www.eb.com Sputnik, any of a series of artificial Earth satellites whose launching by the Soviet Union beginning on Oct. 4, 1957, inaugurated the Space Age. Sputnik 1, the first satellite launched by man, was a 184-pound (83.6-kilogram) capsule. It achieved an Earth orbit with an apogee (farthest point from Earth) of 584 miles (942 km) and a perigee (nearest point) of 143 miles (230 km), circling the Earth every 96 minutes and remaining in orbit until early 1958 when it fell back and burned in the Earth's atmosphere. Sputnik 2 carried the dog Laika, the first living creature to be shot into space and orbit the Earth. Eight more Sputnik missions with similar satellites carried out experiments on a variety of animals to test spacecraft life-support systems; they also tested reentry procedures and furnished data on space temperatures, pressures, particles, radiation, and magnetic fields. ----------------------------------------------------------------------------------------- Earth satellite, man-made object launched into a temporary or permanent orbit around the Earth. Spacecraft of this type may be either manned or unmanned, the latter being the most common. The idea of an artificial satellite in orbital flight was first suggested by Sir Isaac Newton in his book Philosophiae Naturalis Principia Mathematica (1687). He pointed out that a cannonball shot at a sufficient velocity from atop a mountain in a direction parallel to the horizon would go all the way around the Earth before falling. Although the object would tend to fall toward the Earth's surface because of gravitational force, its momentum would cause it to descend along a curved path. Greater velocity would put it into a stable orbit, like that of the Moon, or direct it away from the Earth altogether. On Oct. 4, 1957, nearly three centuries after Newton had proposed his theory, the Soviet Union launched the first Earth satellite, Sputnik I. Sputnik circled the Earth every 96 minutes, and its simple radio signal was heard by scientists and radio operators across the world. The United States orbited its first satellite, Explorer 1, three months later (Jan. 31, 1958). Explorer, though much smaller than Sputnik, was instrumented to detect radiation and discovered the innermost of the two Van Allen radiation belts, a zone of electrically charged solar particles that surrounds the Earth. Since these initial efforts, more than 5,000 Earth satellites have been orbited by at least 15 different nations. The satellites vary widely in size and design, ranging from a tiny sphere of several pounds equipped with only two radio transmitters to heavily instrumented space laboratories weighing many tons. They are equally diverse in function. Scientific satellites are chiefly used to collect data about the Earth's surface and atmosphere and to make astronomical observations. Weather satellites transmit photographs of cloud patterns and measurements of other meteorological conditions that aid in weather forecasting, while communications satellites relay telephone calls, radio and television programs, and data communications between distant parts of the world. Navigation satellites enable the crews of oceangoing vessels and airplanes to determine the position of their craft in all kinds of weather. Some satellites have distinctly military applications, such as reconnaissance and surveillance. Satellites can be placed in any number of different orbits. The particular path selected is largely determined by the function of the spacecraft. Most weather and reconnaissance satellites, for example, are fired into a polar orbit in which the Earth's polar axis is a line on the orbital plane. Because the Earth rotates under polar-orbiting satellites, they pass over its entire surface within a given time period, providing full global coverage. Communications satellites, on the other hand, are generally placed into an equatorial orbit, which enables them to circle the most densely populated regions of the Earth from west to east. Moreover, communications satellites comprising a network or system are nearly always launched to a distance of 22,300 mi (35,890 km) above the Earth. At this altitude, the motion of a satellite becomes synchronized with the Earth's rotation, causing the craft to remain fixed over a single location. If properly positioned, three communications satellites travelling in such a synchronous orbit can relay signals between stations around the world. See also spacecraft. ----------------------------------------------------------------------------------------- The History of Technology Space exploration. The rocket, which has played a crucial part in the revolution of military technology since the end of World War II, acquired a more constructive significance in the U.S. and Soviet space programs. The first spectacular step was Sputnik 1, a sphere with an instrument package weighing 184 pounds (83 kilograms), launched into space by the Soviets on Oct. 4, 1957, to become the first artificial satellite. The feat precipitated the so-called space race, in which achievements followed each other in rapid succession. They may be conveniently grouped in four chronological although overlapping stages. The first stage emphasized increasing the thrust of rockets capable of putting satellites into orbit and on exploring the uses of satellites in communications, in weather observation, in monitoring military information, and in topographical and geological surveying. The second stage was that of the manned space program. This began with the successful orbit of the Earth by the Soviet cosmonaut Yury Gagarin on April 12, 1961, in the Vostok 1. This flight demonstrated mastery of the problems of weightlessness and of safe reentry into the Earth's atmosphere. A series of Soviet and U.S. space flights followed in which the techniques of space rendezvous and docking were acquired, flights up to a fortnight were achieved, and men "walked" in space outside their craft. U.S. weather satellite orbiting the Earth. By courtesy of National Aeronautics and Space Administration The third stage of space exploration was the lunar program, beginning with approaches to the Moon and going on through automatic surveys of its surface to manned landings. Again, the first achievement was Soviet: Luna 1, launched on Jan. 2, 1959, became the first artificial body to escape the gravitational field of the Earth, fly past the Moon, and enter an orbit around the Sun as an artificial planet. Luna 2 crashed on the Moon on Sept. 13, 1959; it was followed by Luna 3, launched on Oct. 4, 1959, which went around the Moon and sent back the first photographs of the side turned permanently away from the Earth. The first soft landing on the Moon was made by Luna 9 on Feb. 3, 1966; this craft carried cameras that transmitted the first photographs taken on the surface of the Moon. By this time excellent close-range photographs had been secured by the United States Rangers 7, 8, and 9, which crashed into the Moon in the second half of 1964 and the first part of 1965; and between 1966 and 1967 the series of five Lunar Orbiters photographed almost the entire surface of the Moon from a low orbit in a search for suitable landing places. The U.S. spacecraft Surveyor 1 soft-landed on the Moon on June 2, 1966; this and following Surveyors acquired much useful information about the lunar surface. Meanwhile, the size and power of launching rockets climbed steadily, and by the late 1960s the enormous Saturn V rocket, standing 353 feet (108 metres) high and weighing 2,725 tons (2,472,000 kilograms) at lift-off, made possible the U.S. Apollo program, which climaxed on July 20, 1969, when Neil Armstrong and Edwin Aldrin clambered out of the Lunar Module of their Apollo 11 spacecraft onto the surface of the Moon. The manned lunar exploration thus begun continued with a widening range of experiments and achievements for a further five landings before the program was curtailed in 1972. The fourth stage of space exploration has looked out beyond the Earth and the Moon to the possibilities of planetary exploration. The U.S. space probe Mariner 2 was launched on Aug. 27, 1962, and passed by Venus the following December, relaying back information about that planet indicating that it was hotter and less hospitable than had been expected. These findings were confirmed by the Soviet Venera 3, which crash-landed on the planet on March 1, 1966, and by Venera 4, which made the first soft landing on Oct. 18, 1967. Later probes of the Venera series gathered further atmospheric and surficial data. The U.S. probe Pioneer Venus 1 orbited the planet for eight months in 1978, and in December of that year four landing probes conducted quantitative and qualitative analyses of the Venusian atmosphere. Surface temperature of approximately 900 F reduced the functional life of such probes to little more than one hour. Research on Mars was conducted primarily through the U.S. Mariner and Viking probe series. During the late 1960s, photographs from Mariner orbiters demonstrated a close visual resemblance between the surface of Mars and that of the Moon. In July and August 1976, Vikings 1 and 2, respectively, made successful landings on the planet; experiments designed to detect the presence or remains of organic material on the Martian surface met with mechanical difficulty, but results were generally interpreted as negative. Photographs taken during the early 1980s by the U.S. probes Voyagers 1 and 2 permitted unprecedented study of the atmospheres and satellites of Jupiter and Saturn and revealed a previously unknown configuration of rings around Jupiter, analogous to those of Saturn. In the mid-1980s the attention of the U.S. space program was focused primarily upon the potentials of the reusable Space Shuttle vehicle for extensive orbital research. The U.S. Space Shuttle Columbia completed its first mission in April 1981 and made several successive flights. It was followed by the Challenger, which made its first mission in April 1983. Both vehicles were used to conduct myriad scientific experiments and to deploy satellites into orbit. The space program suffered a tremendous setback in 1986 when, at the outset of a Challenger mission, the shuttle exploded 73 seconds after liftoff, killing the crew of seven. The early 1990s saw mixed results for NASA. The $1.5 billion Hubble Space Telescope occasioned some disappointment when scientists discovered problems with its primary mirror after launch. Interplanetary probes, to the delight of both professional and amateur stargazers, relayed beautiful, informative images of other planets. For later developments in space technology and exploration, see the BRITANNICA BOOK OF THE YEAR. ----------------------------------------------------------------------------------------- 20th-Century International Relations THE WORLD AFTER SPUTNIK Soviet progress and American reaction. Premier Khrushchev anticipated the new correlation of forces in his foreign policy address to the 20th Party Congress in 1956. Soviet H-bombs and missiles, he said, had rendered the imperialists' nuclear threat ineffective, the U.S.S.R. an equal, the Socialist camp invincible, war no longer inevitable, and thus "peaceful coexistence" inescapable. In Leninist doctrine this last phrase implied a state of continued competition and Socialist advance without war. The immediate opportunities for Socialism, according to Khrushchev, derived from the struggle of the colonial peoples, which the U.S.S.R. would assist through foreign aid, propaganda, subversion, and support for "wars of national liberation." The Soviet successes in outer space just 40 years after the Bolshevik Revolution were powerful evidence for Khrushchev's claims that the U.S.S.R. had achieved strategic equality and that Communism was the best system for overcoming backwardness. Sputnik restored Soviet prestige after the 1956 embarrassment in Hungary, shook European confidence in the U.S. nuclear deterrent, magnified the militancy of Maoist China, and provoked an orgy of self-doubt in the United States itself. The two Sputnik satellites of 1957 were themselves of little military significance, and the test missile that launched them was too primitive for military deployment, but Khrushchev claimed that long-range missiles were rolling off the assembly line "like sausages," a bluff that allowed President Eisenhower's opponents --and nervous Europeans--to perceive a "missile gap." Khrushchev in turn tried to capitalize on the apparent gap in a series of crises, but his adventurous policy only provoked perverse reactions in China, the United States, and Europe that undermined his own political support at home. Eisenhower was apprised in advance of Soviet missile progress thanks in part to overflights of the U-2 spy plane. By the time of Sputnik the Pentagon already had several parallel programs for ballistic missiles of various types, including the advanced, solid-fueled Polaris and Minuteman. The great fleet of B-47 and B-52 intercontinental bombers already deployed also assured continued American strategic superiority through the early 1960s. The frugal Eisenhower thus tried to play down the importance of Sputnik and to discourage a race for arms or prestige, but he was frustrated by a coalition of Democrats, journalists, academics, and hawks of both parties who insisted that the United States not only leapfrog the Soviets in space and missiles but also increase federal support to education, extend more military and economic aid to the Third World, and expand social programs at home intended in part to polish the American image abroad--in short, pursue the Cold War more vigorously. Eisenhower conceded to this mood in 1958 by sponsoring creation of the National Aeronautics and Space Administration and passage of the National Defense Education Act, accelerating weapons programs, and deploying intermediate-range missiles in England, Italy, and Turkey. He also acknowledged the expanded Soviet threat in his State of the Union address in 1958: "Trade, economic development, military power, arts, science, education, the whole world of ideas--all are harnessed to this same chariot of expansion. The Soviets are, in short, waging total cold war." A similarly total American response to this challenge, requiring virtually wartime levels of national mobilization to outdo a totalitarian system in whatever field of endeavour it chose to emphasize, would, in Eisenhower's mind, however, have undermined the free market and fiscal soundness that were the foundation of American strength in the first place. Liberal economists argued in response that a sharply expanded role for the federal government was a matter of survival in the "space age" and would even stimulate economic growth, military prowess, and social progress. ----------------------------------------------------------------------------------------- The World Wars INVASION OF THE SOVIET UNION, 1941 The German attack on the Soviet Union, 1941. Axis and Allied movements in Europe and North Africa, 1940-42, and (inset) German invasion of the. . . For the campaign against the Soviet Union, the Germans allotted almost 150 divisions containing a total of about 3,000,000 men. Among these were 19 panzer divisions, and in total the "Barbarossa" force had about 3,000 tanks, 7,000 artillery pieces, and 2,500 aircraft. It was in effect the largest and most powerful invasion force in human history. The Germans' strength was further increased by more than 30 divisions of Finnish and Romanian troops. (see also Index: Eastern Front) The Soviet Union had twice or perhaps three times the number of both tanks and aircraft as the Germans had, but their aircraft were mostly obsolete. The Soviet tanks were about equal to those of the Germans, however. A greater hindrance to Hitler's chances of victory was that the German intelligence service underestimated the troop reserves that Stalin could bring up from the depths of the U.S.S.R. The Germans correctly estimated that there were about 150 divisions in the western parts of the U.S.S.R. and reckoned that 50 more might be produced. But the Soviets actually brought up more than 200 fresh divisions by the middle of August, making a total of 360. The consequence was that, though the Germans succeeded in shattering the original Soviet armies by superior technique, they then found their path blocked by fresh ones. The effects of the miscalculations were increased because much of August was wasted while Hitler and his advisers were having long arguments as to what course they should follow after their initial victories. Another factor in the Germans' calculations was purely political, though no less mistaken; they believed that within three to six months of their invasion, the Soviet regime would collapse from lack of domestic support. The German attack on the Soviet Union was to have an immediate and highly salutary effect on Great Britain's situation. Until then Britain's prospects had appeared hopeless in the eyes of most people except the British themselves; and the government's decision to continue the struggle after the fall of France and to reject Hitler's peace offers could spell only slow suicide unless relief came from either the United States or the U.S.S.R. Hitler brought Great Britain relief by turning eastward and invading the Soviet Union just as the strain on Britain was becoming severe. On June 22, 1941, the German offensive was launched by three army groups under the same commanders as in the invasion of France in 1940: on the left (north), an army group under Leeb struck from East Prussia into the Baltic states toward Leningrad; on the right (south), another army group, under Rundstedt, with an armoured group under Kleist, advanced from southern Poland into the Ukraine against Kiev, whence it was to wheel southeastward to the coasts of the Black Sea and the Sea of Azov; and in the centre, north of the Pripet Marshes, the main blow was delivered by Bock's army group, with one armoured group under Guderian and another under Hoth, thrusting northeastward at Smolensk and Moscow. The invasion along a 1,800-mile front took the Soviet leadership completely by surprise and caught the Red Army in an unprepared and partially demobilized state. Piercing the northern border, Guderian's tanks raced 50 miles beyond the frontier on the first day of the invasion and were at Minsk, 200 miles beyond it, on June 27. At Minsk they converged with Hoth's tanks, which had pierced the opposite flank, but Bock's infantry could not follow up quickly enough to complete the encirclement of the Soviet troops in the area; though 300,000 prisoners were taken in the salient, a large part of the Soviet forces was able to escape to the east. The Soviet armies were clumsily handled and frittered their tank strength away in piecemeal action like that of the French in 1940. But the isolated Soviet troops fought with a stubbornness that the French had not shown, and their resistance imposed a brake by continuing to block road centres long after the German tide had swept past them. The result was similar when Guderian's tanks, having crossed the Dnepr River on July 10, entered Smolensk six days later and converged with Hoth's thrust through Vitebsk: 200,000 Soviet prisoners were taken; but some Soviet forces were withdrawn from the trap to the line of the Desna, and a large pocket of resistance lay behind the German armour. By mid-July, moreover, a series of rainstorms were turning the sandy Russian roads into clogging mud, over which the wheeled vehicles of the German transport behind the tanks could make only very slow progress. The Germans also began to be hampered by the scorched earth policy adopted by the retreating Soviets. The Soviet troops burned crops, destroyed bridges, and evacuated factories in the face of the German advance. Entire steel and munitions plants in the westernmost portions of the U.S.S.R. were dismantled and shipped by rail to the east, where they were put back into production. The Soviets also destroyed or evacuated most of their rolling stock (railroad cars), thus depriving the Germans of the use of the Soviet rail system, since Soviet railroad track was of a different gauge than German track and German rolling stock was consequently useless on it. Nevertheless, by mid-July the Germans had advanced more than 400 miles and were only 200 miles from Moscow. They still had ample time to make decisive gains before the onset of winter, but they lost the opportunity, primarily because of arguments throughout August between Hitler and the OKH about the destination of the next thrusts thence: whereas the OKH proposed Moscow as the main objective, Hitler wanted the major effort to be directed southeastward, through the Ukraine and the Donets Basin into the Caucasus, with a minor swing northwestward against Leningrad (to converge with Leeb's army group). In the Ukraine, meanwhile, Rundstedt and Kleist had made short work of the foremost Soviet defenses, stronger though the latter had been. A new Soviet front south of Kiev was broken by the end of July; and in the next fortnight the Germans swept down to the Black Sea mouths of the Bug and Dnepr rivers--to converge with Romania's simultaneous offensive. Kleist was then ordered to wheel northward from the Ukraine, Guderian southward from Smolensk, for a pincer movement around the Soviet forces behind Kiev; and by the end of September the claws of the encircling movement had caught 520,000 men. These gigantic encirclements were partly the fault of inept Soviet high commanders and partly the fault of Stalin, who as commander in chief stubbornly overrode the advice of his generals and ordered his armies to stand and fight instead of allowing them to retreat eastward and regroup in preparation for a counteroffensive. Winter was approaching, and Hitler stopped Leeb's northward drive on the outskirts of Leningrad. He ordered Rundstedt and Kleist, however, to press on from the Dnepr toward the Don and the Caucasus; and Bock was to resume the advance on Moscow. Bock's renewed advance on Moscow began on Oct. 2, 1941. Its prospects looked bright when Bock's armies brought off a great encirclement around Vyazma, where 600,000 more Soviet troops were captured. That left the Germans momentarily with an almost clear path to Moscow. But the Vyazma battle had not been completed until late October; the German troops were tired, the country became a morass as the weather got worse, and fresh Soviet forces appeared in the path as they plodded slowly forward. Some of the German generals wanted to break off the offensive and to take up a suitable winter line. But Bock wanted to press on, believing that the Soviets were on the verge of collapse,