Researchers have published new data showing that long distance space travel, such as a manned mission to Mars, would pose serious health risks to astronauts because of the exposure to deep space radiation. The finding is based on measurements from an instrument on the spaceship that carried the Mars rover, Curiosity, to the Red Planet.
From the time the U.S. space agency, NASA, launched its Mars Space Laboratory in November 2011, until the time it touched down on the Red Planet, an instrument called the Radiation Assessment Detector or RAD took detailed measurements of high energy particles that would bathe astronauts on a deep space mission.
Radiation exposure on a trip to Mars or a six-month stint aboard the International Space Station has long been a concern to space scientists.
Cary Zeitlin at Southwest Research Institute in San Antonio, Texas, and colleagues analyzed the RAD data collected during a 253-day, 560-million-kilometer journey to Mars.
The heavily shielded instrument, similar to the protection of a space suit, recorded the amount of on-board radiation exposure that would be expected to hit humans traveling to Mars or other deep space destinations.
They found the amount of radiation exposure was a large fraction of what is considered an acceptable lifetime limit.
“The concern is not so much any immediate effects on people, although those are possible, but long-term health effects like cancer or damage to the central nervous system,” Zeitlin said.
Zeitlin made his comments in a podcast interview with the journal Science, which published the study.
Humans would be exposed to two types of radiation on board the spacecraft; constant low-energy particles called Galactic Cosmic Rays, or GCRs, and solar particle radiation which fluctuates with sun spot activity. The amount of accumulated radiation exposure for astronauts on a round-trip to Mars, according to Zeitlin, would be the equivalent of getting a whole-body CT scan every five to six days.
It might be possible to beef up protective gear and improve the insulation of spacecraft to better protect astronauts against solar radiation. But Zeitlin says constant exposure to cosmic rays poses a more difficult problem.
“They can typically go through several inches of solid matter shielding without being attenuated (reduced) very much. So astronauts in deep space will get a continuous low radiation dose,” Zeitlin said.
Zeitlin and colleagues will continue to take radiation measurements as the Curiosity rover bumps along the Martian surface. Researchers want to get a complete picture of the radiation risks to humans who would spend time on the Red Planet, if and when a mission is undertaken.