Endeavour prepares to return to Earth after nearly 16 days aloft

After more than 15 days in space, the six crew members of the Endeavour made final preparations to return to Earth Wednesday on its final mission and the next-to-final mission for NASA's 30-year-old space shuttle program.

The shuttle crew was scheduled to begin deorbit preparations at 9:26 p.m. ET and to close Endeavour's payload bay doors at 10:49 p.m.

Entry Flight Director Tony Ceccacci was expected to poll the crew at 1:19 a.m. Wednesday on whether to go ahead with the deorbit burn.

If the burn is approved, Cmdr. Mark Kelly Is expected to fire Endeavour's engines at 1:29 a.m. to slow it down enough that it falls out of orbit, leading ultimately to a planned touchdown at 2:35 a.m. on runway 15 of the Kennedy Space Center's Shuttle Landing Facility.

Kelly said the mothballing of Endeavour will not mean an end to space missions. "The retirement of Endeavour and the shuttle fleet will not end the human need to explore," he said in comments from space that were posted on NASA's website. "It is and always will be part of who we are. The United States will build other spaceships better than those of today. Even if they are years in the future, they will nevertheless increase our knowledge of the world, generate an enormous benefit to the economy and inspire our children."

The crew members awoke at 5:57 p.m. to the song "Sunrise Number 1," performed by the band Stormy Mondays and chosen for the honor in an online vote.

Endeavour unlocked from the International Space Station late Sunday after spending more than 11 days docked to the orbiting laboratory, where the astronauts installed a cosmic ray detector. The $2 billion, 15,000-pound machine is already at work "gathering information that could improve our understanding of the universe," Kelly said.

Endeavour leaves International Space Station

When it launched, Endeavour had already traveled almost 116.4 million miles in space on 24 previous flights, had spent 283 days in space and had orbited the Earth 4,423 times, according to Kelly, whose brother Scott led a previous mission.

On July 8, space shuttle Atlantis is to make NASA's final shuttle flight in the 30-year program. Thousands of people turned out Tuesday night at Kennedy Space Center to watch it make the three-mile trip from the Vehicle Assembly Building to the launch pad.

"Look how majestic it looks rolling out to the launch pad," said astronaut Sandy Magnus to reporters. "Look at that and see what we can do when we put our minds to it."