Most of us associate radiation with that twang of anxiety you feel upon entering a CAT scan machine or having the X-ray operator drape the lead bib over you before bolting out of the room. But the type of radiation we’re exposed to on Earth is nothing compared to that which exists in open space. It is there that solar energetic particles (SEPs) and galactic cosmic rays (GCRs) would make the long voyage to Mars a naturally hazardous one.
NASA’s Mars rover Curiosity has helped us determine how much radiation astronauts would have to combat on the way to Mars. Over 180 days, the average total dose would be 300 mSv. This is 15 times the annual exposure limit for a worker at a nuclear power plant (see: Homer Simpson). A weak Martian atmosphere means that the travelers wouldn’t get much relief upon landing either. Curiosity’s data indicated that while a visitor to the surface could be exposed to only half of the GCRs, any protection from SEPs is too inconsistent to deem it anywhere near safe.
A chart showing the radiation that travelers to Mars would be be exposed to compared to the earthly radiation sources we’re more familiar with. (JPL)
“The variability [in radiation levels] was much larger than expected,” said Don Hassler, head author of the recent paper in Science on Curiosity’s radiation measurements. He added that “[this creates] variability in weekly and monthly dose rates. There are also seasonal variations in radiation.”
Below is a Curiosity Rover Report explaining (at 1:42) how Curiosity reads radiation levels on the surface of Mars. The video even includes some simulated future astronauts with cool purple light thingies in their hands. No info is provided on cool purple light thingy technology.
Jennifer Eigenbrode of the Goddard Institute of Space Studies, a co-author of the aforementioned paper, points out how this variation in radiation is crucial in assessing the habitability of Mars. Eigenbrode says that “radiation is probably the key parameter in determining how much alteration organics are experiencing in the rocks on the surface.” These radiation levels provide us with valuable information on where – and when in the history of the planet – to look for signs of life. In addition to helping us look for past and current life on Mars, the radiation readings can get us thinking about how we could preserve and protect future life there – i.e., astronauts with cool purple light thingies.
We hope you won’t worry too much about CAT scans or X-rays, since they produce relatively low levels of radiation in the grand scheme of things. And to put your mind fully at ease, know that they also pale in comparison to the largest source of Earthly radiation — the inhalation of radon — which you could be experiencing right now and you’d never even know! Feel better!?