A small container holding some of Tombaugh's ashes are fixed to the inside upper deck of New Horizons, bearing the inscription: "Interned herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system's ‘third zone,' Adelle and Muron's boy, Patricia's husband, Annette and Alden's father, astronomer, teacher, punster, and friend: Clyde W. Tombaugh (1906-1997)."
Some of the other mementos onboard the probe include a CD with images of staff who worked on the project, a small piece of SpaceShipOne (the craft that completed the first manned private spaceflight in 2004), a pair of state quarters from Florida and Maryland (where the probe was launched and built respectively), and a 1991 U.S. stamp of the dwarf planet bearing the motto: "Pluto: Not Yet Explored."