English: Gary Flandro, Voyager mission grand tour creator, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft.