科技英语新闻:UARS poses negligible threat to life, property on Earth: Australian expert

CANBERRA, Sept. 24 (Xinhua) -- Australian scientists on Saturday said a satellite due to re-enter Earth poses a negligible threat to life and property on Earth.

U.S. National Aeronautics and Space Administration's Upper Atmosphere Research Satellite (UARS), which weighs more than five tons, is expected to re-enter the Earth's atmosphere at 1058 (AEST) on Saturday. The U.S.-based Center for Orbital and Re-entry Debris Studies estimates that re-entry could occur up to seven hours before or after this time.

According to Nonathan Nally, a former editor of two space magazines and currently editor of the Australian Space News website, the satellite poses a negligible threat to life and property on Earth.

"Most of the satellite will burn up on re-entry, with perhaps as many as 26 stronger or harder small pieces surviving to reach the surface," Nally said in a statement.

"But with the majority of the Earth comprising oceans or uninhabited (or very sparsely populated) remote regions, the chances are overwhelming that any pieces of UARS that survive re- entry will fall harmlessly and never be seen again."

Since the spacecraft is no longer powered, U.S. National Aeronautics and Space Administration has no control over where it comes down, but Nally said there is a small chance that debris from the satellite could land in Australia.

Debris from SkyLab, another satellite which plunged to Earth, was scattered over parts of Western Australia in 1979. Skylab weighed about 77 tonnes, many times more than the UARS.?

Dr Alice Gorman, a lecturer in the Department of Archaeology, specializing in space archaeology, at Flinders University in South Australia, said the UARS satellite re-entry is very reminiscent of Skylab in 1979.

"There is the same exaggeration of the hazard through the media, public anxiety as the advance warning allows for speculation, and a lack of understanding of what the risks actually are," he said in a statement.

"Should it land in Australia, we might expect the same rush for souvenirs as we saw with Skylab, as anything that has been in space has a special meaning on Earth."?

UARS was launched on 12 September 1991 and decommissioned on 15 December 2005. Its total dry mass is about 5.5 tonnes. UARS is one of the largest NASA satellites to plunge back to Earth uncontrolled in the last 30 years.

Since the beginning of the Space Age in the late-1950s, there have been no confirmed reports of an injury resulting from re- entering space objects.? Nor is there a record of significant property damage resulting from a satellite re-entry.