HOUSTON --
Efforts to fully recover critical Russian computer systems aboard the
International Space Station (ISS) will likely continue through the rest of the
week, with no quick fix at hand, a top NASA official said Thursday.
Bill
Gerstenmaier, NASA's associate administrator for space operations, said the
Russian systems are down again after a brief
seven-minute period earlier today. But during that time, Russian engineers
uploaded commands to put the station in a more stable configuration as work
continues to trace the glitch, he added.
"It's going
to take time. It will not be quick," Gerstenmaier told reporters during a
briefing here at NASA's Johnson Space Center. "Unless we get lucky right away
and find the problem, it'll be a couple days [that] we'll probably be in this
configuration."
Possible
sources for the glitch may be power quality issues associated with the
station's new starboard solar arrays, which
unfurled Tuesday, NASA said. Software anomalies, a mismatch in the
station's U.S.-to-Russian power transfer system and electromagnetic interference
may also be candidates for the computer crash, the space agency has said.
The spate
of recent false fire alarms aboard the ISS, meanwhile, has been found to be
associated with the ongoing computer issue, Gerstenmaier added.
Computer
crash
Two vital
computers, one governing navigation and attitude control and the other command
and control systems, went
offline inexplicably early Wednesday, leaving some of the station's Russian
systems unavailable to its three-person crew and seven visiting shuttle
astronauts. Those systems include Russian thrusters used to orient the ISS when
its U.S.-built gyroscopes are unavailable, as well as the Elektron oxygen
generator and other systems.
The
Elektron, and some others aside from the thrusters, can be operated manually
without computer control, said Gerstenmaier, who stressed the current computer
issue is not serious enough to warrant abandoning the space station.
"I think
we're a long way from that scenario," he said.
But since
Thursday's computer crash, the ISS has depended solely on its control moment
gyroscopes for attitude control, with the thrusters on NASA's visiting Atlantis shuttle serving
as backup. Astronauts aboard Atlantis have powered down unnecessary lighting,
laptops and other systems in order to conserve power for the possibility of a
one day or so extension to their already
extra-long mission to continue serving as the station's attitude control
system backup, NASA said.
Space
station managers hope to fix the computer issue before Atlantis undocks, since
the Russian thrusters are preferred to be functioning in case the station's
gyroscopes are overwhelmed - or 'saturated' - just after the orbiter's planned
June 21 departure.
"Ideally,
we'd would like to have the Russian computer systems up and operating when the
shuttle undocks," Gerstenmaier said. "The concern is really attitude control,
and can we find ways of providing attitude control without using these
computers."
Thrusters aboard
unmanned Russian Progress cargo ships, two of which are docked at the ISS, are
among several alternatives to control the station's orientation, he added.
Russian
flight controllers woke the station's Expedition 15 crew, commanded by
cosmonaut Fyodor Yurchikhin, much earlier than planned this morning so the
astronauts could help in the troubleshooting process. Russian communications
with the ISS are handled through ground stations, which are within range of the
orbital laboratory earlier in the day, NASA said.
"We won't
ask how you're doing because we can imagine," Russian flight controllers said
later, adding that a crewmember will again have to stay up overnight. "Are you
running out of steam yet?"
"No we're
okay," Yurchikhin replied. "And we're ready to work."
NASA is
broadcasting the space shuttle Atlantis' STS-117 mission live on NASA TV. Click here for mission updates and
SPACE.com's video feed.
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