"The agency is monitoring a medical concern with a crew member that arose Wednesday afternoon," NASA officials wrote in a blog post on January 7th. While the astronaut — who was never named, for privacy reasons — stabilized quickly, their condition was serious enough to bring home the Crew-11 mission home early.

"Spaceflight is much larger than any single person," Cardman said. "In my opinion, this is a really excellent example of risk analysis and decision-making, and I'm very proud of the decision they made."

Space serves as an example of an "isolated, confined environment" or ICE, which produces numerous stresses on the body, the brain, and social ties, a recent study in the peer-reviewed Work and Health journal explained. There are decades of research in this field, examining environments like Antarctica, submarines, "analog" space bases with simulated astronauts, and outer space itself.

Underlying the ICE environment is this: no easy escape from Antarctica, a submarine, or especially a space station when something goes wrong. Astronauts usually have years of experience in ICE before even being selected as an astronaut, whether as pilots with combat experience or as expedition members on remote scientific voyages. And then there is the typical five to ten years of strict NASA training on thinking like an astronaut when the worst arises, before flying to space.

"I already feel very confident that we get really excellent training, especially for any kind of urgent situation that might arise. We're really well-trained to get a situation stable," Cardman said.

"Training actually works very well," said Crew-11's Japanese astronaut Kimiya Yui of the mindset that kicked in, with similar sentiments shared by crewmates Mike Fincke (NASA) and Oleg Platonov (Roscosmos).

Making a successful, safe decision in ICE requires careful communication between the remote team — in this case, the astronauts aboard the ISS — and the team of experts back home, which was in principal Mission Control and a team of international medical experts.

"The team came together, and it wasn't just this team, but the whole team... around the world," Fincke said.  "And we were able to come home safely to our families, back to beautiful planet Earth."

Even casual followers of the space program will know that other emergencies have arisen in space, with some leading to the loss of life of crew. By coincidence, the crew flew home not long before NASA's annual Day of Remembrance for fallen astronauts, which honors the group of spaceflyers who died either while on mission or in training.

It's a somber list to consult, including examples such as the loss of 14 astronauts (combined) on the Challenger and Columbia space shuttle disasters of 1986 and 2003, another three who died in a launch-pad fire while finalizing the Apollo 1 mission for launch in 1967, a single Russian cosmonaut who died when his parachute failed to deploy on Soyuz 1 in 1967, and three other cosmonauts whose cabin fatally depressurized as Soyuz 11 came to a close in 1971. (Private spaceflight also had Virgin Galactic's crash-landing in 2014, which killed one pilot during a test flight.)

The typical process when emergencies occur, either fatal or not, is to create an investigatory board that looks at all factors of the incident. You can think of it as similar to what happens after an airplane crash or near-miss in aviation, although space has another level of difficulty, given all missions are, to an extent, developmental.

Both the engineering and the humans involved in the critical decisions are considered in these investigations, which can take years to complete.

And so that the recommendations are not ignored, the NASA space community formally remembers everybody on the Day of Remembrance (which falls in late January or early February, depending on the year).

And from time to time, when serious concerns arise about an ongoing mission, an old hand in the room will recall the thinking on a mission like Challenger, like the social media conversation that arose in late January between NASA administrator (and commercial astronaut) Jared Isaacman and former NASA space shuttle manager Wayne Hale.

No less a figure than Neil Armstrong talked about this "lessons learned" process. Armstrong — a test pilot by training — was best-known for being the first person to walk on the moon during Apollo 11 in 1969, but he also was part of the crew that stabilized Gemini 8 from a potentially fatal spin in space in 1966.

"To me, it [Gemini 8] re-emphasized the fact that you've got to expect some of these things are going to go wrong, and we always need to prepare ourselves for handling the unexpected. And you just hope those unexpected things aren't something that you can't cope with," Armstrong, who died in 2012 of complications from surgery at age 82, said in a 2001 NASA oral interview.

"So throughout Apollo, everybody I knew was always saying, 'What if?' and, 'Is it possible that this could happen?' And, 'What will we do?' Just that process of continually questioning, built your confidence in your ability to handle whatever comes along," Armstrong added.

While a handful of private citizens with little ICE training flew into space over the decades, this process has accelerated with recent commercial flights, of just a few minutes in space, aboard Virgin Galactic and Blue Origin. There's an ongoing debate about how much these passengers understand about the dangers of space and how they would prepare for issues, although the companies involved emphasize that their training would be beneficial in case of an emergency.  

SpaceX has also flown non-professional astronauts recently, but its missions are not suborbital hops for a few minutes — and therefore require more funding and training. Axiom Space, a company in Houston, uses SpaceX to fly commercial missions to the ISS, which is even more demanding as all occupants on the station require basic training on how to operate safely.

"The culmination of this training is known as 'Emergency Simulations," Axiom wrote in 2023 in a discussion about its Ax-2 mission, which, like all missions, was led by a retired NASA astronaut. "During these simulations, the Ax-2 crew members take what they have learned in a classroom and mockup-based training, and put it to the test during a series of simulated ISS emergencies. The astronauts are in NASA's ISS mockups, while a team of instructors surprises them with a scenario such as a fire, cabin depressurization, or a toxic leak into the ISS atmosphere."

NASA's Isaacman flew twice aboard SpaceX on orbital, non-ISS missions that he, a billionaire, both funded and commanded. But Isaacman is also a highly trained pilot capable of operating high-performance aircraft, allowing him insight into the dangers of operating up high — including in space.

"There's no atmosphere. There’s radiation. There is micrometeoroid debris," Isaacman said in a 2024 interview with Embry-Riddle Aeronautical University, which he did as an alumnus. "We have to keep going, just as the explorers did hundreds of years ago, and along the way... life will be better for humankind. So, we don't have a choice not to proceed. We just kind of have to go with caution."

While the number of people simultaneously in space is small compared to seven billion individuals on Earth, it hit a record 20 individuals a couple of times in recent years, according to statistics kept by spaceflight statistic analyst Jonathan McDowell and, of course, Supercluster's own Astronaut Database and Stations Dashboard. There may be a nuance in the statistics as not everyone agrees on the "boundary" of space, but the point is true that there are more private space missions than ever.

Below is a non-comprehensive shortlist of other times people successfully "escaped" space as circumstances warranted, or survived in space because it was deemed safe to do so, after a critical incident.

An apparent micrometeoroid strike on the Chinese Shenzhou 20 spacecraft happened when the vehicle was docked at the Tiangong Space Station, which Supercluster tracks on our website and app. The Chinese decided to move the crew onto an undamaged spacecraft for reentry and to fly Shenzhou 20 home autonomously. A similar scenario played out with a Soyuz spacecraft at the ISS in 2022-23, which forced some crew members to stay much longer than anticipated due to the vehicle swap.

Starliner was on a test flight, operated by Suni Williams and Butch Wilmore, two highly experienced NASA astronauts who were former test pilots themselves, on its first crewed ISS mission. Supercluster tracked and covered the mission extensively through our suite of utilities and editorial coverage. During the final approach, some issues arose during engine firing that could not easily be diagnosed in space. The crew safely docked with ISS and worked with the ground on troubleshooting. After several months, NASA swapped the crew to a SpaceX Crew Dragon for reentry and flew the Starliner home autonomously, to preserve safety. Starliner will fly its next mission uncrewed as Boeing aims to complete certification to fly astronauts for future ISS missions. Williams is now retired from NASA.

At some point in ISS operations, an astronaut developed a blood clot that required medical treatment. Their name and their year of operation were not disclosed due to privacy reasons. Since it was the first time a blood clot arose in space, NASA (in consultation with outside medical doctors) used a combination of blood thinners and ultrasound scans to keep the astronaut safe in orbit. The drug treatment was slightly complicated by a shortage of the needed medicine on the ISS, but a spacecraft shipment eventually resolved it. The astronaut safely completed their mission and returned to Earth.

While NASA spacesuits — originally designed for the space shuttle program of 1981-2011 – have experienced a few leaks over the years, the most critical occurred when European Space Agency astronaut Luca Parmitano was mid-spacewalk. Parmitano emerged safely, although the spacewalk had to be cut short, and water was clinging to his face during repressurization in the ISS. NASA made numerous changes to its spacewalk procedures, allowing for 12+ years of safe spacewalks afterwards — and counting. It takes years to procure and develop spacesuits due to their expense and complication, as they are essentially little spacecraft. The same spacesuits are therefore still (carefully) used for ISS operations, although NASA aims to have a new generation ready for the post-ISS era.

The ISS uses ammonia as a coolant, and a few times it has leaked to an extent that requires spacewalk repairs by astronauts. One of the more prominent incidents took place in 2001, when ammonia was sprayed in the vicinity of NASA astronaut Robert Curbeam. during the first of the STS-98 spacewalks Curbeam was connecting cooling lines between the newly-installed Destiny module and the station’s external ammonia coolant system, a small amount of ammonia leaked from one of the hoses and formed frozen ammonia crystals on his spacesuit. NASA directed Curbeam to remain in direct sunlight for about a half-hour so that the ammonia crystals could vaporize (“bake off”) from the suit before he returned to the airlock, and his crewmates brushed off remaining crystals. Afterward the airlock was partly repressurized and vented to help remove any ammonia, and the crew inside wore oxygen masks for a short period as an extra precaution. Noone was harmed.

A fire erupted on the Russian space station in 1997 due to a failure in the oxygen-generating system, briefly endangering six Russian and American crew members on board. As NASA put it: "The searing flame, lasting several minutes, not only cut off access to one of the two Soyuz escape vehicles but also filled the station’s modules with smoke." Astronauts put out the fire safely, and the space station's life support systems cleared up the smoke within a few hours. Mir's structure was undamaged, and the crew was deemed physically healthy; the incident was used to inform the design and procedures of the International Space Station.

These were two separate incidents, with the first one attributed to excessive mass on a Soyuz crewed spacecraft flying around Mir, and the second due to issues with remotely controlling a Soyuz cargo spacecraft on its final approach to the space station. Some of the firefighting crew members of Mir were still on board when the 1997 collision took place, causing a depressurization of the Spektr module that was successfully (and permanently) isolated from the rest of the space station. Due to a combination of its age and funding challenges, Mir was deorbited four years after the last incident, in 2001.

This was a Soviet Union mission that was supposed to be six months long, after docking at the Salyut 7 space station. Illness by the mission commander, Vladimir Vasyutin, forced the crew to depart two months into their stay for a safe return to Earth. Little was said about his medical condition at the time, likely due to privacy concerns. It is said to be the first-ever medical evacuation in space.

The infamous Apollo 13 mission was flown by Lovell, Haise, and Swigert, and launched on April 11th, 1970. The plan was for NASA to achieve a third lunar landing. Two days into the flight, on April 13th, an oxygen tank inside the Service Module exploded, an event NASA describes as a “catastrophic failure” that crippled the spacecraft’s electrical and life support systems and caused the crew to radio the now-famous message, “Houston, we’ve had a problem.”

According to NASA’s mission report, the explosion led to the loss of Oxygen Tank No. 2, damage to Tank 1, and a near-total shutdown of the Command Module, making a lunar landing impossible. Mission Control and the crew activated the Lunar Module Aquarius as a lifeboat, using its power, oxygen, and propulsion systems to keep the astronauts alive for the four-day journey back to Earth—an unplanned use that NASA notes had never been tested for such duration. Engineers developed real-time procedures for navigation, power conservation, carbon-dioxide removal, and thermal control, all of which the crew executed with extreme precision. Despite dangerous cabin temperatures, water shortages, and rising CO₂ levels, NASA’s mission team guided Apollo 13 back to safety, and the crew splashed down in the Pacific Ocean on April 17th, 1970.

Elizabeth Howell is a Canadian space journalist based in Ottawa.

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