Nobody's Going to Mars Anytime Soon

A roundtrip mission to Mars would get you a minimum of 1 Sievert of radiation exposure (that's 1,000 mSv). Congratulations, spaceman -- you're in the pink. See here.

Popular Science

"You May Not Even Make It There At All

All of these scenarios only become critical issues if you actually make it to Mars in the first place. But the sad truth is you might not even survive the trip. Barring any complications with the spacecraft’s hardware or any unintended run-ins with space debris, there’s still a big killer lurking out in space that can’t be easily avoided: radiation.

Beyond lower Earth orbit, the deep space environment is filled with cosmic rays—highly energized particles. This space radiation easily penetrates the walls of spacecraft, and it’s possible that long-term exposure can have weird effects on human health.

A recent study on mice revealed that long-term exposure to cosmic rays might lead to some abnormal changes in the brain. After subjecting mice to simulated cosmic rays, researchers noticed the mice had lost many important brain synapses. Subsequent behavioral studies on the mice showed they exhibited less curiosity and seemed confused—an eerie result, with upsetting implications for a future trip to Mars."

NASA

"The greatest threat to astronauts en route to Mars is galactic cosmic rays--or "GCRs" for short. These are particles accelerated to almost light speed by distant supernova explosions. The most dangerous GCRs are heavy ionized nuclei such as Fe⁺²⁶. "They're much more energetic (millions of MeV) than typical protons accelerated by solar flares (tens to hundreds of MeV)," notes Cucinotta. GCRs barrel through the skin of spaceships and people like tiny cannon balls, breaking the strands of DNA molecules, damaging genes and killing cells.

Astronauts have rarely experienced a full dose of these deep space GCRs. Consider the International Space Station (ISS): it orbits only 400 km above Earth's surface. The body of our planet, looming large, intercepts about one-third of GCRs before they reach the ISS. Another third is deflected by Earth's magnetic field. Space shuttle astronauts enjoy similar reductions.

Apollo astronauts traveling to the moon absorbed higher doses--about 3 times the ISS level--but only for a few days during the Earth-moon cruise. GCRs may have damaged their eyes, notes Cucinotta. On the way to the moon, Apollo crews reported seeing cosmic ray flashes in their retinas, and now, many years later, some of them have developed cataracts. Otherwise they don't seem to have suffered much. "A few days 'out there' is probably safe," concludes Cucinotta.

But astronauts traveling to Mars will be "out there" for a year or more. "We can't yet estimate, reliably, what cosmic rays will do to us when we're exposed for so long," he says."

Z Med Phys. 2004;14(4):267-72.

Radiation hazard during a manned mission to Mars.

Jäkel O¹.

Author information

• ¹Deutsches Krebsforschungszentrum, Heidelberg, Germany.

Abstract

The radiation hazard of interplanetary flights is currently one of the major obstacles to manned missions to Mars. Highly energetic, heavy-charged particles from galactic cosmic radiation can not be sufficiently shielded in space vehicles. The long-term radiation effects to humans of these particles are largely unknown. In addition, unpredictable storms of solar particles may expose the crew to doses that lead to acute radiation effects. A manned flight to Mars currently seems to be a high-risk adventure. This article provides an overview on the radiation sources and risks for a crew on a manned flight to Mars, as currently estimated by scientists of the US National Administration for Space and Aeronautics (NASA) and the Space Studies Board (SSB) of the US National Research Council.