In new research that delivers a blow to hopes of finding safe ways to send humans back to the moon or on to Mars, scientists have found that as little as a month in space can significantly depress the immune systems of mice, potentially making astronauts susceptible to ailments that their bodies would easily brush off on Earth.

But other research, published only a week before, suggests that other aspects of immune function might not suffer as badly from weightlessness as had previously been thought. Scientists have been trying to unravel the health effects of space travel, and figure out ways to combat them, since at least 1966. 

That’s when five Texas college students agreed to spend 20 days as the world’s ultimate couch potatoes. For three weeks, these previously active young men took to bed, not even getting up to walk to the toilet. NASA’s moon landings were looming, and prolonged bed-rest, medical researchers figured, was the best way to mimic the enforced inactivity of spaceflight.

What they found was disconcerting. When the young men finally staggered back to their feet, they were not only weak as kittens, but from a cardiovascular and exercise physiology standpoint, their bodies had (temporarily) deteriorated by the equivalent of several decades worth of ageing.

Weightlessness

The researchers found that a mere month of weightlessness altered bone marrow proteins involved in the production of B-lymphocytes, the white blood cells responsible for antibody production. The effect was strong enough that it persisted at least a week after the mice were returned to Earth.

In 2016, Bertile says, a team from NASA’s Johnson Space Flight Centre in Houston, Texas, examined the medical records of 46 astronauts who had spent a total 20.57 years aboard the International Space Station. “The data showed that 46 percent of them faced immunological problems,” he says.

These conditions, reported in 2016 in the International Journal of General Medicine, ranged from persistent skin rashes to prolonged congestion or nasal irritation, skin infections, cold sores, urinary tract infections, and allergic reactions. All were significant enough to be classified as “notable” as opposed to “minor” health events.

It’s also an interesting complement to Spielmann’s own work, which appeared last week in the Journal of Applied Physiology. That study used blood samples from 23 astronauts, taken at several times before, during, and after six-month stints on the International Space Station.

Immune system activity 

Antibodies last long enough in the blood that their presence during spaceflight could be a carry-over from before launch. Free light chains, Spielmann says, have half-lives of only two to six hours, so their presence is a marker of at-the-moment immune system activity. His team had expected the astronauts’ blood to display decreased numbers of B-lymphocytes and reductions in antibodies as their stints in space progressed. But that wasn’t the result. “We didn’t see much,” he says.

In addition, the two studies looked at different portions of the immune process. Bertile’s examined what was going on at the cellular level inside the bone marrow. Spielmann’s looked at immune function in the blood.

Research has found that their immune systems could experience a triple whammy — one from the effect of weightlessness, another from the effect of social stresses, and a third from the fact that research has shown that not only do pathogens easily accumulate in the close confines of a spacecraft or space station, but exposure to space radiation appears to make these pathogens more virulent.

Many people carry viruses such Epstein-Barr or varicella zoster, the virus that causes chickenpox in children … and which can return as shingles in adults. Coming down with shingles on a trip to Mars sounds like a special kind of hell. But Spielmann says his research indicates that there may be a way to offset this risk.

If the B-lymphocytes are actually producing the level of antibodies his research suggests they are, then it’s possible to carry vaccines with you on a trip to Mars and use them midway to stimulate the immune system to prevent latent viruses from re-emerging later in the trip.

“You can vaccinate an astronaut in transit and know they will remain protected,” he says. It’s the type finding that indicates that even though space travel will always have health risks, the more we understand about them, the better are our chances of combatting them. If so, then maybe, eventually, we will someday watching Neil Armstrong’s one small step on the Moon become an even greater giant leap to Mars.