Spacewalkers prep for arrival of new Russian module


Credit: NASA TV/Spaceflight Now

Two Russian cosmonauts used the International Space Station’s Poisk docking compartment as an airlock for the first time Wednesday in a six-hour 48-minute spacewalk to begin preparing the nearly identical Pirs module for removal next year. A new laboratory module will be parked in its place later.

Expedition 64 commander Sergey Ryzhikov and Sergey Kud-Sverchkov began the year’s eighth spacewalk at 10:12 a.m. EST. The excursion, the first for both cosmonauts, came just two days after arrival of four astronauts aboard a SpaceX Crew Dragon commercial ferry ship.

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 spent more than an hour making sure Poisk’s never-before-used side hatch could be safely opened and tightly shut with an airtight seal and that the hatch leading into the main body of the station was leak free when the compartment was at or near vacuum.

Wearing their Orlan spacesuits, Ryzhikov and Kud-Sverchkov partially depressurized Poisk for an initial round of leak checks. NASA crewmate Kate Rubins carried out similar tests from inside the Russian segment of the station and the pressure on both sides was rock solid.

The cosmonauts then took Poisk to vacuum, opened the side spacewalk hatch for the first time and inspected its seals for any signs of foreign object debris or damage. Spare sealing material was available if needed, but the inspection found no signs of any trouble.

They then closed the hatch and ran additional leak checks before re-opening it and floating outside just after 11 a.m. to begin the 232nd spacewalk devoted to station assembly and maintenance.

The first item on the agenda is to install a new fluid-flow regulator to help circulate liquids in the Russian Zarya module, the station’s first module, launched 20 years ago Nov. 20. But the cosmonauts were unable to open the the equipment carrier, and flight controllers told them to return it to the airlock and press on with other work. The regulator will be replaced during a future spacewalk.

The cosmonauts then retrieved a materials science space exposure pallet from the Pirs module and disconnected a telemetry cable connecting Pirs to the Zvezda module. The cable was reconnected to Poisk, beginning the process of ending the use of Pirs as an airlock.

The spacewalkers repositioned a rocket plume impingement detector and retrieved an experiment tray that helps engineers assess micrometeoroid impacts before returning to Poisk and closing the hatch a final time at 5 p.m. Spacewalk duration was six hours and 48 minutes, pushing total station spacewalk time to 1,458 hours and 51 minutes.