The U.S. Postal Service anticipates New Horizon's closest encounter with Pluto on the 14th of July because, unknown by many until now, the probe actually has a special passenger on board - a stamp.
The stamp was produced in 1991 as part of a planetary set, with Pluto being the only planet without a robotic companion. Since no spacecraft has ever gotten as far as Pluto before, there is no robot to show off in the stamp illustration. Instead, it bears the words "Not Yet Explored."
The encounter will make space history - completing the initial reconnaissance of our classical solar system - and, because the stamp is affixed to the probe, it will make some postal history, too, according to SPACE.
It will become the first U.S. postage stamp to be present on the event that made its design outdated and it will also be the stamp to have travelled the farthest.
"It was my idea to send it," New Horizons principal investigator Alan Stern told Astronomy Magazine, Washington Post reports. "For many years, people had waved that stamp around as sort of a call to arms - as a motivating graphic - 'Not yet explored.' That stamp had been in so many presentations by that point, I knew it would please people to have it go along."
