L+500 and counting: 500th person in space

Among the seven astronauts launching on space shuttle Endeavour on Saturday, four are making their first flight, an achievement in any astronaut's career. One of the four however, will also be setting a benchmark as the 500th person in history to fly into space.Endeavour's pilot Doug Hurley, mission specialists Chris Cassidy and Tom Marshburn, together with arriving space station flight engineer