Near the end of his third moonwalk, Apollo 15 commander Dave Scott was completing his final tasks at the lunar module equipment storage assembly. Dave picked up the small Moon mail pouch and placed it on the worktable. Inside were a single envelope franked with a hand perforated, die-proof pair of the 8-cent postage stamps specially designed for this historic occasion, and a stamp pad, and two different rubber handstamps. Two cancellation devices were provided, as the exact date could not be set preflight but would take place when Dave had completed scheduled tasks.

Dave began the ceremony. "Just to show that a good postal service takes care of the mail just about any place in the universe, I have the pleasant tasks of canceling here on the Moon the first stamp of a new issue to commemorate the United States' achievements in space. I'm sure a lot of people have seen pictures of the stamp. The first one is here on an envelope. At the bottom is printed, 'United States in Space, a decade of achievement'. I'm very happy to play postman." Dave continued, "I'll pull out a cancellation device and cancel this stamp. It is August the second, 1971, first day of issue. Where can be a better place to cancel a stamp than right here, at Hadley Rille."

Apollo 15 was the first United States post office to function on the Moon. In the centuries to come, tens, then hundreds of permanent post offices will be constructed in space stations, on the Moon, and Mars, and everywhere humans will travel to live and work.