Introduction to Space Exploration

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Introduction to Space Exploration

Mankind will migrate into space, and will cross the airless Saharas which separate planet from planet and sun from sun.

Winwood Reade, The Martyrdom of Man (1872)

Humans have always been explorers. When ancient humans stumbled across unknown lands or seas, they were compelled to explore them. They were driven by a desire to dare and conquer new frontiers and by a thirst for knowledge, wealth, and prestige. These are the same motivations that drove people of the twentieth century to venture into space.

By definition, space begins at the edge of Earths atmosphere, just beyond the protective blanket of air and heat that surrounds the planet. This blanket is thick and dense near the surface and light and wispy farther away from the planet. About sixty-two miles (one hundred kilometers) above Earth the atmosphere becomes quite thin. According to the Fédération Aéronautique Internationale, in The 100 km Boundary for Astronautics (June 25, 2004,, this altitude is considered the first feathery edge of outer space.

The very idea of space exploration has a sense of mystery and excitement about it. Americans call their space explorers astronauts. The term astronaut is a combination of two Greek words: astron (star) and nautes (sailor). Thus, astronauts are those who sail among the stars. This romantic imagery adds to the allure of space travel.

The truth is that space holds many dangers to humans. Space is an inhospitable environment, devoid of air, food, or water. Everywhere it is either too hot or too cold for human life. Potentially harmful radiation flows in the form of cosmic rays from deep space and electromagnetic waves that emanate from the Sun and other stars. Tiny bits of rock and ice hurtle around in space at high velocities, like miniature missiles.

Space is not readily accessible. It takes a tremendous amount of power and thrust to hurl something off the surface of Earth. It is a fight against the force of Earths gravity and the heavy drag of an air-filled atmosphere.

Getting into space is not easy, and getting back to Earth safely is even tougher. Returning to Earth from space requires conquering another mighty force: friction. Any object penetrating Earths atmosphere from space encounters layers and layers of dense air molecules. Traveling at high speed and rubbing against these molecules produces a fiery blaze that can rip apart most objects.

It was not until the 1950s that the proper combination of skills and technology existed to overcome the obstacles of space travel. The political climate was also just right. Two rich and powerful nations (the Soviet Union and the United States) devoted their resources to besting one another in space instead of on the battlefield. It was this spirit of competition that pushed humans off the planet and onto the Moon in 1969.

Once that race was over, space priorities changed. In the twenty-first century, computerized machines do most of the exploring. They investigate planets, asteroids, comets, and the Sun. Human explorers stay much closer to Earth. They visit and live aboard space stations in orbit a couple hundred miles above the planet. On Earth people dream of longer journeys because most of space is still an unknown sea, just waiting to be explored.


Since the earliest days people have looked up at the heavens and dreamed of flying there. In ancient Greek and Roman mythology gods and goddesses rode chariots through the skies or had wings of their own. In Greek mythology these included Eros (god of love), Nike (goddess of victory), Hermes (the messenger to the gods), and Apollo (god of the arts). In Roman mythology they were called Cupid, Victoria, Mercury, and Apollo, respectively.

One famous Greek tale concerned Icarus and his father, Daedalus. Imprisoned on an island, they decide to escape by building wings of feathers and wax for themselves and flying to freedom. However, Icarus disregards his fathers warning against flying too close to the Sun, and the heat melts the wax in his wings. When Icaruss wings fall apart, he plunges to his death in the sea.

In about A.D. 160 the Greek writer Lucian of Samo-sata (125?-200?) wrote the story True History about a sailing ship whisked to the Moon by a giant waterspout. The sailors find the Moon inhabited by strange creatures that are at war with beings living on the Sun. In a later story, Icaromenippus, an adventurer more successful than Icarus uses eagle and vulture wings to fly to the Moon.


Centuries later the great Italian painter and engineer Leonardo da Vinci (1452-1519) foresaw the day that humans would fly. He wrote, There shall be wings! If the accomplishment be not for me, tis for some other. Leonardo made several sketches of human-powered flying machines and gliders with birdlike wings.

At the time, astronomical knowledge was limited, and it was widely believed that Earth was the center of the universe and everything else revolved around it. The Polish astronomer Nicolaus Copernicus (1473-1543) studied the motion of the heavens and drew different conclusions. In 1543 he published the famous book De Revolutionibus Orbium Coelestium (On the Revolutions of the Heavenly Spheres). Copernicus insisted that Earth and the other planets orbit the Sun. He said, At the middle of all things lies the sun.

The first telescopes appeared in Europe during the early 1600s. Even though historians are not sure who invented the telescope, they know that the Italian astronomer Galileo Galilei (1564-1642) popularized their use. Galileo also improved the design and power of the telescope. He used several to study the cosmos and published his findings in the 1610 book Sidereus Nuncius (Starry Messenger).

At about the same time the German astronomer Johannes Kepler (1571-1630) was also studying the solar system. He discovered that planets move according to mathematical rhythms, and he derived laws of planetary motion from these rhythms that are still being studied. In 1593 Kepler wrote Galileo a letter in which he said, Provide ships or sails adapted to the heavenly breezes, and there will be some who will not fear even that void.

The mechanics of spaceflight were explored by the English physicist Sir Isaac Newton (1642-1727). Newton first unraveled the mysteries of gravity on Earth and then extended his findings into space. He was the first to explain how a satellite (an orbiting body) could be put into orbit around Earth.

Newtons thought experiment, as it was called, proposed a cannon atop a tall mountain as a theoretical means for putting an object into orbit around Earth. The cannon shoots out projectiles one after another, using more gunpowder with each successive firing. Newton said each projectile would travel farther horizontally than the previous one before falling. Finally, there would be a projectile shot with enough gunpowder that it would travel very far horizontally and when it began to fall toward Earth, its path would have the same curvature as Earths surface. The projectile would not fall to Earths surface but continue to circle around the planet. It would be another two centuries before humans could prove Newtons theory.

It was only a few decades after Newtons death that humans began to fly on earthly breezes. During the late 1700s the French brothers Joseph-Michel Montgolfier (1740-1810) and Jacques-Etienne Montgolfier (1745-1799) built the first hot-air balloons. On November 21, 1783, the two brothers ascended to five hundred feet and sailed across the city of Paris. They landed safely miles from the city and offered champagne to the terrified villagers there. The age of flight had begun.


Science fiction is a category of literature in which an imaginative story is told that incorporates at least some scientific principles to give it a sense of authenticity and believability. It is a mixture of science and imagination. The term science fiction is generally credited to the writer Hugo Gernsback (1884-1967), who published a magazine devoted to such stories and started book clubs for science-fiction fans. His legacy lives on in the Hugo Award, a literary award given each year by the World Science Fiction Society.

Jules Verne

The French author Jules Verne (1828-1905) was one of the earliest science-fiction writers to incorporate space travel in his stories. In 1865 he wrote De la terre á la lune: Trajet direct en 97 heures 20 minutes (From Earth to the Moon: Passage Direct in Ninety-seven Hours and Twenty Minutes), a tale of an ambitious gun club in the United States. The men build a massive cannon in Florida and shoot a metal sphere toward the Moon. Inside are three astronauts who plan to explore the lunar surface. Their target misses the mark, and they wind up orbiting the Moon instead. It was the first space travel story based on physics, rather than on pure fantasy.

Five years later Verne published the sequel Autour de la lune (All around the Moon). The astronauts use small onboard rockets to propel their sphere safely back to Earth, where it splashes down and floats in the ocean. A nearby ship rescues the men and takes them home to a heroes welcome. The similarities are striking between these stories and the actual events of the Apollo flights one hundred years later.

Edward Everett Hale

In 1869 the American writer Edward Everett Hale (1822-1909) published a remarkable science-fiction tale in the Atlantic Monthly. His tale The Brick Moon describes the work of some clever American inventors who decide to build a large beacon to sit in the sky and glow as a constant reference point for ships at sea. To accomplish this goal, the men build a large brick sphere set atop a hill. A track leads down the hill to two giant spinning wheels that are set in a gorge and turned by water from a rushing river. The wheels are to catapult the brick moon into space.

One day the brick moon accidentally rolls away from its restraints and is flung into space with some of the workers and their families aboard. For months their friends on the ground search the night skies with telescopes until finally they spot the satellite in Earth orbit. They are amazed to see its occupants living happily on the satellite surface. On occasion the occupants send signals back to Earth by forming a long line and simultaneously making large and small jumps into the air to spell out messages in Morse code.

The story is prophetic in one interesting respect: during the construction of the brick moon the inventors are plagued by constant design changes, funding problems, and criticism from the public and the press. These difficulties would become common ones for the space programs that later developed.

H. G. Wells

Around the turn of the twentieth century the English author Herbert George Wells (1866-1946) wrote popular space travel stories including The War of the Worlds (1898) and The First Men on the Moon (1901).

The War of the Worlds featured Martian invaders landing spacecraft near London and terrorizing the population with destructive machines and poisonous gas. In the end the humans prevail when a common germ kills the Martians. During the 1930s the story was made into a radio play and rewritten for an American audience. On October 30, 1938, the play was broadcast as a mock newscast. Some listeners thought the news was real, which created scattered incidents of panic.

The First Men on the Moon also included unfriendly aliens, this time on the Moon. Some daring explorers from Earth travel to the Moon and are captured by antlike creatures called Selenites. The name is derived from Selene, the mythical Greek goddess of the Moon. The story features little actual science and is generally considered more of a romantic adventure tale set in space.

Georges Méliès

In 1902 the French director Georges Méliés (1861 1938) created the first-known science-fiction motion picture. Le voyage dans la lune (The Trip to the Moon) is an eleven-minute silent film very loosely based on the Verne stories about Moon travel.

This time five brave Frenchmen are catapulted to the Moon, where their rocket actually lands in the giant right eye of the man in the Moon. The astronauts begin exploring, but are captured by unfriendly Selenites. The explorers manage to escape back to their spacecraft and push it off the edge of the Moon to fall back to Earth. They splash down in the sea and return to France as heroes.


On December 17, 1903, the American brothers Orville Wright (1871-1948) and Wilbur Wright (1867-1912) made history at Kitty Hawk, North Carolina, with the first sustained flights of a powered aircraft. Each brother took two flights that day. The longest flight covered about 850 feet and lasted just under one minute. The modern age of aviation had begun.

In 1905 the Fédération Aéronautique Internationale (FAI; was formed in Europe by representatives from Belgium, France, Germany, Great Britain, Italy, Spain, Switzerland, and the United States. The FAI became the official organization for cataloging and verifying aeronautical feats around the world.

Aviation got off to a slow start in the United States. The earliest planes were notoriously dangerous, and several aspiring adventurers were killed flying them. Neither the American public nor the federal government was convinced that airplanes were safe and effective. The mood in Europe was much different. Engineers in France, England, and Germany produced their own versions of reliable and versatile aircraft.


When World War I began in Europe in 1914, the power of aerial warfare became apparent immediately. The United States realized that it was behind its European counterparts in aviation expertise, and in an effort to correct the situation the U.S. government formed the Advisory Committee for Aeronautics (ACA) in 1915. Later, the word national was tacked on, and the agency became known as the NACA. The NACA began an ambitious campaign of research and development into aircraft design and flight theory.

By the end of the war in 1918 the United States had made great progress in the field of aviation, including the development of commercial airlines and postal air services. In addition, public attitudes about flying were beginning to change. The daring feats of World War I pilots such as the American ace Eddie Rickenbacker (1890-1973) and the German legend Manfred von Richthofen (1882-1918) had brought an air of excitement to flying.

In 1919 the New York City hotel owner Raymond Orteig (1870-1939) offered a $25,000 prize to the first aviator who could fly nonstop from New York to Paris or from Paris to New York. The Orteig Prize inspired one of the greatest flying feats of the century. A young man named Charles A. Lindbergh Jr. (1902-1974) convinced businessmen in St. Louis, Missouri, to finance his attempt to win the prize. Lindbergh had earned his flying reputation as a successful airmail pilot and barnstormer (one who performs flying stunts at air shows). On the morning of May 20, 1927, he took off from Long Island, New York, in his monoplane the Spirit of St. Louis. Thirty-three and a half hours later he landed on a Parisian airstrip amid throngs of cheering spectators. Lindbergh was an instant hero, and flying was suddenly of vital interest to Americans, who thrilled to the adventures of pilots such as Amelia Earhart (1897-1937), Wiley Post (1899-1935), Howard Hughes (1905-1976), and Douglas Wrong-Way Corrigan (1907-1995).

Meanwhile, the NACA continued its work in aviation science. Orville Wright joined the organization and remained a member until his death in 1948. During these decades the NACA drove many developments within the field of aeronautics, except for one: rockets.


There are four men in history who are considered the founders of modern rocket science: Konstantin Tsiolkov-sky of Russia, Hermann Oberth of Austria-Hungary, Robert Goddard of the United States, and Wernher von Braun of Germany. All four were working on rocket science during the early years of the twentieth century. Even though they were scattered around the world, they reached similar conclusions at about the same time.

Konstantin Tsiolkovsky

Konstantin Tsiolkovsky (1857-1935), a Russian schoolteacher, was inspired by a love of science and by Vernes stories, and he even tried his hand at science fiction, before and after becoming a scientist. Tsiolkov-sky studied the theoretical concepts of rocket flight, such as gravity effects, escape velocity, and fuel needs. He developed a simple mathematical equation relating the final velocity of a rocket to the initial velocity, the starting and ending mass of the rocket, and the velocity of the rocket exhaust gases. Tsiolkovskys equation became a fundamental concept of rocket science and is still taught in the twenty-first century.

In 1895 Tsiolkovsky wrote Dreams of Earth and Sky. The book described how a satellite could be launched into an orbit around Earth. Later publications included Exploration of the Universe with Reaction Machines and Research into Interplanetary Space by Means of Rocket Power, both published in 1903. Figure 1.1 shows some of Tsiolkovskys designs for liquid-propelled rockets. Two decades later, he wrote Plan of Space Exploration (1926) and The Space Rocket Trains (1929).

Tsiolkovsky believed that rockets launched into space would have to include multiple stages. That is, instead of having one big cylinder loaded with fuel, the fuel must be divided up among smaller rocket stages linked together. As each stage uses up its fuel, it could be jettisoned away so the remainder does not have to carry dead weight. Tsiolkovsky reasoned that this was the only way for the mass of a rocket to be reduced as its fuel supply was depleted.

Tsiolkovsky predicted in a 1911 letter, Mankind will not remain on Earth forever, but in its quest for light and space will at first timidly penetrate beyond the confines of the atmosphere, and later will conquer for itself all the space near the Sun.

Hermann Oberth

Hermann Oberth (1894-1989) was born in Transylvania, Romania, which was part of the Austro-Hungarian Empire. As a teenager, Oberth studied mathematics and began developing sophisticated rocket theories. He studied medicine and physics at the University of Munich. During the 1920s he wrote two important papers: Die Rakete zu den Planeten-räumen (The Rocket into Interplanetary Space) and Wege zur Raumschiffart (Methods of Achieving Space Flight).

In 1923 Oberth predicted that rockets can be built so powerfully that they could be capable of carrying a man aloft. He proposed bullet-shaped rockets for manned missions to Mars and an Earth-orbiting space station for refueling rockets. Like his Russian counterpart, Oberth advocated multistage rockets fueled by liquid propellants.

Oberth s writings were hugely popular and influenced the movie producer Fritz Lang (1860-1976) to make a movie about space travel called Die Frau im Mond (The Woman in the Moon) in 1929. Oberth served as a technical adviser on the film. He also inspired the German rocket club known as Verein for Raumschiffahrt (VfR; Society for Spaceship Travel). The VfR put Oberths theories into practice by building and launching rockets based on his designs.

As World War II (1939-1945) drew near during the 1930s, the Nazi government put Oberth and other VfR members to work developing rockets for warfare, rather than for space flight.

Robert Goddard

Robert Goddard (1882-1945) was an American physicist born in Worcester, Massachusetts. In a speech made in 1904 he said, It is difficult to say what is impossible, for the dream of yesterday is the hope of today and the reality of tomorrow, and Goddard spent the rest of his life making rocket flight a reality. After graduating from college, he taught physics at Clark University in his hometown. He also spent time on a relatives farm experimenting with explosive rocket propellants. Unlike his Russian and Austro-Hungarian counterparts, Goddards rocket science was more experimental than theoretical. In all, he was granted seventy patents for his inventions. The first two came in 1914 for a liquid-fuel gun rocket and a multistage step rocket. He is believed to be the first person to prove experimentally that a rocket can provide thrust in a vacuum.

Much of Goddard s research was funded by the Smithsonian Institution and the Guggenheim Foundation. The U.S. government showed little interest in rocket science except for its possible use in warfare. Late in World War I Goddard presented the military with the concept for a new rocket weapon, later called the bazooka. After the war Goddard worked part time as a weapons consultant to the U.S. armed forces.

In 1920 the Smithsonian published Goddards famous paper A Method of Attaining Extreme Altitudes, in which he described how a rocket could be sent to the Moon. The idea was greeted with skepticism from scientists and derision from the media. The New York Times published a scornful editorial ridiculing Goddard for this fanciful notion. Goddard was stung by the criticism and spent the rest of his life avoiding publicity. His low-profile approach kept his work from being well known for many years. The one person who did take a keen interest in him was Charles Lindbergh, who played a key role in securing funding for Goddards rocket research from the Guggenheim Foundation.

On March 16, 1926, Goddard achieved the first-known successful flight of a liquid-propelled rocket. (See Figure 1.2.) Throughout the next decade he labored quietly in the desert near Roswell, New Mexico, developing increasingly more powerful rockets. In 1935 Goddard launched the first supersonic liquid-fuel rocket. (Supersonic means faster than the speed of sound. Sound waves travel at about seven hundred miles per hour, depending on the air temperature.) A year later Goddards achievements finally received recognition when the Smithsonian published another of his papers, Liquid Propellant Rocket Development.

He continued his work until 1941, when the United States entered World War II. Until his death in 1945, Goddard worked with the military to develop rocket applications for aircraft. Three decades later the New York Times finally issued an apology for its 1920 editorial about him. The date was July 17, 1969, and three American astronauts were on their way to the Moon. The newspaper admitted that Goddard had been right after all. The Goddard Space Flight Center near Washington, D.C., and the Goddard crater on the Moon are both named after him.

Wernher von Braun

World War II ushered in the rocket age. The Nazi government of Germany was eager to use rockets against its enemies. The great talents and minds of the VfR were directed to forget about space travel and concentrate on warfare. During the early 1940s Germany developed the most sophisticated rocket program in the world. At its helm was the brilliant young Wernher von Braun (1912-1977).

Von Braun had been Oberths assistant during the 1930s and an active member of the VfR. He was put in charge of developing a rocket weapon to terrorize the British population. Von Brauns team included Oberth and hundreds of people who worked on the remote island Peenemünde. They developed the rocket-powered Ver-geltungswaffens (weapons of vengeance), which were called V weapons for short.

There were two series of V weapons. The V-1 carried a ton of explosives and traveled at a top speed of about four hundred miles per hour. This was slow enough that British gunners could blow apart the V-1s as they descended through the air. Thousands of V-1s were launched against England, but roughly half never impacted the ground.

Far more lethal was the V-2. This was truly a rocket with a top speed around two thousand miles per hour. The V-2s traveled far too fast to be shot down and terrified the British public. In V-2: Hitlers Last Weapon of Terror (BBC News, September 7, 2004), Paul Rincon reports that over 1,300 V-2s were launched against England during World War II, killing 2,724 people.

On September 8, 1944, the first V-2 rocket fell on London. The National Aeronautics and Space Administration (NASA) notes in The Robotic Exploration of Space (June 30, 2004, that von Braun reportedly turned to his colleagues and said, The rocket worked perfectly, except for landing on the wrong planet. The tide had already turned against Germany. By early 1945 the country was being invaded by the Soviets from the east and the Allies from the west. To be in position to surrender to U.S. forces, von Braun moved his team near the German-Swiss border.

A negotiated surrender was worked out in which von Braun turned over himself, people on his team, and vital plans, drawings, rocket parts, and documents. In exchange, the U.S. Army agreed to transport the team to the United States and fund its work on a U.S. rocket program. The army called the agreement Operation Paperclip. It had no way of knowing that this move was going to put Americans on the Moon.


Even before World War II ended the United States began developing rocket-powered planes. In 1943 the NACA initiated the research program in conjunction with the air force and navy. Because the planes were experimental, they were given the name X-aircraft. In 1944 a company called Bell Aircraft began work on the XS-1, with the S standing for supersonic. Later, the S was dropped, and the plane became the X-1.

On October 14, 1947, the U.S. Air Force captain Charles (Chuck) Yeager (1923) flew the X-1 at the speed of sound, which is known as Mach 1. The X-1 was only the first of many high-performance planes tested in the program. Eventually, X-planes flew at hypersonic speeds, that is, speeds greater than Mach 5 (five times the speed of sound). In X-15: Hypersonic Research at the Edge of Space (February 24, 2000,, NASA explains that the X-15 was a rocket-fueled plane tested during the late 1950s and early 1960s. It was taken up to an altitude of approximately forty-five thousand feet by a carrier plane, a B-52 aircraft, and released. A rocket engine was then fired to propel the X-15 to incredible speeds and heights. On November 9, 1961, an X-15 flew at Mach 6.04, the fastest suborbital speed ever reached. On August 22, 1963, an X-15 soared across the boundary into space to an altitude of sixty-seven miles. This record would remain unbroken for more than four decades.

The X-series were high-speed, high-altitude planes unlike any ever built before. Most of them were tested over desolate desert areas near Muroc, California. Daring young test pilots flew the X-series planes. However, this was a dangerous profession. Many pilots were killed or seriously injured while testing the X-series planes. The pilots who survived became the first men considered for the nations astronaut program.


The term cold war is used to describe U.S. relations with the Soviet Union from the end of World War II to 1991, when the Soviet Union collapsed. During this period, which is chiefly marked by a mutual mistrust and rivalry that led to a buildup of arms, both nations developed extensive nuclear weapons programs. Each thought the other was militarily aggressive, deceitful, and dangerous. Each feared the other wanted to take over the world. This paranoia was in full force when space exploration began.

The International Geophysical Year

In 1952 a group of American scientists proposed that the International Council of Scientific Unions (ICSU) should sponsor a worldwide research program to learn more about Earths polar regions. Eventually, the project was expanded to include the entire planet and the space around it. The ICSU decided to hold the project between July 1957 and December 1958 and call it the International Geophysical Year (IGY). Geophysics is a branch of earth science that focuses on physical processes and phenomena in the earth and its vicinity.

The IGY time period was selected to coincide with an expected phase of heightened solar activity. Approximately every eleven years the Sun undergoes a one-to two-year period of extra radioactive and magnetic activity. This is called the solar maximum. The ICSU hoped that rocket technology would progress enough to put satellites in Earth orbit during the next solar maximum and collect data on this phenomenon.

Sixty-seven countries participated in various ways in the IGY project. The American delegation to the ICSU was led by the National Academy of Sciences, which consisted of a team of scientists from businesses, universities, and private and military research laboratories to conduct American activities during the IGY.

Ballistic Missiles

Following World War II both the United States and the Soviets began researching the feasibility of attaching warheads to long-range rockets that were capable of traveling halfway round the world. These weapons were eventually called intercontinental ballistic missiles (ICBMs). They could be equipped with conventional or nuclear warheads. The United States had introduced the nuclear warfare age by dropping two atomic bombs on Japan to end World War II in August 1945.

By the early 1950s the U.S. Air Force was actively testing three different ICBMs under the Navaho, Snark, and Atlas programs. This work was highly classified as a matter of national security. The United States and the Soviet Union both engaged in massive spying campaigns throughout the cold war. In 1955 American spies brought word that the Soviets were close to completing ICBMs capable of reaching U.S. cities.

The Soviet rocket work was spearheaded by Sergei Korolev (1906-1966). He oversaw the development of the R-7, the worlds first ICBM, and is considered the father of the Soviet space program.

Sputnik 1

Throughout the mid-1950s the United States worked to construct a successful science satellite for the IGY. This work proceeded separately from ICBM development. However, at the time only the military had the expertise and resources to build rockets capable of leaving Earths atmosphere. The navy was charged with developing a rocket capable of carrying a package of scientific instruments into Earth orbit. In 1957 testing was still ongoing and proceeding poorly when the United States received shocking news.

On the evening of October 4, 1957, the Soviet Union news service announced that the nation had successfully launched the first-ever artificial satellite into Earth orbit. It was called Sputnik, which means companion in English. The word also translates as satellite, because a satellite is Earths companion in an astronomical sense. Launched atop an R-7 Semiorka rocket, the satellite weighed 184 pounds, was about the size of a basketball, and circled Earth every ninety-eight minutes.

A Secret Surprise

The launch announcement of Sputnik 1 was both a disappointment and a surprise to American scientists. They knew their Soviet counterparts were working on a science satellite for the IGY but had no idea the Soviets had progressed so quickly. The American scientists had openly shared information about their research during ICSU meetings. By contrast, the Soviet government forbade its scientists from disclosing any details about their work. Sputnik 1 had been developed and launched in near total secrecy. According to Hugh Sidey, in Oct. 4, 1957: The Space Race Lifts Off (Time, March 31, 2003), Lloyd Berkner, the president of the ICSU, learned about the launch while at a dinner party at the Soviet embassy in Washington, D.C., when a reporter from the New York Times whispered the news to him.

The American public was even more shocked by the announcement. Millions went outside in the darkness to look for the satellite in the night sky. Witnesses said it was a tiny twinkling pinpoint of light that moved steadily across the horizon. The satellite continuously broadcast radio signals that were picked up by ham radio operators all over the world. Ham radio is communication using short-wave radio signals on small amateur stations.

The Sputnik 1 signals were another unpleasant surprise for American scientists. It had been universally agreed that IGY satellites would broadcast radio signals at a frequency of 108 megahertz. The United States had already built a satellite tracking system designed for this frequency. However, Sputnik 1 transmitted at much lower frequencies, ensuring that U.S. scientists would not be able to pick up its data.

Sputnik 2 A Dog in Space

The success of Sputnik 1 caught the United States off guard and unprepared. For the first time, the American public realized that the Soviets probably had the capability to launch long-range nuclear missiles against the United States. A month later there was even further dismay when the Soviets launched a second satellite.

Sputnik 2 was much larger than its predecessor and carried a live dog, a husky-mix named Laika, into orbit. The American press nicknamed her Muttnick. It was a one-way trip for her as the Soviet scientists had not yet worked out how to bring the spacecraft safely back to Earth. At the time the Soviet news agency bragged that Laika survived for a week aboard the spacecraft. Decades later scientists admitted that Laika died only hours after launch when she panicked and overheated in her tiny cabin.

The United States Reacts

The American public was scared by the size of Sputnik 2, which weighed more than one thousand pounds. Furthermore, it was common knowledge that the United States did not have a rocket capable of carrying that much weight into space. There was an uproar in the media, and politicians demanded to know how the Soviet Union had gotten so far ahead of the United States in space technology. President Dwight D. Eisenhower (1890-1969) charged the U.S. military to do whatever it took to put a satellite in space.

The U.S. Navys efforts to build a satellite had proved unsuccessful. The military turned to von Braun and his team of rocket scientists working for the U.S. Army. On January 31, 1958, the first American satellite soared into orbit. It was named Explorer 1 and rode atop a Jupiter-C rocket developed by the von Braun team at Huntsville, Alabama. (See Figure 1.3.)

A few months later the Soviets answered with Sputnik 3, a miniature physics laboratory sent into orbit to collect scientific data.

In October 1958 the United States formed the National Aeronautics and Space Administration to oversee the nations

space endeavors. Even though it was a civilian agency charged with operating peaceful missions in space, NASA would rely heavily on military resources to achieve its goals.


On April 12, 1961, the cosmonaut (Russian astronaut) Yuri Gagarin (1934-1968) became the first human to travel beyond Earths atmosphere, enter the frontier of space, and return safely to Earth. Gagarin was born in a village near Gzhatsk (now Gagarin) in central Russia. He grew up in a peasant family, dreaming of becoming a pilot. Before being recruited to be a cosmonaut, Gagarin was serving as a lieutenant in the Soviet air force.

The article Gagarin: Son of a Peasant, Star of Space (BBC News, April 1, 1998) reports that his flight took him roughly 300 kilometers (186 miles) above Earth and that he spent 1 hour and 48 minutes circling the planet, completing one entire orbit and part of another one. His cramped spacecraft was equipped with a radio for communicating with ground control. Looking down at the planet beneath him, he said, The Earth is blue. How wonderful. It is amazing.

The weightlessness bestowed by space travel had always been a worry for scientists. There is a common misconception among the public that there is no gravity in space. This is not true. Actually, the force of gravity remains strong for great distances around Earth. Objects and people that leave Earths atmosphere experience weightlessness, because they are in free fall toward Earth throughout their trip.

At the time of Gagarins flight, scientists were not sure how the human body would react to weightlessness. His spacecraft included a computerized automatic pilot, in case Gagarin lost consciousness or was unable to move. This fear proved to be unfounded. The mission showed that humans can not only withstand weightless-ness but can also function quite well in it.

Gagarin returned to Earth safely. He ejected from his spacecraft somewhere over Russia and parachuted to the ground. He became a national hero and an international sensation. His picture was on the front page of every major newspaper in the world.

The scientific teams in the United States were impressed with Gagarins accomplishment but also envious of it. In Yuri Gagarin: First Man in Space (, December 20, 2007), NASA notes that an agency spokesman congratulated the Soviets for their achievement and summed up the U.S. space program with these glum words: So close, but yet so far.In Huntsville, Alabama, von Braun was more blunt, saying, To catch up, the U.S.A. must run like hell.


In Alan B. Shepard, Jr. (February 04, 2005,, Tara Gray states that a month later the first American entered space. On May 5, 1961, Alan B. Shepard Jr. (19231998) soared to an altitude of 116 miles in the spaceship Freedom 7. He spent fifteen minutes and twenty-eight seconds in a suborbital flight. Suborbital means less than one orbit. In other words, a suborbital flight does not complete an entire circle around Earth. Shepards flight was much shorter in distance and time than Gagarins flight had been. A few months later Gherman Titov (19352000), the second cosmonaut in space, completed seventeen and a half orbits around Earth. NASA knew it would be a year or more before it could accomplish a similar feat.

The United States was tired of coming in second place. Because there was no way to beat the Soviets at the orbital space race, President John F. Kennedy (19171963) decided to start a new race. His advisers recommended that the United States put a manned spacecraft in orbit around the Moon or even land a man on the Moon. Either one would require the development of a huge new rocket to supply the lifting power needed to boost a spaceship out of Earth orbit. Neither the Soviets nor the Americans had such a rocket.

On May 25, 1961, President Kennedy revealed his decision to the world in the speech Special Message to the Congress on Urgent National Needs ( His words ignited the biggest race in human history: First, I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish.


Suddenly, all eyes were on the Moon. Earths closest neighbor had been a subject of fascination since the first humans gazed up at the night sky.

Most of the features on the Moon were named during the 1600s by the Italian astronomer Giambattista Riccioli (1598-1671). Riccioli was a Jesuit priest, a member of the Roman Catholic order the Society of Jesus, which is devoted to missionary and educational work. At the request of the church, Riccioli devoted his life to astronomy and telescopic studies. At the time, the writings of Kepler and Copernicus were popular and controversial. In keeping with church doctrine, Riccioli disputed Copernicuss claim that Earth was not the center of the universe.

Despite this gross error, Ricciolis work proved useful to later scientists. He published a detailed lunar map that he developed with Francesco Maria Grimaldi (16181663), a fellow Jesuit and Italian physicist. This map featured Latin names for lunar features, elevations and depressions were named after famous astronomers and philosophers, and large dark flat areas that looked like bodies of water were named Oceans or Seas.

Four hundred years later, humans on opposite sides of Earth took aim at these features. During the early and mid-1960s NASA and the Soviets sent dozens of photographic probes to take pictures of the Moon. Some probes proved successful, and some did not. Four NASA probes crashed into the Moon, but they had beamed back valuable photographs before impacting the lunar surface. In February 1966 the Soviet probe Luna 9 softly set down in the Ocean of Storms, the largest of the lunar seas. Four months later, NASAs Surveyor 1 probe landed nearby.

Both countries needed lunar data to support their efforts to send humans to the Moon. During this time Soviet officials did not even acknowledge that they had a manned lunar program. Those in the U.S. program suspected that they did but could not be sure. It was not until years later, when Sergei Leskov recounted the story in How We Didnt Get to the Moon (Izvestiya, August 18, 1989), that the United States learned how determined the Soviet Union was at trying to beat the Americans to the Moon.


The U.S. effort to put men on the Moon was named the Apollo program. It actually included three phases:

  • Mercurysuborbital and orbital missions of short duration
  • Geminilonger duration orbital missions including extravehicular activity (space walking) and docking of spacecraft in space
  • ApolloManned lunar landings in which a module containing two astronauts softly lands on the Moon; a third astronaut remains in lunar orbit while the other two explore the Moons surface

Shepards historic 1961 flight was considered the first Mercury mission. Over the next two years five more successful Mercury flights were conducted. In 1965 a series of ten manned Gemini missions began. They were completed near the end of 1966.

Soon after it started, it became apparent that the Moon program was going to be expensive. On September 12, 1962, President Kennedy ( reinforced his commitment to the project during a speech at Rice University in Houston, Texas. Kennedy said, We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.


One key goal in the United States and the Soviet Union was the development of a large and powerful rocketa so-called superbooster. NASA called its super-booster a Saturn rocket, and the Soviets named their rocket the N-1.

Development of the Saturn rocket series began in 1961 under the direction of von Braun. He had actually been pitching the idea to the military for several years. Before the Apollo program NASA used relatively small rockets that were capable of lifting a few hundred to a few thousand pounds into Earth orbit.

The Scout rocket was used to launch small satellites and probes weighing up to three hundred pounds. It was devised by combining aspects of rockets used by the armed forces (the navys Polaris and Vanguard rockets and the armys Sergeant rockets). The Thor, Atlas, and Titan series evolved from air force rockets first developed as ICBMs. During the mid-1960s the military replaced most of its Atlas rockets with Minuteman missiles. Modified Atlas rockets were used to launch satellites and for the Mercury program. The Titan II was used during the Gemini program.

The Saturn series evolved from von Brauns Jupiter rockets. Legend has it that the Saturn got its name because it was one step beyond the Jupiter rocket, just as Saturn is the next step beyond Jupiter in the solar system. The Saturn V, with a height of 364 feet, is the largest rocket ever built. (See Figure 1.4.) It had to be to push the one-hundred-ton Apollo spacecraft toward the Moon.


The Soviet space program continued to flourish. In September 1968 an unmanned probe called Zond 5 became the first spacecraft to travel around the Moon and return to Earth. The pressure was on NASA to speed up the Apollo program.

On January 27, 1967, three American astronautsVirgil I. Grissom (1936-1967), Edward H. White (1930-1967), and Roger B. Chaffee (1935-1967)were killed when a flash fire raced through their capsule during a routine practice drill. They were the first human casualties of the space program. To honor their memory, their tragic mission was named Apollo 1. The tragedy stunned

the nation. Some politicians even called for the program to end, but Apollo continued.

The next manned Apollo mission was launched on October 11, 1968. Apollo 7 successfully conducted a flight test and returned to Earth. It was followed in rapid succession by the more ambitious missions of Apollo 8, Apollo 9, and Apollo 10, each of which tested a lunar or command module in lunar or Earth orbit. The mission to set humans on the Moon was named Apollo 11 and scheduled for July 1969.

By this time the Soviets had desperately tried to get their own manned lunar program going. However, the N-1 rocket kept failing its launch tests. The Soviets realized that it would not be ready before the Apollo 11 launch. Still hoping to steal some of the thunder from the Americans, the Soviets launched a robotic probe named Luna 15 to the Moon. It was designed to gather samples from the lunar surface and return to Earth before the Apollo 11 expedition. Launched on July 13, 1969, Luna 15 completed fifty-two Moon orbits before it crashed into the lunar surface on July 21, 1969, and was lost.

Meanwhile, on July 20, 1969, Apollo 11 set down safely on the Moon near the Sea of Tranquillity. Late that evening the astronaut Neil A. Armstrong (1930-) stepped out of the spacecraft to become the first human to stand on the Moon. Approximately half a billion people on Earth watched the historic event on television. Four days later the Apollo 11 crew returned to Earth to a heroes welcome. There were six more Apollo missions to the Moon before the program ended in 1972.


NASAs space program introduced a new kind of hero to American culture: the astronaut. When the Mercury program began, NASA selected seven men to be astronauts: Grissom, Shepard, M. Scott Carpenter (1925-), Gordon Cooper (1927-2004), John Glenn (1921-), Walter M. Schirra Jr. (1923-2007), and Donald K. Slayton (1924-1993). They were called the Mercury Seven. The men were all successful military test pilots known for their bravery and professional piloting skills.

The men had to pass strenuous batteries of physical, mental, and medical tests to become astronauts and begin their training to go into space. To the American public, the Mercury Seven captured the bold and daring spirit of famous flyers such as Richthofen and Lindbergh. They were instant superstars and began receiving thousands of fan letters. Once NASA realized the great popularity of the astronauts, it used them as goodwill ambassadors for the agency. The astronauts traveled around the country speaking to civic groups and clubs to elicit public support for the space program.

NASA scientists originally envisioned astronauts as mere guinea pigs for space experiments. They were intended to be passive passengers covered with medical sensors and sealed inside space capsules completely controlled by operators on the ground through onboard computers. The astronauts rebelled at this notion and insisted on many changes, including installation of windows and manual piloting controls on the space capsules. When the Gemini program began, NASA selected nine more astronaut candidates and soon dozens after that. NASA notes in The Apollo Program (1963-1972) (July 24, 2007, that by the end of the Apollo program, thirty-four American astronauts had traveled into space.

In 1979 the story of the original Mercury Seven was profiled in the book The Right Stuff by Tom Wolfe. In the book, Wolfe describes the tremendous pressures put on the first astronauts during the space program, their dedication to serving their country, and how they reacted to fame and glory. In 1983 the book was made into a popular movie of the same name.


During the early years of space flight, American relations with the Soviet Union were at their worst. John Pike et al. explain in R-46 (July 29, 2000, that only months after the Soviets put their first cosmonauts in space the Soviet premier Nikita Khrushchev (18941971) made the veiled threat, We placed Gagarin and Titov in space, and we can replace them with other loads that can be directed to any place on Earth. The meaning was clear to the American public: the Soviet Unions powerful rockets could carry nuclear warheads just as easily as they carried humans.

Détente is a French word that means a relaxation of strained relations. The United States and the Soviet Union occasionally enjoyed periods of detente during the cold war, particularly in their space activities. In 1965 a joint project was undertaken in which American and Soviet scientists shared information they had learned about space biology and medicine.

In October 1967 the two countries negotiated the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies (January 1, 2004,, which is more commonly known as the Outer Space Treaty. The treaty provides a basic framework for activities that are and are not allowed in space and during space travel. The main principles are:

  • Nations cannot place nuclear weapons or other weapons of mass destruction in Earth orbit or elsewhere in space.
  • Outer space is open to all humankind and all nations for exploration and use.
  • Outer space cannot be appropriated or claimed for ownership by any nation.
  • Celestial bodies can only be used for peaceful purposes.
  • Nations cannot contaminate outer space or celestial bodies.
  • Astronauts are envoys of mankind.
  • Nations are responsible for all their national space activities whether conducted by governmental agencies or nongovernmental organizations.
  • Nations are liable for any damage caused by objects they put into space.

The Outer Space Treaty was signed on January 27, 1967, by the United States, the Soviet Union, and the United Kingdom. Over the next four decades it would be signed by more than one hundred nations.

In 1969 NASA proposed the development of American and Soviet spacecraft that could dock with each other in space for future missions of mutual interest. In July 1975 the docking procedure proved to be successful during the Apollo-Soyuz Test Project. The mission was largely symbolic, and many people considered it wasted money that could have been spent on space exploration.

Near the end of the Apollo program the two countries agreed to a number of cooperative projects including the sharing of lunar samples, weather satellite data, and space medical data.


In the minds of most Americans, the space race was over the day Apollo 11 set down on the Moon. Even though NASA carried out six more Apollo missions, public interest and political support for them faded quickly. Neither the U.S. nor the Soviet government was interested in racing to somewhere else in space. Both governments decided to concentrate on putting manned scientific space stations in low Earth orbit (LEO).

LEO is approximately 125 to 1,200 miles above Earths surface. LEO is the orbit of choice for most satellites and for all crewed missions. Spacecraft in LEO travel at about seventeen thousand miles per hour and circle Earth once every ninety minutes or so. Below this altitude air drag from Earths atmosphere is still dense enough to pull spacecraft downward quickly. Beyond LEO lies a thick region of radiation known as the inner Van Allen radiation belt. This region poses a hazard to human life and to sensitive electronic equipment.

Soviet Programs

Between 1971 and 1986 the Soviets put eight space stations into LEO or just below it. These included stations called Salyut 1 through Salyut 7 and the more ambitious space station Mir. Dozens of cosmonauts visited and inhabited the stations, often for many months. The Soviets repeatedly set and broke human space duration records at their stations. In 1995 the cosmonaut Valery Polyakov (1942) completed a 437.7-day mission aboard Mir. Even in 2008 this stood as the longest period spent in space by any human. Eventually, all the Soviet stations fell out of orbit and were destroyed by reentry to Earths atmosphere. Even though none were meant to be permanent, the Mir station did stay in orbit for fifteen years.

U.S. Programs

In 1973 NASA launched its own space station called Skylab. It orbited within LEO of 268 to 270 miles above Earth. NASA wanted to build a large space station in which to conduct scientific investigations in LEO. Without political support the agency had to put this plan on hold. Instead, NASA concentrated on a new type of reusable space plane called the space shuttle. The space shuttle was to the be the workhorse of the U.S. space program, ferrying astronauts and supplies back and forth to the space station.

NASA received the funding it needed to develop the shuttle by promising to build a vehicle that could carry military, weather/science, and commercial satellites into LEO. Before the shuttle program, all satellites were launched aboard expendable rockets that could not be reused. The reusability of the shuttle was one of its best selling points. Also, each shuttle could carry a crew of five to seven people that could conduct scientific experiments in LEO and deploy and repair satellites as needed.

Despite a number of design challenges, the first space shuttle was ready for flight by 1981. On April 12, 1981, the first test mission was conducted. Before the end of the year a space shuttle carried an orbiting solar observatory into LEO. Two dozen more missions were carried out before disaster struck in 1986. By this time there were four space shuttles in NASAs fleet. Missions were rotated between the vehicles to perform needed maintenance and repairs.

On January 28, 1986, the space shuttle Challenger exploded seventy-three seconds after liftoff. All seven crewmembers aboard were killed. The shuttle fleet was grounded for more than two years, during which time NASA restructured the program and redesigned key elements of the spacecraft. In October 1988 space shuttle flights resumed once again.

By this time the Soviet Union was politically disintegrating. Within three years the United States former archenemy had splintered into dozens of individual republics, and the cold war was officially over. The Russian Republic took over the space program begun by the Soviet Union. The Soviet space program came under the operation of the new Russian Space Agency in 1992. The agency was renamed the Russian Aviation and Space Agency (Rosa-viakosmos) in 1999, when it was assigned additional responsibilities in aviation. In 2004 those responsibilities were removed and the agency was renamed the Russian Federal Space Agency (Roscosmos).

International Plans

During the 1990s the United States and Russia entered a new era of cooperative space ventures. American astronauts visited the Mir station and Russian cosmonauts traveled aboard U.S. space shuttle missions. In 1993 the United States invited Russia to join in building an International Space Station (ISS) to be put in LEO. The Russians agreed. The ISS program eventually included Canada, Japan, and eleven European nations as full partners and Brazil as a contributing partner.

ISS construction began in 1998. The station was designed for continuous human inhabitation and detailed scientific investigations. The Americans and Russians took turns adding components to the station and crewing it with astronauts and cosmonauts. All transport of heavy materiel was delegated to the U.S. space shuttle fleet because the Russians did not have a spacecraft capable of carrying heavy weight into LEO. Throughout 1999 and the next three years nearly all shuttle missions were devoted to ISS construction.

During the first mission of 2003 another space shuttle was lost in an accident. On February 1, 2003, the space shuttle Columbia disintegrated during reentry over the western United States. Again, seven crewmembers were killed. The shuttle fleet was grounded for more than two years, ceasing construction on the ISS. Russian spacecraft ferried supplies to the station and handled crew changes.

In July 2005 the Space Shuttle Program resumed operations with a successful return-to-flight test mission. ISS construction proceeded in 2006 and 2007 as six space shuttle missions were conducted. Additional missions are planned through 2010, when the Space Shuttle Program is scheduled to end.


The United States dedication to the ISS changed dramatically in January 2004, when President George W. Bush (1946-) announced a new goal for the nations space program: to return to the Moon and travel to Mars and beyond. The so-called Vision for Space Exploration ( requires the development of a new fleet of spacecraft capable of carrying astronauts beyond LEO into the solar system.


The advent of the space age introduced a wealth of information to science-fiction authors. They were able to produce works that were more sophisticated than those of the past.

One of the most innovative of these authors was Gene Roddenberry (1921-1991). During the mid-1960s he created the television show Star Trek. This was a futuristic tale about a mixed crew of humans and aliens that explored the galaxy in the starship Enterprise during the twenty-third century. The television show was not popular during its original run but over the next few decades it developed a loyal fan base and spawned a number of movies.

In 1974 thousands of Star Trek fans wrote to the U.S. government requesting that one of the newly developed space shuttles be named Enterprise. NASA gave the name to the prototype shuttle model used for flight testing.

Another notable science-fiction work of the 1960s was the film 2001: A Space Odyssey (1968), which was based on a story by Arthur C. Clarke (1917-2008). Astronauts exploring the Moon find a mysterious artifact. Believing that it came from Jupiter, they set off for that planet on an amazing spacecraft. The ship is equipped with a supercomputer named HAL that malfunctions and turns against the human crew. The film features little dialogue, but it became a hit for its very imaginative plot and spectacular views of futuristic space travel.

In 1977 the science-fiction film Star Wars debuted and became one of the most popular movies of all time. Set a long time ago in a galaxy far, far away, the film tells the story of an adventurous young man who leaves his home world to join a band of rebels fighting against a tyrannical empire. The movie was renowned for its story, characters, adventure, and special effects. The Star Wars franchise went on to include five more highly successful films and a book series.

Hollywood movies featuring hostile space aliens invading Earth were a staple of 1950s pop culture. Such films captured the paranoia and fear that Americans felt about the communist threat from the Soviet Union. Beginning in the 1970s a gentler viewpoint of aliens emerged in movies such as Close Encounters of the Third Kind (1977), ET: The Extraterrestria l (1982), Cocoon (1985), and Contact (1997). However, horrific and murderous aliens remain a staple of science-fiction films, as evidenced in the popularity of Alien (1979) and its sequels, Independence Day (1996), and War of the Worlds (2005).


Space programs that use human explorers are expensive. It is cheaper to build and send mechanized (robotic) spacecraft to do the exploring. During the 1960s the Apollo program dominated the spotlight, but it was not the only space exploration project in operation.

Beginning in 1962 NASA launched robotic probes that flew by Mercury, Venus, and Mars and beamed back photographs of them. During the 1970s more sophisticated robotic spacecraft landed on Mars or were sent to fly by the outer planets (Jupiter, Saturn, Uranus, Neptune, and Pluto). These missions were given heroic names, including Mariner, Viking, and Voyager.

In 1990 a robotic spacecraft called Magellan was put into orbit around Venus on a four-year mission to collect data about the planet. The spacecraft was named after Ferdinand Magellan (1480?-1521), the Portuguese explorer who led the first sailing expedition to circumnavigate the world. In 1995 a spacecraft named after Galileo Galilei began orbiting Jupiter.

Interplanetary exploration is tough, even for machines. During the 1990s NASA lost five out of the six robotic spacecraft that it sent to Mars. In 2001 NASA sent Mars Odyssey, which went into orbit around the planet. It was joined two years later by the European Space Agency (ESA) spacecraft Mars Express Orbiter. However, a lander from this mission was lost on its way to the surface. In 2004 NASAs Mars Exploration mission successfully put down two rovers on Mars: Spirit and Opportunity. The rovers were expected to last about three months, but as of February 2008 they were still exploring the surface of Mars.

In June 2004 NASAs Cassini spacecraft went into orbit around Saturn after a seven-year journey from Earth. The orbiter released the ESA-provided Huygens probe, which provided the first-ever close-up photographs of Titan, Saturns largest moon. Also in 2004 NASA launched the Messenger orbiter toward Mercury. That spacecraft is scheduled to arrive there in 2011. In 2006 two new robotic explorersNASAs Mars Reconnaissance Orbiter and the ESAs Venus Express Orbiter went into orbit around their respective target planets. In 2007 NASA launched the Phoenix Mars mission, which will send a lander to the planet in May 2008.

Not all space exploration requires long-distance travel. Advances in computers and telescopes have allowed scientists to do a lot of exploring with robotic spacecraft stationed nearby Earth. Dozens of these high-technology machines take photographs, measure radiation waves, and collect data on galactic and solar phenomena.

The latest generation of robotic explorers are designed to snatch samples in outer space and return them to Earth. The first such mission to return was conducted by the NASA spacecraft Genesis. In September 2004 it crash-landed in the Utah desert following an equipment malfunction during reentry. Regardless, some of its valuable cargo was savedsamples of the solar wind (charged particles emitted from the Sun) collected a million miles from Earth. Also in 2004 the NASA spacecraft Stardust sailed nearby the comet Wild 2 as it journeyed around the Sun. Stardust collected dust particles believed to be 4.5 billions years old and returned them safely to Earth in January 2006.

In November 2005 Japans Hayabusa spacecraft landed on the asteroid Itokawa between Earth and Mars to collect dust samples. Equipment and communication problems have plagued the mission, and scientists are hopeful, but not certain, that the samples were collected and will return to Earth in 2010.


Application satellites are spacecraft put into Earth orbit to serve as tools of earth science or for navigation, communication, or other commercial purposes. Even though they are not really space explorers, they would not be possible without the technology of the space age.

On April 1, 1960, NASA launched the first successful meteorological satellite TIROS 1 (Television Infrared Observation Satellite). The spacecraft was equipped with television cameras to film cloud cover around Earth. This is an example of an active satellite (one that collects data or performs some other activity and transmits signals back to Earth).

Over the next few decades weather satellites grew increasingly more sophisticated in their capabilities. The primary satellites that followed TIROS 1 were Nimbus, TOS (TIROS Operational Satellite), ITOS (Improved TOS), SMS (Synchronous Meteorological Satellite), NOAA (National Oceanic and Atmospheric Administration), and GOES (Geostationary Operational Environmental Satellite). Other application satellites perform various duties for earth scientists, such as mapping oceans and land masses or measuring the heat and moisture content of Earths surface.

On August 12, 1960, NASA launched ECHO 1, its first communications satellite. It was a large metallic sphere that reflected radio signals. NASA maintains a whole series of communication satellites in Earth orbit that allow the agency to communicate with astronauts and relay data to robotic spacecraft during missions. They are called Tracking and Data Relay Satellites.

Many communications satellites are placed in Earth orbit 22,241 miles from the planets surface. At this distance they are anchored in place by Earths gravity and are in synch with its revolution rate. In other words, they move around Earth at the same speed that it revolves around its axis. This is called a geosynchronous orbit. Some satellites are placed in a geosynchronous orbit directly above Earths equator and appear from Earth to hover in space at the exact same location all the time. They are in a geostationary orbit.

Navigation is the act of determining ones position relative to other locations. Before the invention of satellites, navigational signals were transmitted by land-based systems using antennas. (See Figure 1.5.) These antennas sent low-frequency radio signals that traveled along Earths surface or reflected off the ionosphere to reach their target receptor. The ionosphere is a layer of atmosphere that begins about thirty miles above Earths surface. Atmospheric gases undergo electrical and chemical changes within the ionosphere. This is what gives it reflective properties.

During the 1970s the U.S. military developed a space-based navigational system called the Global Positioning System (GPS). This system relies on satellites in Earth orbit to handle signal transmissions. (See Figure 1.6.) During the 1980s GPS was made available for international civil use. Over the next two decades it became one of the most popular navigational tools in the world.


SpaceShipOne was the first privately built and financed craft to fly a human into space. For more than three decades, the only way for humans to access space was through government-operated space programs. This

all changed on June 21, 2004, when SpaceShipOne carried Mike Melvill (1941-) to an altitude of sixty-two miles (one hundred kilometers), which is considered the boundary of space by the FAI.

SpaceShipOne was designed and built by Scaled Composites, a California-based firm. The funding was provided by the American billionaire Paul G. Allen (1953), a cofounder of the Microsoft Corporation. Allen financed the project as a way to have some meaningful impact on space exploration. During the development of SpaceShipOne, Allen became aware of the Ansari X Prize ( $10 million prize offered by private investors to the developers of the first nongovernmental reusable space plane. The Ansari X Prize was the brainchild of Peter H. Diamandis (1961), an aerospace engineer and entrepreneur in space tourism. His inspiration was the Orteig Prize, which was won in 1927 by Lindbergh, when he flew nonstop across the Atlantic Ocean between New York and Paris. Lindberghs flight incited interest and investment in aviation. Diamandis believed his prize would launch another new industry: private space travel

In 1994 Diamandis started the X Prize Foundation to raise money for the prize. His first investors were businesspeople in St. Louis, Missouri, the same city that played a key role in Lindberghs flight many years before. Over the next decade Diamandis received support from a number of backers, including Arthur C. Clarke, the astronaut Edwin E. (Buzz) Aldrin Jr. (1930), and Erik Lindbergh (1965), Lindberghs grandson. However, the foundation still struggled to raise the funds it needed.

In 2004 the foundation received a financial boost. Space enthusiasts Anousheh Ansari (1966-) and her brother-in-law Amir Ansari (1970-) made a multimillion-dollar contribution to the prize fund. The Ansaris were born in Iran but had immigrated to the United States and formed a successful telecommunications business. The X Prize was renamed the Ansari X Prize in their honor.

By 2004 dozens of teams were developing rockets and spacecraft to compete for the prize. The rules required that the spacecraft carry three people (or at least one person plus the equivalent weight of two people) to an altitude of at least one hundred kilometers. The feat had to be accomplished twice within a two-week period using the same spacecraft.

Scaled Composites used a two-part flight sequence to boost SpaceShipOne into space. A manned twin-turbojet plane called White Knight lifted off from a runway carrying the smaller manned space plane attached to its belly. (See Figure 1.7.) After reaching an altitude of approximately forty-seven thousand feet, the space plane was released. Immediately, its rockets were fired to propel it vertically into space. It then turned and reentered the atmosphere and glided to a landing at the same air strip from which it took off.

On September 29, 2004, SpaceShipOne achieved an altitude of 63.9 miles (102.8 kilometers) with Melvill at the controls. The successful flight garnered international media coverage and increased interest in the competition. On October 4, 2004, a large crowd gathered at an airstrip in Mojave, California, to watch SpaceShipOne attempt to make history. They were not disappointed. Brian Binnie (1953-) took the space plane to an altitude of 69.6 miles

(112 kilometers) to win the Ansari X Prize. The news was broadcast around the world, and President Bush telephoned the team to offer his congratulations.

The people behind the Ansari X Prize and Space-ShipOne purposely used parallels to events in aeronautical history to build their legacy. The concept of the prize drew on the symbolism and romanticism attached to Lindberghs heroic flight. Important announcements and flights were conducted on dates of significance to space enthusiasts. The first test flight of SpaceShipOne to break the sound barrier occurred on December 17, 2003the one hundredth anniversary of the first powered flight of the Wright brothers. The Ansaris multimillion dollar contribution to the X Prize fund was announced on May 5, 2004, the forty-third anniversary of Shepards flight into space. The date October 4 was chosen as the day for SpaceShipOnes prize-winning flight attempt, because it was the date in 1957 when the Soviet Union launched Sputnik 1, the first artificial satellite to go into space.

According to Diamandis, the X in X Prize stood for the Roman numeral ten (as in the $10 million prize) and for the X in experimental (as in the famous X-series of experimental planes flown during the 1950s and 1960s). The X-series flights were extremely important to the development of space travel. The White Knight carrier plane was named after two test pilots (Robert White and William Pete Knight) who flew the X-15 aircraft in the early 1960s. SpaceShipOne s prize-winning flight broke the altitude record set by an X-15 in 1963, a record that had stood for more than four decades.

However, the achievements of SpaceShipOne will likely be remembered for their effects on the future of aeronautics, not their ties to the past. The first nongovernmental manned space flight offers tantalizing prospects for private individuals to travel into space. It may represent the birth of a new industry and a means for many people to experience the adventure of space flight. (For further information on SpaceShipOne, see Chapter 3.)


The space age introduced new areas of commerce for the worlds entrepreneurs. Companies engaged in aviation, aeronautics, and aerospace activities have been the most direct beneficiaries. However, other industries have seized upon space-based opportunities, primarily the businesses of commercial satellite services and space tourism.

In 2004 President Bush directed NASA to pursue greater participation of private industry in space exploration. One result was the Commercial Orbital Transportation Services (COTS) Program. NASA reports in the press release NASA Invests in Private Sector Space Flight with SpaceX, Rocketplane-Kistler (August 18, 2006, that the COTS Program designated $500 million in seed money for commercial enterprises that can develop reliable and cost-effective space transportation systems. The final systems will not be turned over to the government, but remain in private hands. NASA plans to be a launch customer of the new services. In August 2006 the money was split between two companies: Space Exploration Technologies (SpaceX) of California and Rocketplane-Kistler of Oklahoma. They will use the money, along with privately raised funds, to develop new space vehicles and systems useful for crewed missions to the ISS and possibly beyond.

Commercial Satellite Services

In 1962 Congress passed the Communications Satellite Act, opening the door for commercial use of satellites in space. For decades these satellites could only be launched by national space agencies (such as NASA). In 1980 Arianespace (a subsidiary of the ESA) became the worlds first commercial space transportation company. Arianespace began offering satellite launches using Ariane rockets at its spaceport in French Guiana (a small country along the northern coast of South America). Its first client was an American telecommunications company.

In 1984 the Commercial Space Launch Act was passed in the United States. The act granted power to the U.S. private sector to develop and provide satellite launching, reentry, and associated services and noted that this would enable the United States to retain its competitive position internationally, contributing to the national interest and economic well-being of the United States.

The Boeing Corporation is a large U.S. aerospace company and a prime NASA contractor. In 1995 Boeing formed a satellite launching business with Russian, Norwegian, and Ukrainian partners. The Sea Launch Company (February 15, 2000, is headquartered in Long Beach, California, and operates a rocket launch platform on a modified oil-drilling platform in the South Pacific Ocean. Boeing owns a 40% share in the company. Its partners include RSC Energia of Russia (25% share); Aker ASA of Norway (20% share); and SDO Yuzhnoye/PO Yuzhmash of Ukraine (15% share). More than a dozen launches of commercial satellites have taken place from the Sea Launch facility since the first launch in 1999.

The Commercial Space Act of 1998 encouraged NASA to set policies to encourage and facilitate the participation of the private sector in the operation, use, and servicing of the ISS. This act received little attention until 2004, when President Bush announced his plan to retire the space shuttle fleet by 2010. The United States expects it will need commercial services to take over many of the tasks historically performed by the shuttle for the ISS program. This should open up many new opportunities in space for enterprising companies.

Space Tourism

Before the 2000s space tourism was limited to occasional space station visits taken by a handful of individuals for multimillion dollar fees. These trips were granted by the Russian Space Agency to raise badly needed funds. Private space tourism companies formed and accepted deposits for future spaceflights on not-yet-developed spacecraft, but these ventures sounded like science fiction to most people. This all changed in 2004 with the successful suborbital excursions of SpaceShipOne. Suddenly, space station visits by private individuals became a viable possibility. New space tourism businesses formed, and the U.S. government rushed to set regulations for private space transportation, an entirely new industry.

COMMERCIAL PASSENGERS ON RUSSIAN MISSIONS. During the late 1980s the Soviet space program was in dire need of money. The Soviet Union was splintering into individual nations, and funds for space travel were in short supply. In 1990 the agency received $28 million from a Japanese media company to take the journalist Tohiro Akiyama (1942-) aboard Mir. A year later a London bank paid an undisclosed amount of money to allow the British chemist Helen Sharman (1963-) to spend a space vacation aboard Mir.

In 2001 Rosaviakosmos charged Dennis Tito (1940), an American businessman, $20 million for a space vacation aboard the ISS. Over the next five years, three more space tourists paid $20 million to be transported by the Russians to the ISS : the South African businessman Mark Shuttleworth (1973) in 2002; the American scientist and businessman Greg Olsen (1945) in 2005; and Anousheh Ansari in 2006. Charles Simonyi (1948), a Hungarian-born businessman, paid $25 million in April 2007 to be the fifth space tourist. The sixth and most recent space tourist is Sheikh Muszaphar Shukor (1972), a surgeon from Malaysia, who visited the ISS in October 2007. Unlike the other space tourists, he did not spend his own money for the trip; instead, it was paid for by Malaysia as part of a purchase of Russian fighter jets.

Russias ISS partners (including NASA) have not shown any interest in space tourism. Initially, NASA refused to let tourists aboard the ISS, but it relented after heated negotiations with Rosaviakosmos. The Russian agency has stated publicly that it hopes to develop space tourism as a thriving business. It sells tourist packages that allow people to undergo simulated cosmonaut training at its facilities in Zvezdny Gorodok (Star City).

THE FUTURE OF PRIVATE SPACE TRAVEL. The first five tourist trips to the ISS were brokered by the American company Space Adventures (2008, The Virginia-based company was founded in 1998 by Diamandis. It also has plans to market suborbital flights aboard a new space plane being developed by a Russian contractor. The plane will take tourists to an altitude just over sixty-two miles above Earth.

Other companies known to be developing commercial spacelines include Virgin Galactic, SpaceX, Rocketplane-Kistler, and Armadillo Aerospace.

The Commercial Space Launch Amendments Act of 2004 instructed the Federal Aviation Administration (FAA) to begin formulating rules to govern the transport of passengers into space aboard commercial spacecraft.

TABLE 1.1 Number of successful space launches worldwide, 1998-2007
1998199920002001200220032004200520062007TotalPercent of launches
SOURCE: Adapted from World Space Launches, in Office of Space Operations, National Aeronautics and Space Administration, December 29, 2007, (accessed December 31, 2007)
SEA = South East Asia.
ESA = European Space A Agency.

In 2006 the FAA issued Human Space Flight Requirements for Crew and Space Flight Participants; Final Rules (Federal Register, vol. 71, no. 241, December 15, 2006). The FAA refers to space tourists as space flight participants. The rules cover issues such as crew training, pilot certification, and requirements for informed consent about the risks of space flight.

Those who do not make it into space during their lifetime also have another option. Several companies around the world offer services to send the cremated ashes of a loved one into space. The service costs anywhere from $5,000 to $15,000.

Commercial Ventures on the Moon?

The U.S. Vision for Space Exploration unveiled in 2004 has spawned interest in possible commercial ventures on the Moon. The lunar surface contains a variety of substances that might be useful in spaceflight or energy applications. Moon soil is rich in oxygen (a spacecraft fuel) and helium-3, an element rare on Earth that could potentially be used in fusion reactions as an energy source.

In September 2007 the X Prize Foundation teamed up with the Internet company Google to offer the Google Lunar X Prize ( for the first privately funded robotic Moon rover. The rover must land on the Moon, rove the surface for at least five hundred meters, and relay specific data and images back to Earth. The prize awards a total of $30 million, including a $20 million grand prize, $5 million for second place, and a $5 million bonus prize for a grand prize or second-place recipient that exceeds the mission requirements. SpaceX will supply the launch vehicle for the Moon rover.


NASA tracks the number of spacecraft launches conducted worldwide each year. Table 1.1 shows the figures for 1998 through 2007. The United States (34%) and Russia (39%) account for 73% of all launches. However, both countries launch satellites for other nations.

Only a handful of launches take place each year to support human spaceflight programs operated by the United States, Russia, and China. The vast majority of launches take place to put unmanned commercial, science, and military satellites into Earth orbit. The science missions are largely devoted to earth science, studying Earths weather, climate patterns, atmospheric conditions, and so on. Military satellites perform reconnaissance (spying) from space or support the communication and navigation needs of armed forces around the world.


Exploration has always been dangerous. Many ancient explorers died during their journeys across deserts, seas, mountains, and jungles. Space exploration has its own casualties.

During the earliest days of space travel dozens of animals were sacrificed for the space program. The United States sent a variety of small animals and primates up in rockets to test the safety of space flight for humans. Few survived the flight or the examination afterward. Some of the so-called astro-monkeys and astro-chimps that lost their lives were named Able, Albert, Bonny, Goliath, Gordo, and Scatback. The Soviets preferred dogs to test their spacecraft. Dogs named Bars, Laika, Lisichka, Mushka, and Pchelka died as a result.

Space programs in both countries have suffered human losses throughout the years as well:

  • January 27, 1967Apollo 1 crew died during a flash fire aboard a capsule on the launch pad undergoing routine testing. The casualties were Grissom, White, and Chaffee.
  • April 24, 1967Soyuz 1 cosmonaut Vladimir Komarov (1927-1967) died during descent to Earth when his parachutes failed to function properly.
  • June 30, 1971Soyuz 11 crew died during descent to Earth when their spacecraft lost its atmosphere due to a leaky valve. The casualties were Georgi Dobrovol-sky (1928-1971), Vladislav Volkov (1935-1971), and Viktor Patsayev (1933-1971).
  • January 28, 1986The space shuttle Challenger crew died shortly after launch because of an explosion caused by leaking hot gases. The casualties were Francis R. Scobee (1939-1986), Michael J. Smith (1945-1986), Judith A. Resnik (1949-1986), Ron McNair (1950-1986), Ellison S. Onizuka (1946-1986), Gregory B. Jarvis (1944-1986), and Christa McAuliffe (1948-1986).
  • February 1, 2003The space shuttle Columbia crew died during Earth reentry when a damaged wing allowed hot gases to enter the spacecraft, tearing the shuttle apart. The casualties were Rick D. Husband (1957-2003), William C. McCool (1961-2003), David M. Brown (1956-2003), Kalpana Chawla (1962-2003), Michael P. Anderson (1959-2003), Laurel B. Clark (1961-2003), and Ilan Ramon (1954-2003).

In January 2004 the NASA administrator Sean OKeefe (1956-) announced that the last Thursday in January will become a day of remembrance for lives lost in the U.S. space program. Each year on this day, NASA employees will observe a moment of silence, and flags will be flown at half-staff to honor the dead.

Like all journeys of discovery, space exploration is a bold and perilous undertaking. Major sacrifices have been made to move humankind closer to the stars. In September 13, 1962, President Kennedy ( aptly described the combination of fear, hope, and yearning that characterizes every journey into space: As we set sail, we ask Gods blessing on the most hazardous and dangerous and greatest adventure on which man has ever embarked.

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Introduction to Space Exploration

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Introduction to Space Exploration