At 9:10 a.m. Central Daylight Time (CDT), NASA approved the de-orbit burn to be performed by Shuttle Commander Scott Altman.
The weather in Florida was too "dynamical" to make a safe call for landing with a deorbit burn about one hour before that touchdown.
The maneuver will take the STS-125 crew out of its orbit so that it can descend (fall) into the Earth's atmosphere for their return to Earth.
Live voice transmissions from the Mission Control Center, in Texas, to the astronauts in space just verified that the de-orbit burn will occur at 9:24:41 CDT. The burn will last two minutes, 36 seconds.
A NASA spokesperson on NASA TV announced at about 9:29 a.m. CDT that the deorbit burn was successful while Atlantis was high above Madagascar off of Africa. No further trims will be needed.
The STS-125 crew is expected to land the shuttle at about 8:39 a.m. Pacific Daylight Time (PDT) in California (10:39 a.m. CDT), at the secondary landing site of Edwards AF Base.
They will be landing Atlantis at Edwards runway 22, from the northeast the southwest. The weather is deemed clear at the landing site. The NASA spokesperson on NASA TV calls the weather at Edwards "pristine."
Watch the landing on NASA Television (check your local TV listing) on on the Internet at https://www.nasa.gov/multimedia/nasatv/.