NASA’s ISS evacuation shows how astronauts prepare for medical emergencies in space
NASA crews undergo extensive training and have access to supplies to treat medical problems, from dental problems to migraines to heart attacks, while in orbit.
By Claire Cameron edited by Jeanne Brner

SpaceX via NASA
from NASA unprecedented decision prematurely end a mission to the International Space Station (ISS) due to a sick astronaut highlights how the agency prepares for medical issues and emergencies in space.
The decision, announced Thursday by new NASA Administrator Jared Isaacman during a press briefing, marks the first time that a space agency has ordered a medical evacuation from an ISS mission.
“Statistically, it probably should have happened several times in the last 25 years that we had people on the International Space Station,” said former NASA astronaut Andrew Feustel, who was commander of an ISS mission when he was at the agency and is now a lead astronaut on the International Space Station. private space company Vast. “But that’s not the case, and part of the reason is the level of medical vetting done, at least currently, on professional government astronauts before they fly into space.”
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This also demonstrates the readiness of the astronauts and the space station to deal with medical problems that arise. Orbiting at least 370 kilometers above Earth, the ISS houses a variety of medical equipment, from an ultrasound machine to a defibrillator, which can be used to diagnose and treat crew members who become ill or injured. It also contains a wide range of medications, including anesthetics, disease medications, hydrating fluids, and antibiotics.
“You can do things like give someone oxygen. You can treat wounds. There’s a whole pharmacy on board,” says Jordan Bimm, a space historian and assistant professor at the University of Chicago.
However, there are limits to the quantity of equipment station can hold. There is no magnetic resonance imaging (MRI) machine to scan crew members, nor enough supplies or space to perform extensive surgical procedures. Despite everything, Catherine Coleman, former astronaut and author of the book Share space, says she performed gallbladder removal as part of her training, even though she was not a medical professional. (The ISS currently does not have the equipment to perform such surgery in orbit.)
Crews are extensively briefed on how to use all equipment on the ISS and, if necessary, they work with teams of doctors on the ground to discuss any medical issues that arise – a system that Coleman likens to telemedicine on Earth.
Astronauts waiting to go to the ISS spend weeks with doctors from different disciplines, including emergency medicine and dentistry, Coleman says. She and her colleagues learned how to set IVs, insert a catheter, perform a tracheotomy to create an airway, and perform life-saving techniques such as cardiopulmonary resuscitation (CPR).
“We do things like that with a lot of supervision, but we actually do it in a way that, if it comes up, we’re prepared to do it,” she says. Once astronauts are aboard the ISS, ground surgeons regularly talk to them about their health and explain how to perform necessary medical procedures. Importantly, she said, this type of close communication was likely key to the care and decision to bring home the distressed Crew Member 11.
Yet despite such guidance, being in the microgravity environment of orbit complicates even the most routine procedures, Coleman says. The station is equipped with a stretcher with straps to hold crew members in place, should they need it for a procedure. And on her first day at the station, Coleman remembers working on how she would perform CPR in near zero gravity.
“Some people place their knees under the stretcher, then they compress the top using their stomach muscles,” she says. “It depends on the person whether that will be enough or not.”
Microgravity also confuses the basis of the body’s health. Fluids move differently through the body when in space, leading many crew members to feel suffocated, for example, or experience headaches and back pains. The space station environment is also known to modify some vision of astronauts in orbit or once back on Earth, and can also cause cardiovascular changes. Crew members regularly collect blood and urine samples and often participate in medical experiments in orbit, making them very attentive to their health.
“We’re lab rats up there, and so we’re really taught to think actively about what we’re doing,” Coleman says.
But the best-laid plans can fail. And perhaps nowhere is this more true than in an extreme environment like space.
“We don’t have an operating room on the ISS, and we don’t really have all the support infrastructure that we need in case of major complications,” says Feustel, former ISS mission commander. “The fallback method for a station in low Earth orbit, which is, you know, [more than] 350 kilometers above the surface is just coming home.”
And that’s what’s happening to Crew-11. Although the ailing crew member’s condition was described Thursday by NASA chief Isaacman as “stable,” the decision to return him to Earth would not have been taken lightly.
“It clearly went to the top of the organization,” Coleman says. “It is not trivial to decide to end a space mission, given the effort put into executing it in the first place.”