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NASA's Odds For Iridium De-Orbit Casualties
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?)
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 I mean, accidentally blowing up a Chinese Embassy during a "war" because a CIA Rolodex is out of date is one thing, but crashing a satellite into Beijing would be a completely different story.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!
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.
Friends don't help friends install M$ junk.
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.
"That's Tron. He fights for the Users."
Whups, you're right. It's even worse than I first stated. I should have dug up that link 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 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.
Free Hans!
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'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
Do you have ESP?
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 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.
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 question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
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
"Don't mess with him, he taunts the happy fun ball."
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!
Free Hans!
The sky is falling!!!!
Really.
I'm serious this time.
All Troll + "offtopic" mods are meta moderated as "Unfair", because you abused the system.
here's the commercial for those interested. It's in
Pervert.
Fire and Meat. Yummy.
(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.
Fire and Meat. Yummy.
...there is no danger, however, as the satellites are now expected to land in Quasi, an uninhabited part of the Australian outback.
NO CARRIER
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!
Free Hans!
Seth
$5 / month hosted VPS on linux = awesome!
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
Play with my webcams and lights here
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.
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.
This Wiki Feeds You TV and Anime - vidwiki.org
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.
-- dR.fuZZo
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.
There's always sufficient, but not always at the right place nor for the right folks.
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.
I'll see your senator, and I'll raise you two judges.
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.
I have discovered a truly marvelous sig, unfortunately the sig limit is too small to contain i
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.
--
--
Do I look like I speak for my employer?
You forgot to mention that the satellite survives with solar panels intact.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
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.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
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.
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
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...
--
Some people have a way with words, and some people, um, thingy.
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*
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?
/* This post not warrantied for mission critical applications. */
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
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.
- I don't care if they globalize against free speech. All my best free thoughts are done in my head.
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...
Ignore Alien Orders
Another use for your Y2K bunker!
EagerEyes.org: Visualization and Visual Communication
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!
Best Slashdot Co
I think that the odds are 1 in 250 that SOMEONE (out of the the five billion) will be hit.
"Those who would sacrifice freedom for a little temporary safety deserve neither freedom nor safety" -Ben Franklin
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?
The only certainty is entropy.
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)
Why yes, I AM a rocket scientist!
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?
I think there is a world market for maybe five personal web logs.
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?
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.
What were the odds of a random person being an Iridium customer? 100-million-to-one?
cheers,
mike
Comment removed based on user account deletion
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.
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.
"Where shall the word be found, where will the word resound? Not here, there is not enough silence." -T.S. Eliot
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.
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
I love Mondays. On a Monday, anything is possible.
Rich...
Ignore Alien Orders
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].
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.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
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.
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.
"The question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
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 for predictions when you can see this from your hometown.
-Jason