The Clementine spacecraft drew its name from the termination phase of its mission profile. After the lunar phase of its mission, it was intended to fly by an asteroid, after which it would be "lost and gone forever."
The Clementine mission was the first U.S. mission to the Moon since the end of Project Apollo, twenty years before Clementine's 1994 launch. The mission was intended to test equipment performance during long-duration spaceflight, after which the probe was scheduled to execute a close pass with an asteroid. Clementine succeeded in the lunar phase, but a malfunction aborted the asteroid flyby. After the mission was over, Clementine drifted ever farther away from Earth, never to return, and so earned its name.