1900 Tsiolkovsky, otherwise known as the father of rocketry, was the first scientist in the world to take interest (in detail) in spaceflight. In his work, Tsiolkovsky fueled his theoretical engine with a mix of liquid oxygen and liquid hydrogen. This mixture is considered the most efficient rocket propellant, even today. Tsiolkovsky never attempted to build a rocket engine, let alone a spacecraft. Although, in 1903, he published an article (manuscript) titled "Exploration of the World Space with Reaction Machines” in a magazine. His discoveries are still very important to space history.

1914 Dr. Robert Hutchings Goddard is credited with building the first liquid-fueled rocket. In 1914 he received two patents, one for liquid fuel rockets, and one for solid fuel rockets. He then started studies of propulsion with various gun powders. Goddard then thought up the idea of a rocket going to the moon and exploding a load of powder to show it’s arrival. He continued to experiment with rockets…..

1926 Goddard’s 1926 rocket was the first successful liquid- propellant rocket. In earlier years he experimented with gunpowder, but found that liquid propellant was a better, more efficient use of fuel. His rocket was launched March 16, 1926 in Auburn, Massachusetts. This rocket was damaged upon impact. Goddard worked on this rocket alone, and was reluctant to publicize it. It is now located in the Smithsonian Institution, National Air and Space Museum, Milestones of flight gallery.

1930 Wernher von Braun was a member of the Verein fur Raumschiffarht (VFR) in the 1930’s. During this same period of time the German military was searching for a weapon which would not violate the Versailles Treaty of World War I, but defend their country. Walter Dornberger, artillery captain, was told to investigate the usage of rockets. He found the VFR, and impressed with them, gave them $400 to build a rocket. Wernher von Braun worked hard, only to watch his rocket fail. Dornberger was impressed with von Braun and hired him to lead the military's rocket artillery unit. With the help of 80 engineers they created successful rockets, one being the V-2. (otherwise known as the A-4)

1944 The V-2 as the first man-made object to leave Earth’s atmosphere. It was developed by the Germans during World War II. Over 1,000 of these rockets fell, killing over 8,000 people. Americans came to Germany and captured the inventor of the V-2, Wernher von Braun. They had him build the exact same design, but for space exploration instead of bombing. That is how, on October 3, 1942, the V-2 reached an altitude of 60 miles, leaving Earth’s atmosphere.

1954 On May 24, 1954 a new altitude record was set for a Western single-staged rocket was set. One of the many Viking spacecrafts reached 159 miles above the Earth. This spacecraft was called the Viking 11, or V-11. Not only did this spacecraft set a new record, but it also took the first picture of hurricane and a tropical storm. This was the first natural color picture of Earth. This rocket was launched from White Sands Missile Range in New Mexico. It is 3 times the size of Rhode Island, making it the largest military installation in the United Sates.

1957 Sputnik 1 launched on October 4, It was the first manmade object to orbit the Earth. It was a Soviet satellite. The artificial satellite traveled 18,000 mph, only taking it 96.2 minutes to complete orbit. Sputnik 1 burned up on January 4, 1958 as it fell from orbit, upon reentering Earth’s atmosphere. It traveled 37,000,000 miles, and spent three months in orbit. It was the first in a series of satellites known as the Sputnik Program.

1961 On April 12, 1961, Yuri Gagarin became the first human man and Soviet to orbit the earth and travel in space. This was his first and last space mission. Gagarin's spacecraft was named Vostok 1. It circled Earth at a speed of 27,400 kilometers per hour. The flight lasted 108 minutes. Once he was in orbit, he had no control over his spacecraft, and his reentry was controlled by a computer program. He landed back on Earh safely. Yuri died in a plane crash while in training for his second space mission.

1961 The flight of the Mercury-Redstone 2 tested the rocket in space and return safely, in preparation for the first American astronaut's journey into space. Mercury-Redstone 2 carried a chimpanzee named Ham and helped proved that humans could safely make the trip. Because of Ham’s successful mission, an American astronaut named Alan Shepherd went into sub-orbital space on May 5, He was the first American astronaut in space.

1967 Five Lunar Orbiter missions were launched in 1966 and 1967 with the purpose of mapping the lunar (moon) surface before the Apollo landings. All five of these missions were successful, and 99% of the moon was photographed. The first three lunar orbiter missions photographed the twenty different bases that were set up for landing. Lunar Orbiter 4 photographed the entire nearside of the moon, and 95% of the far side. Lunar Orbiter 5 got the rest of the photographs needed for the Apollo missions.

1969 On July 20, 1969 Neil Armstrong, Micheal Collins, and Edwin (Buzz) Aldrin landed on the moon. Neil Armstrong was the first man to set foot on the moon, and as he did so he said the famous quote “One small step for man, One giant step for mankind.” This mission was called Apollo 11. President Kennedy had challenged the nation to have a man set foot on the moon by the end of the 1960’s. He said this because he felt the U.S. was falling behind the Soviet Union in technology. Two short months later, the Apollo 11 landed on the moon.

1971 The Mariner 9 became the first spacecraft to orbit another planet. It was launched on May 30, 1971 and reached Mars on November 13, The 1,116 pound spacecraft orbited Mars two times daily for a year. The Mariner 9 combined two missions (due to the failure of Mariner 8). It mapped 70% of the Martian surface, and studied the changes in the atmosphere and on the surface of Mars.

1971 Salyut 1 was the first space station that was put into orbit. The Soviets launched it on April 19, The main purpose of Salyut 1 was to study the effects of spaceflight on the human body, and to take pictures of the Earth from space. The Salyut was originally called the “Zarya,” but this was changed so their was no confusion between the station and the ground. The first crew tried to dock the station failed, and they returned home. (The air had become toxic, but they all were returned to health). The next crew succeeded in docking, but tragically died 24 days later. The next crew mission was cancelled.

1972 On April 16, 1972 the Apollo 16 was launched from the Kennedy Space Center. It was the fifth Apollo mission that involved humans landing on the moon. The crew members for this mission were John W. Young, Thomas K. Mattingly II, and Charles M. Duke Jr. The main reason for this mission was to investigate the lunar surface in the Descartes highland area. This mission was a success, 95 kilograms of lunar samples were collected. This mission concluded on April 27, 1972.

1973 The Skylab was the first U.S. space station and the world's first big space station. It was launched on May 14th, 1973 by a Saturn V Rocket. Skylab's purpose was to serve as a laboratory for scientific experiments in space until February Three crews visited Skylab. Each of the Skylab crews set new time records. The last crew set a record that was not broken for over 20 years. On July 11, 1979, after six years of orbit, the Skylab reentered the Earth's atmosphere and disintegrated, scattering debris in the Indian Ocean, and parts of Western Australia.

1973 On May 14, 1973 America launched their first space station. It was called the Skylab.

1976 On August 20, 1975 the Viking 1 spacecraft was launched into space. It arrived at Mars on June 19, It consisted of an orbiter and a lander. It was the first U.S. space probe to land on another planet. The main purpose of this mission was to get high resolution images of Mars soil, characterize the composition of the atmosphere and the surface, and to try to find life on Mars. On July 25, 1976, when the Viking 1 was getting images to find a possible landing spot for its sister ship (Viking 2), it spotted a hill that resembled a human face.

1979 While the Skylab was in orbit it took images of the Sun. From these images scientists have discovered that coronal holes do exist. Coronal holes are seen as dark regions in which the hot coronal material is very thin. Before plans to reuse the Skylab with the Space Shuttle could begin, the space station reentered Earth’s atmosphere and disintegrated. That is why further studying in coronal holes has been postponed.

1981 The first reusable space shuttle was launched on April 12, The space shuttle was named Columbia. Of its three main parts, the orbiter space plane, rocket boosters, and external fuel tank, only the fuel tank is not reused after a mission. It was two years behind due to technical troubles. There were only two people on the crew for the first mission in Their names were John W. Young and Robert L. Crippen. Colombia completed many missions before crashing later in the 1980’s.

1983 On April 4, 1983 the Challenger launched for the first time. That mission saw the first spacewalk of the Space Shuttle program, as well as the first satellite in the Tracking and Data Relay System constellation. The shuttle was built by Rockwell International’s Space Transportation Systems Division in Downey, California. It was the second Space Shuttle Orbiter to be put into service, Columbia being the first in service. It took a photo of Earth that shows Australia.

1986 On February 20, 1986, the core module of the space station Mir was launched. Later, six other modules were launched to make seven pressurized modules. Mir served as a microgravity research laboratory where crews conducted experiments in biology, physics, astronomy, meteorology, and spacecraft systems in order to develop the “thing” needed for permanent occupation in space. The Mir space Station stayed in orbit from 1986 to 2001 (15 years).

1990 The Hubble Space Telescope was deployed from the Space shuttle to orbit Earth on April 25, Hubble photos has amazed many people around the globe. It was named after Edwin Hubble. The Hubble telescope was supposed to be launched in 1985, but after the Challenger disaster in 1986 it was postponed. When the telescope finally was launched into space, it had a small problem. The mirror was too flat, it was off by about 50 times smaller than the thickness of a piece of hair. This problem was fixed, and it now has the quality it was supposed to have in the first place. It is still in orbit.

1995 Galileo was made to study Jupiter and its moons. It was launched on October 18, 1989 by the space shuttle Atlantis. It arrived on Jupiter on December 7, 1995, a little more than six years later. Galileo was the first spacecraft to orbit Jupiter, and it launched the first probe into Jupiter's atmosphere. The spacecraft measured atmospheric composition, and directly observed ammonia clouds (pictured). On September 21, 2003, after 8 years of service, and 14 years in space, Galileo’s mission was terminated.

1996 The Mars Pathfinder, launched on December 4, 1996 and safely landed on Mars on July 4, The lander opened, and exposed the Sojourner Rover, which performed many experiments on the Martian surface. The rover carried many scientific instruments to study the atmosphere, climate, geology, and the composition of its rocks and soil. It was powered by solar panels. It has six wheels and is controlled by an Earth-based operator. The flight team lost communication with the Sojourner on September 27, 1997, after 83 days of daily commanding and data return. In all, Sojourner operated 12 times its expected lifetime of seven days.

1998 The first module to be lifted to space (for the International Space Station) was Russia’s Zarya Control Module. It was launched on November 20, The second module to be lifted to space was America’s Unity Node connecting segment. It was lifted on December 4, More modules have been lifted since then, but the International Space Station is still not complete. It is planned to be completed in late 2011.