International Space Station Status Report #14, 2005

Report #14
3 p.m. CST, Friday, March 18, 2005
Mission Control Center, Houston

The crew aboard the International Space Station turned its attention to
spacewalks this week with repair and preparatory work in two airlocks.

Expedition 10 Commander Leroy Chiao spent the beginning of the week
installing a new heat exchanger in Quest, the U.S. airlock. Working
meticulously with stubborn bolts and attachments, Chiao swapped out the
faulty heat exchanger with a new unit delivered earlier this month.

The job sets the stage to restore use of Quest as a base for spacewalks
using U.S. spacesuits. The heat exchanger unit provides cooling for the U.S.
spacesuits while they are connected to the airlock. Chiao finished the
repair ahead of schedule and had spare time to work on several other tasks
around the Station, such as replacing a hard drive in a laptop computer.

Flight Engineer Salizhan Sharipov began preparing the Russian Pirs Docking
Compartment, which also serves as a Russian airlock, for the second and
final spacewalk the pair will conduct. Chiao assisted by gathering U.S.
tools, such as helmet lights and a tool caddy, which they will use in
conjunction with the Russian equipment. They also gathered antennas and
cabling they will install during the spacewalk. Sharipov and Chiao are
scheduled to step outside March 28 for nearly six hours to continue the
external outfitting of the Space Station and deploy a German satellite
experiment.

Sharipov did further troubleshooting on the Elektron oxygen-generating
system, which ran intermittently throughout the week. Its periodic shutdowns
have caused no concern for the replenishment of oxygen in the Station cabin.
Russian experts will continue to monitor its condition. The Elektron, which
converts water into oxygen, is one of several methods that can be used to
provide oxygen in the Station cabin.

Two control moment gyroscopes (CMGs) are maintaining the Station's
orientation after a third gyroscope lost power on Wednesday. A circuit
breaker, called a Remote Power Controller, failed and removed power from
that gyroscope. Attempts to reset the breaker were unsuccessful. There is no
impact to current Station activities. Two gyros are adequate to maintain the
orientation of the complex.

Specialists are continuing to evaluate the condition of the circuit breaker.
The circuit breaker could be replaced by conducting a spacewalk to perform
that work, but the plans and timing of that activity remain to be
determined. A fourth gyroscope that failed in June 2002 is set to be
replaced on the Space Shuttle's Return to Flight mission, STS-114, this
spring.

Also this week, the Station crew slid into their seats inside the attached
Soyuz spacecraft to check their fit. The Soyuz seats are outfitted with
customized cushions to protect the riders during landing. The fit of the
cushions is checked periodically throughout the mission to ensure a
comfortable and safe seat home for the crew. Chiao and Sharipov have about
five weeks remaining until their return to Earth, with their undocking and
landing in Kazakhstan scheduled for April 25.

Information about crew activities on the Station, future launch dates and
Station sighting opportunities from Earth, is available on the Internet at:

http://spaceflight.nasa.gov/

The next International Space Station Status report will be issued on Friday,
March 25, or earlier if events warrant.




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Jacques :-)

www.spacepatches.info

"Jacques van Oene" wrote in message
i.nl...
Two control moment gyroscopes (CMGs) are maintaining the Station's
orientation after a third gyroscope lost power on Wednesday. A circuit
breaker, called a Remote Power Controller, failed and removed power from
that gyroscope. Attempts to reset the breaker were unsuccessful. There is
no
impact to current Station activities. Two gyros are adequate to maintain
the
orientation of the complex.

Specialists are continuing to evaluate the condition of the circuit
breaker.
The circuit breaker could be replaced by conducting a spacewalk to perform
that work, but the plans and timing of that activity remain to be
determined. A fourth gyroscope that failed in June 2002 is set to be
replaced on the Space Shuttle's Return to Flight mission, STS-114, this
spring.

Does this mean that there is a spare circuit breaker for the CMG aboard ISS?
This news release is a bit unclear about where the spare is currently
located (i.e. on ISS or on the ground).

Thanks,
Jeff
--
Remove icky phrase from email address to get a valid address.

Does this mean that there is a spare circuit breaker for the CMG aboard ISS?

Yes.

At least one spare RPC already is aboard the space station and
Discovery's crew will deliver four more.
http://spaceflightnow.com/news/n0503/16cmg/

"Jim Kingdon" wrote in message
news
Does this mean that there is a spare circuit breaker for the CMG aboard
ISS?

Yes.

At least one spare RPC already is aboard the space station and
Discovery's crew will deliver four more.
http://spaceflightnow.com/news/n0503/16cmg/

Four more? I suppose for such a critical part, it doesn't hurt to keep
several spares, especially if they don't take up too much space/weight on a
launch.

It's unfortunate that the part requires an EVA to replace, but I'm sure
that's unavoidable.

Jeff
--
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Four more? I suppose for such a critical part, it doesn't hurt to keep
several spares, especially if they don't take up too much space/weight on a
launch.

It isn't just that it is critical, it is that it is known to have a
(suspected) design defect and the new design isn't ready yet. Or so I
gather from

Gerstenmaier said the power control module has 17 channels and that a
suspect transitor believed to be susceptible to failures in identical
devices used throughout the station apparently caused the gyro circuit
to trip open Wednesday. An identical failure knocked CMG-2 off line
last year, requiring Fincke and Expedition 9 commander Gennady Padalka
to replace the unit.

Gerstenmaier said engineers are developing a new design to eliminate
the transistor problem and that in the meantime, he viewed the most
recent failure as a relatively minor glitch.
http://spaceflightnow.com/news/n0503/17cmg/

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