Apollo 10

Apollo 10

Apollo 10's Lunar Module, Snoopy, approaches the Command and Service Module Charlie Brown for redocking
Mission type	Crewed lunar orbital CSM/LM flight (F)
Operator	NASA
COSPAR ID	CSM: 1969-043A[1] LM: 1969-043C
SATCAT no.	CSM: 3941 LM: 3948
Mission duration	8 days, 3 minutes, 23 seconds
Spacecraft properties
Spacecraft	Apollo CSM-106 LM-4
Manufacturer	CSM: North American Rockwell LM: Grumman
Launch mass	42,775 kg[2]
Landing mass	4,945 kilograms (10,901 lb)
Crew
Crew size	3
Members	Thomas P. Stafford John W. Young Eugene A. Cernan
Callsign	CSM: Charlie Brown LM: Snoopy
Start of mission
Launch date	May 18, 1969, 16:49:00 (1969-05-18UTC16:49Z) UTC[3]
Rocket	Saturn V SA-505
Launch site	Kennedy LC-39B
End of mission
Recovered by	USS Princeton
Landing date	May 26, 1969, 16:52:23 (1969-05-26UTC16:52:24Z) UTC
Landing site	15°2′S 164°39′W / 15.033°S 164.650°W / -15.033; -164.650 (Apollo 10 splashdown)
Orbital parameters
Reference system	Selenocentric
Periselene altitude	109.6 kilometers (59.2 nmi)
Aposelene altitude	113.0 kilometers (61.0 nmi)
Inclination	1.2 degrees
Period	2 hours
Lunar orbiter
Spacecraft component	Command and service module
Orbital insertion	May 21, 1969, 20:44:54 UTC
Orbital departure	May 24, 1969, 10:25:38 UTC
Orbits	31
Lunar orbiter
Spacecraft component	Lunar Module
Orbits	4 (while solo)
Orbital parameters
Periselene altitude	14.4 kilometers (7.8 nmi)
Docking with LM
Docking date	May 18, 1969, 20:06:36 UTC
Undocking date	May 22, 1969, 19:00:57 UTC
Docking with LM Ascent Stage
Docking date	May 23, 1969, 03:11:02 UTC
Undocking date	May 23, 1969, 05:13:36 UTC
Left to right: Cernan, Stafford, Young Apollo program ← Apollo 9 Apollo 11 →

Apollo 10 (May 18–26, 1969) was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing (Apollo 11, two months later^[4]). It was designated an "F" mission, intended to test all spacecraft components and procedures short of actual descent and landing.

After the spacecraft reached lunar orbit, astronaut John Young remained in the Command and Service Module (CSM) while astronauts Thomas Stafford and Gene Cernan flew the Apollo Lunar Module (LM) to within 14.4 kilometers (7.8 nmi) of the lunar surface, the point at which powered descent for landing would begin on a landing mission. After four orbits they rejoined Young in the CSM and, after the CSM completed its 31st orbit of the Moon, they returned safely to Earth.

While NASA had considered attempting the first crewed lunar landing on Apollo 10, mission planners ultimately decided that it would be prudent to have a practice flight to hone the procedures and techniques. The crew encountered some problems during the flight: pogo oscillations during the launch phase and a brief, uncontrolled tumble of the LM ascent stage in lunar orbit during its solo flight. However, the mission accomplished its major objectives. Stafford and Cernan observed and photographed Apollo 11's planned landing site in the Sea of Tranquility. Apollo 10 spent 61 hours and 37 minutes orbiting the Moon, for about eight hours of which Stafford and Cernan flew the LM apart from Young in the CSM, and about eight days total in space. Additionally, Apollo 10 set the record for the highest speed attained by a crewed vehicle: 39,897 km/h (11.08 km/s or 24,791 mph) on May 26, 1969, during the return from the Moon.

The mission's call signs were the names of the Peanuts characters Charlie Brown for the CSM and Snoopy for the LM, who became Apollo 10's semi-official mascots.^[5] Peanuts creator Charles Schulz also drew mission-related artwork for NASA.^[6]