The Upper Atmosphere Research Satellite (UARS) is finally plunging back to earth on Sept. 23, Friday, but NASA scientists are unsure about the location of its fall.
The UARS, launched on Sept. 15, 1991, by the space shuttle Discovery. Originally designed for a three-year mission, UARS measured chemical compounds found in the ozone layer, wind and temperature in the stratosphere, as well as the energy input from the sun. Together, these measurements helped define the role of Earth's upper atmosphere in climate and climate variability. The 35-foot-long, 15-foot-diameter UARS was decommissioned on Dec. 14, 2005.
According to the last estimation, UARS should crash somewhere between 57 degrees north latitude and 57 degrees south latitude which means crash zone covers most of the planet, particularly the inhabited parts.
The out-of-control, out-of-fuel 6-ton satellite is currently orbiting the earth and succumbing to its gravity.
Talking about its probable crashing zone, Steve White, a Fresno State Physics Professor, said "It's a hard calculation problem; we don't know the exact instant when it's going to come down, and it's moving really fast. It actually orbits the Earth every 90 minutes."
However, scientists say the risk of getting hit by the satellite parts is almost negative as most of it will burn up after entering the atmosphere. Only about 1,200 pounds should survive, scattered over perhaps a 500-mile-wide area, NASA said.
UARS was deployed from the shuttle Discovery in 1991 to study Earth's atmosphere and its interactions with the sun. The $750 million mission measured the concentrations and distribution of gases which cause ozone depletion, climate change, and it also studied the dynamics of the upper atmosphere.
NASA says readings from UARS provided conclusive evidence that chlorine in the atmosphere, originating from human-produced chlorofluorocarbons, is at the root of the polar ozone hole.
Researchers have confirmed that no hazardous material is left in the satellite. However, they have urged people to not to touch any fallen parts.
ibtimes.com