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Mars probe records radiation blasts that could affect future
astronauts, NBC News, By Alan Boyle, 3 Aug 12 Even before its landing, NASA’s Mars Science Laboratory has sent back its first scientific results — shedding light on the radiation exposure that astronauts would face during a future mission to the Red Planet.
The good news is that the spacecraft’s protective shell, which is
similar to the shielding being developed for NASA’s Orion deep-space
capsule, reduces the exposure inside the spacecraft to about a
hundredth of what it was outside the spacecraft. That’s according to
Don Hassler, the principal investigator for the Radiation Assessment
Detector that’s installed on the MSL Curiosity rover.
The bad news is that the internal exposure levels measured during
MSL’s 8-month-plus cruise to Mars would still constitute “a
significant contribution to an astronaut’s career limit,” Hassler
said…..
Preparing the way for humans
Although the habitability question is the $2.5 billion mission’s top
issue, Mars Science Laboratory will also gather data to help NASA
prepare for eventual human missions to Mars. The early readings from
the Radiation Assessment Detector, known as RAD, are part of that
investigation. AD’s readings are still being analyzed in advance of
submission to a scientific journal, Hassler told me, but the exposure
equaled “a few tens of percent” of NASA’s career limit. And that’s
just for a one-way trip. Astronauts would face additional exposure
during their work on Mars and on the return trip.
NASA’s career limit for radiation exposure  is in the range of 1 to 4
sieverts, depending on the age and gender of the astronaut. The space
agency associates that level with a 3 percent excess risk of cancer.
Space radiation has long been recognized as one of the biggest space
hazards humans would face on long-duration trips beyond Earth’s
protective magnetic field, but the RAD results are expected to
represent the best effort to quantify that hazard for Mars trips. RAD
will continue to monitor radiation exposure on the Martian surface
throughout Curiosity’s two-year primary mission…..

Experts are looking into potential ways to beef up the radiation
shielding for deep-space journeys — for example, by distributing water
and other supplies in a particular way around the outside of the
capsule, or by creating a more heavily shielded “safe haven” for use
during solar storms. In addition to solar storms, galactic cosmic rays
contribute to radiation exposure levels in space.
After the landing, RAD will be able to compare the space exposure
levels to the exposure levels on Mars itself. The Martian surface is
thought to be pummeled by radiation to a far greater degree than
Earth, primarily due to the fact that the Red Planet has a much
thinner atmosphere and no global magnetic shield to divert
electrically charged particles. Hassler said the RAD experiment could
lead to much better models to predict the effects of space radiation
on future deep-space astronauts.
http://cosmiclog.nbcnews.com/_news/2012/08/02/13089624-mars-probe-records-radiation-blasts-that-could-affect-future-astronauts

August 8, 2012 - Posted by Christina Macpherson | technology, USA