Ask Onix
Updated 20 January 2026 - The International Space Station (ISS) saw its first full-crew evacuation in response to a medical emergency last week, underscoring the persistent risks of human spaceflight.
Emergency return to Earth
On 15 January, the four astronauts of ISS Crew-11 splashed down in the Pacific Ocean after one crew member developed a medical condition that could not be treated aboard the station. American astronauts Mike Fincke and Zena Cardman, Japanese astronaut Kimiya Yui, and Russian cosmonaut Oleg Platonov had arrived in August 2025 for a planned six-and-a-half-month mission. Instead, all four returned together in the SpaceX Dragon capsule that originally delivered them.
Training for the worst
Astronauts undergo rigorous simulations to prepare for emergencies such as fires, toxic leaks, or rapid depressurization. Meganne Christian, senior exploration manager at the UK Space Agency and a reserve astronaut for the European Space Agency (ESA), describes the training as deliberately overwhelming.
"They won't tell you what's going to happen-fires, ammonia leaks, all sorts of different things-and you just have to deal with them. It's designed to be a situation that will never happen, but it's really to get you ready for the idea that lots of things could happen at once, and you have to be able to make decisions on your feet."
Meganne Christian, UK Space Agency
Psychological resilience is a key factor in astronaut selection. Candidates are evaluated through interviews and team exercises to assess their ability to remain calm under pressure.
Historical context and current protocols
Contingency planning for space emergencies dates back to 1966, when NASA commissioned the Rand Corporation to study potential threats, including medical emergencies, oxygen deprivation, and radiation exposure. The findings influenced the Apollo and Space Shuttle programs and remain relevant today.
Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, explains that a fundamental rule of human spaceflight is maintaining a "ferry ship" ready for immediate evacuation. However, this system has limitations. In November 2025, the crew of China's Tiangong space station faced a crisis when their spacecraft was damaged by space debris, requiring a replacement capsule.
Another constraint is that if one crew member falls ill, the entire crew must return together. "You have to keep everyone together and bring the whole crew home," McDowell says. "Otherwise, you've left them there without a ride home."
Rapid response and future challenges
Astronauts follow the mantra "go slow to go fast," prioritizing methodical responses over panic. In an emergency, they assess the situation, follow checklists, and act as a team. For example, in the event of a fire, they would locate all crew members, don respirators, activate fire extinguishers, and seal off affected modules.
Nicole Stott, a former astronaut, emphasizes the importance of training in maintaining composure. "There are things you know you just need to immediately do to make safe the situation, take care of all of your crewmates, and make sure that no one's left behind," she says.
The escape capsule also serves as a safe haven, allowing the crew to assess the situation before deciding whether to leave the station. In a worst-case scenario, they could return to Earth within hours. However, missions to the Moon or Mars present new challenges. A return from the Moon would take days, while a Mars mission would require waiting years for the next opportunity.
McDowell notes that future deep-space missions will demand higher risk tolerance and more advanced medical capabilities. "You're going to have to accept a higher level of risk, and you have to have more extensive medical equipment-a hospital module and not just a first aid kit," he says.
Lessons from isolation and future rescue plans
Christian has experienced isolation similar to that of a Mars mission during her time at the Concordia research station in Antarctica. The station is cut off during winter, making emergency rescues nearly impossible. The crew relied on self-sufficiency, a doctor, and a backup base for evacuation drills.
As the ISS nears the end of its operational life, researchers are revisiting the concept of space rescue. Grant Cates, a senior project leader at The Aerospace Corporation's Space Safety Institute, highlights a "capability gap" in current rescue protocols. He advocates for maintaining a spacecraft on standby and developing universal docking adapters to enable cross-nation or commercial rescues.
Cates also suggests that future Mars missions should adopt a fleet approach, similar to historical ocean voyages, where multiple ships travel together to mitigate risks. "They didn't go typically with one ship; they sailed with multiple ships so that if one ship had a problem, you could transfer the people and supplies to the other remaining ships," he explains.
Rising risks and upcoming missions
NASA's upcoming Artemis II mission, set to launch in the coming weeks, will take astronauts beyond the Moon for the first time since 1972. The mission will rely on a single capsule with no backup spacecraft or evacuation plan once beyond Earth orbit. Any emergency would leave the crew dependent on mission control and their training.
The recent ISS evacuation serves as a reminder that space exploration remains fraught with danger, even as humanity prepares to venture farther into the solar system.
