Tuesday, May 23, 2017

Short Spacewalk Complete After Successful Installation Work

Astronaut Jack Fischer waves while attached to the Destiny laboratory during a spacewalk to replace a failed data relay box and install a pair wireless antennas. Credit: NASA

Expedition 51 Commander Peggy Whitson and Flight Engineer Jack Fischer of NASA concluded their spacewalk at 10:06 p.m. EDT. During the spacewalk, which lasted two hours and 46 minutes, the two astronauts successfully replaced a computer relay box, and installed a pair of antennas on station to enhance wireless communication for future spacewalks.

Tuesday’s spacewalk was ordered when an external computer known as a multiplexer-demultiplexer failed Saturday. Two such avionics boxes are used to control a wide variety of station systems and while one can carry the load on its own, NASA managers wanted to get a replacement installed as soon as possible to restore full redundancy.

The spacewalk began at 7:20 a.m. EDT when Whitson and Fischer switched their spacesuits to battery power. After leaving the station’s Quest airlock, the astronauts split up, with Whitson making her way to the lab’s power truss where the failed MDM was located and Fischer moving to the Earth-facing side of the Destiny laboratory module.

He had no problems installing the wireless antennas while Whitson removed the failed MDM. But when attempting to install the replacement box, she felt the central primary bolt holding it in place was not as secure as she expected. She then removed the MDM and reported small shavings or debris floating from the vicinity of the central bolt hole.

Fischer retrieved a cleaning tool from the airlock and helped Whitson spray compressed nitrogen into the primary bolt hole and two secondary fittings to clean out any debris.

Whitson re-installed the MDM and while two of the three bolts did not drive in as many turns as expected, engineers decided the box was firmly in place.

After plugging in an ethernet cable, Whitson stood by while flight controllers activated the replacement MDM for initial tests and checkout. A few minutes later they reported the box appeared to be in good shape and working normally.

Whitson and Fischer then collected their tools and made their way back to the Quest airlock. Repressurization started at 10:06 p.m., officially bringing U.S. EVA-43 to a close.

Spacewalkers have now spent a total of 1,250 hours and 41 minutes working outside the station during 201 spacewalks in support of assembly and maintenance of the orbiting laboratory. This was the 10th spacewalk for Whitson, who moves into third place all-time for cumulative spacewalking time, and the second for Fischer.

No comments:

Post a Comment