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KUALA LUMPUR (NST): A dead American satellite the size of a bus is expected to fall back to earth this weekend and Malaysia is among the countries within its impact zone.

But the satellite is expected to break up into smaller pieces upon re-entry and the risk to public safety or property from the falling debris is said to be extremely small.

Nevertheless, Malaysia’s National Space Agency (Angkasa) is monitoring updates from the National Aeronautics and Space Administration (Nasa) of the United States.

NASA's Falling UARS Satellite Explained (Infographic) (Credit: Karl Tate (Space.com)) - Click for larger image

The satellite is Nasa’s decommissioned Upper Atmosphere Research Satellite (UARS), and so far, the US space agency could not put the exact time and place where the 6,000kg object would fall. Nasa’s latest update showed the expected re-entry date as tomorrow, US time, plus or minus a day. This puts the expected date for Malaysia between tomorrow and Sunday.

Angkasa’s spokesman said their team, based at the National Observatory at the Bukit Malut Dam in Langkawi, Kedah, is monitoring the satellite.

“Although it is difficult to use the facility’s telescope to track the satellite, we will still try,” he said yesterday.

“Our team is also monitoring Nasa’s website round-the-clock for the latest updates on the expected time and location of the re-entry.” Angkasa, unlike Nasa, does not have the equipment or expertise to monitor space debris or near-earth objects.

The spokesman said members of the public could also monitor the updates through the Nasa website at http://www.nasa.gov/uars.

He said there was no need for people to worry as the satellite would break up into pieces and the odds of being struck was estimated at 1 in 3,200.

He said the 20-year-old research satellite was expected to break up into more than 100 pieces as it reentered the atmosphere, most of them burning up.

Twenty-six of its heaviest metal parts are expected to reach Earth, the biggest chunk weighing 136kg.

The debris could be scattered over an area of about 800km.

The UARS’ trajectory takes it between 57 degrees north latitude and 57 degrees south latitude, which is also its crash zone.

The zone covers everything from Canada down to the tip of South America, and from Siberia down to the tip of Africa and Australia.

The UARS was launched on Sept 12, 1991, aboard space shuttle mission STS-48 and it was deployed on Sept 15, 1991. It was the first multiinstrumented satellite to observe numerous chemical components of the atmosphere for better understanding of photochemistry. UARS ceased its productive scientific life in 2005.

US media advised its citizens not to pick up any debris that they suspect came from the satellite.

The space agency says there are no toxic chemicals present, but there can be sharp edges. Also, it’s government property. It’s against the law to keep it as a souvenir or sell it on eBay. Nasa’s advice is to report any findings to the police.

US media reports said that UARS was getting advance publicity because it was the biggest Nasa satellite to make an uncontrolled re-entry in about three decades.

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Additional info from http://reentrynews.aero.org/

Object Description:

Type: UARS Satellite
Int’l Designation: 1991 063B
Launched: 12 SEP 1991 @ 23:11 UTC
Site: Deployed from Shuttle Discovery on 15 September 1991
Mission: Upper Atmosphere Research Satellite

Reentry Prediction:

Predicted Reentry Time: 23 SEP 2011 @ 20:00 UTC ± 14 hours
Prediction Epoch: 21 SEP 2011 @ 13:00:58.904 UTC
Prediction Ground Track:


For clarity, ground track plot is limited to ± 6 hours

Legend
Yellow Icon – location of object at predicted reentry time
Orange Line – area of visibility at the predicted reentry time for a ground observer
Blue Line – ground track uncertainty prior to predicted reentry time (ticks at 5-minute intervals)
Yellow Line – ground track uncertainty after predicted reentry time (ticks at 5-minute intervals)
White Line – day/night divider at predicted reentry time (Sun location shown by White Icon)
Note: Possible reentry locations lie anywhere along the blue and yellow ground track.