- By: Sheyna E. Gifford
- Posted on: February 18, 2014
Nearly everything we know about the radiation exposure on a trip to Mars we have learned in the past 200 days.
For much longer, we have known that space is a risky place to be, radiation being one of many reasons. We believed that once our explorers safely landed on the surface of Mars, the planet would provide shielding from the ravages of radiation. We didn’t how much, or how little, until very recently. Radiation and its variations impact not only the planning of human and robotic missions, but also the search for life taking place right now.
The first-ever radiation readings from the surface of another planet were published last month in the journal Science. The take-home lesson, as well as the getting-there lesson and the staying-there lesson, is this: don’t forget to pack your shielding. [Mars Radiation Threat to Astronauts Explained (Infographic)]
“Radiation is the one environmental characteristic that we don’t have a lot of experience with on Earth because we’re protected by our magnetosphere and relatively thick atmosphere. But it’s a daily fact of life on Mars,” said Don Hassler, the lead author on the paper, “Mars’ Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover.”
Measuring radiation on Mars
On Earth, we often associate radiation exposure with fallout from catastrophes such as Chernobyl and Fukushima. We sometimes worry over CAT scans, chest X-rays or transcontinental flights. However, according to the Health Physics Society, the biggest source of radiation for most of us, by far, is inhaled radon. The sky above our heads and the earth beneath our feet are typically the least of our worries.
In open space, human beings continuously contend with intense solar and cosmic background radiation. Solar energetic particles (SEPs) and galactic cosmic rays (GCRs) turn a trip to Mars into a six-month radiation shower.
The Mars rover Curiosity has allowed us to finally calculate an average dose over the 180-day journey. It is approximately 300 mSv, the equivalent of 24 CAT scans. In just getting to Mars, an explorer would be exposed to more than 15 times an annual radiation limit for a worker in a nuclear power plant.
Data from Curiosity also demonstrated that landing only partially solves the problem. Once on the Martian surface, cosmic radiation coming from the far side of the planet is blocked. This cuts down detected GCRs by half. The protection from strong solar particles, though, is shoddy and inconsistent. Substantial variations in SEPs occur as the meager Martian atmosphere is tussled by solar wind.
“The variability [in radiation levels] was much larger than expected,” Hassler said. “[This creates] variability in weekly and monthly dose rates. There are also seasonal variations in radiation.”
Study co-author Jennifer Eigenbrode, from the Goddard Institute of Space Studies, described how fluxes in radiation are critical in determining the possibility of life on the Red Planet.
“Radiation is probably the key parameter in determining how much alteration organics are experiencing in the rocks on the surface,” Eigenbrode said.
Read the rest of this very interesting article and find other worthy stories at space.com
NOTE: What this means to us, in the biggest picture of human survival, is that we need to create and develop technology that protects human beings from the deadly radiation that exists outside our own planet, if we are to eventually conquer long term and long distance space travel. Rich
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