International Space Station managers are firming plans for a Feb. 16 spacewalk by two cosmonauts that will resume efforts to prepare the 11-year-old Pirs module for an eventual departure and replacement with the Russian segment Multipurpose Laboratory Module/European robot arm combination.
Oleg Kononenko and Anton Shkaplerov will spend five to six hours moving one of two manual Strela cargo booms from Pirs to Poisk, a newer Russian segment docking/airlock module; installing five space debris shields on the Zvezda service module; and attaching external science experiments.Cosmonaut Sergei Volkov outside the International Space Station's Russian segment during the most recent spacewalk aboard the orbiting science lab. Photo Credit/NASA TV
The scheduled excursion is the first outside the station since Aug. 3, when cosmonauts Sergei Volkov and Alexander Samokutyaev were forced to scratch efforts to transfer Strela-1 after they encountered difficulties with the deployment of an educational satellite and ran out of time for the task.
The larger Russian Russian Multipurpose Laboratory module/European robot arm combination will replace the discarded Pirs, docking at the space facing port on the Zvezda module. The launching of the Russian module/robot arm combination aboard a Proton rocket is tentatively scheduled for mid-2013.
As predicted by the NASA-managed 15-nation space station program last year, the amount of U. S. and Russian spacewalk activity has dropped substantially as the assembly of the U. S. segment came to a close with the shuttle's retirement in July 2011.
Current estimates call for 1-3 spacewalks annually, primarily to handle external maintenance needs. The activity, which program partners prefer to keep to a minimum to permit a greater focus on scheduled internal science experiments, could increase substantially in response to a major systems failure.
In that vein, NASA station managers are closely following the behavior of a main bus switching unit, a component of the vaulting external cooling and power systems, on the station's central truss structure.
The MBSU, which displayed some erratic behavior last year, is functioning but not responding to commands, Mike Suffredini, NASA's space station program manager, told a Feb. 2 news briefing.
If it does not fail, the switching unit will be replaced during the next U.S. spacewalk, a maintenance excursion tentatively planned for late summer or early fall.
Nonetheless, NASA completed contingency planning in January for a rapid response spacewalk to deal with a sudden failure.
"We are ready to go outside if we have to," said Suffredini. "Of course, that would be a significant impact to our regularly scheduled activities."