Upper Atmosphere Research Satellite (UARS), the 20-year old six-ton NASA science satellite which took an unpredictable course and tumbled through the upper atmosphere, fell back to Earth today, according to a statement by the NASA.

NASA however said that the exact place where it landed on the earth was not known as yet.

“Most of the time, it was rotating over Canada and Africa as well as vast portions of the Pacific, Atlantic and Indian oceans in its falling journey to the Earth. Therefore, the details of where and when it landed exactly on the earth are not known,” said the statement.

The 6-ton satellite was dispatched into space in 1991 to study ozone and other chemicals in Earth’s atmosphere but it has been slowly losing altitude after it completed its mission in 2005.

The debris of the satellite could spread over 500 miles and with most of the planet covered in water and vast uninhabited deserts, it could have landed in water somewhere, said the NASA.