The current
crew of the International Space Station (ISS) will not make a special effort to replace a faulty circuit breaker that hobbled one of three
gyroscopes used for orientation this week, NASA's ISS program manager said
Thursday.
Instead,
ISS Expedition 10 commander Leroy Chiao and flight engineer Salizhan Sharipov
will go ahead as planned with a March 28 spacewalk to install antennas and
other equipment to the exterior of the space station.
"It will
not impact [the spacewalk] at all," said NASA ISS program manager Bill
Gerstenmaier of the circuit breaker glitch during a teleconference with
reporters. "We're perfectly fine with using two control moment gyroscopes for
that EVA."
The space
station requires a minimum of two functional U.S.-built gyroscopes to maintain
its position in space without switching to propellant-driven Russian thrusters.
Gerstenmaier
said that a known fault with a single transistor within the circuit breaker,
known as a Remote Power Control Module (RPCM), apparently caused a power loss
an ISS gyroscope Wednesday. The fault is identical to an earlier glitch
that forced Expedition 9 astronauts to make an unplanned spacewalk
repair last year.
"When we
made the change out we knew the transistor had a fault in it and we assumed it could
show up again [and] we were hoping it wouldn't be the case," Gerstenmaier said.
"But it looks like it is."
Space
station officials said they will continue to examine other ISS systems to make
sure the circuit breaker is the only failure.
A
spacewalk for another day
ISS
managers said the earliest the RPCM could be replaced could be during the next
space shuttle flight, STS-114, aboard Discovery, since a two astronauts on that
mission are already planning to replace a broken gyroscope. If that falls
through, the spacewalk repair could be reset for later this summer, they added.
"It
certainly is possible and doable," said NASA astronaut Michael Fincke, who
spent six months as ISS flight engineer during the Expedition 9 mission and
helped make the initial RPCM fix. "It should go even smoother and faster them."
The RPCM
glitch is one of several currently afflicting the space station and its crew,
ranging from broken exterior lights to a finicky Russian oxygen generator and a
broken toilet, both of which were repaired earlier today by Sharipov.
"The things
that are going on at the space station are normal," Fincke said, adding that
Expedition 10's Chiao and Sharipov are doing a fine job of balancing the
demands of maintenance and science aboard the ISS.
Also today,
NASA officials released their Implementation Plan for the International Space
Station Continuing Flight, a 210-page document addressing ISS-related issues
for the agency's shuttle return-to-flight effort.
"We tried
to be as thorough and creative with these things, to look at what's going on at
the station, to keep it operational," Gerstenmaier said.
advertisement
