Flight 15P of SpaceShipOne (X0) was the first privately funded human spaceflight. It took place on June 21, 2004. It was the fourth powered test flight of the Tier One program, with the previous three test flights reaching much lower altitudes. The flight carried only its pilot, Mike Melvill, who thus became the first non-governmental astronaut. This flight was a full-altitude test, but not itself a competitive flight for the Ansari X Prize, the prize for the first non-governmental reusable crewed spacecraft. Problems were encountered during the flight but later corrected, paving the way for SpaceShipOne to make competitive flights later in 2004. We celebrate this remarkable flight with a postcard and stamp in its honour …