An Encyclopedia of the History of Technology part 68 ppt

PART THREE: TRANSPORT 652 occupied what was left of Peenemunde and the V-2 production plants, and obtained the assistance of a number of V-2 technicians. After learning all they could about V-2 technology, the USSR and the USA exploited their advantage in different ways. By 1949 both had atomic weapons, but these were heavy and bulky and would need an enormous rocket to carry them. America relied on aircraft to deliver atomic weapons from European bases within striking distance of Soviet territory, and began developing winged cruise missiles capable of carrying atomic warheads. Rocket development was shelved until smaller, lighter warheads were available. Soviet work concentrated on developing the large rockets that would be needed to carry a nuclear warhead across the Atlantic. Meanwhile, scientists had realized that advances in rocket technology had made it possible to launch a small satellite. The International Geophysical Year scheduled for 1957–8 provided a good reason; both the Soviet Union and the USA announced satellite programmes for the IGY, but little attention was paid to the Soviet announcement. American belief in their technological leadership was shattered when the Soviet Union launched the world’s first artificial satellite, Sputnik 1, on 4 October 1957 (Figure 13.3). On 4 November, Sputnik 2 followed. Both satellites were, for the time, large and heavy, showing that the Russians had developed rockets more powerful than any the Americans had at the time. On 6 December the experimental American Vanguard satellite launcher exploded on its launch pad, in full view of the world’s press. The events of those three months had shown that space technology was a powerful propaganda weapon, and in the ‘cold war’ climate between East and West, an undeclared ‘space race’ began between the two superpowers. MANNED SPACEFLIGHT AND THE SPACE RACE On 12 April 1961 a Russian became the first man in space, when Yuri Gagarin’s Vostok spacecraft completed a single orbit of the earth. Their powerful booster rocket had enabled the Russians to score another space first. As a result, President Kennedy announced that the United States would land a man on the moon ‘before the decade is out’. Meanwhile, the American Project Mercury succeeded in sending Alan Shepard on a short hop into space, and on 10 February 1962, John Glenn became the first American to orbit the earth. The Russian Vostok programme produced more space ‘firsts’: two spacecraft in orbit at once and the first woman in space, Valentina Tereshkova on 16 June 1963. A ‘new’ Soviet spacecraft was launched in October 1964, Voshkod. On its first flight it carried three cosmonauts, and on the second and final mission in March 1965, Alexei Leonov carried out the first spacewalk. What was not disclosed at the time was that Voshkod was really an adapted Vostok spacecraft. To get three men into orbit, the escape system had been SPACEFLIGHT 653 removed to save weight. In the event of a launch failure, the cosmonauts would have had no means of escape. The next American spacecraft was the two-man project Gemini. Gemini missions in 1965 and 1966 saw the first American spacewalk, and proved that the orbital docking techniques vital to the later Apollo moon missions were practical. But in January 1967 the American space programme suffered its first casualties; astronauts Grissom, White and Chafee were killed in a fire aboard their Apollo spacecraft during a ground test before what was to have been the first manned Apollo mission. The ensuing enquiry uncovered flaws in the spacecraft, costing Apollo a year’s delay. A little later the Soviet programme suffered a major setback. Vladimir Komarov was killed on 23 April 1967 when the new Soyuz spacecraft crashed after re-entry into the earth’s atmosphere. It appears that the spacecraft was spinning, causing its parachute lines to become tangled. The Apollo programme prepared for a moon landing with tests of the giant Saturn V (Figure 13.4) booster rocket which was to carry the two part Figure 13.3: A model of Sputnik 1, the first artificial earth satellite. PART THREE: TRANSPORT 654 spacecraft into orbit. To save time, the Americans tried a novel approach. Instead of the more usual course of testing the rocket stage by stage, the first Saturn V took off with all its stages live on 9 November 1967. An unmanned test of the complete Apollo spacecraft (including the separate lunar lander) in earth orbit followed on 4 April 1968, and a manned orbital test, Apollo 7, on 11 October. Two unmanned Soviet Zond spacecraft also orbited the moon in September and November 1968. These may have been tests for a manned flight, but Apollo 8 became the first manned spacecraft to orbit the moon in December 1968. The Apollo 9 astronauts tested the spacecraft and lunar lander in earth orbit during March 1969, and Apollo 10 carried out a rehearsal for the necessary docking manoeuvres in moon orbit during May. Then on 20 July, on the Apollo 11 mission Neil Armstrong became the first man to set foot on the moon. Four more landings followed, punctuated by a near disaster when an oxygen tank on Apollo 13 exploded during its trip to the moon, and the astronauts safely returned to earth using the lunar module as a liferaft to return to earth. With Apollo 17 in December 1972, the American lunar exploration programme came to an end. Government funding was not forthcoming for ambitious future programmes such as moon bases, a space station and a manned landing on Mars. The only part of these plans to survive (although in a modified form) was the Space Shuttle, a re-usable spacecraft originally intended to service the space station. During the 1970s, manned spaceflight concentrated on long-term stays in space. The USA’s sole space station, Skylab, was launched in 1973 and demonstrated the ability of astronauts to carry out emergency repairs in space, but after three crews had visited the station, the programme came to an end. Skylab itself re-entered the earth’s atmosphere in 1979, parts falling in Australia. Delays in the Space Shuttle programme prevented an intended attempt to boost the station into a longer-lasting orbit. The first joint American-Soviet spaceflight, the Apollo-Soyuz mission, took place in 1975: after this, there would be no American manned spaceflights until the Space Shuttle. In contrast, throughout the decade the Russians continued with their Salyut series of civil and military space stations. The first, Salyut-1, was launched in 1971 and the first crew to stay in the station, Dobrovolsky, Patsayev and Volkov, were killed when their Soyuz II spacecraft depressurized during the return to earth. Salyut 6, launched in 1977, stayed in orbit until 1982, and was the first successful space station. Unlike Skylab, Salyuts carried engines to maintain their orbit, but in 1980, a major new development took place, when Salyut 6 was refuelled by a ‘Progress’ unmanned supply ship. The Russians now had a viable long-duration space station system, capable of being readily resupplied from earth. SPACEFLIGHT 655 In April 1981 the long-awaited first flight of the Space Shuttle took place, and America again had a manned spaceflight capability. The next four years saw the shuttle ‘Space Transportation System’ demonstrate the capacity to repair satellites in orbit, and return them to earth. The European Space Agency’s Spacelab manned laboratory was also flown aboard the Shuttle in December 1983. Scientists on the earth and in space could now collaborate in carrying out experiments in the space environment. In January 1984, President Reagan announced an American plan to build a permanent manned space Figure 13.4: The launch of a Saturn V vehicle carrying three astronauts to the moon on the Apollo 15 mission, 26 July 1971. NASA. PART THREE: TRANSPORT 656 station, to become operational in the 1990s. During 1985, Shuttle astronauts also demonstrated that large structures could be built in space, an important step towards the space station. The Russians demonstrated their lead in long term spaceflight during 1984, when three cosmonauts stayed aboard Salyut 7 for 238 days, almost eight months. As 1985 drew to a close, manned spaceflight was seemingly becoming almost routine and, with four Space Shuttles now operational, NASA had scheduled sixteen missions for 1986. Other nations such as Japan and France were considering developing smaller versions of the Space Shuttle, and the Russians were known to be developing a shuttle of their own (a prototype of which was unveiled in 1989). Then, on 28 January 1986, the space shuttle Challenger exploded shortly after liftoff, killing its crew of seven. Among them was the first American civilian in space, a schoolteacher, Christa McAuliffe. Over two and a half years were spent in correcting faults in the Shuttle boosters before the next launch in 1988. The American space programme was inevitably delayed, but its ultimate direction, a permanent manned space station, remained unchanged. The first steps towards such a station were taken by the Russians in February 1986, with the launch of a Salyut-sized space station named Mir (Peace), probably the first module of a permanent space station to be assembled in orbit. SATELLITE TECHNOLOGY Sputnik, although it was a small, simple satellite, equipped only with sensors to measure the temperature and density of the upper atmosphere, proved the feasibility of launching a satellite and placing it in earth orbit. On the day that Sputnik 1 was orbited, plans for the idea of the launching of a US satellite were resurrected; a launch was promised in 90 days. On 6 December an attempt was made to launch Vanguard 1. The rocket ignited and lifted off the pad. One second later it lost thrust and fell back to earth, exploding upon impact. The satellite, thrown free, rolled across the ground with its beacon transmitter chirping away. Five days later, Werner von Braun and his team at Huntsville, Alabama, were given approval to launch America’s first satellite. Within 85 days, Explorer 1 was in orbit. It was a small satellite less than 1m (3ft) long, 150cm (6in) in diameter, with a mass of barely 5kg (11lb). It carried some simple experiments which included a Geiger-Mueller tube to record cosmic rays. Data recorded by any ‘events’ were stored on a miniature tape recorder and transmitted to earth on demand. This experiment, in fact, was instrumental in locating the Van Allen radiation belts that surround the earth. Since those early days thousands of satellites have been launched not only by the two major space powers but also by many other nations, some using SPACEFLIGHT 657 their own launch vehicles. The earliest satellites were, in essence, primitive devices capable of only simple measurements and having the capability to relay small amounts of data back to earth. However, as with all technology, advances have been dramatic and today the satellite is a sophisticated and complex machine, in many cases possessing its own on-board computer. Satellities can be divided into a number of distinct types, depending on their purpose. The main groups are: communication satellites, meteorological satellites, military satellites, remote sensing satellites, scientific and astronomical satellites. The earliest were mainly intended for scientific purposes. However, 1 April 1960 saw the launch of Tiros 1. Launched by a Thor-Able rocket this US spacecraft demonstrated the feasibility of using satellites for global weather observations. Following Tiros 1, a series of more advanced Tiros satellites followed, ending with Tiros 10 on 2 July 1965. The latest Tiros satellites are very sophisticated spacecraft which, as well as earth observation equipment, have advanced search and rescue antennas to provide data for locating and identifying ships in trouble or aircraft that have come down in remote places. Since 1966 the entire earth has been photographed at least once a day on a continuous basis. Data can be used to study cloud movements, sea temperatures and to trace ice field movements in the Arctic and Antarctic. Combined with ground and balloon data they serve the meteorological community by providing as accurate a picture of the global weather as is possible. Communication satellite technology began with the launch of Echo 1 satellite on 11 August 1960. This large reflective (mylar) balloon was used as a passive communication system, simply reflecting radio waves from one point on the globe to another. The first true communication satellite was Telstar 1, launched on 10 July 1962. Although only an engineering test vehicle, Telstar 1 demonstrated the feasibility of using satellites for transmitting television pictures over large distances without the use of land lines. Telstar had a low orbit (952 × 5632km) (590 × 3492 miles) making it impractical for long-term communication use. For practical purposes the satellite’s orbit must be geostationary (35,880km (22,245 miles) above the equator of the earth) and Syncom 3 (launched on 19 August 1964) was the first to achieve this. Syncom 3 broadcast live the opening ceremonies of the Tokyo Olympics. In 1964 the organization INTELSAT (International Telecommunications Satellite Organization) was formed in which a number of nations contributed to a common satellite system, sharing the resulting revenues. Intelsat 1 (Early Bird) was launched on 3 April 1965 to become the first truly commercial communication satellite. Further Intelsat satellites followed, each with a higher capacity than the last. Intelsat 1 could transmit 240 telephone channels and one television channel. By 1980, Intelsat V satellites were capable of transmitting 12,000 telephone and two television channels. Today, there are hundreds of communication satellites in geostationary orbit regularly transmitting television, telephone and telex data all over the globe. PART THREE: TRANSPORT 658 Many nations have launched satellites purely for military purposes, mainly for surveillance and communication. Little information is released on these satellites. Two areas where satellites have proved invaluable in scientific research have been in the fields of remote sensing of the earth and astronomy. The most important development in remote sensing, observing the earth from orbit, took place with the launch of the American Landsat 1 satellite on 23 July 1972. From its near polar orbit, Landsat 1 returned over 300,000 detailed images of the earth until its retirement in January 1978. The Landsat 5 satellite (launched on 1 March 1984), had a sophisticated array of cameras sensitive at visible and infra-red wavelengths capable of spatial resolution of the order of 20m (66ft). The images returned by the Landsat spacecraft have been put to extensive use by scientists studying cartography, agriculture, oceanography, geology and many other branches of science which have a direct human resource use. The earth’s atmosphere is a severe hindrance to astronomers. It not only absorbs many wavelengths in the electromagnetic spectrum, but its constant state of movement severely limits the spatial resolution possible with groundbased telescopes. Satellite observatories provide a means of eliminating these problems. Hundreds of purely astronomical satellites have been launched and some of the most successful have been the OAO series, IUE and IRAS. The Orbiting Astronomical Observatories (OAO) programme began in 1959 and in 1966 OAO 1 was launched by an Atlas-Agena rocket from Cape Canaveral. However the most successful satellite was OAO 3, launched on 21 August 1972 and named Copernicus. Its battery of UV and X-ray telescopes was responsible for charting 200 previously unknown X-ray sources. It was also the first satellite to observe the source Cygnus X-1, the most likely candidate for a black hole. The International Ultraviolet Explorer (IUE), launched in 1978, was a joint NASA, ESA and UK project; with its ultraviolet telescope it has observed thousands of astronomical sources, many invisible from earth, and has provided astronomers with data on the chemical composition and structure of stars, nebulae and galaxies. IRAS (Infra-red Astronomical Telescope) was launched on 25 January 1983, and like IUE provided much data, this time at infra-red wavelengths. Its primary instrument, a 60cm (2ft) Cassegrain telescope, was cooled to—271°C in a liquid helium Dewar flask. The helium ran out on 21 November 1983. PROBES TO THE MOON While most of the publicity and glory of lunar exploration has been given to the manned Apollo missions, it was the unmanned probes of the early and mid- 1960s that paved the way for these missions. The first four American attempts at launching a lunar probe were unsuccessful and on 12 September 1959 the Soviet SPACEFLIGHT 659 Union launched the Luna 2 probe, which impacted 800km (500 miles) north of the visual centre of the moon. It thus became the first man-made body to reach a celestial object. Very soon after Luna 2, the Russians again achieved a space ‘first’ when Luna 3 photographed the invisible face of the moon. After these early days, the pace of lunar probe launches accelerated. The American Ranger series of spacecraft were intended to photograph the lunar surface in advance of the Apollo landings. The first six Ranger missions were failures, but Ranger 7 (launched 28 July 1964) sent back more than 4000 high-resolution photographs before impacting in the Sea of Clouds. Two more later Rangers returned more than 13,000 images between them. In 1963 the Russians were planning for a lunar soft landing. The first attempts were unsuccessful. Luna 9 finally succeeded in 1966 and the spacecraft returned the historic first pictures from the moon’s surface. The rapid sequence of the Russian lunar launches leading up to Luna 9 was a direct response to its American competitor, the Surveyor spacecraft. Surveyor 1 softlanded on the moon barely four months after Luna 9, returning 11,000 pictures over a six-month period. The Surveyor craft were more sophisticated than the Luna vehicles. Further Surveyor landings examined the surface in regions representative of Apollo landing sites. At the same time as the Surveyor craft were landing on the moon, the Americans were launching Lunar Orbiter spacecraft aimed at returning very high resolution photographs of the lunar surface. During 1969 while all the American efforts were directed towards the Apollo programme, the Russians were landing more lunar craft in a bold attempt to soft-land and return to earth with lunar soil samples. This ambitious programme failed to pre-empt the Apollo 11 landing, but in 1970 Luna 16 did achieve the goal of returning a sample to earth. The Russians never tried to send men to the moon, concentrating solely on robot explorers. Luna 21 carried a rover vehicle (called Lunokhod) which for four months roamed over 37,000 metres (23 miles) on the surface under command from ground control. PROBES TO THE PLANETS Since the early 1960s there has been great activity directed towards sending space probes to either make close encounters with, or land on, the planets. Up to the launch of the Jupiter probe, Pioneer 10 in 1972, the efforts of the USA and USSR were concentrated on the inner planets. The first successful fly-by of Venus took place on 14 December 1962 by the Mariner 2 craft. Two further Mariners encountered Venus; Mariner 5 in 1967 and Mariner 10 in 1973. Mariner 10 took the first pictures of the cloud tops of the dense atmosphere of Venus, after which it went on to fly-by Mercury. The Soviet Union, meanwhile, concentrated on soft landings on Venus. Venera 4, launched on 12 June 1967, released a spherical capsule (1m (3ft) in diameter) when 45,000km (28,000 PART THREE: TRANSPORT 660 miles) from the planet. A parachute then permitted a slow descent through the atmosphere. During the 94-minute descent, it recorded temperatures of 370°C and sent back data on the pressure, density and chemical composition of the atmosphere. However it was a later spacecraft, Venera 7, that was the first to survive the journey to the planet’s surface, relaying data such as pressures in excess of 90 atmospheres (1320psi) and a temperature of 475°C. Later more sophisticated spacecraft succeeded in sending back pictures of the rocky surface of Venus: Veneras 13 and 16 in 1982 actually returned colour pictures and undertook remote analysis of the soil. Mars, the red planet, has received its due attention from Russian and American spacecraft. Mariners 6 and 7 returned many close-up pictures of the surface in 1969 and the Russian Mars spacecraft actually tried to soft-land on the surface, but without success. However, this feat was achieved by the Viking 1 and 2 spacecrafts in 1976. The sophisticated Viking craft returned excellent pictures of the surface from their scanning cameras, as well as analysing the Martian soil. No organic compounds were found in the samples analysed but the tests did not totally rule out the possibility of there being some form of primitive life on the planet. Possibly the most stunning and exciting results of planetary exploration have come from the probes sent to the giant outer planets. The two American Pioneer spacecraft, Pioneers 10 and 11 were launched in 1972 and 1973 respectively on trajectories that would enable both craft to fly-by Jupiter. After a journey of 21 months they sent back the first detailed images of the planet. After its encounter with Jupiter, Pioneer 10 used the Jovian gravitational field to swing out of the solar system while Pioneer 11 was re-positioned on a flight path to intercept Saturn. Again, close-up images of Saturn and its extensive ring system were relayed back to Earth. These two missions were ‘scout’ missions for the more sophisticated Voyager spacecraft, Voyager 1 and 2, identical craft launched on 5 September and 20 April 1977 respectively. The Voyager spacecraft has a mass of over 800kg (1765lbs) with a high-gain antenna 3.7m (12.2ft) in diameter and a sophisticated array of detectors and high and low resolution TV cameras. The spacecraft functions are carried out by an onboard programmable computer and its communication transmitter is designed to transmit data, over a billion kilometres of space, at the rate of 115,200 bits per second, even though its transmitter has a power of only 23 watts. On 5 March 1979, Voyager 1 made the closest approach (278,000km (172,300 miles)) to Jupiter, returning fascinating detailed images of the clouds in the Jovian atmosphere. The craft made close-up fly-bys of the four Galilean satellites Io, Ganymede, Callisto and Europa, discovering, rather surprisingly, that Io showed signs of active vulcanism. Voyager 2 made its closest approach to Jupiter on 9 July 1979, returning 15,000 images of the planet and discovering five new satellites. Both craft were then programmed for the 20- month journey to Saturn, which they encountered on 12 November 1980 and SPACEFLIGHT 661 25 August 1981 respectively, again returning many startling images of Saturn and its moons. Whereas Voyager 1 then began to travel out of the solar system plane, Voyager 2 encountered Uranus on 26 January 1986 and Neptune on 25 August 1989. LAUNCH VEHICLES The success of the early satellites depended greatly on the development of reliable launch vehicles. At the end of the Second World War the Americans, Russians and British captured German rocket hardware and many of the personnel involved in its development (see p. 649). The Americans launched many V2 rockets from White Sands, New Mexico, in a series of tests involving rocket propulsion and guidance. This Bumper Wac programme, as it was called, was only moderately successful, but it gave the Americans much useful experience in rocket technology. At the same time they were developing a number of short and long range missiles. A direct descendent of the V2 was the Redstone missile. Using liquid oxygen as fuel it had a range of 800km (500 miles). Two versions of the Redstone, the Jupiter A and Jupiter C, evolved during the missile test programme of the 1950s, to become significant in the early phases of the nation’s space effort. The Jupiter C was first launched on 20 September 1950 and carried a payload nearly 5000km (3000 miles) down range from Cape Canaveral. It was, in fact, a form of the Jupiter C, re-named Juno I, which successfully launched America’s first satellite, Explorer 1, in 1958. Following on from Juno I was the Juno II vehicle. Ten Juno IIs were used in space research from 1958 to 1961, but it will best be remembered as the ancestor of the giant Saturn launch vehicle. The Saturn 1 launch was commissioned in 1958 to provide capacity for large payloads. It was composed of a central Jupiter tank surrounded by eight Redstone tanks. The Saturn’s 100 per cent launch record between 1961 and 1965 provided the platform for the late Apollo lunar missions. The vehicle used in the Apollo missions was the Saturn V. This was a four-stage launcher whose first stage was powered by five F1 engines generating, in total 3400 tonnes of thrust. The USA has developed other launch vehicles primarily for unmanned satellite and space probe missions. The Scout is a four-stage solid fuel vehicle first launched in 1961 and still in service in the 1980s. Other liquid fuel vehicles include the Titan, developed from the ICBM of the same name, and the Delta, developed from the Thor missile. The USA’s most recent vehicle is the Space Transportation System (STS), commonly called the Space Shuttle. It was designed to provide a relatively cheap vehicle with most of its components being re-usable, in contrast to the usual expendable launch vehicle. Conceived in 1969, the STS’s eventual design . with, or land on, the planets. Up to the launch of the Jupiter probe, Pioneer 10 in 1972, the efforts of the USA and USSR were concentrated on the inner planets. The first successful fly-by of Venus. of there being some form of primitive life on the planet. Possibly the most stunning and exciting results of planetary exploration have come from the probes sent to the giant outer planets. The. pictures and undertook remote analysis of the soil. Mars, the red planet, has received its due attention from Russian and American spacecraft. Mariners 6 and 7 returned many close-up pictures of the surface