The secret project dubbed, “A Study of Lunar Research Flights” and nicknamed “Project A119,” was seriously being considered until it was scrapped because military officials were worried it would hurt the people on Earth.

The Daily Mail reports that astronomer Carl Sagan’s calculations were used regarding the dust and gas the blast would generate. The website also states that physicist Leonard Reiffel told the Associated Press in an interview in 2000 that a U.S. nuclear flash from Earth might have “intimidated” the Soviets.