Mars trip radiation said 'survivable'

Astronauts on a long-term, round-trip mission to Mars would experience radiation exposure levels considered significant but survivable, NASA says. Radiation data gathered by NASA's Mars rover Curiosity -- both on the way to the Red Planet and while on the planet's surface -- suggest astronauts on a two-and-a-half year mission there would receive a total radiation dose of about 1.1 sieverts, the space agency reported. "The rough ballpark average for an astronaut career limit is on the order of a sievert," Curiosity scientist Don Hassler of the Southwest Research Institute in Boulder, Colo., said Monday. Data from instruments on Curiosity show radiation levels on the Martian surface -- about 0.7 millisieverts a day -- are similar to the 0.4 to 1.0 daily millisieverts astronauts in low-Earth orbit encounter, SPACE.com reported. Levels encountered in space during the long trip to Mars would be a greater concern, scientists said. Radiation levels recorded by Curiosity instruments during the 8-month voyage to Mars averaged 1.9 millisieverts a day. "We can survive the Mars surface," Hassler said. "The hard part is the cruise." Hassler made the comments at the annual fall meeting of the American Geophysical Union in San Francisco.