The techniques of rocket propulsion also originated long ago. Ancient rockets used gunpowder as fuel, very much as in fireworks today. In ad 1232 in China the city of Kaifeng was reportedly defended against the Mongols by the use of rockets. From the Renaissance onward, references were made to the proposed or actual military use of rockets in European warfare. As early as 1804 the British army established a rocket corps equipped with rockets that had a range of about 1830 m (about 6000 ft).
In the U.S. the foremost pioneer in rocket propulsion was Robert Goddard, a professor of physics at Clark College (now Clark University). He began experimenting with liquid fuels for rocketry in the early 1920s. He launched the first successful liquid-propelled rocket on March 16, 1926. During the same general period, studies on spaceships and rocket propulsion were being conducted in several parts of the world. About 1890 Herman Ganswindt (1856-1934), a German law student, conceived of a solid-propellant spaceship that demonstrated a marked awareness of the stability problem. Konstantin Tsiolkovsky, a Russian schoolteacher, published in 1903 A Rocket into Cosmic Space, which proposed the use of liquid propellants for spaceships. In 1923 a German mathematician and physicist, Hermann Oberth (1894-1989), published his prophetic work, Die Rakete zu den Planetenräen (The Rocket into Interplanetary Space). The book was supplemented by Walter Hohmann (1880-1941), a German architect, who published in 1925 Die Erreichbarkeit der Himmelskörper (The Possibility of Reaching Celestial Bodies), which contained the first detailed calculation of interplanetary orbits.
World War II provided the impetus and motivation for the development of long-range suborbital rockets. The U.S., the Soviet Union, Great Britain, and Germany simultaneously developed rockets for military purposes. The most successful were the Germans, who developed the V-2 (a liquid-propellant rocket used in the bombardment of London) at Peenemüa village near the Baltic coast. At the close of the war, the U.S. Army brought back a number of the V-2s, which were then used in the U.S. for experimental research in vertical flights. Some German engineers went to the USSR after the war, but the leading rocket experts went to the U.S., including Walter Dornberger (1895-1980) and Wernher von Braun.
Artificial Satellites and Space Probes
The long history of myths, dreams, fiction, science, and technology surrounding space travel culminated in the dramatic launching of the first artificial orbiting earth satellite, Sputnik 1, by the USSR on Oct. 4, 1957. Sputnik Zemli, meaning "traveling companion of the world," is the Russian name for an artificial satellite, a companion of the earth as it travels around the sun. In the U.S. this name was abbreviated to Sputnik.
Early Artificial Satellites
Sputnik 1 was an aluminum sphere, 58 cm (23 in) in diameter, weighing 83 kg (184 lb). It orbited the earth in 96.2 min. The elliptic orbit of the satellite carried it to an apogee of 946 km (588 mi) and a perigee of 227 km (141 mi). The sphere contained instruments which, for 21 days, radioed data concerning cosmic rays, meteoroids, and the density and temperature of the upper atmosphere. At the end of 57 days the satellite reentered the atmosphere of the earth and was destroyed by aerodynamic frictional heat.
The second artificial earth satellite was also a Soviet space vehicle, called Sputnik 2. It was sent aloft on Nov. 3, 1957, with a dog named Laika aboard, and it relayed the first biomedical measurements in space. Sputnik 2 reentered the atmosphere of the earth and was destroyed after 162 days aloft.
While Sputnik 2 was still in orbit, the U.S. successfully launched its first earth satellite, Explorer 1, from Cape Canaveral (named Cape Kennedy 1963-73), Fla., on Jan. 31, 1958. The 14-kg (31-lb) cylindrical spacecraft, 15 cm (6 in) in diameter and 203 cm (80 in) long, transmitted measurements of cosmic rays and micrometeorites for 112 days and gave the first satellite-derived data leading to the discovery of the Van Allen radiation belts.
On March 17, 1958, the U.S. launched its second satellite, Vanguard 2; a precise study of variations of its orbit showed that the earth is slightly pear-shaped. Using solar power, the satellite transmitted signals for more than six years. Vanguard 2 was followed by the American satellite Explorer 3, launched on March 26, 1958, and by the Soviet satellite Sputnik 3, launched on May 15. The 1327-kg (2925-lb) Soviet spacecraft measured solar radiation, cosmic rays, magnetic fields, and other space phenomena until the craft's orbit decayed in April 1960.
Lunar Probes
As the closest neighbor of the earth, the moon has been the objective of many space missions. In 1958 the first attempts by the U.S. and the USSR at lunar probes failed. The Russian Luna 2, launched Sept. 12, 1959, hit the moon 36 hr later. Since that date many moon shots have been made by both countries, with mixed results. The first photographs of the far side of the moon were taken by Luna 3, which was launched by the USSR on Oct. 4, 1959. One of the most dramatically successful moon shots was the mission accomplished by Ranger 6, launched by the U.S. on July 28, 1964. Just before hitting the side of the moon that faces the earth, it transmitted 4316 television pictures of the lunar surface from altitudes of about 1800 km (about 1120 mi) to about 300 m (about 1000 ft), giving earth-bound humans their first close-up view of the moon.
On Jan. 31, 1966, the USSR launched Luna 9, which made the first soft landing on the moon; that is, it landed without being destroyed. The U.S. followed with Surveyor 1 on May 30, which also made a soft landing on the lunar surface. It sent back to earth 11,150 close-up photographs of the moon.
Aside from the scientific information that was gathered, much of the interest of the lunar missions centered on the American program to land an astronaut on the moon. To this end a number of further automated moon flights were undertaken, among which were two soft landings made by Surveyor 3 and 5 in 1967. Both craft, after taking about two days for their journeys, sent back to earth a large number of television pictures of the lunar surface. Surveyor 3 picked up samples of lunar soil and examined them by television camera. Surveyor 5 chemically analyzed the lunar surface, using an alpha-particle scattering technique; this was the first on-site analysis of an extraterrestrial body.
Another spacecraft that contributed to future lunar landings was the Lunar Orbiter. In 1966 and 1967 five Lunar Orbiters circled the moon, relaying thousands of photographs to earth. From these photographs, landing sites were selected for the Apollo moon-landing program.
Two other automated lunar projects by the USSR are noteworthy. The Luna 16 spacecraft, launched Sept. 12, 1970, landed on the moon and placed about 113 gr (about 4 oz) of lunar soil in a sealed container that was then launched from the moon and recovered in the USSR. Luna 17, launched Nov. 10, 1970, softlanded an automated lunar-roving vehicle, Lunokhod 1, equipped with a television camera and solar batteries. During ten lunar days the vehicle, controlled from the earth, traveled 10.5 km (6.5 mi) on the moon, relaying television pictures and scientific data. Luna 21 in 1973 repeated this performance, placing Lunokhod 2 on the moon.
The U.S. spacecraft Lunar Prospector, launched in January 1998 on a mission to orbit the moon for at least a year, was designed to map the composition of the moon's surface. NASA's first lunar mission in 25 years, the probe detected water ice at the lunar poles, confirming an indication by the U.S. Defense Department's Clementine probe in 1994.
An article from Funk & Wagnalls® New Encyclopedia. © 2005 World Almanac Education Group. A WRC Media Company. All rights reserved. Except as otherwise permitted by written agreement, uses of the work inconsistent with U.S. and applicable foreign copyright and related laws are prohibited.
