The bio-belt assembly, worn over the liquid-cooling garment, contains preamplifiers for sensors placed next to the skin. The sensors acquired electrical signals which determined respiration rate and electrocardiograms of the astronauts. The preamplifiers relayed the signals to the spacecraft telemetry system for transmission to Earth. The urine collection and transfer assembly provided for emergency containment of liquid waste when spacecraft facilities were not available. Liquid waste was subsequently transferred from the collection assembly to the spacecraft waste-management system. The portable life-support system (PLSS) created and maintained a livable atmosphere inside an astronaut’s space suit during activity on the lunar surface. Worn as a backpack, the PLSS could be used for as long as four hours at a time. The PLSS supplied oxygen for breathing purposes, suit pressurization, and ventilation. It also removed contaminants from oxygen circulating through the suit and supplied water and oxygen for body cooling. Conversion of exhaled carbon dioxide into oxygen was accomplished through a lithium-hydroxide cartridge also contained in the PLSS. An emergency supply of oxygen was contained in the oxygen purge system mounted on top of the PLSS. When fully charged, the pack weighs 38 kilograms (84 pounds) on Earth or 6.3 kilograms (14 pounds) on the Moon. The space suit on exhibit is from the National Aeronautics and Space Administration. V-2 (A-4) [Illustration: 61. British-supervised postwar launch of V-2 in Germany.] [Illustration: 62. V-2.] The German V-2, originally designated A-4, represents the beginning of modern rocketry. The V-2 was the first proof that large rockets of the sort described by the space-flight pioneers of the early twentieth century could be successfully built and flown. It was also the forerunner of the intercontinental ballistic missile system. Developed by a team of engineers working under the direction of Dr. Wernher von Braun at Peenemunde, Germany, the V-2 work laid the foundation for the Redstone missile through the Saturn series of space launch vehicles. Four-thousand V-2s were fired against Allied targets in England and on the continent in 1944 and 1945. After World War II, captured V-2 rockets were used to train American technicians in missile launch procedures and to carry the first payloads of scientific instruments into the upper atmosphere in the United States. The operational V-2 rocket structure consisted of three sections. The nose housed the warhead and control mechanisms. The fuel tanks carried liquid oxygen and alcohol propellants. The rocket engine, turbopumps, and control surfaces were contained in the tail section. Jet deflector vanes positioned in the stream of exhaust gases and external vanes maintained attitude and directional control during the powered portion of flight.