Sen—Expedition 42 Commander Barry “Butch” Wilmore and Flight Engineer Terry Virts successfully completed the second of three planned spacewalks outside the International Space Station (ISS) today, but another helmet leak has caused concern.
The spacewalk officially began at 1151 UTC (6:51 am EST) when the astronauts switched their spacesuits to battery power, and ended 6 hours, 43 minutes later at 1834 UTC (1:34 pm EST) with the repressurization of the Quest airlock.
During repressurization Virts' helmet developed a minor leak with some water detected. It brought back memories of astronaut Luca Parmitano, whose helmet frighteningly filled with water, nearly drowning him, during a spacewalk which had to be cut short, back in July 2013.
This time the leak came at the end of an otherwise successful spacewalk, which saw the astronauts continue to work at the speed they set on their first EVA on Saturday. They completed all the planned work ahead of schedule and were able to move on to some of the 'get ahead' tasks scheduled for the third spacewalk which was to take place on Sunday, but the helmet leak may now put that in doubt.
These spacewalks are needed to prepare cables for new docking ports that will allow future crews launching on commercial spacecraft to dock to the space station and for the eventual arrival of private crewed spacecraft.
Two bundles of cables were routed in preparation for the arrival of two Boeing built International Docking Adapters, that will be delivered to the station on a pair of SpaceX Dragon cargo spacecraft later this year. Boeing’s Crew Space Transportation (CST)-100 and SpaceX’s Crew Dragon will use the adapters to deliver astronauts to the space station later this decade.
Ground controllers had manoeuvred the space station’s large robotic arm, Canadarm2, in place several days ago in preparation for Virts to lubricate rollers, brackets and screws at the arm's latching end, which had been performing sluggishly over the past year.
The grease gun, or Ballscrew Lubrication Tool (BLT), gave Virts some problems. "This is not a precision instrument!" he was heard to say.
Meanwhile Wilmore prepared two berthing mechanisms on the Tranquility module for the relocation of the Permanent Multipurpose Module (which is used for storage on the station) and the arrival of the Bigelow Expandable Activity Module (BEAM) later this year.
BEAM, built by Bigelow Aerospace, is a module, designed to be compact enough to fit inside the SpaceX Dragon cargo ship. On arrival at the ISS it can be installed onto the Tranquility connecting node and a pressurization system then inflates the module to its full size. BEAM will undergo a two-year test period at the ISS, during which crew members and ground-based engineers will gather performance data, to evaluate expandable space habitat technology.
It was the third spacewalk for Wilmore and the second for Virts. Wilmore now has clocked up 19 hours and 58 minutes during his three spacewalks. Virts has spent 13 hours and 24 minutes outside during his two excursions. The pair were assisted by Italian astronaut Samantha Cristoforetti who acted as the spacewalk choreographer and robotic-arm operator.
Wilmore then moved to complete some get ahead tasks, attaching 18 wire ties to the station for the planned installation during Sunday’s spacewalk of the Common Communications for Visiting Vehicles (C2V2). If it takes place, that will see a further 122 metres (400 ft) of cables being deployed, bringing the total to 233 metres (764 ft) of cable routed across the three spacewalks.
Astronauts have now spent a total of 1,159 hours and 8 minutes (48.5 days) conducting space station assembly and maintenance during a total of 186 spacewalks.
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