Flying upside down and backwards just off the tip of Madagascar over the Indian Ocean, shuttle commander Eileen Collins and pilot James Kelly fired Discovery's twin braking rockets at 7:06:18 a.m. EDT to begin the hour-long descent to a California landing.
The deorbit rocket firing lasted two minutes and 42 seconds, changing the shuttle's velocity by about 187 mph and dropping the far side of its orbit deep into the atmosphere. Touchdown on runway 22 at Edwards Air Force Base, Calif., is expected at 8:12 a.m. EDT, 54 minutes before sunrise local time.
CBS News Space Consultant William Harwood reports this would be the 50th shuttle landing at Edwards Air Force Base and the first since June 2002. The touchdown, before dawn California time, would make Discovery's return the first night shuttle landing at Edwards since September 1991 and just the sixth overall in program history.
Discovery had no luck earlier Tuesday as it orbited the earth hoping for clouds, rain and lightning storms to move away from the Kennedy Space Center at Cape Canaveral, NASA's preferred location for shuttle landings.
NASA first tried to bring Discovery back to Florida Monday - but failed, twice, due to bad weather - and things went pretty much the same this morning, as the astronauts aimed at, and then were waved off of, landing slots for 5:07 a.m. and 6:43 a.m. EDT at Cape Canaveral.
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Discovery on its way back to Earth.
"How do you feel about a beautiful clear night with a breeze down the runway in the high desert of California?" Ham radioed Discovery as the shuttle crew waited for permission to try or skip a Florida landing.
"We are ready for whatever we need to do," replied Collins.
"What we had is continued instability at the Cape. Just within the last 15 minutes or so, we had another couple of small cells popping up around 15 to 20 miles that came out of nowhere, just off the coastline and growing. Predicted to have some lightning activity here shortly," said astronaut Ken Ham in Houston. "So the official forecast is holding electrified clouds off the coast of the Cape, which we're not going to send you through."
If the weather at Edwards deteriorates, NASA still has one more place to bring the shuttle down: the White Sands Missile Range in New Mexico. That's considered to be unlikely, however; rain is also a possibility at White Sands.
The directions to redirect toward California came just minutes after controllers told Collins the weather seemed to be clearing in Florida and they hoped to get the crew to the Kennedy Space Center. Conditions then took a turn for the worse.
Collins was understanding. She said her crew was familiar with Florida storms and was "not surprised at all."
"I've been in your shoes many times so I understand," Collins told Mission Control.
NASA instructed the astronauts to continue landing preparations and begin drinking large amounts of fluids, which are necessary for re-entry because bodily fluids are lost in the weightless environment of space.
The astronauts began their day with a chorus of "Good Day, Sunshine," the Beatles standard played by NASA Mission Control as it woke up the shuttle crew for the day they hope will be their return to Earth.