About 98 hours after launch, Apollo 10 was in its 12th orbit around the Moon when Commander Tom Stafford and Lunar Module Pilot Gene Cernan entered the Lunar Module Snoopy and separated from the Command Module Charlie Brown. Flying free, Stafford and Cernan took Snoopy into a station-keeping orbit about 67 by 72 miles around the Moon. They then fired the descent stage engine as though going in for a landing. The 27.4 second burn, which saw the engine fire at 10 percent thrust for the first 15 seconds before increasing to 40 percent thrust for the rest of the burn, took the spacecraft into a highly elliptical orbit: 70 miles at apogee and just 10 miles above the surface at perigee. They flew over Landing Site 2, the site at the Sea of Tranquility where Apollo 11 would land two months later.