ISS Expedition 73 crew wraps up spacewalk
Science missions continue aboard
The astronauts and cosmonauts of Expedition 73 have returned to a packed schedule of research and maintenance aboard the International Space Station (ISS) following a successful spacewalk on May 1, 2025, to upgrade the station’s power infrastructure.
Nasa astronauts Anne McClain and Nichole Ayers led the five-hour and 44-minute spacewalk, during which they installed new hardware on the space station’s port-side truss. The upgrade paves the way for installing a new rollout solar array, part of an ongoing effort to enhance the station’s power generation capacity.
On May 2, the duo focused on cleanup and recovery tasks. Their first order of business was reorganising the Quest airlock, the module used to exit and re-enter the station during extravehicular activities. After stowing away the hardware they had used during the mission, they checked their spacesuits, inspected water tanks, and collected water samples for further chemical analysis. These samples will be examined to assess water purity and help ensure the continued reliability of the suits during future spacewalks.
Joining McClain and Ayers later in the day were fellow Nasa astronaut Jonny Kim and Japan Aerospace Exploration Agency (JAXA) station commander Takuya Onishi. The four crew members held a video conference with mission engineers on Earth to review the procedures and results of May 1’s spacewalk. The ground team and astronauts discussed the efficiency of the upgrade tasks and the performance of their equipment, as part of Nasa’s continuous push to refine extravehicular operations.
The spacewalk itself was a multi-step mission. In addition to preparing the truss structure for the new solar array, McClain and Ayers repositioned a communications antenna, installed a jumper cable to enhance electrical connectivity, and removed several bolts from a micrometeoroid shield. Each of these tasks is critical to ensuring the station’s structural readiness and the long-term sustainability of its systems in the harsh space environment.
Meanwhile, the rest of the crew remained active across various scientific endeavours—Nasa’s Jonny Kim dedicated part of his day to an experiment involving tomato plants. The study explores the possibility of growing crops without relying on photosynthesis, an investigation that could hold transformative potential for future long-duration missions to the Moon or Mars. Cultivating food in space would significantly reduce reliance on resupply missions and enhance crew autonomy.
Commander Onishi, representing Jaxa, conducted microbiological research using a cutting-edge 3d microscope. He examined bacteria in liquid samples to better understand how microorganisms behave in microgravity. The findings could support the development of more effective methods to monitor water quality aboard spacecraft and detect pathogens that could pose risks to crew health.
While the US and Japanese astronauts focused on science and systems recovery, their Russian counterparts, part of the Roscosmos segment of the crew, concentrated on data gathering and station maintenance.
Veteran cosmonaut Sergey Ryzhikov took advantage of a daytime orbital pass over South America to photograph the aftermath of a recent landslide in Brazil. The images will contribute to ongoing Earth observation and disaster response programmes, using the unique vantage point of low Earth orbit to assess environmental changes in near real-time.
Fellow Roscosmos engineer Alexey Zubritsky worked with vibration monitoring equipment. He downloaded data collected during spacecraft dockings and undockings, providing engineers on Earth with key metrics on the structural stresses endured by the ISS. The results could help inform the design of future space stations or long-duration habitats.
Rounding out the Russian trio, Flight Engineer Kirill Peskov conducted safety and maintenance checks in the Nauka science module. He inspected radiation detectors worn by McClain and Ayers during their recent spacewalk to evaluate exposure levels, a vital task in managing astronaut health. He also cleaned smoke detectors in Nauka to ensure the continued functionality of fire detection systems, which are crucial for crew safety in the enclosed environment of the station.
Hero image: Nasa astronaut Anne McClain is pictured near one of the International Space Station’s main solar arrays during a spacewalk to upgrade the orbital outpost’s power generation system and relocate a communications antenna. Credit: Nasa
