II.

Spacecraft and Supporting Systems

Each manned Apollo mission consisted of two spacecraft: the Command and Service Module (CSM) designed for orbital and reentry operations; and the Lunar Module (LM) designed for lunar landing, surface operations, ascent from the Moon, and rendezvous with the CSM. The exceptions were Apollo 7 and 8, which flew the CSM only. The CSM comprised the command module, with the crew compartment and the reentry heat shield, and the service module, with the major support systems and consumables (such as propulsion systems, electrical power, food, and water). The LM comprised the descent stage, for landing and delivery of the lunar-surface equipment, and the ascent stage, with the crew compartment and independent systems for ascent from the Moon’s surface and rendezvous with the CSM.

Apollo missions used a crew of three astronauts. During launch, all three astronauts were in the CSM. After leaving Earth orbit, the crew separated the CSM from the LM and the part of the launch vehicle surrounding the LM, then maneuvered the CSM to dock with the LM to extract the LM from the launch vehicle so that the crew could transfer between the two craft. After three days’ transit time to the Moon, the CSM and LM entered into lunar orbit. Two astronauts then transferred to the LM, separated from the CSM, and descended to the lunar surface. The third astronaut continued to operate the CSM in lunar orbit.

A.

Launch System

The launch vehicle used for lunar missions was the Saturn V rocket designed specifically for Apollo craft. The Saturn launch vehicle family and the design of its support facilities were derived from technology developed by rocket engineer Wernher von Braun and his team at Peenemünde, Germany, during World War II. Von Braun brought his work and his team to the United States in 1945.

The Saturn V consisted of three stages used in sequence to boost spacecraft into Earth orbit and on toward the Moon. The CSM and LM were mounted separately, in tandem, on top of the Saturn rocket system. At liftoff, the entire launch vehicle (including spacecraft) was 109 m (363 ft) high; it weighed 2.8 million kg (6.3 million lb); and the five Saturn first-stage engines generated 3.5 million kg (7.7 million lb) of thrust. During the Apollo program, 12 Saturn V rockets were launched from the Kennedy Space Center at Cape Canaveral, Florida, and all were successful.

B.

Lunar Surface Systems

After landing, the LM became a habitable lunar base serving as living quarters, communications center, storage facility, equipment carrier, and supply center for food and water. The cylindrical LM crew compartment was less than 2.4 m (8 ft) in diameter and only 1 m (3.3 ft) deep. The lifetime and capacity of this lunar base was increased from less than two days for the first three lunar landing missions to over three days for the final three lunar exploration missions.

The performance of the astronaut Extravehicular Mobility Unit (EMU) was a key element in the success of Apollo. The EMU consisted of the astronaut space suit and the Portable Life Support System (PLSS). The EMU provided oxygen and pressure to sustain life in the vacuum of space; it protected the astronaut from thermal, radiation, and optical effects as well as meteorite impact; and it provided sufficient mobility and dexterity to enable the astronaut to perform useful work on the lunar surface. The PLSS was recharged with oxygen and cooling water from LM supplies after each outside excursion, known as an Extra Vehicular Activity (EVA). On the final three lunar exploration missions, the PLSS life-support capability for a single excursion was more than doubled to over seven hours.

Lunar surface equipment included a variety of cameras, geology tools, rock and soil sample containers, several individual science experiments, and the multidiscipline Apollo Lunar Surface Experiments Package (ALSEP). ALSEPs measured topological and geophysical characteristics of the Moon and were set into place and left behind by the astronauts. They were nuclear powered and designed to operate for at least five years—several lasted much longer. The final three missions (Apollo 15-17) also carried the two-man Lunar Roving Vehicle (LRV) with additional geology tools, experiments, and sample containers. The LRV vastly increased the range and capability of lunar surface exploration.

C.

Support Facilities

The success of Apollo also was dependent on a number of facilities on Earth. Foremost among these were the test and qualification facilities for spacecraft, launch vehicles, and the EMU; simulators and trainers to prepare the astronauts for the mission; the launch complex at Cape Canaveral; the worldwide tracking and communications network; and the Mission Control Center in Houston.