Human stomach presents major obstacle to deep space travel

Future trips to Mars and beyond might be hampered by stomach-disrupting radiation affecting humans that can cause cancer or hinder nutrient absorption, according to new Nasa research.

The Nasa study involved exposing mice to low doses of electrically charged iron particles, one of the most harmful forms of galactic cosmic radiation (GCR).

Other control groups were also exposed to heavy iron ions or to gamma rays, while a third group 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 also 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.

This outcome follows previous studies which showed that long space journeys could also do damage to astronaut’s brains and may even age them prematurely.

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

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

“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,” Datta said.

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

Last month, the European Space Agency said it was concerned that astronauts on a mission to Mars would be exposed to at least 60 per cent of the total radiation dose limit recommended for their career during a single journey to and from the Red Planet. 

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