HOUSTON—Cosmonauts Sergey Prokopyev and Dmitri Petelin made progress with an upgrade to the International Space Station (ISS) Russian segment’s Nauka Multipurpose Laboratory Module during a seven-hour spacewalk late on May 3, but not without some difficulty.

The excursion, to relocate an experiment airlock from the Rassvet module to Nauka, got underway at 4 p.m. EDT. It followed an April 18-19 overnight spacewalk by the two cosmonauts in which they relocated a radiator from Rassvet to Nauka, and precedes a third spacewalk planned for May 12 to deploy the radiator, provide it with coolant and power it on.

Rassvet, a module with a docking port used primarily for cargo storage, was launched to the ISS aboard a NASA space shuttle mission in May 2010. The 43-ft.-long Nauka, which launched on a Russian Proton rocket in July 2021, provides scientific research volume, a docking port and an airlock for spacewalks.

Once outside the Russian segment’s Poisk airlock to start the second spacewalk in the series, Prokopyev and Petelin made their way to the Rassvet’s exterior, where they disconnected electrical cables, removed protective thermal insulation and disconnected several launch locks from the cylindrical, 1,792-lb. experiment airlock. The airlock is used to expose scientific experiments to the space environment when depressurized and opened.

Working from a command post inside the ISS Russian segment, fellow cosmonaut Andrey Fedyaev commanded the European Space Agency’s 36-ft.-long robot arm, which launched as part of the Nauka module, to reach out, grapple and slowly relocate the experiment airlock from Rassvet to Nauka.

Prokopyev and Petelin monitored the robot arm relocation, which took a little more than an hour, leading to the mechanical berthing of the airlock to Nauka at the 5-hr. 16-min. point in the spacewalk, but not without some challenges.

Efforts by Fedyaev to proceed with an automated latching of the airlock to the Nauka berthing port led to a series of misalignments.

Finally, Prokopyev and Petelin moved close enough to the berthing site to direct their helmet lights onto the latching mechanism and manually align the airlock with the docking mechanism, leading to a successful linkup.

Next, the spacewalkers connected a half dozen power cables between the airlock and Nauka.

They ended the excursion with the jettison of a bundle of trash from the relocation activities. The trajectory, opposite that of the ISS, will cause the bundle to burn up in the Earth’s atmosphere.

Initially, the first of the three Russian spacewalks was to get underway on Nov. 25, 2022. The excursion was delayed due to problems with the water coolant circulation pumps in the Russian Orlan space suits worn by the two cosmonauts. The first outing was re-scheduled for Dec. 14, but then delayed again by an external coolant leak on the docked Soyuz MS-22 crew transport capsule, which has since been replaced.

Finally carried out beginning late April 18, the first of the three spacewalks for the radiator relocation spanned nearly eight hours.