NASA Relies on Thrusters to Steer Station

NASA Relies on Russian-Made Thrusters to Steer International Space
Station Following Malfunction

The Associated Press


CAPE CANAVERAL, Fla. Dec. 5 — NASA is relying on Russian-made
thrusters to steer the international space station following a new
malfunction with the U.S. motion-control system, officials said
Friday.

Flight controllers detected spikes in current and vibration in one of
the station's three operating gyroscopes on Nov. 8. Last week, when
the gyroscopes were used again to shift the position of the orbiting
outpost, all three worked fine.

To prevent further trouble and give engineers time to evaluate
everything, the gyroscopes will not be used for at least the next
month and the Russian thrusters will assume control, said flight
director Joel Montalbano. The station must be periodically moved into
a new position to prevent the exterior from getting too hot from the
sun.

The main drawback is the use of thruster fuel. For now, the two-man
station has more than enough fuel to spare, said program manager Bill
Gerstenmaier.

A fourth gyroscope broke in 2002. Only two good gyroscopes are needed
at any given time to control the space station.

"It's not where we want to be and we definitely don't want to get
there, but we have much backup capability ... and we're not in any
kind of real crisis," Gerstenmaier said.

Gyroscopes are too big to fit into a Russian supply ship, so NASA
cannot send up a spare until the shuttles are flying again. The
shuttle fleet has been grounded since Columbia broke apart during
re-entry in February.

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