Snoopy was the Apollo 10 lunar module used to rehearse the procedures for a Moon landing in May 1969.
Apollo 10 carried Thomas Stafford, John Young, and Eugene Cernan. Stafford and Cernan flew the lunar module separately from the command module, descending to about 15.6 kilometres above the lunar surface before rendezvousing with Young in lunar orbit.
The module was nicknamed Snoopy, while the command module was called Charlie Brown. NASA selected the names from the Peanuts characters because Snoopy had become associated with monitoring mission safety.
Apollo 10 tested the complete landing sequence but stopped short of landing. Its close approach exposed a serious guidance issue involving the lunar module’s navigation system, which engineers corrected before Apollo 11.