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Two Russian cosmonauts suited up for a spacewalk outside the International Space Station Wednesday to begin preparing the Pirs airlock and docking compartment for removal next year to make way for attachment of a new laboratory module.
The excursion, starting around 9:30 a.m. EST, also will validate using the Poisk docking compartment, on the opposite side of the station from Pirs, as an airlock for future Russian spacewalks after its older counterpart has been removed.
The spacewalk comes two days after arrival of four astronauts aboard a SpaceX Crew Dragon commercial ferry ship and will be carried out by Expedition 64 commander Sergey Ryzhikov and Sergey Kud-Sverchkov, both making their first trips outside the space station.
For identification, Ryzhikov, call sign EV-1, will be wearing a spacesuit with red stripes and using helmet camera 20 while Kud-Sverchkov, EV-2, will use a suit with blue stripes and helmetcam 18.
Nearly identical to Pirs, Poisk was launched almost exactly 11 years ago, on Nov. 10, 2009, and attached to the Zvezda module’s upper port two days later. It has been used as a docking port for unpiloted Progress cargo carriers and Soyuz crew ferry ships many times but never as an airlock.
Before venturing outside, the cosmonauts planned to spend about an hour making sure Poisk’s never-before-used side hatch can be safely opened and tightly shut with an airtight seal and that the hatch leading into the main body of the station is leak free when the compartment is at or near vacuum.
Wearing their Orlan spacesuits, Ryzhikov and Kud-Sverchkov first planned to partially depressurize Poisk for an initial round of leak checks. NASA crewmate Kate Rubins will carry out similar tests from inside the Russian segment of the station.
The cosmonauts then will take Poisk to vacuum, open the side spacewalk hatch for the first time in the module’s history and inspect its seals for any signs of foreign object debris or damage. Spare sealing material is available if needed.
They then plan to close the hatch and run additional leak checks before re-opening it and floating outside to begin the 232nd spacewalk devoted to station assembly and maintenance, the eighth station EVA so far this year.
The first item on the agenda is to install a new pump to help circulate fluids in the Russian Zarya module, the station’s first module, launched 20 years ago Nov. 20.
The cosmonauts then will retrieve a materials science space exposure pallet from the Pirs module and disconnect a telemetry cable. The cable will be reconnected to Poisk, beginning the process of ending the use of Pirs as an airlock.
After cleaning a window on the Zvezda module, the spacewalkers will reposition a rocket plume impingement detector and retrieve an experiment tray that helps engineers assess micrometeoroid impacts. Their final task is to photograph the exterior of the Russian segment.