communications antennas, ascent rocket engine and propellant to return to lunar orbit and rendezvous with the Apollo Command and Service Modules. The spacecraft–LM The Apollo spacecraft was composed of three parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable (single-use) spacecraft consisted of a combined command and service module (CSM) and an Apollo Lunar Module (LM). Two additional components complemented the spacecraft stack for spac T… The Apollo spacecraft was composed of three parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable (single-use) spacecraft consisted of a combined command and service module (CSM) and an Apollo Lunar Module (LM). Two additional components complemented the spacecraft stack for space vehicle assembly: a spacecraft–LM adapter (SLA) designed to shield the LM from the aerodynamic stress of launch and to connect the CSM to the Saturn launch vehicle and a launch escape system (LES) to carry the crew in the command module safely away from the launch vehicle in the event of a launch emergency. The design was based on the lunar orbit rendezvous approach: two docked spacecraft were sent to the Moon and went into lunar orbit. While the LM separated and landed, the CSM remained in orbit. After the lunar excursion, the two craft rendezvoused and docked in lunar orbit, and the CSM returned the crew to Earth. The command module was the only part of the space vehicle that returned with the crew to the Earth's surface. The LES was jettisoned during launch upon reaching the point where it was no longer needed, and the SLA remained attached to the launch vehicle's upper stage. Two uncrewed CSMs, one uncrewed LM, and one crewed CSM were carried into space by Saturn IB launch vehicles for low Earth orbit Apollo missions. Larger Saturn Vs launched two uncrewed CSMs on high Earth orbit test flights, the CSM on one crewed lunar mission, the complete spacecraft on one crewed low Earth orbit mission, and eight crewed lunar missions. After conclusion of the Apollo program, four CSMs were launched on Saturn IBs for three Skylab Earth orbital missions and the Apollo–Soyuz Test Project. The major part of the Apollo spacecraft was a three-man vehicle designed for Earth orbital, translunar, and lunar orbital flight, and return to Earth. This consisted of a command module supported by a service module, built by North American Aviation (later North American Rockwell). The service module was unpressurized and contained a main service propulsion engine and hypergolic propellant to enter and leave lunar orbit, a reaction control system to provide attitude control and translational capability, fuel cells with hydrogen and oxygen reactants, radiators to dump waste heat into space, and a high gain antenna. The oxygen was also used for breathing, and the fuel cells produced water for drinking and environmental control. On Apollo 15, 16 and 17 it also carried a scientific instrument package, with a mapping camera and a small sub-satellite to study the Moon. A major portion of the service module was taken up by propellant and the main rocket engine. Capable of multiple restarts, this engine placed the Apollo spacecraft into and out of lunar orbit, and was used for mid-course corrections between the Earth and the Moon. The service module remained attached to the command module throughout the mission. It was jettisoned just prior to reentry into the Earth's atmosphere. The Apollo Lunar Module was a separate vehicle designed to land on the Moon and return to lunar orbit, and was the first true "spaceship" since it flew solely in the vacuum of space. It consisted of a descent stage and an ascent stage. It supplied life support systems for two astronauts for up to four to five days on the Apollo 15, 16 and 17 missions. The spacecraft was designed and manufactured by the Grumman Aircraft Company. The descent stage contained the landing gear, landing radar antenna, descent propulsion system, and fuel to land on the Moon. It also had several cargo compartments used to carry, among other things: the Apollo Lunar Surface Experiment Packages ALSEP, the modularized equipment transporter (MET) (a hand-pulled equipment cart used on Apollo 14), the Lunar Rover (Apollo 15, 16 and 17), a surface television camera, surface tools, and lunar sample collection boxes. The ascent stage contained the crew cabin, instrument panels, overhead hatch/docking port, forward hatch, optical and electronic guidance systems, reaction control system, radar and communications antennas, ascent rocket engine and propellant to return to lunar orbit and rendezvous with the Apollo Command and Service Modules. On all flights through Apollo 7, the SLA panels remained hinged to the S-IVB and opened to a 45-degree angle, as originally designed. But as the Apollo 7 crew practiced rendezvous with the S-IVB/SLA containing a dummy docking target, one panel did not open to the full 45 degrees, raising concern about the possibility of collision between the spacecraft and the SLA panels during docking and extraction of the LM in a lunar mission. Wally Schirra compared it to the "angry alligator" from Gemini 9. This led to a redesign using a spring-loaded hinge release system which released the panels at the 45-degree angle and pushed them away from the S-IVB at a velocity of about 5 mph (8 km/h), putting them a safe distance away by the time the astronauts pulled the CSM away, rotated it through 180 degrees, and came back for docking. The LM was connected to the SLA at four points around the lower panels. After the astronauts North American Rockwell, 'Apollo Command Module News Reference', 1968. NASA TN D-7083: Launch Escape Propulsion Subsystem Apollo Operations Handbook Lunar Module Subsystems Data