SALMON, US - A fireball spotted streaking across the night sky late on Monday in the western United States was almost certainly the body of a rocket used by China in December to launch a satellite, an astronomer said Tuesday.
Residents in Rocky Mountain states such as Idaho, Utah and Montana reported seeing the rocket as it disintegrated in the atmosphere about 70 miles (113 km) above Earth, said Chris Anderson, manager of the Centennial Observatory at the College of Southern Idaho in Twin Falls.
An organisation that studies orbital debris, or space junk, and attempts to pinpoint when and where objects will re-enter Earth's atmosphere had earlier predicted that the rocket which began its descent last year after sending a Chinese satellite into orbit would likely be seen about 2 a.m. local time in northern Russia, Anderson said.
The rocket, which was orbiting Earth about every 87 minutes, made an early appearance elsewhere and in fiery fashion likely because its orientation may have changed as it tumbled through space in its final orbit, affecting the rate of speed, he said.
"It's devilishly difficult to predict exactly when things will come down and where because it depends so much on the atmospheric drag and the orientation of the object as it plows through the air," Anderson said.
NASA/Jet Propulsion Laboratory Solar System Ambassador Patrick Wiggins also told The Salt Lake Tribune newspaper he was"95 per cent sure" the fiery sighting was of the re-entry of a Chinese rocket body used to launch the satellite Yaogan Weixing-26 in December.
Space junk like parts of rocket launchers and inactive satellites are a pressing problem for Earth's orbit, according to the European Space Agency, which in 2013 called for the debris to be removed to avoid crashes that could cost satellite operators dearly and knock out mobile and GPS networks.
A finding by the agency at the time suggested the density of debris was likely to trigger an in-orbit collision every five years.
The agency estimated roughly 29,000 objects larger than 4 inches (10 cm) were orbiting Earth at average speeds of 15,500 miles per hour (24,945 kph), or 40 times faster than airplanes travel.