic issue is the unpredictability of interaction with the atmosphere during re-entry. For a nice-shaped object, like a space shuttle or an Apollo capsule, you can be pretty certain what's gonna happen, but for a rough shaped object like a satellite, which is decidely non-aerodynamic, and which is going to break into pieces at various unpredictable times during the re-entry, it's a lot fuzzier. Add to this the fact that the atmosphere as a whole expands and contracts.

    Still, I wouldn't have thought that, say, the Pacific would be that hard to hit -- especially for a satellite that's still got heaps of fuel. You could use all this fuel to bring them in on a quite steep descent; a steeper attack into the atmosphere would make things more predictable, I think.

  • of hitting someone? (Score:3)

    by donglekey ( 124433 ) on Sunday December 10, 2000 @08:44PM (#568119) Homepage
    1 in 250 of hitting someone? If you think about it, the odds of hitting someone being that high would mean that the odds of it hitting something at all would be pretty huge. Maybe not a person, but a building, a car, etc. Seems that this will probably be on the news when it happens because of the choas it might cause, and of course the obligatory paranoia from the average person that will follow.

  • applicable laws? (Score:3)

    by dR.fuZZo ( 187666 ) on Sunday December 10, 2000 @09:07PM (#568120)
    Now, obviously, if someone got hit and killed (uhm...yeah, you wouldn't think it would just disfigure them, would you?) then there would be legal liability. But, other than that, does anyone know if they could have been legally prevented from doing a mass "de-orbiting"? Could a country prevent them from doing it just because it could potentially endanger their citizens?

    1-in-249 means it's unlikely, but not vastly improbable, and it seems a bit disturbing that a company could do something that would ("only") have a 0.4% chance of killing someone.
  • If it were a 1 in 250 chance that it would kill Fidel Castro or Saddam Hussein, the USG would put ten more Iridium networks in space for the express purpose of de-orbiting them.
  • Homer Simpson?
  • In an unrelated note, one of Pentagon officials voiced his excitement about new super secret weapon system that is going to be used as an anti-terrorist measure. First tests are scheduled for early next year. "We're going to crush that evil terrorist organization led by Laden once and for all ! They would think that sky is falling !".

    However, we were not able to get an explanation about "falling sky"; "it is a secret, you know", we were told.

    Also, we were informed by one of our sources, close to Pentagon, that there seem to be a huge demand for hard working hats among US military officials.

    However, we still don't know either these two facts are related.

    --
  • Ok fine the chances are 1:250, but when it hits you the chances are 100% isn,t it? So we can't just let it go quoting some silly ratios.
  • I mean, he's one of the only people I know (true fact) who survived a plane crashing into his parent's house.

    Will lightning strike twice ... we can only hope ...

  • Back in 1979 when Skylab was comming down, the odds, IIRC, were as follows...

    150 to 1 that someone somewhere would be hit. So 250 to 1 seems an improvement in accuracy. (Or worse accuracy, depending on POV.)

    150,000 to 1 (or somesuch, I don't recall as clearly) that you personally would be hit. (The first 150 to 1, though I recall vividly.)

    Also at the time, newscasters were fond of pointing out that if you check your homeowner's policy, it usually specifically states that it covers damage caused by falliing spacecraft.
  • Maybe this should be a sign to NASA or someone that a concerted space junk pickup program should be initiated. Someone needs to take the initiative here. I was looking at a map of where man made objects are orbiting, and they were extremely concentrated around the equator. I know that's still a big circle, but eventually this will become a problem. Sure the space shuttle could pick these things up and bring them home, but isn't there an easy way to break them up into smaller pieces and deorbot them without launching and relaunching the vehicle that does this? Maybe an orbiting arm that can rip old satelites apart and drop the pieces one at a time. Any ideas?

    Nate
  • IANAA (I Am Not An Astrophysicist) but, is it possible that these critters could be deorbited in a way to maximise the chance that they could survive reentry? Depending on how well they could be aimed, that would give the Pentagon 74 brand new orbiting bombs...

    Just an idea, not sure how feasible it is.
  • I believe it is industry standard to undertake controlled de-orbiting manauvers to avoid the most populated areas. I suppose Iridium's financial myopia may have also precluded this but that is extremely neglegent. As you can see Russia is taking great pains to make sure Mir doesn't hit anyone when (if) it comes down. And if you think thats bad, imagine what they're going to have to do with the ISS when it becomes too dangerous to live in! Still, if we didn't have so many damn people in the world the odds would be a lot lower.
  • That "Rocket a Day" plan reminds me of what Craig McCaw et al plan for the Teledesic [teledesic.com] network. They plan to launch 288 satellites, and McCaw talks about treating it more like a mass-production scenario than has been the case for other satellites and their launches.
  • Keep in mind that this is the odds of _a_ person dying out of billions. Compare the odds of _a_ person dying in the next 14 months from:

    - automobile related incidents
    - a plane crash
    - power line electrocution
    - medical error
    - heating fuel fires

    Just about any technology has risks far more likely than satellite related death.

    People blow these things *way* out of proportion.
  • Check your math. It's much easier to calculate the probablility that no one gets hit and subtract that from 1. 1 - (1 - 1/18405)^74 = .004013 or 1/249.2 which was probably rounded to 1/250 so that the reporters would be too confused.

    The lesson: Don't do a hairy sum when a simpler calculation will do.
  • What goes up must come down, particularly in LEO (Low Earth Orbit). Natural variations in the thickness of the atmosphere, caused by the 11-year sunspot cycle, mean that anything in LEO has to fly through a few wisps of atmosphere every so often. Add to this the odd micrometeoroid or other bit of space junk smacking into the things and any given LEO object only stays up a century or so.

    All working satellites have attitude jets and a limited fuel supply to deal with life's little calamities - but that has to run out sometime.

    Personally, I think this 1 in 250 figure is highly suspicious. There's a lot of ocean out there, and I'd be willing to guess that they've got a reasonable amount of maneuverability to the point that they can drop one of these within a few thousand square miles of ocean. Surely there's plenty of such spots in the Pacific that don't hit an island, and probably they ought to be able to miss shipping lanes too.

    --

  • These numbers seem way out of whack. Kind of implies that the world is relatively densely populated. I really don't think that is the case. Consider the following interesting trivia question:

    If you gave every person on the earth a cubicle two meters by two meters square, what percentage of the Earth's population would fit on Vancouver island?

    Vancouver island is 31,284 square km. For each square km, we can fit 500 x 500 = 250,000 people. With 250,000 people per sq km x 31284 sq km = 7.8 billion people!!!

    Therefore, the surprising answer is over 100%. That is, every person on earth could fit with room left over.

    Given that, it seems to me that the chances of a satellite hitting someone would be exceedingly small...and certainly a lot smaller than 1 in 250!

  • You forgot to mention that the satellite survives with solar panels intact.

  • Re:Helmet (Score:4)

    by istartedi ( 132515 ) on Sunday December 10, 2000 @10:04PM (#568155) Journal

    Several years ago when I was commuting regularly on the Metro near Arlington, VA; there was a guy who took the same train who always wore a helmet. It even had a special plexiglass shield for the face. He did not appear to be mentally retarded--just strange.

    The helmet may or may not have protected him from any falling objects, but it certainly protected him from strangers. Nobody went near the guy.

    Anyhow, if there is a subway nearby, I would think that's enough to protect you from the debris.

  • It is no joke that large corporations and government entities hide information from us on a day to day basis.

    As Noam Chomsky has said time and time again...
    http://www.zmag.org/chomsky/audio/pcpm/
    ...these organizations spend billions upon billions of dollars to make you think what they want you to think. The multi-billion dollar PR industry is very open about the fact that they want to control your minds.

    That is what allows them to spend millions of dollars of tax payer money on the military research that creates things like irridium which can be then turned over to the private sector so the wealthy can profit from it.

    And of course they're not going to tell you that on top of making you pay for it, the process of tearing it down might kill you.

    ___________________________
    http://www.hyperpoem.net [hyperpoem.net]
  • It wasn't really the satellite that killed him, it was dating that woman, who was just bad luck. I mean, look at her past several boyfriends! black widow that one.
  • I assume that they mean there's a 1 in 250 chance of someone being injured or killed as the result of an impact -- indirect causes included.

    The chances of someone actually getting clocked by the satellite itself couldn't be that high. It would have to be raining thousands or millions of them.

  • Who says I'm worried about myself? It could be anyone. Pull any statistic you want, but 250 to 1 is one of the worst if not the worst re-entry odds ever.
  • The odds of there being someone hit at all are 1 in 250.

    Hmmm. Well, I suspect the statistics suggested in the joke still stand unless Iridium had ~24 million customers.

    Now, what are the odds it'll hit a former Iridium customer...

    --
  • Nice strawman, now how do those odds compare to anything about debris and re-entry? Not at all.

    The facts are the 250 to 1 is amongst the worst if not the worst odds in re-entry history. Using your "logic" why care about death when eventually we're all gonna die?

    *roll*
  • Of course, these odds aren't comparable to each other. The Iridium odds are 1 in 250 that a piece of debris will hit one of the 6,117,737,000 people on this planet. The odds of winning the Oregon Lottery are 1 in 335 out of the Oregon state population of 3,316,154 (only some of whom actually play the Oregon lottery).

    Big, big difference in probability calculations there.

    --

  • Again, I have no idea why they insist on downing these things. For a little less orbital debris? Since they presumably actually work, why doesn't the government just buy them; even if they don't use them right this second they can maintain their orbits until a time when they will be useful...
    --
  • You need a lot of extra energy to move something into infinite space. Don't forget that these satellites are still quite close to the earth, (about 100-200 miles from the surface). Compared to the size of the earth that is still pretty close, and gravity is still quite strong up there.

    It may seem things are 'weightless' in orbit, but that's not true. The gravity is still present, but the satellites are basically in a never ending free fall. If you want to climb into a higher orbit, you'd still have to counteract 90% of the earth's gravity. Once you're a couple of thousand miles away, it gets a lot easier, though.

    Moving them in a higher orbit has tremendous costs associated with them. If not, the space shuttle could just visit geostationary satellites. The space shuttle never does that. It only stays in the lower orbits, simply because it doesn't have the fuel to go up that high.

  • The article states that there is a 1 in 250 chance a piece of debris will hit somebody. This means that any one person has a 1 in 250 * 6 billion = 1.5 trillion chance of getting nailed.

    If anyone's worried about this, they should coat themselves immediately with liquid rubber (available at hardware stores) to protect against lightning, ebola and cooties.


    *** Proven iconoclast, aspiring epicurean ***

  • Ok, the odds are 1:250 that SOMEONE SOMEWHERE (out of 6 billion+ people) will die from a Iridium reenty--That is 1 in 1.2 TRILLION that you will, personally. In other words, astronomically low. It's probably more likely that your monitor will explode, killing you as you attempt pull off a successful FP, than it is a piece of an Iridium will land on you. Does that mean you should sue CmdrTaco?
  • You make a great point, but we (the U.S. or anybody, AFAIK) don't have a space-based missile defense system. That's the hotly debated "Star Wars" project that's been floating around (haha) since Reagan. Also, I recall reading about small particles in low orbit being more dangerous than large orbiting objects. If we blew up Iridium satillites or Mir, it would create a lot of debris (impossible to track) that space-bound vehicles (Space Shutttle) might be damaged by.

    The following may be redundant, since I haven't read all responses yet, but here goes. It seems that if any of these objects (and the doubtless many to come) are to be "forced down," shouldn't they be recoverable? It's bad environmental and scientific policy just to drop 'em and forget 'em. I'm no hippie or a scientist (or a hippie scientist), but it seems a waste. Oh, yeah, the goverment makes these decisions. /rolls eyes

  • Simple economics (Score:3)

    by Argy ( 95352 ) on Sunday December 10, 2000 @10:39PM (#568185)
    While you often hear "you can't put a value on a human life," we do it all the time. Juries do it when they award damages for deaths. We do it ourselves, probabilistically, when we decide how much various safety features are worth to us in a car. Or which airline to ride...lots of people will take ValuJet (now AirTran) at half the cost of reputable airlines despite their safety record.

    Let's put a value on human life of, say, $10 million, for the sake of argument. (US juries seem to value US lives at $1 or $2 million, so $10 million worldwide leaves a big margin of error). So Iridium will pay $10 million if someone gets hit. They're staring at a 1:250 chance (dubious, but that's NASA's guess) at paying that. Then they're expected cost of hitting people is $10,000,000/250, or $40,000. Now do you think they can find a way of launching 74 satellites into higher orbits for less than $40,000?

    Damn would it be ironic if I was the one who got hit. :-)
  • Since the things might land in the Australian outback, I wonder whether or not any of the Survivor 2 contestants will get hit...
  • The real problem is not someone being hit by them. It's people trying to avoid being hit by them. Think about the PR situation. By the time 10 or so of them had hit, someone would have had pieces to show on worldwide TV. Since the re-entry points are roughly predictable, this would produce a demand for preventive evacuations of target areas. That would cost billions and kill more people in traffic accidents than any possible reentry problem.
  • What would it take to send a few rockets out and nudge the satelites in the other direction; e.g. out into space. We've already put a ton of space junk up in and around Earth's orbit, but I would hate to see someone die simply because we couldn't push these things out into the limitless infinity of space.
  • Maggie.

    She was a cutie.

    That satellite had a part in his death though! :-)

    Although, from what I know of the orbital inclinations of satellites that do scientific reseach, they aren't high enough to make it to those (Alaskan) latitudes. It would have had to have been a spy satellite in a polar orbit (90 degree orbital inclintation) thaty killed him. And if that were the case the feds would have impounded his body since it had melded with the satellite! :-)

    Rich...


  • Another use for your Y2K bunker!
  • No. The top of my list is to go peacefully, in my sleep, like my grandfather did. Not screaming in terror like the passengers in his car.

    Actually, in bed, of old age, surrounded by grieving descendants, would be better than getting hit by space junk!

  • I think that the odds are 1 in 250 that SOMEONE (out of the the five billion) will be hit.
  • This has got to be a load. How many meteors end up as meteoroids per day? As far as I know, there's never been any confirmed human death by meteoroid. Why would a mere 74 satellites pose such a threat when no one in recorded history has been provably killed by anything falling from space?
  • Well, any pretty small chunk is going to get ablated by air friction. It's the big, not-so-dense, tough chunks you have to worry about. Density isn't exactly the driving factor, but denser objects have a higher mass per surface area. Therefore, a light object with a high surface area (like a titanium fuel tank) is going to decelerate rather rapidly, and possibly not ablate as much. What I don't know is whether the rapid deceleration is going to increase or decrease the ablation due to air friction...I haven't the vaguest idea what that math looks like. (the aerodynamics I understand rather well, but heat transfer is next semester. : )

    Multiply 1 in 20,000 by 70 satellites and the odds don't look so good. However, I can't understand how the odds could possibly be so high...these satellites just aren't that massive, and the ocean is a great big target compared to a human. (or even compared to a densely populated region)
  • While you were posting that a couple hundred people died of hunger, probably a few thousand died of curable diseases. Meanwhile you fret about a 250:1 chance of someone dying.
  • Last I checked, though this could change if Bush becomes president, you could plunk this thing down on 70% of the Earth and not have to worry about hitting anything except fish. Are the same idiots who concieved Iridium going to be the ones firing them down onto the other 30%? Cause it seems to me like taking object A, shooting it in an almost perfectly Newtonian environment (space) towards point B, with acceleration due to gravity G already known, etc. etc., should be a pretty easy math problem to work out. Especially if you already figured out a way to build them, blast them into space atop what amounts to a huge stick of dynamite, position them into geosynchronous orbit, and, oh yeah, provide phone service for the entire world. Can someone elaborate as to how in the world they could possibly de-orbit one of these things into my back yard?

  • But what a way to go!! (Score:3)

    by RJ11 ( 17321 ) <serge@guanotronic.com> on Sunday December 10, 2000 @08:53PM (#568220) Homepage
    That is sooo cool! Seriously. I mean, of all the ways to go, isn't getting hit with an Iridium satellite at the top of you list?
  • Multiply that by 518 chances and you get about 1 in 257.
    Strictly speaking, multiplying here is the wrong thing to do. Assuming each impact is an independent random event, then the probability of there being zero impacts is:

    1 - ((1 - 0.0000075) ^ 518)

    Numerically, the results are 1 in 257.9 for the correct method and 1 in 257.4 for your incorrect method; with small probabilities and small numbers of events, your method is a good approximation. (It becomes a problem when p*n isn't << 1.)

  • Or starting fires, property damage, etc. Its negligence, bring on the lawsuits.

  • You know your business is in trouble... (Score:5)

    by nakaduct ( 43954 ) on Sunday December 10, 2000 @08:57PM (#568230)
    ... when a given person is more likely to be hit in the head with a piece of your infrastructure than to actually buy the service you're selling.

    What were the odds of a random person being an Iridium customer? 100-million-to-one?

    cheers,
    mike

  • Comment removed (Score:3)

    by account_deleted ( 4530225 ) on Sunday December 10, 2000 @08:58PM (#568231)
    Comment removed based on user account deletion
  • Actually....I seem to remember seeing a figure that you could house the entire population of earth comfortably in an area the size of Texas.

    This doesn't really surprize me, Cities areally arn't that big compared to the sparsly populated areas. However....I still don't accept it as an argument that "there arn't too many humans".

    In any case, you must remember, the people who came up with this statistic know quite a bit about these stalites, including current velocity, position etc. They also know how they are being de-orbited, probably how much fuel is in whatever is being used to generate the proper force to take them out of orbit etc. (along with knowledge of what the most common failure modes for such things are).

    Given all that data, they can probably rule out alot of areas as places where they will land. That would go a long way to changing the figures.

    Then again...its always possible that the figures were cooked up for some other reason. There are, of course, "lies, damned lies, and statistics".

    -Steve

  • OK, let's run the numbers (Score:4)

    by upper ( 373 ) on Sunday December 10, 2000 @11:13PM (#568236)
    The article says there are 74 satellites in the constellation, and it lists four types of parts which are likely to survive. Of these, the "structural bracket" sounds like something there will be several of, so say there are 7 pieces per satellite. That's 518 pieces.

    Now, the area of the earth is about 5.6e+15 square feet, and the population is about 6e+9 people. Assume each person takes occupies 7 sq ft, without overlap. Then 0.00075% of the earth's surface is covered by people. Multiply that by 518 chances and you get about 1 in 257.

    An interesting variation: assume that each person has a 100 sq ft region in which impacts could kill or injure them, e.g. by knocking the roof in or scattering debris. These regions cover 0.01% of the globe. There's about 1 chance in 18 that one of the pieces will hit one region.

    I assumed that the re-entries were uniformly distributed; the NASA study assumed that the re-entries were untargeted -- presumably NASA excluded the polar regions which aren't under the orbits. And they may have made different assumptions about area occupied by each person and number of pieces per satellite.

    In fact, my guess is that this "study" was done by one person in an hour or so, mostly spent looking through the Iridium parts lists. "memo" is probably a more accurate term.

    Of course, as other posters have pointed out, these odds drop by 2-3 orders of magnitude if the satellites can hit a target the size of the pacific.

  • My thoughts exactly. How difficult is it to hit a target as big as an ocean?

    And what idiot approved Iridium in the first place if they never had a workable plan how to safely deorbit the things?
  • You realize of course that blowing things up in space with a missile would result in MORE debris (both the sattelite bits and the missile bits), right? Many of which will be too small to track.

    Some of those little chunks of metal are likely to be whipping about at even higher velocity after the blast, endangering other sattelites and anything we send up there.

    Blowing things up in space may look cool on a movie screen but in reality, turning the ionosphere into a meat grinder is a really bad idea.
    ---
    Where can the word be found, where can the word resound? Not here, there is not enough silence.
  • The odds are 1 in 250 that one of the 60-odd satellites will hit SOMEONE. This does not mean that YOU have a 1 in 250 chance of being hit. This means that there is a 1 in 250 chance that a falling satellite will hit 1 of ~7 billion people on earth. The odds that one will hit YOU are 1 in 250*7x10^12 or ... 1 in 1.75 trillion. Yes, that's right. There is a one in one trillion chance that Motorla will kill you with a piece of falling phone equiment. Get over it.
  • In the very best case, leaving the satellites up doesn't make their inevitable re-entry any safer. By any reasonable standard, it is more dangerous to leave them up. Right now the satellites have generous fuel margins and working control systems; and could be aimed with at least some precision. Waiting until they are derelict means giving up all that control.

    Also, the Iridium orbits will decay into orbits that cross the path of the space station and other manned spacecraft; Iridium satellites are all in low polar orbits. As these orbits decay naturally, they will be at similar altitudes to the manned systems. While a 10lb titanium fuel tank might damage a car that it falls onto somewhat, a 1000lb satellite would vaporize (literally) the space station.

    The bigger question is 'why were these satellites allowed to be launched at all?' This (imho flawed) analysis could have been done before the satellites were launched. It was obvious from the beginning that they would deorbit relatively soon. If it is an unacceptable risk now, it was certainly just as unacceptable then.

    thad

  • Isn't this just like Northern Exposure? When Rick got killed by a falling satellite?. Wow.

    Rich...

  • One should notice that NASA has its statistical analysis incorrect. If the odds of hitting someone for each rentry are 1 in 18,405, then the odds of at least one of the 74 reentries hitting someone is about .4067%, or 1 in 245.

    Their number of 1 in 250 is obviously calculated by multiplying 18,405 by 74, which is incorrect. They should be using the formula: P = Sum[p*(1-p)^n,n,0,74].

  • I know you're joking, but I'd like to point out that the "outback" covers most of the Australian continent. To paraphrase the pythons, it's big,really really big, and ginourmously huge all at once. Imagine two-thirds of the United States with a total population of about half a million people, and 400,000 of them located in a dozen towns/cities.

    By the way, don't believe all the hype about survivor II's "isolated outback location". By US or European standards, it's isolated. By Australian standards, it's actually pretty close to a reasonably large town/small city. It's less than 200 miles from a popular coastal resort!
    If you really want isolation, might I suggest the Canning Stock Route [demon.nl].

  • rest easy (Score:3)

    by Performer Guy ( 69820 ) on Sunday December 10, 2000 @11:39PM (#568248)
    Yea but you have to realize that the risk of a real person i.e. an American citizen, getting injured is much more remote.

    I wonder what they place the odds of 1000 people getting injured at. One of those puppies deorbiting into the U.N. building while it's in session or on onto a cruise liner in the Atlantic or onto the Golden Gate at rush hour for example.

    My point? These statistics are pretty meaningless, we can't halt the space program because of irrational fears. Pop tarts have killed & injured more people than space junk, as has just about any inane thing you care to mention. The merits of satelite networks easily outweigh the risks.
  • Now the earth will be even more densely populated when the satellites rain down firy death...

    Okay, sure, so the chances aren't that high that anyone will be hit, but I still find it remarkable that a US company was able to do this without so much as a peep from the other countries that are put at risk. Much as I want to encourage private industry to exploit space, this kind of thing does suggest to me that perhaps we need to set up some more stringent international rules on what sorts of launches are permitted.

  • There is a phenomena known as "Iridium-Flares" by which one can see the very bright sun reflections off of the iridium satellites. Go to Heavens-Above.com [heavens-above.com] for predictions when you can see this from your hometown.

    -Jason

  • Quite a bit, actually--even as far out as they are, the satelites are still bound rather tightly to earth. Shoving them out a ways would just give them eccentric orbits, causing them to eventually make an uncontrolled reentry. It would take quite a kick to free them, or put them into a solar orbit.

    However, I have a hard time imagning the odds they quote. Frankly, humans don't cover that much of the surface area of the earth. Maybe if you randomly dropped ~70 titanium fuel tanks on the earth from space you would get those odds, but even a lame attempt at deorbiting into the ocean should drop the odds substantially.

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