June 5, 2019
Ryan Whitwam

Radiation Makes Human Missions to Mars Too Dangerous: ESA

All of humanity save for a handful of astronauts have the advantage of living inside the protective bubble of Earth’s magnetic field. As space agencies and private companies look toward a future of people living on the moon and Mars, we have to contend with an unpleasant reality: the radiation out there is lethal. Any attempt to send humans to Mars right now would undoubtedly result in severe health problems, but scientists at the European Space Agency (ESA) are studying the issue in hopes of making space safe for humanity.

We’re all exposed to low levels of radiation on the surface of Earth, but most of it is deflected by our thick atmosphere and magnetic field. Mars has neither of those, and even spacecraft designed to shield fragile organic beings can’t stop all the dangerous cosmic rays. A in space hits astronauts with as much radiation as a year on Earth. The ESA estimates that astronauts on a mission to Mars would get radiation doses up to 700 times higher than on Earth.

From experiments like the NASA Twins Study that spending time in space can cause long-term changes to gene expression, and problems are likely to mount the longer someone is in space. Even on the International Space Station (ISS) under controlled conditions, astronauts are exposed to 200 times more radiation than pilots or radiology technicians. Mission control can abort spacewalks and maintenance if it believes solar events will produce increased radiation levels. That may not always be an option on long-term missions to Mars.

The ESA is currently working with researchers at five particle accelerator laboratories in Europe. These facilities can simulate cosmic radiation by accelerating atoms to a significant fraction of the speed of light. Bombarding materials and biological samples with these particles can help assess the impact of cosmic radiation as well as test new ways to block it.

NASA’s upcoming Orion test launch, currently on the books for summer 2020, will afford the ESA team another chance to study radiation away from Earth’s protective influence. The test dummies on that mission will have integrated radiation monitors to track exposure during the three-week mission around the moon.

Research on mitigating cosmic radiation is already making progress. ESA researchers have found that lithium is especially effective at shielding samples from dangerous radiation. Of course, lithium is unstable in the presence of moisture. It would take a lot of material research before lithium finds its way into spacecraft shielding. In any case, plans to send humans to Mars in the next few years still seem a bit premature.

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