After hours of worldwide suspense, NASA said it was working on Saturday to confirm the time and the place where its six-ton Upper Atmosphere Research Satellite made its fiery plunge to Earth.
The old research spacecraft was targeted to crash through the atmosphere after midnight Eastern Daylight Time, with Canada and Africa potentially in the crosshairs. There were unconfirmed reports that a fireball display was seen in northern Canada, but no official verification of those reports.
Late Friday night, NASA said it expected the satellite to come crashing down between 11:45 p.m. and 12:45 a.m. ET Saturday. During that time frame, it was going to be passing over the Atlantic, Pacific and Indian oceans, as well as Canada and Africa. After the appointed time, NASA said it was "working to confirm the re-entry location and time and will provide an update shortly."
Any surviving wreckage is expected to be sparsely distributed within a 500-mile (800-kilometer) swath. "The risk to public safety was very remote," NASA said in a statement.
The projected time of re-entry was pushed later and later during the satellite's final hours.
"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, 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 orbit.
"In the last 24 hours, something has happened to the spacecraft," said NASA orbital debris scientist Mark Matney.
The Upper Atmosphere Research Satellite, or UARS, was the biggest NASA spacecraft to crash back to Earth, uncontrolled, since the post-Apollo 75-ton Skylab space station and the more than 10-ton Pegasus 2 satellite, both in 1979.
Russia's 135-ton Mir space station slammed through the atmosphere in 2001, but that was a controlled dive into the Pacific.
About two dozen pieces of the UARS satellite — representing 1,200 pounds of heavy metal — are expected to rain down somewhere. The biggest surviving chunk should be around 300 pounds (150 kilograms).
Earthlings can take comfort in the fact that no one has ever been hurt by falling space junk — to anyone's knowledge — and there has been no serious property damage. NASA put the chances that somebody somewhere on Earth would get hurt at 1-in-3,200. But any one person's odds of being struck were estimated at 1-in-22 trillion, given that there are 7 billion people on the planet.
"Keep in mind that we have bits of debris re-entering the atmosphere every single day," Matney said in brief remarks broadcast on NASA TV.
In any case, finders definitely aren't keepers.
Any surviving wreckage belongs to NASA, and it is against the law to keep or sell even the smallest piece. There are no toxic chemicals on board, but sharp edges could be dangerous, so the space agency is warning the public to keep hands off and call police.
The $740 million UARS was launched in 1991 from space shuttle Discovery to study the atmosphere and the ozone layer. At the time, the rules weren't as firm for safe satellite disposal; now a spacecraft must be built to burn up upon re-entry or have a motor to propel it into a much higher, long-term orbit.
NASA shut UARS down in 2005 after lowering its orbit to hurry its end. A potential satellite-retrieval mission was ruled out following the 2003 shuttle Columbia disaster, and NASA did not want the satellite hanging around orbit posing a debris hazard.
Space junk is a growing problem in low-Earth orbit. More than 20,000 pieces of debris, at least 4 inches in diameter, are being tracked on a daily basis. These objects pose a serious threat to the International Space Station.
Re: ALERT!!! Nasa Satellite 'To Hit Earth Within Hours'
maybe it is all fake. maybe it is all a rouse, a red herring, a distraction. maybe we should all be looking down at the earth for soemthing that's happening, instead of up at the sky.
Quoting: Anonymous Coward 1506317
I am starting to think it was all a distraction.Since its still circling around but also probably already crashed thats certainly a good possibility.Have to admit they have held a lot of peoples attention for a few days.
Quoting: Anonymous Coward 1783282
It's not a distraction. NASA admitted UARS is the 2011 IADC exercise.
[link to www.nasa.gov]
"At the recommendation of NASA, the IADC has accepted UARS as the subject of the 2011 IADC Reentry Risk Object Exercise.
UARS does NOT meet the IADC definition of a risk object."
UPDATE #13 - As of 10:30 p.m. EDT on Sept. 23, 2011, the orbit of UARS was 85 miles by 90 miles (135 km by 140 km). Re-entry was expected between 11:45 p.m. Friday, Sept. 23, and 12:45 a.m., Sept. 24, Eastern Daylight Time (3:45 a.m. to 4:45 a.m. GMT). During that time period, the satellite was passing over Canada and Africa, as well as vast areas of the Pacific, Atlantic and Indian oceans. The risk to public safety was very remote. NASA is working to confirm the re-entry location and time and will provide an update shortly.
The pieces should miss North America, but may land somewhere in the Pacific. The AP reported that, as of Thursday evening, the satellite appeared to be on a trajectory to splash into the desolate South Pacific sometime Saturday morning Guam time, according to a map published by the Aerospace Corp., which uses Air Force tracking data.
In place of tracking they have the following blurb and a series of static maps.
I assume the think it may be down
Sat, 24 Sep 2011 12:55:17 AM EDT
As of 10:30 p.m. EDT on Sept. 23, 2011, the orbit of UARS was 85 miles by 90 miles (135 km by 140 km). Re-entry was expected between 11:45 p.m. Friday, Sept. 23, and 12:45 a.m., Sept. 24, Eastern Daylight Time (3:45 a.m. to 4:45 a.m. GMT). During that time period, the satellite was passing over Canada and Africa, as well as vast areas of the Pacific, Atlantic and Indian oceans. The risk to public safety was very remote. NASA is working to confirm the re-entry location and time and will provide an update shortly.