Manned spaceflights carried out by NASA


Presentation / Essay (Pre-University), 1997
15 Pages

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Contents

Introduction

History of rockets and the

competition between the USA and the USSR

Unmanned missions

First manned missions

Mercury program

Gemini program

Apollo program
Apollo 11 - ” The giant leap ”
Other Apollo missions

Skylab

Space Shuttle missions

Sources

Introduction

Since mankind had begun to perceive its surroundings, the sun, the Moon and the stars played an important role in its evolution. Religions were based upon stars, magician predicted the future because of astronomical constellations and emperors compared themselves to the sun. The universe conveyed the impression of something giant, powerful, infinite and untouchable, so to speak, it was an object of interest.

Throughout the centuries the attitude towards the cosmos changed, because people changed. At the beginning, primitive tribes as well as sophisticated cultures adored the stars, and were convinced, that the Earth was in the middle of the universe. Later, Galleleo Gallelei said, that it was the other way around, and therefore he was persecuted by the Christian Church.

Whatever people thought of the universe, they always dreamed of reaching out for the stars. They climbed up mountains, to be nearer to the stars and they believed, that there was a man, sitting on the Moon and extraterrestrials on the Mars. Even the French author Jules Verne wrote in his novel ”Journey to the Moon”, that a few men are shot on the Moon with a giant canon-bullet. This was in the 19th century. His fellows laughed at him, and announced him nuts or at least a dreamer.

But within the our century, things changed. Scientific progress made it possible, to transport objects and even men - of course men and women - away from Earth, up to the sky. Life couldn’t be the way it is, if we wouldn’t have satellites for communication, observation and other important sectors. All this requires flights into the space. Although unmanned missions are the biggest part of space-flights, they are not nearly as spectacular, popular and exciting as manned missions. Think of the millions of people, who watched Neil Armstrong, stepping down the Eagle and setting his foot on the Moon or the world-wide shock after the Challenger-disaster. Even in the cinema, the men in space attract the audience, for instance, films like Apollo 13 or Star Trek.

Manned space-travel always fascinated people and millions of children dreamed of becoming an Astronaut. In the following chapters I want to give a (small) insight of the fascination ”manned space-travel”, limited to the US space-flights.

History of rockets and the competition between the USA and the USSR

In the 13th century, Chinese scientist invented a powder, which exploded, when it came in contact with fire. A hundred years later, a monk named ”Berthold der Schwarze” invented a similar substance: the ”Black powder”. The Chinese were the first, who constructed basic rockets and used them at the siege of cities.

Until the beginning of this century, some improvement were made, but in the principle, the rocket was the same as ever: unreliable, limited to a small payload and small ranges, and it seldom hit the target.

At the end of the 19th century, the Russian physicist Konstantin Eduardowitsch Ziolkowskij suggested, to use them as space-ships, and he was promptly derided. After the First World War, in which rockets were hardly used, scientists and military personal started working on rockets, which were powered by liquid substances.

During the 1930s the Germans were one step ahead of America, Great Britain and Russia. By order of the Führer, the research on rockets was intensified. One of the lead- ing scientists was Wernher von Braun, who constructed the V 2. This was the first large liquid fuel rocket, and it was a milestone in the history of technology as well as in the history of destruction. This rocket could carry more payload and fly longer distances than any rocket ever built. The Germans launched the V 2 on targets in the south of Great Britain, especially London. Although it was a masterpiece of engineering, the V 2 had just small influence on the result of World War Two: Germany capitulated in May 1945. When Hitler realized, that the war was already lost, he gave orders to destroy the re- search centre and the launch-site at Peenemünde, so that the enemies would have no chance of getting the German technology.

The Allies - once frightened of the German rockets - now showed great interest in this technology. Both, the USA and the USSR, tried to persuade the German engineers to work for the former enemy. The result was, that most of the scientists, e. g. Wernher von Braun, went to the USA, whereas the workers were brought to the USSR.

During the following years, the USA and the USSR became enemies in a conflict, which had a formative influence on the second half of the 20th century: the Cold War. The two countries realized, that rockets were powerful weapons, especially in conjunc- tion with the nuclear bomb. Therefore large efforts were made, to improve the German rockets. Apart from the purpose of a weapon, it seemed to be possible, to shoot objects into space, such as machines, who made communication easier or even capsules, which were capable of carrying men away from Earth. A competition between the USA and the USSR started, and both superpowers tried to be the first nation in space and - on a long term base - the first nation on the Moon.

Unmanned missions

The first climax of this competition was in 1957 (October 4), when the Soviet Union launched Sputnik Zemli (”travelling companion of the world”). Sputnik was an aluminium-globe, which circled round the Earth for 57 days. For the duration of 21 days, it sent data of the intensity of cosmic rays and the denseness and temperature of the upper atmosphere down to Earth.

Although Sputnik provided little information, his psychological impact was enormous. While the Russians spoke of a ”victory over the West” and of a ”superiority of communism”, the United States had to admit, that the Soviet Union was ahead.

The USA was the first nation to build the A- and the H-bomb; It was the first nation to break the sound barrier; It was the First Nation. But now, these achievements faded, considering Sputnik. This realisation of the American backlog was the ”Sputnik Shock”.

Just one month after the lift-off of Sputnik 1, Sputnik 2 was launched. It was an- other milestone in space-travel: Sputnik 2 had the first living being in space aboard, a bitch called Laika. After 162 days in space, where the capsule transmitted biomedical data of Laika to Earth, it destroyed itself by aerodynamic frictional heat, when reentering Earth’s atmosphere.

Now it was USA’s turn to get into space. While Sputnik 2 was orbiting Earth, the United States launched Explorer 1 (January 31, 1958) from the space centre in Cape Canaveral1. The 14-kg satellite transmitted information about cosmic rays and micrometeorites for 112 days. Some of these discoveries were pioneering, such as the discovery of the Van-Allen-radiation-belts.

In the same year, the National Aeronautics and Space Administration (NASA) was founded. It’s functions were to plan, direct and conduct all US aeronautical and space activities, except those that are primarily military. By establishing this agency, the USA wanted to become the leading nation in the space.

During the next years, many Earth satellites were launched. They carried out meas- urements of the magnetic field, cosmic rays and other space phenomena, but both super- powers knew, that the next step would be a man in space. It was a matter of prestige, who would be the first.

First manned missions

To get people into the orbit, the USSR and the USA developed space-programs, called Vostok and Mercury. Technical progress had to be made, because the responsible agencies couldn’t take the risk of a crash. Beside the topic of reliability, the engineers had to face the problems of an environment, that was more hostile to men that anything else. In the shadow of the Earth, the temperature is nearly absolute zero, whereas it’s fatally high under direct sun irradiation. There is neither air, nor oxygen in the space, and the absence of air-pressure involves the danger of an explosion. Last but not least, the cosmic rays are dangerous for living beings and can influence the space-ship’s instruments. All these matters had to be taken into consideration.

Again it was the Soviet Union, which came out an top. On April 12, 1961, Vostok 1 lifted off, and aboard was Yuri A. Gagarin. He circled around the Earth once, and landed safely in Siberia, 1 hour 48 min after the launch. At his journey he reached an apogee2 of 327 km.

Meanwhile, the United States brought the Mercury space-program in shape. Already three weeks after Vostok 1, Freedom 7 and it’s pilot Cmdr. Alan B. Shepard. left the Earth for 15 minutes. It was just a suborbital flight with a ballistic trajectory, but one year later, on February 20, 1962, Lieutenant Colonel John H. Glenn became the first astronaut to orbit the Earth.

Mercury program

This program was initiated in 1958, shortly after NASA had been founded. The objective was, to carry out six manned space-flights. The Mercury program lasted about 4 2/3 years, from the time of the official go-ahead to the completion of the last mission in 1963.

Above all, scientists wanted to know, how men would cope with the cosmic conditions, especially with the effects of weightlessness. Another mission objective was a save recovery of both, man and spacecraft.

In addition to these aims, some more guidelines were laid down. To limit the costs to an acceptable level, existing technology and off-the-shelf equipment should be used wherever practical. This meant, that the Mercury spacecraft would be placed into orbit by an existing launch vehicle (Enhanced Atlas and Redstone ICBMs3 ).

A major demand was safety. Therefore a reliable launch-escape system had to be developed and built, to separate spacecraft and crew from the launch vehicle in case of impending failure. Because the possibility of a failure of the automatic systems was present at all times, the pilot must be able to control the spacecraft’s altitude manually. To achieve a soft landing, it was necessary to cover the spacecraft with a heat-protecting shield, since the temperature reaches more than 1000°C when the vehicle reenters atmosphere. Engineers puzzled over these demands, and finally they came up to the expectations by constructing the Mercury spacecraft.

The success of the program wasn’t just related to the spacecraft. That’s why NASA especially directed its attention to the selection of the astronauts. While technicians and scientists worked on new space-ships, space-travel became technologically practicable. On the other hand, the physiological and psychological aspect - and possible problems, which could arise - remained an enigma.

NASA made high demands in the selection of the six astronauts, they were looking for. Apart from excellent health and fitness, they had to dispose of technical know-how and a pilot training. Here it seemed, that military pilots were cut for the job, especially because they knew, how to fly a high-performance aircraft and how to handle difficult and dangerous situations.

Another reason, why military personal was preferred, was to demonstrate Russia that the space-race wasn’t an amusing contest, in which both nations tried half-hearted to come into space to pass the time. It was the other way around. The competition of space- exploration, was a matter of prestige, and the nation, which would win this race, would be regarded as the most advanced and sophisticated nation. This wasn’t just a contest of sci- entists, who made useless achievements; it was a battle between two superpowers, which had nothing in common, except of the intention to excel each other. Therefore it was an element of the Cold War, as well as the armament-race. The first two stages were con- quered by the USSR (Sputnik, Y. Gagarin) in rapid succession of the United States. In order to stick to the point, military personal gave the impression of a threat more than anyone else.

At the end of the first selection, 36 men met the requirements. They had to pass extraordinary physical examinations. Most of them accepted further examinations, knowing, that they were scheduled to pass through extreme mental and physical environmental tests. The medical histories, worked out on these men, were probably the most accurate ones, ever made on a living being.

Nevertheless, just one of the 32 candidates failed the tests. The rest was sent for further tests, such as stress-tests, suit tests, acceleration tests, vibration tests, heat tests and loud noise tests; each candidate had to prove his physical endurance on treadmills, tilt tables, with his feet in ice water, and by blowing up balloons until exhausted. They were asked questions like ”Who am I?” and ”Whom would you assign to the mission if you could not go yourself?” to check their psyche. The remaining elite of 18 men had to undergo another test of their technical qualifications, and at the end, seven men were de- cided to meet the expectations. By mid-April 1959 theses men were presented to the world as the first Astronauts, which is an allusion to ”Argonauts”, a former designation for the pioneers of ballooning.

Until May 1961, the designated astronauts had to undergo an extensive training and lots of simulations of potential failures. Then, two suborbital flights were carried out (Cmdr. Shepard, Capt. Grissom) followed by the orbital ones. In the years of 1962/63 Lieut. Col. John Glenn, Lieut. Col. Scott Carpenter, Cmdr. Walter Schirra, and Major Leroy Gordon Cooper orbited the Earth 34 times. At this moment, Russia was far ahead. The seven flights of the Vostok program reached a total of 381 hours in space, at times, two spacecraft were in space simultaneously and they launched the first spacecraft, navigated by a woman (Valentina Tereshkova). The USA could just come up with 84 ”spacehours” and 6 flights. There were no casualties on both sides.

The most important results of Mercury were, that there was no problem for a man, to stay and work in space, even for a duration above one day. These results paved the way for further missions. The faith in technology was an absolute one.

Gemini program

After the Sputnik shock and during the Mercury program, when the United States realized their backlog, John F. Kennedy announced, that an astronaut will walk on the Moon ”before the decade is out”. For that purpose, the Apollo program was planned. But before it could be launched, further preparations had to be done. That’s why the Gemini program was brought to life. The equivalent Russian program was the Voskhod space- program.

Gemini’s objectives were:

- To subject two men and the supporting equipment to long duration flights - a requirement for projected later trips to the Moon or deeper space.
- To effect rendezvous and docking with other vehicles, and to maneuver the docked vehicles in space.
- To perfect methods of reentry and landing the spacecraft at a pre-selected land-landing point. At the Mercury program a deviation from the planned landing site of more than 300 km was no rareness.
- To gain additional information concerning the effects of weightlessness on crew members and to record the physiological reactions of crew members during long duration flights (Gemini 7 stayed in space for 13 days and 18 hours!).

On March 23, 1965, the astronauts Grissom and Young lifted off to a 6-hour- mission into the orbit. This was five months after three Cosmonauts flew in Voskhod 1 and three weeks after the first Soviet space-walk, which lasted just ten minutes.

Until November 1966, nine more Gemini-spaceflights were carried out, all declared successful. Space-walks have been performed, the first computer for manoeuvrecalculation has been used and rendezvous-manoeuvres have been tested. Again, neither the United States, nor the Soviet Union had to mourn about casualties.

The Gemini program had two major effects on the US. First, they knew, that there were no obstacles to the Apollo program, and second, the USA was on the passing lane. During the Gemini program, the USA was 1088 hours in space, two men at a time; that results in 2176 man-hours. Although the two Voskhod missions resulted just in 50 space-hours (124 man-hours), they were finished, before the Gemini program was started.

Apollo program

Since 1962, the United States began to work on the missions to the Moon. A completely new spacecraft had to be designed and built.

Apollo was a three-part spacecraft: the command module (CM), the crew's quarters and flight control section, the service module (SM)4 for the propulsion and spacecraft support systems and the lunar module (LM), to take two of the crew to the lunar surface, support them on the Moon, and return them to the CSM in lunar orbit. The boosters for the program were the Saturn IB for Earth orbit flights and the Saturn V for lunar flights.

During the development, in 1967, a tragedy happened. While performing ground tests with the Apollo spacecraft, the capsule caught fire. Because of the pressurized pure-oxygen atmosphere inside the spacecraft, a flash fire engulfed and killed the three astronauts. As a result of this tragedy, the Apollo program was delayed more than a year while major review of vehicle design and materials was accomplished. Until the 1986 Challenger disaster, this was the worst incident in American space-travel.

But 1967 wasn’t a dark year for NASA only. On April 23, 1967 cosmonaut Komarov was launched in the first manned flight of a new Soviet spacecraft Soyuz. Following reentry into the Earth's atmosphere and deployment of landing parachutes, the shroud lines became twisted, and Komarov plunged to his death. The Soviet space program was set back nearly two years.

Although the Apollo program was delayed, there were no changes in the mission objectives:

- To carry out a program of scientific exploration of the Moon.
- To achieve preeminence in space.
- To develop man’s capability to work in the lunar environment.
- To establish the technology to meet other national interests in space. (es- pecially military interests)

Step by step NASA approached its goal. The first orbital flight of the Saturn rocket and the Apollo spacecraft took place in October 1968. The astronauts Schirra, Eisele and Cunningham circled Earth for 163 times, and the performance of rocket and spacecraft came up to everyone’s expectations. Next step was to circle around the Moon. This was first done by Borman, Lovell and Anders in December 1968. They took photographs from the lunar surface, to complete the maps, which were obtained by unmanned lunar satellites during the previous years. After ten orbits, they reentered atmosphere and landed safely. The third and fourth Apollo-flight, that were not scheduled to land on the Moon, were launched in March and April 1969. It was up to them, to perform a separa- tion of LM and CSM and to descend as far as 15 km above the lunar surface.

Meanwhile, the USSR saw, that they had no chance of winning the race to the Moon. Because of the 1967 disaster and the resultant setback, the Soviet Union was contented with unmanned lunar missions. They concentrated upon Earth’s orbit.

Apollo 11 - ” The giant leap ”

On July 16, 1969, the United States took the venture and launched Apollo 11, with the astronauts Neil Armstrong, Michael Collins and Edwin Aldrin aboard.

They arrived at Moon’s orbit on schedule, and Aldrin and Armstrong transferred to the lunar module. Lieut. Col. Michael Collins remained in lunar orbit following the sepa- ration, piloting the command and service module. The LM descended to the surface of the Moon on July 20, landing at Mare Tranquilitatis. A few hours later, Armstrong de- scended the ladder and stepped onto the surface of the Moon. His first words were, ”That’s one small step for a man, one giant leap for mankind.” He was soon joined by Aldrin, and the two astronauts spent more than two hours walking on the lunar surface.

They gathered 21 kg of stone samples, took photographs, and set up a solar wind experiment, a laser-beam reflector and a seismic experiment package. Armstrong and Aldrin also hoisted the American flag and talked with U.S. President Richard M. Nixon by satellite communications. Millions of people watched the astronauts on the Moon live by TV. Returning to the LM and discarding their space suits, the two astronauts rested several hours before lift-off. They left the Moon in the ascent stage of the LM, using the lower half, which remained on the Moon, as a launchpad. The ascent stage was jettisoned after docking with the CSM and the transfer of the astronauts to the space- craft. The return flight of Apollo 11 was without mishap and the vehicle was recovered on July 24 in the Pacific Ocean near Hawaii.

TIME wrote in 1969:

”After centuries of dreams and prophecies, the moment had come. Man had broken his terrestrial shackles for the first time and set foot on another world. Standing on the lifeless, rock-studded surface he could see the Earth, a lovely blue and white hemisphere suspended in the velvety black sky. The spectacular view might well help him place his problems, as well as his world, in a new perspective.”

The landing on the Moon attracted great interest, not just in the USA. In was one of the first events, that was broadcast live all over the world. The American self-confidence was strengthened and the belief in the invincibility of science and engineering was omni- present. Now the leading position of the United States was undisputed. The general feel- ing was, that the Moon landing signaled a first step on a new plateau of evolution.

Other Apollo missions

Until December 1972, six more attempts of lunar landings were made. Five of them were carried out successfully and one (Apollo 13) was a ”successful failure”:

On April 11, 1970, Apollo 13, carrying the astronauts Lovell, Haise and Swigert was launched. The craft encountered difficulties during the flight when an oxygen tank ruptured. The astronauts found themselves compelled to cancel their planned landing on the lunar surface. Instead they swung behind the Moon, using the power and survival sys- tems of the LM and were brought back to Earth by the navigating technology of the mis- sion control centre in Houston, Tx, for a splashdown in the South Pacific Ocean on April 17.

Back on Earth, the astronauts were celebrated more than any other crew, except the one of Apollo 11. With skill, courage and luck they succeeded and survived.

On the whole, the Apollo program was a success, and not comparable to any Soviet space-program. While the Americans were busy with the Moon, the USSR carried out the Sojus-program, which lasts until today - with improvements of course.

Skylab

Following the Apollo program, NASA wanted to bring a space-station into Earth’s orbit. The Soviets launched their first space station, called Salyut, in 1971, but after 21 days it reentered atmosphere and was destroyed, according to the plan.

America’s first and (until today) only space station was Skylab. Designed for long duration mission, Skylab mission objectives were twofold: To prove that humans could live and work in space for extended periods, and to expand our knowledge of solar astronomy with beyond Earth-based observations.

Skylab was damaged during launch on May 25, 1973, but the crew carried out outof-the-spacecraft repairs, erected a heat-shielding canopy over the exterior of the spacecraft, and freed a jammed solar panel. A second crew spent 59 days in orbit and the third and final crew, 84 days. The Skylab project was considered completely successful. More than 740 hours were spent in observing the sun by telescopes, 175000 solar pictures were returned to Earth and 46 000 photographs of the Earth's surface.

It was the site of nearly 300 scientific and technical experiments: medical experi- ments on human’s behaviour at zero gravity, solar observations and detailed Earth re- sources experiments. On July 11, 1979, during its 34 981st orbit, the empty Skylab plunged to Earth, raining fiery debris over sparsely populated western Australia and over the Indian Ocean.

The US Skylab program was much more extensive and complex than the Soviet Salyut program. Skylab weighed 88 900 kg compared with the 18 600 kg Salyut. In contrast to the estimated 99 m3interior space of Salyut, Skylab had 357 m3, about three and onehalf times greater. Although no details about the Salyut program were published, it’s likely, that it wasn’t as successful as Skylab.

Space Shuttle missions

For a long time, from November 1973 (last Skylab mission) to April 1981 (first Space Shuttle flight) the manned space-travel of the NASA was in hibernation. Except of one Apollo mission in 1975, where an American spacecraft and a Russian Sojus capsule met in orbit for the first time, no manned spaceflights were carried out.

By the end of the 70’s, NASA began to work on an STS (Space Transportation System), better known as Space Shuttle. The Shuttle, a manned, multipurpose space plane, was designed to carry payloads of up to 30 tons and up to seven astronauts.

When a Space Shuttle is launched, it receives its fuel from the solid-fuel boosters on each side. After these boosters are burnt-out, they’re dropped, recovered and used again. The large tank between the boosters provides fuel during the flight in the higher atmosphere. When reentering atmosphere, tiles protect the Shuttle from heat, and the landing is similar to an ordinary plane.

Because of the shuttle’s flexibility, its planned use for satellite deployment and the rescue and repair of previously launched satellites, its proponents saw it as a major advance in space exploration. Others, however, worried, that NASA was placing too much reliance on the Shuttle, to the disadvantage of unmanned vehicles and missions.

The first test flight was delayed until April 12, 1981, because of various design problems. The first operational flight took place on November 11, 1982, with a crew of four aboard the orbiter Enterprise. Two commercial communications satellites were deployed during the mission.

Until the end of 1985, 23 Space Shuttles were launched. There were never any major problems and no casualties. Despite such successes, the Shuttle program was falling behind in its planned launch program, was increasingly being used for military tests, and was meeting stiff competition from the European Space Agency's unmanned Ariane program for the launch of satellites.

Then, on January 28, 1986, the shuttle Challenger was destroyed about one minute after launch because of the failure of a sealant ring on one of its solid boosters. The booster nosed into the main propellant tank of liquid hydrogen and oxygen, causing a near-explosive disruption of the entire system. Seven astronauts were killed in the disas- ter. The tragedy brought an immediate stop to Shuttle flights until systems could be ana- lyzed and redesigned. A presidential commission headed by former secretary of state William Rogers and former astronaut Neil Armstrong placed much of the blame on NASA’s administrative system and its failure to maintain an efficient system of quality control.

People’s faith in technology was shocked. This anti-technology feeling was intensified, when a nuclear powerplant in Chernobyl, USSR, exploded, and the nuclear fall-out contaminated vast parts of Europe. As a result of the Challenger disaster, all Space Shuttle missions were cancelled indefinitely.

After the Challenger disaster, the O-ring seals on the solid rocket booster were redesigned to prevent recurrence of the Challenger failure. The shuttle launch program resumed on September 29, 1988, with the flight of Discovery and its crew of five astronauts. On this mission, a NASA communications satellite was placed in orbit and a variety of experiments were carried out. The success of this 26th mission encouraged the US to resume an active launch schedule. One more flight was planned for 1988, and a total of 39 were scheduled through 1992. The long-delayed $1.5 billion Hubble Space Telescope was deployed by space shuttle in 1990 but, because of an optical defect, initially failed to provide the degree of resolution it was designed to have.

Because of the breakdown of communism and the subsequent end of the Soviet Un- ion, NASA got the chance to cooperate with the former enemy. In one point, the Russia was ahead of the USA: The had the space station Mir at their disposal. In 1995 and 1996, US Space Shuttles rendezvoused with Mir four times. Now Astronauts and Cosmotauts lived together for months, which was unthinkable in the decades ago. Although Mir is an old space-station - one might say its ready to be scrapped - it provides good and impor- tant information. The countless incidents could be interpreted as a training for extrater- restrial crisis-management.

Sources

Apollo 13 (movie)

Encyclopaedia Britannica ( http://www.eb.com ) Microsoft Encarta 98 (German edition) Microsoft Encarta 94 (English edition)

National Aeronautics and Space Administration ( http://www.ksc.nasa.gov ) TIME Almanac of the 20th Century

Spezialgebiet: “Manned US Spaceflights” Page 15

Further plans

People often think of colonies upon other planets, but these are - from the point of view of today’s technology - just dreams. Space-travel has always attracted men and inspired them, for instance movies like Star Wars, Star Trek or any other Science-Fiction movies. Noone knows, which technological level mankind can reach within 100 years, but perhaps a voyage to other planets is within reach.

Within the next years, NASA, ESA (European Space Agency), Japan and Russia will build up space station Alpha, to relieve Mir. This space-station will be larger

[...]


1 From 1963 to 1973 Cape Canaveral was called Cape Kennedy.

2 Point of an elliptic trajectory, where the distance between space-craft and Earth is on a maximum. opposite: peri- gee.

3 Intercontinental ballistic missile. Missiles, used to bring nuclear weapons to their targets.

4 When together, the two modules are called CSM.

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Details

Title
Manned spaceflights carried out by NASA
College
Real Centro Universitario Maria Cristina
Course
English
Author
Year
1997
Pages
15
Catalog Number
V95548
File size
410 KB
Language
English
Tags
Manned, NASA, English
Quote paper
Markus Sonnleitner (Author), 1997, Manned spaceflights carried out by NASA, Munich, GRIN Verlag, https://www.grin.com/document/95548

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