(PhysOrg.com) -- In 1972, Apollo astronauts narrowly escaped a potential catastrophe. On August 2nd of that year, a large and angry sunspot appeared and began to erupt, over and over again for more than a week, producing a record-setting fusillade of solar proton radiation. Only pure luck saved the day. The eruptions took place during the gap between Apollo 16 and 17 missions, so astronauts missed the storm.