Women astronauts could be 'more tolerant to spaceflight,' research shows

Inspiration 4 crew Sian Proctor (left) and Hayley Arceneaux (right) in orbit. (SpaceX/Inspiration 4)

Samples from the private Inspiration 4 mission with SpaceX helped reveal early evidence that men and women recover differently after their time in orbit.

On Tuesday, a series of research papers called the Space Omics and Medical Atlas (SOMA) package was published in the Nature Portfolio journals with research using biomedical data collected during the Inspiration 4 mission, NASA and JAXA missions.

Some of the most critical data from the SOMA research came from the four citizen astronauts who flew on a SpaceX Crew Dragon on the Inspiration 4 mission in September 2021. The mission was funded and commanded by American business executive Jared Isaacman. Hayley Arceneaux, Sian Proctor and Chris Sembroski joined Isaacman on a three-day flight into low-Earth orbit.

The blood, skin and other samples collected by the Inspiration 4 crew helped researchers across 25 countries publish 27 papers showing the changes astronauts experience even with short-duration spaceflights


Inspiration 4 medical officer and crew member Hayley Arceneaux in orbit with a photo of herself as a child. Arceneaux is a childhood cancer survivor who later became a physician's assistant. (SpaceX/Inspiration 4)


Researchers found that T-cells and monocyte cells showed the largest degree of chromatin changes in the immune system after spaceflight. However, space explorers recovered from about 95% of the biological changes, returning to their baseline months after the mission. 

On average, female crew members returned to baseline faster across all cell types for their chromatin landscape than male astronauts, according to SOMA research. 

Study author Christopher Mason, of Weill Cornell Medicine, said that while both sexes quickly returned to baseline, there "seems to be a little bit of evidence that females return a bit more quickly."

He theorized that women could be better adapted to physical changes because of the ability to have children. 

"Maybe being able to tolerate large, large changes in physiology and fluid dynamics may be great for being able to manage pregnancy, but also manage the stress of spaceflight at a physiological level," Mason said.

It's still too early for researchers to say that women make better space explorers than men. The researchers estimated they would need a few hundred more astronaut samples to confirm this theory. According to the Supercluster Astronaut Database, less than 100 women have been to space, whereas more than 600 men have.

"We don’t have the full answer yet as to why women seem to be more tolerant to spaceflight," Mason said.

Another SOMA researcher, Susan Bailey, with Colorado State University, said that although this new research shows women can bounce back a little faster, there is a caveat.


"A word of caution is that some previous work has shown that females may be more susceptible to some of the radiation-induced cancers like breast and even lung," Bailey said. "There is always a flip side to the coin."

Only recently have researchers begun to study the effects of how spaceflight radiation exposure could impact female reproduction, but the results have not been conclusive. 

"Still, the low number of female astronauts does not allow for assessment of the risk of spaceflight on gynecological cancer," the authors of a comprehensive review of previous research wrote in January.

The SOMA research on human spaceflight could inspire future studies on how different sexes and ages react to spaceflight. 

Scientists said the Inspiration 4 crew was a good study sample because the astronauts included both sexes and diverse ages. At 29, Arceneaux was the youngest American to orbit Earth. The other crew were ages 38, 42 and 51.

"We have this huge range now of ages," Bailey said. "It's just really a remarkable opportunity to see how different people respond."

With increasing private spaceflights and access to space, the medical data needed to confirm some of these early theories on women in space will eventually become possible. 

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