The Upper Atmosphere Research Satellite, which was used to measure the ozone layer, spans 35 by 15 foot (three by 10 meters) and weighs 13,000 pounds (5,900 kilograms). Nasa noted : The satellite, which carries 10 scientific instruments for measuring wind, temperature and ozone chemistry, was officially decommissioned in 2005.
"As of Sept. 16, 2011, the orbit of UARS was 140 mi by 155 mi (225 km by 250 km). Re-entry is expected Sept. 23, plus or minus a day. The re-entry of UARS is advancing because of a sharp increase in solar activity since the beginning of this week," NASA said in a brief update on its Web site."If you find something you think may be a piece of UARS, do not touch it. Contact a local law enforcement official for assistance."
The satellite's orbit passes over most of the planet, from as far north as northern Canada to the southern part of South America.
The largest chunk of wreckage from UARS is expected to be about 151 kg, says Nicholas Johnson, chief scientist of NASA's Orbital Debris Program office at the Johnson Space Center in Houston.
Tag : satellite crash 2011 video, satellite falling
As of Sunday, UARS was in a 215-km by 240-km high orbit around Earth. and today in a 190 km, Re-entry is expected some time on Friday, although it could happen as late as Saturday.(News for Nasa satellite crash ) " NASA estimates the debris footprint will be about 500 miles (800 kilometers) long," the space agency said.
update : Pieces of a defunct satellite that plummeted to Earth have settled, NASA said Saturday morning
The space agency said the Upper Atmosphere Research Satellite "is down," according to the space agency's Twitter page. NASA said debris fell to Earth between 11:23 p.m. ET Friday and 1:09 a.m. ET Saturday, but it was not immediately clear where the pieces may have landed.
NASA said the satellite pierced through the atmosphere over the Pacific Ocean, but the exact time and location were not known .About two dozen pieces of the satellite were expected to survive the crash through the Earth's atmosphere.
Late Friday night, NASA predicted satellite parts would pass "over Canada and Africa, as well as vast areas of the Pacific, Atlantic and Indian oceans."
"The risk to public safety is very remote," NASA said.
The 26 pieces expected to survive the descent -- made of stainless steel, titanium and beryllium that won't burn -- ranged from about 10 pounds to hundreds of pounds, according to NASA.
"The U.S. is very safe from (the satellite) ... It's final orbit did not cross the United States," the space agency tweeted early Saturday.
But reports of suspected sightings emerged from San Antonio, Texas, where a TV photographer caught images of bright objects darting rapidly in the night sky, and from Hawaii, where Robert Jeffcoat saw what he believed were two chunks from the satellite.
Jeffcoat was running errands when the first flying object left a thick, white trail that lingered in the sky for about 20 minutes, he said. A second object followed the same path and was "massive," he said.
"It's was like a comet, but smoke," he said. "I'm guessing it landed in the ocean, the way it was going."
Mark Matney of NASA's Orbital Debris team in Houston said before spacial rubbish fell that there was no way to know exactly where the pieces would come down.
"Part of the problem is, the spacecraft is tumbling in unpredictable ways, and it is very difficult to very precisely pinpoint where it's coming down even right before the re-entry," Matney said.
The Federal Aviation Administration released an advisory Thursday warning pilots about the falling satellite, calling it a potential hazard.
"It is critical that all pilots/flight crew members report any observed falling space debris to the appropriate (air traffic control) facility and include position, altitude, time and direction of debris observed," the FAA statement said.
The FAA said warnings of this sort typically are sent out to pilots concerning specific hazards they may encounter during flights such as air shows, rocket launches, kites and inoperable radio navigational aids.
NASA said space debris the size of the satellite's components re-enters the atmosphere about once a year. Harvard University astrophysicist Jonathan McDowell noted that the satellite is far from being the biggest space junk to come back.
Latest update :
A bus-sized US satellite that hurtled unpredictably toward Earth crossed over Africa and the northern Atlantic before likely plunging into the Pacific Ocean off California, NASA said on Saturday.
The six-tonne Upper Atmosphere Research Satellite (UARS) fell from the sky between 11:23 pm Friday and 1:09 am Saturday (0323-0509 GMT Saturday), the space agency said, but there were no sightings or reliable accounts of damage.
"We have got no reports of anyone seeing anything that we believe are credible," NASA chief orbital scientist Nick Johnson said, noting that the "vast majority" of its flight track had been over water.
The best and latest estimate, made by the Joint Space Operations Center at Vandenberg Air Force Base in California at two hours before entry, put the re-entry time at 0416 GMT.
"If the re-entry point was at 0416 GMT, then all that debris wound up in the Pacific Ocean," said Johnson.
NASA had maintained that the risk of the satellite causing harm to people on land was remote.Since the satellite was circling Earth just about every hour and a half before it fell, it covered a vast amount of territory in its final loop, according to a map NASA posted on its website at nasa.gov/uars.
It started off on the eastern coast of Africa before going over the Indian Ocean, up the Pacific over Canada, over the northern Atlantic and then down western Africa before ending in the Indian Ocean again, Johnson said. but ...
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