What are the top risks?

Conducting real or simulated spacewalks creates a risk that crew members could be compromised or injured. Extravehicular activities (EVAs), or spacewalks, are only conducted periodically at the International Space Station for various maintenance and research tasks. EVAs during Artemis III and beyond will build on NASA’s experience from Apollo, Shuttle, and the space station, but also come with unique challenges such as navigating new, unexplored, and unfamiliar regions of the Moon’s surface with new technologies. During deep space missions, EVAs will occur more frequently and last longer, creating new physical and mental demands.

What can be done about it?

Researchers must consider the pressure and oxygen levels in both the habitat and the spacesuit. When the difference between atmospheric pressures is large, transitioning from the habitat to the spacesuit can cause decompression sickness. Researchers have created “prebreathe protocols” to ensure crew members are exposed to high levels of oxygen before EVA, primarily to help remove nitrogen from the body and mitigate the risk of decompression sickness.

NASA engineers are also working to improve the design of spacesuits so they will remain durable and safe while also offering dexterity and biomedical monitoring. Maintaining bone and muscle strength through exercise can also help crew members better sustain the weight of a spacesuit during surface missions, where there will be greater gravity—and thus an increased weight of the suits. Ongoing work aims to balance pressure, oxygen, and the physical and mental demands of EVAs to ensure crew member health and mission success.

Did you know?

NASA astronauts James Voss and Susan Helms hold the record for the single longest EVA on March 12, 2001. It lasted 8 hours and 56 minutes.

Formal risk description: Risk of mission impacting injury and compromised performance and long-term health effects due to EVA operations

Research in support of this risk: Latest evidence