Length 1.2 m. (3 ft., 10 in.) Diameter 11 cm. (4 in.) Propellant Pressurized carbon dioxide and acetone Thrust 23 kg. max. (50 lb.) Velocity 168 m./sec. max. (550 ft./sec.) Altitude 975 m. (3200 ft.) Viking 12 [Illustration: 29. Viking 12 lift-off.] The Viking rocket family, numbering 14, grew out of the Navy’s efforts to develop an upper atmosphere research program. With enough time between launches to incorporate modifications suggested by experience with earlier Vikings, no two rockets of the series were exactly alike; however, there were two basic types of Vikings. The first seven rockets were taller, thinner, and had larger fins than those numbered 8-14; rockets in the second set were heavier, with fuel capacity greatly increased, and were designed either to go higher than the early Vikings or to carry heavier payloads to the same altitude. Viking’s highest altitude was 254 kilometers (158 miles) following a launch from White Sands on May 24, 1954. Experiments flown on these rockets measured air temperature, density, pressure, and composition, as well as providing cosmic and solar radiation data. One of the few failures in this program was Viking 8, the first rocket of the second set, which unexpectedly tore loose from the launch stand while being test-fired. Viking was conceived at the Naval Research Laboratory, designed and produced by the Glenn L. Martin Company of Baltimore, Maryland, and powered by a liquid-propellant engine by Reaction Motors, Inc. The rocket on exhibit is from the Hayden Planetarium and Martin Marietta Aerospace. Length 13.7 m. (45 ft.) Diameter 1.1 m. (3 ft., 9 in.) Propellant Alcohol Oxidizer Liquid oxygen Thrust 9300 kg. (20,500 lb.) Velocity 6480 km. (4025 mi.) per hr. Altitude 193 km. (120 mi.) with a 402-kg. (887-lb.) payload MOUSE [Illustration: 30. MOUSE model displays some of the earliest solar cells made (under square cover on front).] The concept of artificial earth satellites was a logical extension of existing sounding-rocket programs. The MOUSE, or Minimum Orbital Unmanned Satellite of Earth, was conceived in 1951 as the smallest possible orbital vehicle capable of performing scientific tasks. While the MOUSE was never built or flown, it demonstrated what could be accomplished by an orbiting vehicle of modest size and weight. The MOUSE would have weighed 45.4 kilograms (100 pounds). It was designed to study cosmic rays, interplanetary dust, and solar ultraviolet and X rays, with the instruments attached to rods projecting from either end. The satellite was to be powered by solar cells.