Slashdot Mirror
Collided Satellite Debris Coming Down?
Jamie found this Bad Astronomy blog on the many reports beginning about 7 hours ago of one or more fireballs in the sky across Texas. That blog's proprietor first doubted that the phenomena could be due to the satellites that collided in orbit last week, but later left the possibility open. The National Weather Service for Jackson, KY put out an announcement about possible explosions and earthquakes across the area and blamed the defunct satellites. "These pieces of debris have been causing sonic booms...resulting in the vibrations being felt by some residents...as well as flashes of light across the sky. The cloud of debris is likely the result of the recent in orbit collision of two satellites on Tuesday...February 10th when Kosmos 2251 crashed into Iridium 33."
An Austin TV station has more reports.
now this would be a cool sight to see, i'm hoping nobody gets hurt from all of this
From a few tons of colliding satellite? Seriously?
Oh dear, someone doesn't have a well tuned sense of scale methinks.
A learning experience is one of those things that say, 'You know that thing you just did? Don't do that.' - D. Adams
"I can now state unequivocally that this is not the result of the satellite collision. The meteor is moving far too quickly for that; satellite collision debris would fall at perhaps 10 km/sec max, while incoming meteoroids are moving at 11km/sec at a minimum, and this thing is screaming across the sky at several dozen km/sec (assuming itâ(TM)s at a typical meteor height of 50 or more km). So I was probably right in the first place, and what we have here is almost certainly a single object, perhaps a meter or two across, and it came from deep space"
My understanding was that the satellites were in an orbit high enough that the debris would float around for several thousand years before being caught by the atmosphere. I suppose a few bits might have had the energy to move closer in, but all in all it sounds more like the Martians have arrived. Might be a good idea to go make some bacteria bombs before they finish building those tripedal walkers.
As someone noted above, I'm now very sure this was a natural piece of cosmic debris, a chunk of asteroid or something similar. I posted a wrapup with my thoughts.
*** Phil Plait, aka The Bad Astronomer http://www.badastronomy.com
Staying in orbit requires a the right velocity. The results of a collision will have different velocities and some of that will de-orbit.
Engineering is the art of compromise.
The FAA issued a Notice To Airmen yesterday predicting debris and asking pilots to report.
I think there may be some conflict between the FAA's safety concerns and NORAD's secrecy. NORAD will weigh in eventually (when they're sure what they can and can't say), but there no reason to throw away the FAA's opinion, even though they are not the "go to" agency.
Will the FSF be marketing an official helmet to protect against sat debris, assuming their tinfoil hats would be sadly insufficient against this new vector?
call it spacebook
rewriting history since 2109
It can only stay up there so long. I read somewhere that they estimated a bulk of the debris will stay in orbit for 10,000 years.
Gravity is a foreign concept to some.
I hate to break it to you, but I seem to recall that ol' Isaac had a lot to say about momentum as well. If it's going to come to believing your speculations as opposed to Newton and Einstein, well, you're going to lose every time, at least in my book.
The satellites were pretty much shredded into perhaps tens of thousands of little bits - and the bits and pieces are going to have a variety of orbits and velocities. I don't think I ever said that NONE of it could be deorbiting this quickly, just that it's very unlikely that very MUCH of it could be doing so, and that it requires a fair amount of debris to make a visible display. Moreover given that the pieces almost certainly don't all have exactly the same velocity, it's highly unlikely that very many of them would deorbit simultaneously.
Gravity is only part of the story.
(Also posted to Bad Astronomy.)
A simple orbital analysis using the ground tracks from, e.g. Heavens-Above.com shows that this was not debris form the collision.
The debris from a collision keeps more or less the same orbit as before, but is spread out along the orbit. (Orbital plane changes require a lot more delta-v than changing the along-track position or altitude, since drift along the orbit accumulates, but displacements across the orbit swing back and forth with each cycle.)
Looking at the ground tracks of
Iridium 33 and
Cosmos 2251
Just eyeballing the tracks, the North-going leg of the orbit of Iridium 33 crosses the latitude of Texas at around 10 PM local time. For Cosmos 2251, it crosses about 4 PM local.
An 11 AM fireball could be Iridium debris, but only if it were heading to the south-south-east. The fireball was heading NNE. So this was NOT debris from either satellite.
Gravity is fighting against a hell of a lot of orbital momentum, so it takes time for these bits to fall. Also since the satellites were going the same way at roughly the same speed all the bits are going to go at roughly that speed and direction. Think of it as one rear ending the other. The big difference is instead of a few km/h difference in speed it might be closer to km/s.
I had the advantage of being taught undergraduate supersonic fluid flow and basic orbital mechanics by a guy that designed satellites and the early scamjets. Others know a lot more than I picked up in those few hours but we are not describing a terribly complex system here.
Except that none of the pieces would be anywhere NEAR that size. The iridium satellite was about half a ton, and the Russian satellite weighed in at just under a ton. Even if they had fused into one solid mass on impact, you still wouldn't have enough material to make up "a couple of tons".
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
http://blog.nexusuk.org
Well, sure, if you're lobbing satellite parts at the moon. The earth has an atmosphere, though. Air resistance doesn't scale linearly. The faster your initial velocity, the greater your loss of velocity due to air resistance. At very high velocities, air resistance increases exponentially. Therefore, double the velocity on de-orbit does not mean double the impact velocity.
A low enough mass won't impact at all - it'll burn up long before it hits the ground.
It might make an impressive impact. Without knowing the variables, you have no basis for concluding that it would.
....here: http://www.chron.com/disp/story.mpl/front/6264797.html
Ceterum censeo Carthaginem delendam esse
call it spacebook
I think spitter is a better name for this event.