Apollo 10 was the final full-dress rehearsal for the lunar landing. Commanded by Thomas P. Stafford, with Command Module Pilot John W. Young and Lunar Module Pilot Eugene A. Cernan, it was the first flight of a complete Apollo spacecraft to the Moon. The crew named their Command Module "Charlie Brown" and their Lunar Module "Snoopy" — names that endeared the mission to the public. Stafford and Cernan took Snoopy down to within 47,400 feet of the lunar surface, testing the descent engine, landing radar, and guidance procedures that Apollo 11 would use two months later. After simulating the landing approach over the Sea of Tranquility, they staged the LM ascent stage and successfully redocked with Young in Charlie Brown. The crew completed 31 lunar orbits before firing the Service Propulsion System engine to return to Earth. Their reentry velocity of 24,791 miles per hour remains the fastest ever achieved by a crewed spacecraft. Apollo 10 proved that the entire Apollo system was ready for the landing itself.