Long-distance space travellers face astronomical stomach upsets

Serious tummy upsets may be one of the greatest obstacles to deep space travel, new research suggests.

Radiation exposure on a trip to Mars or beyond could significantly damage astronauts’ stomachs and intestines, according to the findings.

This is likely to result in long-term functional impairments, such as ineffective nutrient absorption, or cancer.

Scientists made the discovery after exposing mice to low doses of electrically charged iron particles, one of the most harmful forms of galactic cosmic radiation (GCR).

Atoms and molecules that carry an electric charge are known as ions.

Lead scientist Dr Kamal Datta, from Nasa’s Specialised Centre of Research at Georgetown University in Washington DC, said: “With the current shielding technology, it is difficult to protect astronauts from the adverse effects of heavy ion radiation.

“Although there may be a way to use medicines to counter these effects, no such agent has been developed yet.

“While short trips, like the times astronauts travelled to the moon, may not expose them to this level of damage, the real concern is lasting injury from a long trip such as a Mars or other deep space missions which would be much longer.”

Heavy ions such as iron and silicon act like tiny, fast-moving bullets and are more destructive than X-rays and gamma rays, which are mass-less high frequency forms of light.

Life on Earth is protected from energetic heavy ions by the planet’s magnetic field, which deflects them away.

The study compared mice exposed to heavy iron ions, others exposed to gamma rays, and a third group that was not subjected to any form of radiation.

Exposures were designed to simulate what astronauts could expect after months in deep space.

Intestinal cells from the heavy ion mice failed to absorb nutrients adequately and formed cancerous polyps.

There was also evidence that iron radiation induced DNA damage and increased the number of “senescent” cells that had stopped dividing.

Senescent cells generate oxidative stress and inflammation that induces more damage, said the team whose findings are reported in the journal Proceedings of the National Academy of Sciences.

Despite the low dose, the effects of heavy ion radiation appeared to be permanent.

The same scientists previously highlighted potential impairment to brain tissue and accelerated ageing linked to exposure to energetic heavy ions on long space trips.

Dr Datta said: “We have documented the effects of deep space radiation on some vital organs, but we believe that similar damage responses may occur in many organs.

“It is important to understand these effects in advance so we can do everything we can to protect our future space travellers.”