Atlantis set to begin deorbit burn
Cape Canaveral - Nasa on Thursday gave the green light for Atlantis to begin its deorbit burn, as the space shuttle approached its re-entry into Earth's atmosphere for a final time.
The "go" order was issued by mission control capsule commander Barry Wilmore shortly after the shuttle began its 200th and last orbit around Earth before a scheduled 05:56 (09:56 GMT) landing at Kennedy Space Centre in Florida.
The deorbit burn is set to begin at 04:49 (08:49 GMT), when the engines will fire for just over three minutes in order to slow the shuttle down just enough for its re-entry in Earth's atmosphere.
Atlantis and its crew of four US astronauts are set to touch down just before dawn, marking the end of the final mission of the 30-year space shuttle programme.