November 18, 2012 | David F. Coppedge

Mars Radiation May Not Be That Bad

Data from the Curiosity rover’s RAD instrument seem to indicate astronauts could survive radiation reaching the surface.

The data are preliminary, but a press release from the Mars Science Laboratory (MSL) team at Jet Propulsion Laboratory graphed measurements from the Radiation Assessment Detector (RAD) on Curiosity and found a cyclic variation over 5 sols (Martian days) corresponding to atmospheric pressure cycles.  The radiation environment appears similar to that endured by astronauts on the International Space Station.

Live Science quoted the principal investigator for RAD  saying, “Absolutely, astronauts can live in this environment.”  He stressed, though, that the data are preliminary, with Curiosity only 3 months into its planned multi-year mission.  The article said, “He and his team have not yet put hard numbers on the Martian radiation levels, though they plan to do so soon.”

The real issue for future exploration, the article continued, “is determining how much of a radation dose any future astronauts would accumulate throughout an entire Mars mission — during the cruise to the Red Planet, the time on the surface and the journey home.”  The cruise part, with no atmosphere, may prove to be the biggest obstacle for human travel.

There’s nothing like “ground truth” to constrain speculation.  Earlier radiation estimates we reported were more pessimistic (e.g., 9/14/2000, 5/02/2001, 5/18/2005, 9/23/2006), so it’s good to see that radiation may not rule out human exploration some distant future day when the world’s governments learn how not to bankrupt themselves.

More data are needed, though, to keep the dream alive.  How often do solar flares and high-energy cosmic rays hit the ground on Mars?  While it’s comforting to learn that the thin Martian atmosphere can dissipate some of the radiation, Mars lacks a global magnetic field and associated Van Allen belts, and has no ozone layer, so it has far less protection than does Earth.  Then there is still the issue of getting astronauts to Mars on a nearly two-year round trip with no protection from the sun’s shooting gallery on the way.  In addition, the types of radiation (UV, charged particles, cosmic rays) have to be accounted for separately and in sum.

As for probabilities for life on Mars, don’t get your hopes up.  Does fewer bullets in a computer room mean better chances for survival?  Millions of years of bombardment, even if lighter than previously estimated, is not conducive to the growth of hopeful monsters.



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