Why astronauts must sleep in a tiny airlock before spacewalking

Space · Published 20 October 2026 Swipe more like this →

In short: Before stepping into the vacuum, astronauts like Mike Good and Garrett Reisman undergo a specific physiological preparation: a literal campout. By sleeping inside the International Space Station's Quest airlock, they perform a vital biological purge that protects them from the physical dangers of rapid decompression.

The primary reason for this 'airlock campout' is to manage nitrogen levels in the body. When astronauts spend extended periods in pressurized environments like the International Space Station (ISS), nitrogen can accumulate in their tissues. If they were to exit into a vacuum or lower-pressure environment too quickly, this nitrogen could form bubbles in the bloodstream—a dangerous condition known as 'the bends.' By sleeping in the Quest airlock, Mission Specialists Mike Good and Garrett Reisman allow their bodies time to purge these gases safely before performing the third and final spacewalk of STS-132.

The mission objectives for this specific extravehicular activity (EVA) involve high-stakes maintenance on the ISS's P6 truss, also known as the backbone segment. The crew is tasked with finishing the replacement of batteries, a critical component for station power. This highlights the ongoing logistical reality of orbital life: even after years of operation, the station requires constant manual intervention and hardware swaps to remain functional.

This preparation reflects the broader rigor of space exploration. While Reisman famously joked about missing out on a 100-day service patch during his 95-day mission in 2008, the reality involves grueling technical demands. From installing high-speed antennas and replacing navigational aids to conducting complex medical research—such as monitoring circulatory health via the Venus Flow investigation or imaging retinas for vision issues—every movement outside the station is a calculated balance of human endurance and engineering necessity.

The transition from 'campout' to 'work' illustrates the unique rhythm of life on the ISS. Crew members must cycle between periods of intense physical labor, like six-hour and 30-minute maintenance shifts, and necessary recovery time. This includes cleaning the airlock, refilling water tanks, and recharging suit batteries, ensuring that both the humans and their equipment are ready for the next deployment.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• Living in a giant vacuum cleaner: the reality of sleeping in orbit
• Sleeping in space is less about comfort and more about survival
• Why astronauts sleep in a giant vacuum cleaner
• How astronauts prepare for the high-stakes transition from orbit back to Earth
• How an astronaut prepares for sleep inside the International Space Station
• How a single satellite mission tracks global rain and snow every three hours
• The engineering paradox of building a heavier rocket on a lighter base
• From candidates to astronauts: ESA’s newest class earns their certification
• How Astronaut Story Musgrave Helped Save the Hubble Space Telescope from Obscurity
• The precise moment humanity expanded its reach into low Earth orbit
• A look back at the scientific achievements of NASA Goddard in 2023
• The surprising musical theme of the European Space Agency's tracking network

More in Space agencies · More in Space · Latest · A–Z · All topics