World holds breath as shuttle prepares to land Tuesday

Homeward bound ... the Discovery crew being interviewed for US television last night before they turned the spacecraft for home

GDO Report

Overnight, the shuttle transformed into an unwieldy 100-tonne glider and was coming into land at an approach 20 times steeper than any commercial airliner.

The shuttle's crew has only one chance at landing when they reach the point of no-return about 5.15pm AEST. The shuttle does not have the fuel or the power to circle around and try again.

As Discovery left the International Space Station, the two space station residents wished the crew, which includes Australian-born Andy Thomas, a safe landing.

"It has really been a pleasure and, no, we are not glad to see you go. We would love to have you stay a little longer," station astronaut John Phillips said. "Have a good flight."

In line with US Navy tradition, Phillips rang a bell to mark his guests' departure and reported through his radio: "Discovery departed."

Thousands of NASA workers as well as the astronaut's anxious families will be watching from near the Cape Canaveral airstrip, praying that the shuttle crew avoids the February 2003 fate of the Columbia, which burned up as it approached Florida.

This mission has been plagued by problems.

The shuttle narrowly escaped being hit by a large chunk of foam during takeoff. An emergency spacewalk was done to remove two pieces of material that threatened to overheat the shuttle during re-entry.

Finally, a piece of billowing thermal blanket appeared to threaten the shuttle's return. NASA engineers finally decided the blanket would disintegrate harmlessly during the superheated re-entry, and gave the all-clear for launch.

The shuttle is due to land at Kennedy Space Centre at Cape Canaveral at 6.46pm Queensland time.

The launch of the next shuttle, Atlantis, is scheduled for September, but that date depends on the ability of NASA's engineers to pinpoint and fix the problem of falling foam from the shuttle's external fuel tank. A similar problem caused the destruction of Columbia and the space agency spent over two years trying to fix the issue.

Meteorologists predict a slight chance of rain, light winds and some clouds. Severe weather could cause a 24-hour postponement of landing or a rerouting to Edwards Air Force Base in California.