The mission was designed as a rehearsal for the main event on the Moon, but it set records of its own. History glazes over Apollo 10 because of the significance of what followed; however, the crew completed the same tasks as Apollo 11 (minus landing on the Moon).
And they used Snoopy, the lunar module, as well as Charlie Brown, the command module, to travel farther and faster than any humans have before or since.
During the mission, Snoopy was jettisoned into space as planned and would have entered orbit around the Sun. However, its location remains a mystery despite efforts by amateur astronomers to search for it using the last known 1969 orbital coordinates. They identified a number of target sites, but so far they’ve been unsuccessful.
Interestingly, many of the other landers’ exact lunar impact sites — including Apollo 11’s Eagle — are also a mystery that future space explorers may someday find and excavate, like underwater archaeologists uncovering Amelia Earhart’s Lockheed Electra.