Shuttle Turns Cartwheels in Space on Final Day in Orbit

The space shuttle Discovery literally cartwheeled through space for part of its final day in orbit Friday as its five crew members prepared for today’s landing at Edwards Air Force Base in California.

The spacecraft was scheduled to touch down at Edwards at 6:35 a.m., 37 minutes after sunrise.

The tumbling maneuver was part of an effort to get a balky experiment in the shuttle’s cargo bay to work, and it apparently succeeded, flight director Al Pennington said from Mission Control in Houston. The purpose of the experiment was to test a radiator designed to carry heat away from NASA’s proposed space station.

Balky Fluid in Pipe

In the experiment, a fluid was supposed to move through a 51-foot-long pipe, transferring the heat, but various attempts to get the fluid moving failed. On Thursday, the Discovery’s maneuvering jets were used to jerk the entire shuttle back and forth in an effort to start the experiment, but even that did not work.

So, on Friday morning, the shuttle was put into a tumbling maneuver, with the tail cartwheeling over the nose as the spacecraft passed 187 miles over Florida, traveling more than 17,000 m.p.h. The craft was rotating at only about one degree a second, but that was enough to create a force of gravity five one-thousandths as great as that on Earth.

“That’s interesting,” Discovery commander Michael L. Coats, 43, said when informed of the “G force” by Mission Control. “It feels like a lot more.”

The Discovery completed five cartwheels.

Today’s scheduled landing will end one of the most trouble-free flights in the history of the shuttle program. There have been a few minor glitches, including the balky heat radiator that precipitated Friday’s orbital gymnastics, but generally there has been little for space officials to worry about.

Lee Briscoe, a Houston flight director who is in charge of landing preparations, said there had been so few problems that it had not been necessary to send the crew many messages.

Briscoe was hoping Friday for a slight crosswind at Edwards. NASA officials are eager to learn how the shuttle--which has no power when it lands and thus descends and touches down as a glider--will cope with crosswinds.

He said he is looking for a maximum crosswind of 15 knots. If the forecast is for crosswinds of between 12 and 15 knots, the shuttle is to land on Edwards’ dry lake bed, where there is plenty of room to maneuver if the vehicle drifts more than expected.

If the winds are less, the shuttle will land on Edwards’ paved runway so that the brakes can be tested. Brakes have been a continual problem for the shuttle fleet, and the paved runway is preferable for that test because the soft surface of the unpaved runway also provides a braking action, thus diluting the results, Briscoe said.

A crowd of 200,000 people was expected to watch the landing, which will be about a mile away regardless of which site is used.

This was the first flight of the year for NASA. Six others are scheduled, including the April flight of Atlantis, when the Magellan spacecraft is to be launched toward Venus, the nation’s first planetary mission in more than a decade.

Atlantis will be followed by Defense Department flights in July and August, and, in October, Atlantis is to fly again, this time to launch the Galileo probe to Jupiter.

In November, the aging Columbia is supposed to return to service and launch a communications satellite, but there is doubt here that the old veteran will be ready by then. Columbia, the oldest shuttle in the fleet, is being refurbished to bring it up to today’s standards, and it has been partly cannibalized for parts for other shuttles.

The final flight of the year is set for December, when the Hubble Space Telescope is to be launched from the Discovery.