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Spacewalkers to Jettison Ammonia Reservoir


Spacewalkers to Jettison Ammonia Reservoir


 Two International Space Station crew members will remove and jettison a 
refrigerator-size ammonia reservoir Monday during a six-hour-plus 
spacewalk from the Quest Airlock of the International Space Station. 

The spacewalk is scheduled to begin at about 6:30 a.m. EDT.(1030 UTC)

Image to right: Cosmonaut Fyodor N. Yurchikhin (left), Expedition 15 
commander representing Russia's Federal Space Agency, and astronaut 
Clayton C. Anderson, flight engineer, work with an Extravehicular 
Mobility Unit (EMU) spacesuit in the Quest Airlock of the International 
Space Station. Image credit: NASA

Astronaut Clay Anderson will be the lead spacewalker, EV1, and will wear 
the spacesuit with red stripes. Fyodor Yurchikhin, the cosmonaut and 
station commander, will be EV2 and wear the all-white suit. Cosmonaut 
Oleg Kotov, in the U.S. laboratory Destiny, will operate the Canadarm2.

After leaving the airlock and setting up equipment, the first task is 
installation of a television camera stanchion. The spacewalkers will 
take it from an external stowage platform and then install it on the 
Earth-facing side of the station's main truss at the interface Starboard 
0-Port 1 (S0-P1) truss segments.

Next they will move to separate tasks. Anderson will reconfigure a power 
supply for an S-Band Antenna Assembly, and then set up and get on a foot 
restraint at the end of Canadarm2. Yurchikhin will replace a circuit 
breaker, called a remote power controller module. It will ensure power 
redundancy for a move of the Mobile Transporter rail car on the 
station's truss.

Back together, Anderson and Yurchikhin will remove flight support 
equipment, where the camera stanchion had been mounted, and an attached 
Flight Releasable Attachment Mechanism. Together they have a mass of 
about 212 pounds.

While Anderson jettisons them from the end of the arm, Yurchikhin will 
move to the Z1 truss, where he will disconnect and stow cabling 
associated with the ammonia reservoir, called the Early Ammonia Servicer 

The EAS was installed on the P6 truss during STS-105 in August 2001, as 
an ammonia reservoir if a leak had occurred. It was never used, and was 
no longer needed after the permanent cooling system was activated last 
December. The EAS has to be removed before the P6 truss can be moved to 
the end of the station's main truss.

With Anderson still on the arm, both crew members will move to the P6 
Truss and release its remaining connections to the station. Once it is 
free, Anderson will hold it while the arm maneuvers him to the jettison 
point, below the right side of the ISS main truss.

The EAS weighs a little over 1,400 pounds on Earth. The jettison will be 
much like that of the stanchion equipment. Anderson will shove the EAS 
opposite the station's direction of travel at a minimum velocity of 
about seven inches (17 cm) per second.

A few hours later, Russian thrusters will reboost the station to provide 
clearance from the EAS. The reboost also will prepare for the Aug. 2 
launch of the Progress 26 cargo carrier and the Aug. 7 launch of 
Discovery to the station.

The final scheduled spacewalk task is cleaning the Earth-facing docking 
port, or Common Berthing Mechanism (CBM) of the Unity node. That is 
being done in preparation for the relocation of Pressurized Mating 
Adapter-3 (PMA-3), scheduled for late August.

The move is being made to clear the PMA-3's present position, on the 
starboard CBM of Unity, for a series of events that will culminate with 
the arrival of the Harmony node and its preparation to receive future 
space shuttles.

After cleanup Anderson and Yurchikhin will re-enter the Quest Airlock 
and conclude the spacewalk a little after noon.

The spacewalk is the first for Anderson and the third for Yurchikhin.

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