Hugh Pickens writes "Space.com reports that an online petition directed at the USPS and its Citizen Stamp Advisory Committee (CSAC) hopes to collect 100,000 signatures or more by March 13, the 82nd anniversary of the announcement of Pluto's discovery as the New Horizons robotic spacecraft gets closer to flyby Pluto and its moons in 2015. 'This is a chance for us all to celebrate what American space exploration can achieve though hard work, technical excellence, the spirit of scientific inquiry, and the uniquely human drive to explore,' reads the petition. Whether or not the New Horizons team is successful in getting the USPS to honor their spacecraft's mission, the probe will have delivered a stamp to Pluto. New Horizons includes nine stowaways including one of the 1991 'Not Yet Explored' Pluto stamps together with other mementos including a Florida quarter, a small container with an ounce of the ashes of Clyde Tombaugh, discoverer of Pluto, and a small segment of 2004 Ansari X Prize winner SpaceShipOne, the first privately-funded crewed spacecraft. 'Why nine mementos? I bet you can guess,' says Dr. Alan Stern, New Horizons' Principal Investigator adding why he wanted to send one of the Pluto stamps on the mission. 'Pluto may not have been explored when that stamp set came out, but we were going to conquer that,' says Stern. 'I wanted to fly it as a sort of 'in your face' thing.'"