Later this week, NASA's New Horizons probe will finally be close enough to Pluto to begin observing the dwarf planet and its moons. Along with a bevy of scientific instrument, the probe has also been carrying a sentimental payload: a tiny tin of the ashes belonging to Clyde Tombaugh, also known as the man who discovered Pluto.


In 1930, spaceflight was still but a dream and and Tombaugh was a young astronomer peering at the sky from the Lowell Observatory in Arizona. He eventually found a curious object in his photographs from night to night—this is the icy ball that would become known as Pluto. Tombaugh died on January 17, 1997, years before Pluto was demoted from planet status.


Tombaugh's ashes on New Horizons. Credit: JHUAPL

When NASA launched New Horizons in 2006, it decided to honor Tombaugh's wish of having his ashes sent to space. A small container with an ounce of his ashes was affixed to the spacecraft and engraved with the following:

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)

Now New Horizons is at the end of its near decade-long journey to the edge of the solar system, and the Tombaugh's ashes are probably the furthest any human has made it from Earth.

The spacecraft is carrying a handful of other secret objects, too, including a small piece of SpaceShip One, a U.S. stamp proclaiming "Pluto: Not Yet Explored," and state quarters for Maryland and Florida, the states where New Horizons was assembled and launched from, respectively. Scientists, they can be a sentimental bunch.


Top image: Artist representation of New Horizons arriving at Pluto. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)