The universe and the solar system

Witness the birth of the Universe and the Solar System at the Space Museum of the Guiana Space Centre :

The Solar System is made up of the Sun and certain other heavenly bodies, particularly the planets which orbit it.
Apart from the Sun itself, the Solar System includes nine principal planets, thousands of asteroids, comets, meteorites and interplanetary dust.

All the principal planets revolve within a disk whose radius is about 6 billion kilometres (or 40 times the average distance between the Earth and the Sun), but it is believed that there is a vast concentration of comet nuclei (the Oort cloud) at distances somewhere between 40,000 and 100,000 times the distance from the Earth to the Sun. The closest star in the Solar System, Proxima Centauri, is 4.2 light years away (i.e. over 40,000 billion kilometres).

Mankind has always looked to the heavens to help him gauge the passing of time, foresee the weather, seek religious inspiration or get his bearings on land or sea. From his observations of the skies he has been able to establish calendars, catalogue the stars and develop mathematical formulas which have slowly opened his eyes to the infinity of Space. Through astronomy Man also made one amazing discovery: the Earth is not the centre of the Universe. The first great discoveries overturned many beliefs and certainties about Man’s place in Space and what lay beyond the confines of our world. Come and follow Copernicus, Tycho Brahe, Kepler, Galileo and Newton on their intellectual journeys.

Exploring the Solar System sounds great but how do we get there?

"The Earth is the cradle of Mankind, but no one lives in his cradle for ever." With these words the pioneer of aeronautics Tsiolkovsky summed up the history of Space Exploration and the desire of Mankind to learn more about the Universe around us.

Once the Earth had been measured out, studied and classified, human curiosity turned to those more distant worlds, the planets, that astronomers had observed from the Earth with telescopes and other optical instruments.
But how were they to break the irresistible grip of gravity and rise above the Earth’s surface to get there? How could they travel in Space, without continuously accelerating?

Beyond our atmosphere, space vehicles travel by jet propulsion (reaction). The principle had been known and applied for centuries (fireworks were invented by the Chinese in the Middle Ages!), but the theory was only understood at the end of the 17th Century when Isaac Newton stated the principle that “every action has an equal and opposite reaction”. Two hundred years later, the Russian Tsiolkovsky in his book ‘Free Space’ seems to have been the first to think of using reaction propulsion for voyages through the cosmos. The first rocket engines were built at the beginning of the 20th Century.
A rocket engine is an autonomous system: it carries the propellants it needs for fuel. Since it requires no physical support it can function either in the atmosphere or in the Space vacuum.

It is propelled forward by the expulsion of gases in the opposite direction.

Under warm indirect lighting, these modules reveal the secrets of the propulsion systems of the Ariane family of launchers. No heavier than a large car, Vulcain, Ariane 5’s main engine, can provide 114 tonnes of thrust! Its cryogenic engine consumes 800 litres of liquid propellant per second (the equivalent of eight full bath-tubs) thanks to two turbo-pumps, of which the one for hydrogen is as powerful as two high-speed trains (16,000 HP). Temperatures in the combustion chambers reach 3,200°C and the gases leave the nozzle at the hypersonic speed of 4.5 km/sec, five times faster than a rifle bullet!