Tile Repair Test Focus Of Spacewalk

From AviationWeek.com Homepage:

Spacewalkers Bob Behnken and Mike Foreman are set to conduct a deferred on-orbit test of a heat shield repair technique today that could come in handy on a future space shuttle mission, and particularly on the upcoming flight to service the Hubble Space Telescope. The pair has a 6:28 p.m. EDT start time for the fourth extravehicular activity (EVA) of the STS-123/1J/A assembly mission to the International Space Station (ISS). It will be the first EVA of the flight that does not involve any station assembly or robotics activity. Instead, Behnken and Foreman will spend about an hour at the beginning of the 6.5-hour spacewalk replacing a circuit breaker to one of the control moment gyros that keeps the station steady in space without the need for precious thruster fuel. The work will require a fairly significant power-down to ISS circuits that must be coordinated with controllers here, so the spacewalkers have been told to avoid the early starts of the three previous EVAs on the mission.

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