Image above: Expedition 12 Commander Bill McArthur (left) and Flight Engineer Valery Tokarev train for a spacewalk inside a mockup of the Quest airlock. European Astronaut Thomas Reiter (center) assists the two crewmembers. Credit: NASA

Station spacewalk to install new cameras
and jettison FPP

It will be on with the new and off with the old during the first station-based spacewalk in U.S. suits in more than two years.

Members of the 12th station crew, Commander and NASA Science Officer Bill McArthur KC5ACR and Flight Engineer Valery Tokarev, are scheduled to install a new camera assembly during the November 7th spacewalk, beginning about 9:30 a.m. EST. They also will remove and jettison the Floating Potential Probe.

McArthur is designated EV1 (for Extravehicular Activity) and will wear the spacesuit with red stripes. Tokarev, EV2, will be in the all-white suit.

The camera assembly installation on the Port 1 Truss is the first of the two primary tasks. The new device is similar to the camera assembly on the Starboard 1 Truss, and will be installed on a P1 lower outboard stanchion. It will have a big role in future station assembly.

The camera assembly will be used after arrival of the P3 and P4 truss segment during STS-115, station assembly flight 12A, next year. It will offer visual perspective to arm operator Steve MacLean, a Canadian astronaut, as he maneuvers the truss segment for installation.

Image above: Expedition 12 Commander Bill McArthur is lowered into the Neutral Bouyancy Lab at the Johnson Space Center to rehearse a spacewalk. Credit: NASA

The truss segment brings with it another radiator and another set of solar wings. Stretching 240 feet from tip to tip, the solar assembly will almost double the total electricity generating capacity of the station.

McArthur and Tokarev are scheduled to spend about three of the spacewalk's planned 5½-hours on the camera assembly installation. They then move, with McArthur in the lead, up the P6 truss to the Floating Potential Probe.

The FPP is situated atop the P6 Truss between the station's solar wings. It was designed to measure the station's electrical potential and compare it to the surrounding plasma. It isn't working.

Photos show FPP fasteners have backed out. That has raised concerns that the fasteners could become detached and perhaps cause damage.

McArthur and Tokarev will release and stow a grounding wire, then release the FPP housing from its stanchion. They will check its condition and then report lighting conditions to Houston with an eye to jettisoning the FPP.

Image above: Expedition 6 crewmembers Ken Bowersox (right) and Don Pettit prepare to exit the station's Quest airlock for a spacewalk. Credit: NASA

Getting rid of the FPP is a little more complicated than just tossing it away. To ensure its safe departure, McArthur is to jettison the device backwards in relation to the direction the station is moving with a smooth motion. He will aim for a velocity of at least half a foot per second. He'll try to throw the FPP 30 degrees upward and 10 degrees to the left of the back of the station.

The spacewalkers are scheduled to spend about 1½ hours on the FPP. If they have time they may do one or more additional tasks at the end of the outing, the first U.S. Quest airlock-based spacewalk from the station since an Expedition 6 spacewalk by Commander Ken Bowersox and NASA Science Officer Don Pettit on April 8, 2003.

One is retrieval of a rotary joint motor controller that has failed. The station uses a number of those controllers, with more coming. Engineers are anxious to get this one back to see what went wrong.

Another is removal and replacement of a remote power controller module, a kind of circuit breaker. This one is on the mobile transporter, which moves along railroad-like tracks on the station's main truss.

The spacewalk is scheduled to end about 3 p.m. EST.

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