An astronaut suddenly couldn’t speak in space. What does that mean for future missions?

Mike Fincke, second from the left in the top row, with the rest of the Expedition 74 crew aboard the ISS, a few weeks before he experienced a medical episode. NASA via CNN Newsource

Five months into his fourth International Space Station mission, veteran NASA astronaut Mike Fincke was having dinner the day before a routine spacewalk. Suddenly, he found himself unable to speak. The episode in January lasted just 20 minutes and while Fincke felt no pain, he became agitated.

“It was completely out of the blue. It was just amazingly quick,” Fincke recently told the Associated Press.

“My crewmates definitely saw that I was in distress. It was all hands on deck within just a matter of seconds,” he said.

Fincke’s fellow astronauts and a series of emergency protocols kept him safe, but NASA still made an unprecedented move: The agency cut short the SpaceX Crew-11 mission, returning Fincke and three of his fellow astronauts to Earth a month early and leaving the station staffed by only three people. Now, this event might play a role in how future missions are designed.

Jared Isaacman, NASA’s administrator, said in a post-splashdown news conference that the early return was due to a “serious medical condition.” He added that while astronauts receive extensive medical training, there are circumstances in which the option to come home is the best one, and that’s why that possibility is built into the agency’s flight plans.

“This is what we trained for. It’s built in our planning. It was executed very well,” Isaacman added. “We will capture any relevant lessons learned to inform preparations for subsequent missions.”

But as NASA pursues long duration missions farther into space, what if it’s no longer as simple to just come back?

Health issues in space

SpaceX Crew-11 returned to Earth safely on January 15, eight days after the episode — meaning this wasn’t an emergency evacuation, which would have unfolded in a matter of hours. Still, Fincke was the first in over 290 visitors to the ISS to return home early due to a health concern.

NASA hasn’t revealed many details about the incident, which tracks with its usual approach of protecting astronaut privacy and keeping all medical matters confidential. Even when studies analyze specific aspects of astronauts’ health, the research typically doesn’t disclose identities. Fincke later revealed the early exit was due to concern for his health, without disclosing any formal diagnosis, though he told the Associated Press the symptoms were likely space-related.

And while the response to his situation was unique, Fincke is far from the first person to experience a medical issue in space.

The strong forces and the weightlessness experienced during space travel have a variety of effects on the human body. NASA has been studying these effects for over 50 years and groups them into five key hazard areas: radiation, isolation, distance, microgravity and hostile environments. These forces can cause ailments including bone and muscle loss, cardiovascular issues, immune dysfunction and vision impairment.

One key process that weightlessness affects is blood flow. Away from Earth’s gravity, blood and other body fluids are pushed up toward the head from the legs and torso, causing swelling in the upper body. In 2019, a study conducted on 11 healthy astronauts — nine unidentified men and two women with an average age of 46 — revealed that six of them suffered from stagnant or reverse blood flow, one experienced a blood clot and another a partial blood clot.

“The environment of space can be disabling, and the strains of space can impact virtually every aspect of your body,” said Dr. Farhan Asrar, an associate professor at the Faculty of Medicine of the University of Toronto. “Space affects your muscle mass, your bone health. We know that fluid shifts have been causing a lot of issues as well.”

He added that certain blood flow issues could also potentially lead to a temporary lapse of speech. “There is something known as a TIA, or Transient ischaemic attack, which is basically a brief episode of a neurological dysfunction, usually due to the blood flow to the brain being interrupted,” Asrar said. “It tends to resolve by itself and not leave any kind of permanent damage.” TIA symptoms can also include dizziness, confusion and loss of balance.

It’s not clear, however, whether Fincke experienced any additional symptoms or if his condition had anything to do with blood flow. The crew used the space station’s ultrasound machine to assess Fincke, likely with guidance from mission control.

“I think they probably looked to assess the overall function of the heart and perhaps some of the other structures,” said Scott Parazynski, a veteran of four Space Shuttle missions who’s also a physician. “You can assess whether or not there are any blockages or partial obstructions to the carotid arteries. That’s what I would have done, had I been on board.”

Fluid shifts are the cause of other types of conditions that astronauts often experience. One is SANS, or spaceflight associated neuro-ocular syndrome. It manifests as swelling in the back of the eye and loss of visual acuity, and NASA estimates that about 70% of International Space Station astronauts have suffered from it. SANS was one of the subjects of study during the Polaris Dawn mission, a five-day private human spaceflight launched by SpaceX. Isaacman partially funded and served as commander of the mission before taking his NASA role.

Spending more than six months in space comes with other potential health risks, including the weakening and loss of bone and atrophying muscles. Astronauts also experience blood volume loss, weakened immune systems and cardiovascular deconditioning, since floating takes little effort and the heart doesn’t have to work as hard to pump blood.

“Deep space, it has its own set of challenges,” Asrar said. “We’re relatively new to exploring further distances in deep space, we’re learning from Artemis II and kind of taking that further. But we know that the exposure to radiation is an issue — not just duration of exposure, but also the type of radiation which tends to be more penetrating in deep space.”

Astronauts exposed to radiation — high energy particles and atoms traveling at the close to the speed of light — suffer an increased lifetime risk for cancer, central nervous system effects and degenerative diseases, according to NASA.

Planning for deep space emergencies

NASA handled Fincke’s medical emergency very professionally and in a measured way, according to Parazynski, who added that one of the advantages of the space station’s close proximity to Earth is that a patient can be stabilized prior to committing them to a rather stressful return to Earth.

“Sometimes it’s better to evaluate the patient there, provide them whatever supportive care that they need, and then make your decision whether or not to bring the astronaut home.”

However, future deep space missions would carry an increased number of health challenges. “The ISS has the ability to be in almost 24-hour connection with Earth,” Asrar said. “So if whatever training the astronauts have doesn’t suffice, they can also get expertise from Earth. However, in deep space, we know communication delays can be an issue.”

The Artemis II crew experienced a communications blackout of about 40 minutes as it transited behind the moon. Astronauts on potential future missions to Mars, once at their destination, would need to wait 20 minutes for any transmission to reach Earth, plus another 20 to receive an answer, due to the amount of time it takes for the signal to travel to Earth and back.

One way to manage the problem would be to include a doctor as a crew member, which wouldn’t be too difficult since many astronauts are also physicians. The first American medical doctor to become an astronaut was Joseph Kerwin in 1973, and since then about three dozen NASA physicians have become astronauts. It’s common in other countries, too: Four of the nine Canadians who have flown in space are physicians.

There wasn’t a medical doctor on board the ISS during Fincke’s medical episode, but NASA administrator Isaacman said he doesn’t believe things would have played out differently had that been the case. He did note, however, that when NASA embarks on missions to Mars, having medical professionals on board would be “additive.”

Crews may eventually be able to anticipate and plan for in-space health care, too. For example, NASA stowed “organ chips” on board Artemis II — bone marrow samples from the astronauts to assess the effects of deep-space conditions, including radiation, on human health. The insights gained from the experiment could lead to individualized treatments, such as personalized medical kits, that ease the way for the astronauts to embark on longer missions — perhaps deeper into the cosmos.

The goal is to one day be able to send up organ chips for astronauts selected for deep space missions ahead of time, so crews can prepare for potential health concerns before they become an issue far from home, according to Lisa Carnell, director of NASA’s Biological and Physical Sciences division.

“We like to say, ‘Know before we go.’ It’s that simple,” Carnell told CNN in a prior interview. “Like, how do we know before we send them to ensure that we bring them back healthy and that they’re as safe as can be? And this is such a simple … eloquent way to do that.”

According to Parazynski, even after 60 years of space missions there are still mysteries to be unpacked in terms of how the human body reacts to weightlessness and how to bring people back to their full health after a long duration spaceflight.

“Going to space is a sort of accelerated aging process,” he added. “When we start to think about sending astronauts to the moon and Mars for long periods of time, how do we support them when they arrive there? And how do we bring them back safely to Earth’s gravity after a year or more away from home? It’s an exciting time in space medicine to start answering some of these questions.”