Hi Gavin,
The problem with re-entry predictions is that the satellite is odd shaped and once broken up, the pieces shapes cannot be determine because it depends on the angle, rotation, type of material and a little wind effects too.
That is why they can only determine within a radius of 500km.
The space shuttle or the soyuz return capsule, on the other hand, comes in intact, with a known aerodynamic performance and it's controlled by the pilots too up to some extent.
UARS Satellite uncontrolled rentry around Sep 23
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Airconvent
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Canada !!!! LOL
Space satellite debris scatters over Canada: NASA
05:09 PM Sep 24, 2011
CAPE CANAVERAL (Florida) - A six-tonne NASA science satellite plunged through the atmosphere early today, breaking up and possibly scattering debris in Canada, NASA said.
There were reports on Twitter of debris falling over Okotoks, a town south of Calgary in western Canada, most likely the remains of the Upper Atmosphere Research Satellite, or UARS, which had been in orbit for 20 years.
Scientists were unable to pinpoint the exact time and place where UARS would return to Earth due to the satellite's unpredictable tumbles as it plowed through the upper atmosphere. Re-entry was believed to have occurred between 11.45 pm Eastern Daylight Time on Friday (11.45am, Saturday, Singapore time) and 12.45am EDT on Saturday.
Stretching 10.7 metres long and 4.6 metres in diameter, UARS was among the largest spacecraft to plummet uncontrollably through the atmosphere, although it is a slim cousin to NASA's 75-tonne skylab station, which crashed to Earth in 1979. REUTERS
Space satellite debris scatters over Canada: NASA
05:09 PM Sep 24, 2011
CAPE CANAVERAL (Florida) - A six-tonne NASA science satellite plunged through the atmosphere early today, breaking up and possibly scattering debris in Canada, NASA said.
There were reports on Twitter of debris falling over Okotoks, a town south of Calgary in western Canada, most likely the remains of the Upper Atmosphere Research Satellite, or UARS, which had been in orbit for 20 years.
Scientists were unable to pinpoint the exact time and place where UARS would return to Earth due to the satellite's unpredictable tumbles as it plowed through the upper atmosphere. Re-entry was believed to have occurred between 11.45 pm Eastern Daylight Time on Friday (11.45am, Saturday, Singapore time) and 12.45am EDT on Saturday.
Stretching 10.7 metres long and 4.6 metres in diameter, UARS was among the largest spacecraft to plummet uncontrollably through the atmosphere, although it is a slim cousin to NASA's 75-tonne skylab station, which crashed to Earth in 1979. REUTERS
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email: gary[at]astro.sg
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"The importance of a telescope is not how big it is, how well made it is.
It is how many people, less fortunate than you, got to look through it."
-- John Dobson.
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Hi Rich, I see, I suppose there are a lot of factors involved in the satellite's final re-entry and break-up. I didn't realise wind would be a factor!
Actually, what I was expressing surprise at was that NASA/US Dept of Defence could not say where it eventually re-entered and the debris fell, after it had happened.
I can understand that they won't be able to predict with too much certainty when it would re-enter and where. But I would have thought their spy satellites used to detect foreign missiles would be able to track it all the way to the ground during and after re-entry, or at least know where it had burnt up at the point of re-entry.
So much so for the movies, or maybe they are "acting blur" as there would be some technological capability involved.
Hi Gary, O Canada!? Ya, I saw a similar report just now on BBC World. But Nasa still says it's the Pacific Ocean, hmmm.... mystery:
http://www.nasa.gov/mission_pages/uars/index.html
"Update #15
Sat, 24 Sep 2011 03:46:42 PM UTC+0800
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."
Actually, what I was expressing surprise at was that NASA/US Dept of Defence could not say where it eventually re-entered and the debris fell, after it had happened.
I can understand that they won't be able to predict with too much certainty when it would re-enter and where. But I would have thought their spy satellites used to detect foreign missiles would be able to track it all the way to the ground during and after re-entry, or at least know where it had burnt up at the point of re-entry.
So much so for the movies, or maybe they are "acting blur" as there would be some technological capability involved.
Hi Gary, O Canada!? Ya, I saw a similar report just now on BBC World. But Nasa still says it's the Pacific Ocean, hmmm.... mystery:
http://www.nasa.gov/mission_pages/uars/index.html
"Update #15
Sat, 24 Sep 2011 03:46:42 PM UTC+0800
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."
Re: UARS Satellite uncontrolled rentry around Sep 23
Source: Yahoo! News-
..CAPE CANAVERAL, Florida (Reuters) - Debris from a defunct six-tonne NASA science satellite that crashed to Earth on Saturday fell harmlessly in a remote area of the South Pacific Ocean, NASA said on Tuesday.
Experts estimated that as much as 1,100 pounds (495 kg) of debris survived the bus-sized satellite's fiery plunge through the atmosphere, which started at midnight EDT on Saturday (0400 GMT on Sunday).
The Joint Space Operations Center at Vandenberg Air Force Base in California determined that the U.S. space agency's Upper Atmosphere Research Satellite (UARS) entered the atmosphere over the Pacific Ocean at 14.1 degrees south latitude and 170.2 west longitude, NASA said in a statement.
That location is in Pacific in the rough vicinity of Samoa. The debris was then scattered between 300 miles and 800 miles (480 km to 1,300 km) from the re-entry point, NASA said.
"This location is over a broad, remote ocean area in the Southern Hemisphere, far from any major land mass," NASA said, adding that the agency "is not aware of any possible debris sightings from this geographic area."
Measuring 35 feet long and 15 feet in diameter (10.6 km long and 4.6 km in diameter), UARS was among the largest spacecraft to plummet uncontrollably through the atmosphere.
NASA now plans for the controlled re-entry of large spacecraft, but it did not when UARS was designed.
The 13,000-pound (5,897 kg) satellite was placed into orbit by a space shuttle crew in 1991 to study ozone and other chemicals in Earth's atmosphere. It completed its mission in 2005 and had been slowly losing altitude ever since, pulled by the planet's gravity.
UARS was one of about 20,000 pieces of space debris in orbit around Earth. Something the size of UARS falls back into the atmosphere about once a year.
(Editing by Jane Sutton and Will Dunham)
..
..CAPE CANAVERAL, Florida (Reuters) - Debris from a defunct six-tonne NASA science satellite that crashed to Earth on Saturday fell harmlessly in a remote area of the South Pacific Ocean, NASA said on Tuesday.
Experts estimated that as much as 1,100 pounds (495 kg) of debris survived the bus-sized satellite's fiery plunge through the atmosphere, which started at midnight EDT on Saturday (0400 GMT on Sunday).
The Joint Space Operations Center at Vandenberg Air Force Base in California determined that the U.S. space agency's Upper Atmosphere Research Satellite (UARS) entered the atmosphere over the Pacific Ocean at 14.1 degrees south latitude and 170.2 west longitude, NASA said in a statement.
That location is in Pacific in the rough vicinity of Samoa. The debris was then scattered between 300 miles and 800 miles (480 km to 1,300 km) from the re-entry point, NASA said.
"This location is over a broad, remote ocean area in the Southern Hemisphere, far from any major land mass," NASA said, adding that the agency "is not aware of any possible debris sightings from this geographic area."
Measuring 35 feet long and 15 feet in diameter (10.6 km long and 4.6 km in diameter), UARS was among the largest spacecraft to plummet uncontrollably through the atmosphere.
NASA now plans for the controlled re-entry of large spacecraft, but it did not when UARS was designed.
The 13,000-pound (5,897 kg) satellite was placed into orbit by a space shuttle crew in 1991 to study ozone and other chemicals in Earth's atmosphere. It completed its mission in 2005 and had been slowly losing altitude ever since, pulled by the planet's gravity.
UARS was one of about 20,000 pieces of space debris in orbit around Earth. Something the size of UARS falls back into the atmosphere about once a year.
(Editing by Jane Sutton and Will Dunham)
..