In his 1970s book, Space, James Michener depicted a fictional Apollo mission that lost its crew to radiation from a massive solar flare. He based his tale on what easily might have been but for lucky timing: a massive flare on Aug. 7, 1972 occurred between Apollo 16 (April) and Apollo 17 (December), mankind's last journeys to the Moon.
The event still resonates today. NASA is preparing to send astronauts back to the Moon and on even longer journeys to Mars. With crews "out there" for extended periods, "the chances go way up that they'll be caught in the middle of a storm," says David Hathaway, a solar physicist at NASA's Marshall Space Flight Center.
"The educated view about the August 1972 flare is that a crew on the surface of the Moon would have gotten really sick." Or worse. Dr. Lawrence Townsend of the University of Tennessee and his colleagues calculated that energetic particles from a super flare, like that recorded by Sir Richard Carrington in September 1859, could kill.