By Xinhua
Washington : Two U.S. astronauts are conducting the fourth spacewalk of shuttle Endeavor’s mission to test a heat shield repair method, NASA TV reported on Thursday.
Spacewalker Robert Behnken and Mike Foreman floated out of the Quest airlock and began their work outside the International Space Station at 6:04 p.m. local time (2204 GMT) on Thursday. Their excursion will last into midnight, said NASA.
They will test a repair method for purposely-damaged heat resistant tiles on the space shuttle Endeavor. This technique is named TRAD, which includes a high-tech caulk gun and sticky, heat-resistant goo for its effectiveness in repairing dings, gouges and other damage in shuttle heat shield tiles.
Once the test is complete, the sample tiles will be returned to Earth to undergo extensive testing on the ground, according to NASA’s mission control center.
In addition, the duo will also replace a faulty station circuit breaker.
Shuttle Endeavor arrived at the station on March 12, delivering a Canadian-built robot Dextre and the first component of Japan’s orbital laboratory Kibo to the space outpost.
During the first three spacewalks, astronauts have successfully assembled Dextre and installed the new lab room. The mission’s fifth and final spacewalk is scheduled on Sunday.