Background By 1967, NASA had devised a
list of mission types, designated by letters, that needed to be flown before a landing attempt, which would be the "G" mission. The early uncrewed flights were considered "A" or "B" missions, while
Apollo 7, the crewed-flight test of the
Command and Service Module (CSM), was the "C" mission. The first crewed orbital test of the
Lunar Module (LM) was accomplished on
Apollo 9, the "D" mission.
Apollo 8, flown to the Moon's orbit without an LM, was considered a "C-prime" mission, but its success gave NASA the confidence to skip the "E" mission, which would have tested the full Apollo spacecraft in medium or high Earth orbit. Apollo 10, the dress rehearsal for the lunar landing, was to be the "F" mission. However, Director of Flight Operations
Christopher C. Kraft and others opposed this, feeling that new procedures would have to be developed for a rendezvous in lunar orbit and that NASA had incomplete information regarding the Moon's
mass concentrations, which might throw off the spacecraft's trajectory. Lieutenant General
Sam Phillips, the Apollo Program Manager, listened to the arguments on both sides and decided that having a dress rehearsal was crucial.
Crew and key Mission Control personnel On November 13, 1968, NASA announced the crew members of Apollo 10. John Young, the command module pilot, was 38 years old and a
commander in the
Navy at the time of Apollo 10. A 1952 graduate of
Georgia Tech who entered the Navy after graduation and became a test pilot in 1959, he was selected as a Group 2 astronaut alongside Stafford. He flew in
Gemini 3 with
Gus Grissom in 1965, becoming the first American not of the
Mercury Seven to fly in space. Young thereafter commanded
Gemini 10 (1966), flying with
Michael Collins. Gene Cernan, the Lunar Module pilot, was a commander in the Navy at the time of Apollo 10. A 1952 graduate of
Purdue University, he entered the Navy after graduation. Selected for the
third group of astronauts in 1963, Cernan flew with Stafford on Gemini 9A before his assignment to Apollo 10. With five prior flights among them, the Apollo 10 crew was the most experienced to reach space until the
Space Shuttle era, and the first American space mission whose crew were all spaceflight veterans. Apollo 10 information film reel. The backup crew for Apollo 10 was
Gordon Cooper as commander,
Donn F. Eisele as command module pilot, and
Edgar D. Mitchell as lunar module pilot. By the normal crew rotation in place during Apollo, Cooper, Eisele, and Mitchell would have flown on
Apollo 13, but Cooper and Eisele never flew again.
Deke Slayton, Director of Flight Crew Operations, felt that Cooper did not train as hard as he could have. Eisele was blackballed because of incidents during Apollo 7, which he had flown as CMP and which had seen conflict between the crew and ground controllers; he had also been involved in a messy divorce. Slayton only assigned the two as backups because he had few veteran astronauts available. Cooper and Eisele were replaced by
Alan Shepard and
Stuart Roosa respectively. Feeling they needed additional training time,
George Mueller rejected the Apollo 13 crew. The crew was switched to
Apollo 14, which saw Shepard and Mitchell walk on the Moon. For projects
Mercury and
Gemini, a prime and a backup crew had been designated, but for Apollo, a third group of astronauts, known as the support crew, was also designated. Slayton created the support crews early in the Apollo program on the advice of McDivitt, who would lead Apollo 9. McDivitt believed that, with preparation going on in facilities across the U.S., meetings that needed a member of the flight crew would be missed. Support crew members were to assist as directed by the mission commander. Usually low in seniority, they assembled the mission's rules,
flight plan, and checklists, and kept them updated. For Apollo 10, they were
Joe Engle,
James Irwin, and
Charles Duke.
Flight directors were
Gerry Griffin,
Glynn Lunney,
Milt Windler, and
Pete Frank. Flight directors during Apollo had a one-sentence job description: "The flight director may take any actions necessary for crew safety and mission success."
CAPCOMs were Duke, Engle,
Jack Lousma, and
Bruce McCandless II.
Call signs and mission insignia The command module was given the call sign
Charlie Brown and the lunar module the call sign
Snoopy. These were taken from the characters in the comic strip,
Peanuts,
Charlie Brown, and
Snoopy. These names were chosen by the astronauts with the approval of
Charles Schulz, the strip's creator, Snoopy had been associated for some time with the space program, with workers who performed in an outstanding manner awarded silver "
Snoopy pins", and Snoopy posters were seen at NASA facilities, with the cartoon dog having traded in his
World War I aviator's headgear for a space helmet. The shield-shaped mission insignia shows a large, three-dimensional
Roman numeral X sitting on the Moon's surface, in Stafford's words, "to show that we had left our mark". Although it did not land on the Moon, the prominence of the number represents the contributions the mission made to the Apollo program. A CSM circles the Moon as an LM ascent stage flies up from its low pass over the lunar surface with its engine firing. The Earth is visible in the background. On the mission patch, a wide, light blue border carries the word APOLLO at the top and the crew names around the bottom. The patch is trimmed in gold. The insignia was designed by Allen Stevens of
Rockwell International.
Training and preparation Apollo 10, the "F" mission or dress rehearsal for the lunar landing, had as its primary objectives to demonstrate crew, space vehicle, and mission support facilities performance during a crewed mission to lunar orbit, and to evaluate the performance of the Lunar Module there. In addition, it was to attempt photography of Apollo Landing Site 2 (ALS-2) in the
Sea of Tranquillity, the contemplated landing site for Apollo 11. According to Stafford, Our flight was to take the first lunar module to the moon. We would take the lunar module, go down to within about ten miles above the moon, nine miles above the mountains, radar map, photo map, pick out the first landing site, do the first rendezvous around the moon, pick out some future landing sites, and come home. Apollo 10 was to adhere as closely as possible to the plans for Apollo 11, including its trajectory to and from lunar orbit, the timeline of mission events, and even the angle of the Sun at ALS-2. However, no landing was to be attempted. ALS-1, given that number because it was the furthest to the east of the candidate sites, and also located in the Sea of Tranquility, had been extensively photographed by Apollo 8 astronauts; at the suggestion of scientist-astronaut
Harrison Schmitt, the launch of Apollo 10 had been postponed a day so ALS-2 could be photographed under proper conditions. ALS-2 was chosen as the lunar landing site since it was relatively smooth and of scientific interest, while ALS-1 was deemed too far to the east. Thus, when Apollo 10's launch date was announced on January 10, 1969, it was shifted from its placeholder date of May 1 to May 17, rather than to May 16. On March 17, 1969, the launch was slipped one day to May 18, to allow for a better view of ALS-3, to the west of ALS-2. Mueller, NASA's Associate Administrator for Manned Space Flight, stated, There had been some speculation about whether or not the crew might have landed, having gotten so close. They might have wanted to, but it was impossible for that lunar module to land. It was an early design that was too heavy for a lunar landing, or, to be more precise, too heavy to be able to complete the ascent back to the command module. It was a test module, for the dress rehearsal only, and that was the way it was used.
Equipment The descent stage of the LM was delivered to KSC on October 11, 1968, and the ascent stage arrived five days later. They were mated on November 2. The
Service Module (SM) and
Command Module (CM) arrived on November 24 and were mated two days later. Portions of the
Saturn V launch vehicle arrived during November and December 1968, and the complete launch vehicle was erected in the
Vehicle Assembly Building (VAB) on December 30. After being tested in an altitude chamber, the CSM was placed atop the launch vehicle on February 6, 1969. The completed space vehicle was rolled out to
Launch Complex 39B on March 11, 1969—the fact that it had been assembled in the VAB's High Bay 2 (the first time it had been used) required the
crawler to exit the rear of the VAB before looping around the building and joining the main
crawlerway, proceeding to the launch pad. The
launch vehicle for Apollo 10 was a Saturn V, designated AS-505, the fifth flight-ready Saturn V to be launched and the third to take astronauts to orbit. The Saturn V differed from that used on Apollo 9 in having a lower dry weight (without propellant) in its first two stages, with a significant reduction to the interstage joining them. Although the S-IVB third stage was slightly heavier, all three stages could carry a greater weight of propellant, and the
S-II second stage generated more thrust than that of Apollo 9. The Apollo spacecraft for the Apollo 10 mission was composed of Command Module 106 (CM-106), Service Module 106 (SM-106, together with the CM known as CSM-106), Lunar Module 4 (LM-4), a spacecraft-lunar module adapter (SLA), numbered as SLA-13A, and a launch escape system. The SLA was a mating structure joining the Instrument Unit on the S-IVB stage of the Saturn V launch vehicle and the CSM, and acted as a housing for the LM, while the
Launch Escape System (LES) contained rockets to propel the CM to safety if there was an aborted launch. At about 76.99 metric tons, Apollo 10 would be the heaviest spacecraft to reach orbit to that point. ==Mission highlights==