Curiosity rover discovers dangerous levels of radiation during Mars transit Alt

While we've learned that radiation levels on Mars are safe for humans, actually getting there in the first place remains a problem. Recent results from Curiosity's Radiation Assessment Detector (RAD) reveal that exposure even while safely ensconced inside a protected spacecraft is dangerously high. Explorers would be bombarded with 466 milliSieverts of high-energy galactic cosmic rays and solar particles during the 253-day transit and the same coming back, with total levels that could exceed NASA's career radiation limit for astronauts. "In terms of accumulated dose, it's like getting a whole-body CT scan once every five or six days," said Cary Zeitlin, a principal scientist from the Southwest Research Institute (SwRI) who's the lead author of the findings. A manned Mars voyage isn't completely out of the question, but it does mean better shielding is necessary before such a trip -- much less a future colony -- becomes a reality.