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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 I mean, accidentally blowing up a Chinese Embassy during a "war" because a CIA Rolodex is out of date is one thing, but crashing a satellite into Beijing would be a completely different story.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!
The sky is falling!!!!
Really.
I'm serious this time.
All Troll + "offtopic" mods are meta moderated as "Unfair", because you abused the system.
...there is no danger, however, as the satellites are now expected to land in Quasi, an uninhabited part of the Australian outback.
NO CARRIER
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"?
What were the odds of a random person being an Iridium customer? 100-million-to-one?
cheers,
mike
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.