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BBC MUNDO RADIO
An
artist's rendition of the Upper Atmosphere Research Satellite (UARS),
launched in 1991 to study Earth's ozone layer. It's now falling back to
Earth. (NASA)
(CBS/AP) (Update:
11:23 pm) CAPE CANAVERAL, Florida - NASA is narrowing the timeframe on
when a 6-ton satellite is expected to collide with Earth.
NASA said late Friday that the satellite is now expected to fall from the sky between 11:45 p.m. EDT and 12:45 a.m. EDT Saturday.
Canada and Africa are in the potential crosshairs, although most of the satellite should burn up during re-entry. The United States isn't entirely out of the woods; the possible strike zone skirted Washington state.
Earlier, it was reported that the satellite clung to space Friday, apparently flipping position in its ever-lower orbit and stalling its death plunge.
"It just doesn't want to come down," said Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics.
McDowell said the satellite's delayed demise demonstrates how unreliable predictions can be. That said, "the best guess is that it will still splash in the ocean, just because there's more ocean out there."
Until Friday, increased solar activity was causing the atmosphere to expand and the 35-foot (10-meter), bus-size satellite to free fall more quickly. But late Friday morning, NASA said the sun was no longer the major factor in the rate of descent and that the satellite's position, shape or both had changed by the time it slipped down to a 100-mile (160-kilometer) orbit.
"In the last 24 hours, something has happened to the spacecraft," said NASA orbital debris scientist Mark Matney.
On Friday night, NASA had earlier said it expected the satellite to come crashing down between 11 p.m. and 3 a.m. EDT. It was going to be passing over the Atlantic, Pacific and Indian oceans at that time, as well as Canada, Africa and Australia.
"The risk to public safety is very remote," NASA said in a statement.
The Aerospace Corp., which tracks space debris, also estimated the strike would happen sometime between about 11 p.m. and 3 a.m. EDT, which would make a huge difference in where the debris falls. Its projections also put almost all of the U.S. in the clear — with Washington state the lone holdout.
More than two dozen chunks of debris are likely to survive re-entry and hit the ground. CBS News correspondent Bill Whitaker reports it will be a fiery end to the old satellite when it bursts back into Earth's atmosphere, which computer models suggest is most likely to happen somewhere over the South Pacific. But not even NASA scientists can say for sure.
FEMA ready for just-in-case scenarios with satellite crash
Wayward satellite likely to fall in South Pacific
CBS News' Bill Harwood says that the UARS has an orbital velocity of approx. 5 miles per second. That creates uncertainty over its position when it descends - a five-minute delay can translate into a difference of 1,500 miles.
CBS News: Bill Harwood's Space Place blog
NASA: UARS updates
Most of the satellite will disintegrate, but 26 pieces - or 1,200 pounds - are expected to rain down somewhere.
Three quarters of the Earth's surface is water, so most likely, nobody will even see it.
The satellite was launched 20 years ago to study the atmosphere.
NASA said late Friday that the satellite is now expected to fall from the sky between 11:45 p.m. EDT and 12:45 a.m. EDT Saturday.
Canada and Africa are in the potential crosshairs, although most of the satellite should burn up during re-entry. The United States isn't entirely out of the woods; the possible strike zone skirted Washington state.
Earlier, it was reported that the satellite clung to space Friday, apparently flipping position in its ever-lower orbit and stalling its death plunge.
"It just doesn't want to come down," said Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics.
McDowell said the satellite's delayed demise demonstrates how unreliable predictions can be. That said, "the best guess is that it will still splash in the ocean, just because there's more ocean out there."
Until Friday, increased solar activity was causing the atmosphere to expand and the 35-foot (10-meter), bus-size satellite to free fall more quickly. But late Friday morning, NASA said the sun was no longer the major factor in the rate of descent and that the satellite's position, shape or both had changed by the time it slipped down to a 100-mile (160-kilometer) orbit.
"In the last 24 hours, something has happened to the spacecraft," said NASA orbital debris scientist Mark Matney.
On Friday night, NASA had earlier said it expected the satellite to come crashing down between 11 p.m. and 3 a.m. EDT. It was going to be passing over the Atlantic, Pacific and Indian oceans at that time, as well as Canada, Africa and Australia.
"The risk to public safety is very remote," NASA said in a statement.
The Aerospace Corp., which tracks space debris, also estimated the strike would happen sometime between about 11 p.m. and 3 a.m. EDT, which would make a huge difference in where the debris falls. Its projections also put almost all of the U.S. in the clear — with Washington state the lone holdout.
More than two dozen chunks of debris are likely to survive re-entry and hit the ground. CBS News correspondent Bill Whitaker reports it will be a fiery end to the old satellite when it bursts back into Earth's atmosphere, which computer models suggest is most likely to happen somewhere over the South Pacific. But not even NASA scientists can say for sure.
FEMA ready for just-in-case scenarios with satellite crash
Wayward satellite likely to fall in South Pacific
CBS News' Bill Harwood says that the UARS has an orbital velocity of approx. 5 miles per second. That creates uncertainty over its position when it descends - a five-minute delay can translate into a difference of 1,500 miles.
CBS News: Bill Harwood's Space Place blog
NASA: UARS updates
Most of the satellite will disintegrate, but 26 pieces - or 1,200 pounds - are expected to rain down somewhere.
Three quarters of the Earth's surface is water, so most likely, nobody will even see it.
The satellite was launched 20 years ago to study the atmosphere.
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