Space Station Stabilized After Gyroscope Fails

NASA was forced to use emergency measures to stabilize the international space station after a gyroscope -- which keeps the massive orbiting laboratory in the correct orientation -- shut down, agency managers said Thursday.

The failure leaves only two of the station’s four gyroscopes running, the minimum needed for normal operation. Another one had failed in June 2002.

And one of the two gyroscopes still operating has vibrated abnormally in recent months, indicating a possible lubrication problem in its bearings.

Mike Suffrendini, NASA’s operations integration manager for the space station, said the problems do not threaten the safety of either the crew or the spacecraft. Even if another gyroscope fails, the space agency could control the station by using the thrusters on an attached Russian module for six months to a year, he added.

The malfunction came Wednesday night, just hours after a two-man crew arrived at the station in a Russian Soyuz capsule to relieve the current U.S. and Russian astronauts on board. There will be an 11-day overlap before the current crew, Michael Foale and Alexander Kaleri, returns to Earth.

When the gyroscope went offline, ground controllers at Johnson Space Center in Houston fired the Russian rocket thrusters repeatedly for 15 minutes to maintain control while the two remaining gyroscopes were prepared to take over stabilization of the spacecraft. The gyroscopes use heavy, 48-inch wheels spinning at 6,600 revolutions per minute to keep the station correctly oriented.

Critics say the malfunction adds to a growing list of headaches and raises the risk that the station is falling apart faster than NASA can complete it -- a scenario raised by many experts more than a decade ago.

Assembly of the station was halted after the space shuttle Columbia accident on Feb. 1, 2003; the shuttle fleet is not expected to resume flying for at least another year. Meanwhile, the space station is orbiting only partially completed, and it requires a fair amount of maintenance to keep running.

“It doesn’t look good,” said Robert Park, a University of Maryland physicist who has testified before Congress about the space station’s problems.

Park said that most of the astronauts’ time aboard the orbiting laboratory has not been dedicated to serious science, but simply to staying alive and keeping the complex ship operating. “It is not producing any scientific output. There is no field of science you can point to and say it has been advanced by research that has been done on the space station,” he added.

Park added that using rocket thrusters to control the station is “hardly trivial,” noting that it would require the almost constant attention of ground controllers.

John Logdson, director of the Space Policy Institute at George Washington University and a former member of the Columbia Accident Investigation Board, said the gyroscope failure was the kind of issue that astronauts were prepared to handle and called it part of the normal business of operating a spacecraft.

“But it highlights the importance of getting the shuttle flying again to get this facility finished, usable and safe,” Logsdon said.

Indeed, the National Aeronautics and Space Administration cannot send up any new gyroscopes because they are too big to transport in Russian launch vehicles.

The first mission for the shuttle when it resumes flying will be to hoist a gyroscope to the space station.

The gyroscope apparently went offline Thursday because of a failure in a power control unit that acts as a remote circuit breaker, much like an electrical panel in a household wiring system, Suffrendini said.

The crew has spare parts to fix the system, but it is on an exterior truss and will require a spacewalk by the station’s replacement crew members, Michael Fincke and Gennady Padalka.

That repair is not expected for at least several weeks while NASA evaluates the problem.

Suffrendini said the power control unit likely failed because of a hybrid circuit which is deteriorating. So far, 13 hybrid circuits have failed for unknown reasons, he said.

The most recent problems highlight the precarious relationship between the space station and the shuttle, which the Bush administration wants to phase out in six years, said John Pike, director of GlobalSecurity.org, a public policy institute in Alexandria, Va.

Without the shuttle, he said, it would be increasingly difficult to keep the space station operating, and American public support for the enterprise could very well wither away.