Back in the Day: lunar rover Apollo 15 is used for the first time In what NASA called the most successful manned flight ever achieved, the Apollo 15 Lunar Roving Vehicle was put into use for the first time on the moon. Commander David Scott and Pilot James Irwin spent three days on the moon while Command Module Alfred Worden orbited it. The two astronauts on the surface explored the area with the first lunar rover, on July 31, allowing them to travel farther from the Lunar Module than had been possible before. They collected and brought back to earth 77kg of lunar material. The mission was generally received as a success but did come in for some criticism as the astronauts carried postage stamps in their space suits without authorization, planning to sell them upon their return to Earth. Also on July 31: Bulgaria signs a non-aggression pact with Greece, Turkey, Romania and Yugoslavia (1938); Pierre Laval, a fugitive leader of Vichy France surrenders to Allied soldiers in Austria (1945); First ascent of K2 by an Italian expedition led by Ardito Desio (1954); The United States and the Soviet Union both sign the Strategic Arms Reduction Treaty START I, to reduce both countries" stockpiles (1991); A bomb explodes in a cafeteria of the Hebrew University of Jerusalem, killing 9 people (2002); Michael Phelps breaks the record of the greatest number of medals won at the Olympics, set by Larisa Latynina (2012). Born on July 31: Maximilian II, Holy Roman Emperor (1527), Alessandro Algardi (1598), John Canton (1718), Jean Dubuffet (1901), Louis de Funès (1914), Primo Levi (1919), Wesley Snipes (1962), Mikko Hirvonen (1980). More about: Back in the Day, Moon, NASA, Space exploration, Space technology