During the Apollo mission, this vehicle, the Lunar Module, will take two men and their scientific instruments to the surface of the moon. While there, it will serve as command post and communication center. And when the astronauts finish their exploration, it will take them back to the orbiting command module for the return trip to Earth. The Lunar Module is actually two spacecraft in one. The lower half, the descent stage, functions to lower the vehicle to a soft landing on the lunar surface, and then later operates as a launching platform for leaving the moon. The upper half, the ascent stage, contains the crew compartment and flight controls. After the lunar exploration period, it is separated from the descent stage and carries the astronauts to rendezvous with the command module. This docking hatch connects the lunar module to the command module. After meeting, the hatch provides crew access between the two. The small window nearby serves only one purpose. Visibility during those critical moments of docking with the command module after the lunar module returns from the moon. Communications play an important role in the trip to the moon, and the lunar module is well equipped for its part of the job. In all, there are 13 antennas for the various modes of reception and transmission. This parabolic antenna is the rendezvous radar used when the lunar module leaves the moon to dock with the orbiting command module. Propulsion 2 occupies prime attention on the lunar module. To jockey the spacecraft into position as it nears the surface of the moon, there are four clusters of rocket engines. Each cluster contains four engines used for controlling the attitude of the spacecraft. They enable the pilot to maneuver the vehicle up, down, forward, backward, or sideways. In the lower portion of the module is the rocket engine which provides the propulsion for the descent to the moon's surface. The thrust is controllable and varies from one to more than 10,000 pounds. Located near the skirt of this descent engine is the landing radar unit. During the soft landing, this unit supplies critical information on altitude, range, and speed. The main hatch in the lower forward section of the Ascent stage is the one through which the astronauts leave the lunar module to explore the lunar surface. Most of the interior space of the lunar module is taken up with instruments, dials, and gauges. The center panel at the commander's station has the major flight control instruments. Some of them are similar to those found in the command module. During the slow descent to the moon, these gauges provide readings on thrust and altitude. The astronauts onboard the lunar module require instant access to a stream of facts and they get it here at the keyboard for a computer. By punching coded words into the computer, the astronauts receive instant information on details of the flight and the spacecraft performance. The spacecraft pilot, like the commander, also has controls for thrust and attitude. The pilot also monitors the abort guidance panel. It gives him current information on all systems and in case of trouble, the best procedure to use. The pilot's center panel contains instruments and switches for the operation of the spacecraft. The lunar module crammed with instrumentation, communications equipment, and propulsion all needed for the important job of jetting two men down two and away from the surface of the moon.