Astronauts Peggy Whitson and Jack Fischer put on spacesuits Friday to head outside the International Space Station for several repair and maintenance tasks, but the duo will likely only complete part of their work after a leaky cooling umbilical delayed the start of their spacewalk.
Mission control in Houston marked the official start of the spacewalk at 9:08 a.m. EDT (1308 GMT), when the atmospheric pressure inside the station’s Quest airlock passed below 1 pound per square inch.
NASA adjusted the normal starting point for a spacewalk — when the astronauts switch their suits to battery power — after a troublesome servicing and cooling umbilical forced forced Whitson to use her spacesuit’s internal electrical supply during final spacewalk preps and depressurization of the airlock.
The umbilical is not part of the spacesuit, NASA said, but is a piece of support equipment inside the space station. It provides power, cooling and communications capability to the spacesuit before the astronauts exit the space station, according to Rob Navias, the NASA TV commentator for Friday’s excursion.
Teams noticed a small water in the umbilical early Friday.
Mission control radioed the astronauts that Friday’s spacewalk will be limited to run around four hours, not the six-and-a-half hour duration originally planned, due to the problem.
The shortened spacewalk means Whitson and Fischer will probably only have time to complete one of the jobs planned Friday — the replacement of a large avionics box that routes telemetry and power to experiments and spare parts mounted on a depot outside the space station.
The ExPRESS Carrier Avionics is located on the starboard-side S3 truss of the space station. A replacement unit was delivered to the outpost aboard an Orbital ATK Cygnus supply ship last month.
Whitson and Fischer are not expected to have time to complete other tasks planned for Friday’s spacewalk, which included the installation of a data connector for the Alpha Magnetic Spectrometer, a particle detector and cosmic physics experiment outside the station.
The duo also planned to add shielding to Pressurized Mating Adapter No. 3, which was recently relocated from the Tranquility module to the Harmony module, where it will receive a new docking mechanism next year for future link-ups with commercial crew spaceships developed by Boeing and SpaceX.
Other jobs in Friday’s spacewalk plan before the umbilical leak included the setup of a new high-definition video camera and a pair of wireless antennas outside the research complex, plus inspections and repairs of insulation on the station’s Japanese robotic arm.
Friday’s excursion is the 200th spacewalk in support of space station assembly and maintenance since December 1998, and the fifth this year.
It is the ninth spacewalk in Whitson’s career, and the first for Fischer.
Whitson, designated EV-1, will wear a spacesuit with red stripes, and carries a helmetcam designated No. 18. Fischer, EV-2, has a white spacesuit with no markings and helmetcam No. 20.
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from Spaceflight Now bit.ly/2qA2PxE
