here, and you can see the three batteries on the bottom half of the module. Each battery is made of 22 cells connected in series. Lots of energy in those batteries, and we basically handled them as if they were explosives. That was because if you ever dropped a wrench across the terminals or such, they would release all of their energy quite quickly.... this was called "rapid spontaneous disassembly".
The batteries were supplied by Gates in Florida, and were very, very carefully matched. They must have done a good job, because the batteries got (partially) charged and discharged every 90 minutes for about 15 years.
Thanks for the concise explanation, DM51.
If I remember correctly, the article said there was no fuel left, which is a good thing.
Hey, if it lands in my yard and makes some pretty craters, I'll offer a CPF discount of 50% to come and stare at it.
Here is just a few:
Nuke powered satellite expected to hit Earth (old news - this already happened)
Russia to build Nuclear powered satellite to gobble up old satellites and space debris - this is what is needed but not sure about the nuke powered:
But if you are saying you know the UARS has no nuclear power than that's good news.
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i thought 'they' could predict reasonably accurately the band that the satelite will land in. f'n' miles either side of the orbit path. and they would have tried for an orbit path that didnt pass over washington new york bejing etc. look at a globe and you will seeyou can pick orbits that spend more time or less time over water and a water landing i would think would be the preferred option.
the debris casualty area - i wonder if that only applies to a hit to a human body or allowance has been made for events like hits to a car plane boat lpg gas tank.
anyway the correct way to calculate the odds for someone in the crash window is 32000 times the number of folks in the crash window, not the number of folks on the planet.
a couple of big chunks expected . is there an expected impact velocity for these chunks ?
The expected impact velocity is complicated. You sure wouldn't want to be under it, but I wouldn't expect sonic booms and secondary splash craters.
That's a bit misleading but it makes more sense to label it as a nuclear battery in a popular science book rather than a radioisotope thermoelectric generator (RTG). RTGs basically use the heat given off from decaying radioactive material to generate electricity and I doubt they are a fissile risk. RTGs have been around for many many decades and are typically used by satellites and probes that require power but have to make long trips where solar panels are impractical. In fact, I believe one of the Voyager probes are still working, although some of the instruments have been shut down.
I suggest starting with 220.127.116.11, but it's a lot of other data included.
this is for my area , 90265 , so. calfornia, you can look up yours at
* September 23 * * * * *
* Satellite Rise time Direction to look Transit time Max elevation Magnitude
* UARS 07:53:36 pm SSW 07:54:44pm 26° 2.0 (visible)
Last edited by TedTheLed; 09-21-2011 at 07:25 PM.
originally cpf member #14 write me at gmail.
As was mentioned, these are made with low density radioactive masses that just get warm. Thermocouples or thermo-electric devices then use the temperature difference between the mass and the rest of the spacecraft to generate electricity. A very nice, simple system with no moving parts. Usually reserved just for deep space probes where solar radiation is very weak, but could be used for LEO (low earth orbit) too, I guess. The downside is that they were heavy and more expensive to launch. In the early days, photo-voltaics were built with rigid substrates instead of the spiffy modern PV's that are flexible enough to roll up for launch and unfurl like a flag later. The early PV's might have been too complicated or unreliable, perhaps?? (just a guess)
When I visit the spaceweather site and punch in the nearest zip code to me, it offers a time to see UARS on the 26th. Is it extrapolating future orbits? I thought it was coming down tomorrow...?
EDIT: North America is out!
NASA analysis does list impact velocities on page 8. The reaction wheels are expected to be the fastest bits, with a velocity of 107m/s. The largest impact energy, though, is the "SSPP structure", with an impact energy of 153kJ. I'm still trying to figure out what "impacting ballistic coefficient" really means. It's in units of kg per cubic meter, so is it just density??
Late Show with David Letterman:
"A satellite is headed toward earth and the people at NASA have no idea where it will land. How would they know? It's not like they're rocket scientists."
0.0003125 * 290,000,000 = 90,625
So my math is off... It's 90,625 out of 290,000,000 probability... Just reduce that to simple fractions
29 out of 92,800....which still comes out to one person out of 3200 would still be hit by something.
Ask me, that's a damn good probability.
I'm afraid that's the wrong way to calculate it. You multiply the population that could be affected by 3200. The probability that someone on earth could be hit by it is 1 in 3200. If you single out one individual in the entire world's population and ask what the chances are of him personally being hit, you multiply the 3200 by 6,000,000,000 and that gives you the 1 in 20,000,000,000 figure.
However, beerwax may be right (post #36) and they may be able to steer the satellite into an orbit that avoids most of the world's population. That would affect the odds. It would reduce the chances further if you happen to live in a "safe" zone, and increase them if you are in the possible impact area. It's a big "if" though, and I rather doubt they have any real control remaining over where it is going to come down.
Resistance is futile...
I heard someone on the radio compare it to dropping a coin into an aquarium and trying to predict where it will land. The only difference is that it doesn't take the coin 6 years to get to the bottom... well, there's also the assurance that the coin will land in water and not hit anybody.
Sorry, I had to remove this image because too many people were hotlinking to it on my server from other web sites.
Last edited by EZO; 01-20-2012 at 07:47 AM.
The Earth gains 40 tons of mass every single day, from falling space dust and rocks. 40 tons of space rocks, falling out of the sky every day. This satellite is totally insignificant in the big scheme of things.
hmmm... just another day until we get close to the re-entry time!! Has anyone started a pool for the re-entry time? Put me down for 4:30pm, central time (GMT + 5, I think). My theory is that one of my old batteries will hit me just as I step out of work.
when the little green men from the next galaxy come to visit they are going to take one look at all our space junk and think ' gee these guys are messy ' .
anyway cool science question how do they measure the change in the mass of the earth over time?
Last I checked both probes were functional, receiving and transmitting data, and cruising through the heliopause on their Interstellar Mission.In fact, I believe one of the Voyager probes are still working, although some of the instruments have been shut down
Not bad for 70's technology.
Has UARS hit yet? Nothing on the BBC. Can I take my helmet off?
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here's the latest news I could find at the moment, off the coast of California, trajectory Seattle-ish
originally cpf member #14 write me at gmail.
OK, so the satellite that was originally possibly going to hit the US, then definitely not going hit the US, then will hit the US, was originally falling faster than expected, then slower then expected, and now falling faster again. Got that?
Screw it. I'm wearing my helmet tomorrow.
I'm heading outside right now. My yard needs a nice crater.
No free goodies from NASA in my garden. Apparently bits of it have been found in Alberta
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UPDATE #15 - NASA’s decommissioned Upper Atmosphere Research Satellite fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. EDT Sept. 24. The Joint Space Operations Center at Vandenberg Air Force Base in California said the satellite penetrated the atmosphere over the Pacific Ocean. The precise re-entry time and location are not yet known with certainty.
UPDATE #14 - NASA’s decommissioned Upper Atmosphere Research Satellite fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. EDT Sept. 24. The satellite was passing eastward over Canada and Africa as well as vast portions of the Pacific, Atlantic and Indian oceans during that period. The precise re-entry time and location are not yet known with certainty.