Kedar P Badu

Pokhara:

The Cassini-Huygens mission to Saturn is the most ambitious space exploration mission ever. It is testing the limits of science and technology by going where no spacecraft has ever gone before.

A robot explorer called Cassini is outbound from the Earth on a seven-year trip to the distant planet Saturn and its moon Titan. Cassini was launched from Cape Canaveral, Florida, on October 15, 1997 and will fly into the orbit around the planet on July 1, 2004. Unlike the earlier Voyager probes, which were designed to fly-by several planets, Cassini is dedicated to research in the vicinity of Saturn. The spacecraft are named after two 17th century astronomers, the Italian-French astronomer Jean-Dominique Cassini who made several key discoveries about Saturn, and the Dutch scientist Christian Huygens who discovered Titan.

When the spacecraft arrives close to Saturn in July this year, it will start circling the giant gas planet for four years. Its tour of Saturn will include many fly-bys of the planet’s icy satellites. Cassini is expected to send 300,000 colour pictures by radio to Earth, including pictures of the largest moon, Titan.

The planet Saturn, famous for its icy rings and enigmatic moon, Titan, are the prime pcientific targets of the international Cassini mission, the most ambitious and far-reaching planetary exploration ever mounted by man. Because of the distance from the sun, Cassini could not conduct its mission to Saturn on solar power. Electrical power is supplied to Cassini by a set of radioisotope thermoelectric generators (RTGs), which convert heat from the natural decay of plutonium. This was necessary to keep electronic systems operating at such temperature. Titan is Saturn’s largest moon, nearly as big as the planet Mars and bigger than either of the planets Mercury and Pluto. The Cassini mission marks the first time a space probe has attempted to land on the moon of another planet, providing the first direct sampling of the Earth-like atmosphere of Titan and the first detailed pictures of its previously hidden surface.

The mission is a joint endeavour of US National Aeronautics and Space Administration (NASA), the European Space Agency (ESA) and the Italian Space Agency (Agenzia Spaziale Italiana). A smaller, ESA-built probe, named Huygens, attached to Cassini, will parachute into Titan’s thick atmosphere carrying scientific instruments and will report on the moon’s atmospheric conditions. Saturn is 930m miles away from the Sun, and consequently, about 746m miles away from Earth. It is the second-largest planet in the Solar System and is made up of hydrogen and helium. Its placid-looking, butterscotch-coloured surface masks a windswept atmosphere where jet streams blow at 1,100 miles per hour and swirling storms roil just beneath the cloud tops. With its bright, complex rings, 18 known moons and magnetic environment, Saturn is a lot like a miniature solar system. Saturn’s family of rings and moons is a one-stop treasure trove, offering countless clues to the history and evolution of planets and solar systems.

Spacecraft passing Saturn earlier found a huge, complex magnetic environment — a magnetosphere — where trapped protons and electrons interact with each other, and with the planet, the planet’s rings, and the surfaces of many of the moons. Saturn’s best-known feature — its bright rings — consists not just of a few rings but of hundreds of rings and ringlets broad and thin. The rings are composed of ice and rock particles ranging in size from grains of sand to boxcars. Although it is believed to be too cold to support life, haze-covered Titan is thought to hold clues to how the primitive Earth evolved into a life-bearing planet. It has an Earth-like, nitrogen-based atmosphere and a surface that many scientists believe probably features chilled lakes of ethane and methane. As Saturn is too far away from Earth (10 times farther away than the Sun), rockets need to acquire great speed to get there.

In order to pick up this speed, Cassini had to fly past Venus, Earth and Jupiter to gain the advantage gravity and to boost its speed and fling it towards ‘destination Saturn’.

Through Cassini, scientists from all over the world hope to gain a better understanding of Saturn, its famous rings, its magnetosphere, Titan, and its other icy moons. Cassini is probably the most ambitious space exploration mission ever launched and is the fruit of active international collaboration. It should be the prelude for future exploration of our surroundings.