The Odyssey begins...

    For sure, you are not the first person to explore the galaxy. We are standing on the firm foundation laid over centuries by generations of passionate scientists and astronauts. The space odyssey, a dream shared by many, started then...

A. Early Developments

    During the centuries when space travel was only a fantasy, researchers in the sciences of astronomy, chemistry, mathematics, meteorology, and physics developed an understanding of the solar system, the stellar universe, the atmosphere of the Earth, and the probable environment in space. In the 7th and 6th centuries BC, the Greek philosophers Thales and Pythagoras noted that the Earth is a sphere; in the 3rd century BC the astronomer Aristarchus of Samos asserted that the Earth moved around the Sun. Hipparchus, another Greek, prepared information about stars and the motions of the Moon in the 2nd century BC. In the 2nd century ADPtolemy of Alexandria placed the Earth at the centre of the solar system in his cosmic scheme, now called the Ptolemaic system.

B. Scientific Discoveries

    Not until some 1,400 years later did the Polish astronomer Nicolaus Copernicus systematically explain that the planets, including the Earth, revolve about the Sun (see Copernican System). Later in the 16th century the observations of the Danish astronomer Tycho Brahe greatly influenced the laws of planetary motion set forth by Kepler. Galileo, Edmond Halley, Sir William Herschel, and Sir James Jeans were other astronomers who made contributions pertinent to astronautics.
Celestial Models by Ptolemy and Copernicus

    Physicists and mathematicians also helped to lay the foundations of astronautics. In 1654 the German physicist Otto von Guericke proved that a vacuum could be maintained, refuting the old theory that nature "abhors" a vacuum. In the late 17th century Newton formulated the laws of universal gravitation and motion. Newton's laws of motion established the basic principles governing the propulsion and orbital motion of modern spacecraft.
Despite the scientific foundations laid in earlier ages, however, space travel did not become possible until the advances of the 20th century provided the actual means of rocket propulsion, guidance, and control for space vehicles.

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