A falling NASA satellite has a chance of about 1/3,200 of hitting a person between Alaska and South America over the next month.
NASA said the 35 foot long, 15 foot wide Upper Atmosphere Research Satellite (UARS) is expected to re-enter Earth’s atmosphere sometime in late September or early October. The 6 1/2 ton satellite will fall over a 500-mile stretch of land someplace between northern Canada and southern South America. Officials say that they will not know for sure where the satellite will land until about two hours before it strikes Earth’s surface, even then, officials say there will be a 6,000 mile margin for error.
“The risk to public safety or property is extremely small, and safety is NASA’s top priority. 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,” NASA said in a press release.
According to a NASA risk assessment, on average, a spacecraft as large as UARS falls back to Earth about once a year. In 2010, a total of 400 pieces of satellites or spent rockets fell to Earth. Most pieces either burned up during re-entry, fell into the ocean or fell over unpopulated areas. UARS is expected to behave similarly as it plummets; though, researchers say, about 1,170 pounds of material from the satellite is expected to reach Earth, the largest of which could weigh nearly 300 pounds. About 26 large objects are expected to survive the fall.
NASA launched the $750 million UARS satellite in 1991 aboard the space shuttle Discovery on a mission to study Earth’s upper atmosphere. It was decommissioned in 2005 and ran out of fuel, beginning its deviation from orbit.
NASA will provide updates weekly until four days before re-entry, then daily until about 24 hours before re-entry, and then at about 12 hours, six hours and two hours before re-entry. The updates will come from the Joint Space Operations Center of U.S. Strategic Command at Vandenberg Air Force Base, Calif., which works around the clock detecting, identifying and tracking all man-made objects in Earth orbit, including space junk, according to the space agency.