Lunar and Planetary Institute

Apollo 10 Mission

Mission Overview

The purpose of the mission was to confirm all aspects of the lunar landing mission exactly as it would be performed, except for the actual landing. Additional objectives included verification of lunar module systems in the lunar environment, evaluation of mission-support performance for the combined spacecraft at lunar distance, and further refinement of the lunar gravitational potential.

Mission Plan

Mission Plan thumbnailThe Apollo 10 mission was the tenth in a series of flights using Apollo-specification hardware and was the first lunar flight of the complete spacecraft. It was also the fourth manned flight of the command and service modules and the second manned flight of the lunar module.

Mission Event List and Timeline

Launch     May 18    11:49:00 am 00:00:00
Earth orbit insertion     12:00:54 pm 00:11:54
Translunar injection     02:28:21 pm 02:39:21
Lunar orbit insertion     May 21    03:44:54 pm 75:55:54
Separation maneuver     May 22    02:36:17 pm 98:47:17
Transearth injection     May 24    05:25:29 am 137:36:29
Splashdown     May 26    11:52:23 am 192:03:23


Apollo 10 launch thumbnailThe space vehicle was launched at 11:49:00 a.m. EST, May 18, 1969, and inserted into an Earth parking orbit of 102.6 by 99.6 miles. The space vehicle consisted of a block II configuration spacecraft and a Saturn V launch vehicle. After 2 1/2 hours of system checkout activities, the translunar injection sequence was executed to start the spacecraft on its way to the Moon.



Apollo 10 spacecraftAll components of the Apollo 10 spacecraft were very similar to those for Apollo 9. The major difference on this mission was the inclusion of a fully configured lunar module. Support structures and mass simulators were added for the modular equipment storage assembly (MESA). The Apollo Lunar Surface Experiments Package (ALSEP) support structure was redesigned and the location of the power system batteries was changed in the descent stage.

Apollo 10 was a “dress rehearsal” for the landing missions that would follow and as such, it was a fully configured spacecraft. Unlike the previous orbiter mission, Apollo 8, which carried a nonfunctioning lunar module test article, this mission included a functional lunar module. This was necessary in order to test descent and return operations, which were the main objectives of the mission. It should be noted, however, that the lunar module was an early design that could not be used for a landing as it was too heavy to return to orbit from the lunar surface.

Command Service Module "Charlie Brown"The command service module consisted of two parts. The command module, 3.63 meters long and shaped like a blunt cone, was at the front or top. Equipped with couches, it served as the crew compartment and control center. Able to accommodate all three astronauts, the command module was also used for reentry. The service module, a 6.88-meter-long cylinder, was at the rear of the command module. It provided the primary propulsion and maneuvering capability of the spacecraft. Most of the consumables (oxygen, hydrogen, and propellant) were also stored in this module, which was jettisoned before reentry.

Lunar Module "Snoopy"The lunar module also had two parts, the descent stage and the ascent stage. The descent stage, or lower part of the lunar module, contained an engine for landing on the Moon. This stage was a 3.23-meter-tall cruciform structure of aluminum alloy, which, with its four legs extended, had a maximum diameter of 9.45 meters. This stage also contained storage bays for equipment, and a ladder attached to one of the legs to give a crew access to the surface. When leaving the lunar surface, the descent stage would serve as the launch platform for the ascent stage. The ascent stage was basically a cylindrical aluminum structure 4.29 meters in diameter and 3.75 meters tall. During their time on the surface, the crew would live in and operate from this part of the spacecraft. It would also be used to return the crew to orbit and the command service module after surface operations were completed.


Thomas P. Stafford, Mission Commander Thomas Stafford, Mission Commander, was born on September 17, 1930, in Weatherford, Oklahoma. He received a bachelor of science degree from the U.S. Naval Academy (1952) and was chosen with the second group of astronauts in 1962. He was back-up pilot for Gemini 3, pilot for Gemini 6, command pilot for Gemini 9 upon the death of a primary crew member, back-up commander for Apollo 7, commander of Apollo 10, and commander of the Apollo-Soyuz Test Project. He resigned from NASA in November 1975.
John W. Young, Command Module Pilot John W. Young, Command Module Pilot, was born on September 24, 1930, in San Francisco, California. He received a bachelor of science degree in aeronautical engineering from the Georgia Institute of Technology in 1952. He was chosen with the second group of astronauts in 1962. He was pilot of Gemini 3, back-up pilot for Gemini 6, command pilot on Gemini 10, back-up command module pilot for Apollo 7, command module pilot for Apollo 10, and back-up commander for Apollo 13. As a member of the Apollo 16 crew, he became the ninth man to walk on the Moon. Following this mission, he was back-up commander for Apollo 17, and flew on STS-1 and STS-9.
Eugene A. Cernan, Lunar Module Pilot Eugene A. Cernan, Lunar Module Pilot, was born on March 14, 1934, in Chicago, Illinois. He received a bachelor of science degree in electrical engineering from Purdue University in 1956 and a master of science degree in aeronuatical engineering from the U.S. Naval Postgraduate School in 1961. He was chosen in the third group of astronauts in 1963. He was the pilot of Gemini 9, back-up pilot for Gemini 12, back-up lunar module pilot for Apollo 7, lunar module pilot on Apollo 10, and back-up commander for Apollo 14. He was the eleventh man to walk on the Moon. Later, he was the deputy director of the Apollo-Soyuz Test Project. He resigned from NASA and the Navy in July 1976.

Back-up crew for this mission were L. Gordon Cooper (back-up commander), Donn F. Eisele (back-up command module pilot), and Edgar E. Mitchell (back-up lunar module pilot).

Splash Down

Apollo 10 image of splash downThe command module was separated from the service module at 191.5 hours, followed by reentry 15 minutes later. Entry was controlled by the primary guidance and navigation system to effect a spacecraft landing very close to the target at about 15°S latitude, 165°W longitude. The crew were retrieved by helicopter soon after daylight and taken aboard the primary recovery vessel, USS Princeton, 39 minutes after landing. The spacecraft was recovered about 1-1/2 hours after the landing.

The Apollo 10 mission took eight days and included a simulated landing on the Moon. All systems in the command and service modules and the lunar module were managed very well. While some problems were encountered, most were minor and none constrained the completion of mission objectives. Communication was generally adequate and the quality of television transmissions extremely good. Crew performance was excellent throughout the mission and timelines were followed very closely.