Cassini-Huygens is the international collaboration to know about the planet Saturn. Cassini–Huygens is a joint effort by NASA’s Jet Propulsion Laboratory (NASA), European Space Agency (ESA), and the Agenzia Spaziale Italiana (ASI) robotic spacecraft mission currently studying the planet Saturn and its moons. Cassini-Huygens is the first spacecraft to orbit Saturn.

The project is the result of the best technical efforts of 260 scientists from the United States and 17 European nations. The Cassini–Huygens spacecraft was launched on October 15, 1997, from Cape Canaveral Air Force Station’s Launch Complex 40 in Florida and entered into orbit around Saturn on July 1, 2004. It took almost seven years to reach Saturn. It sailed nearly 3.5 billion kilometers.

The spacecraft has two elements:

• The Cassini orbiter, named after the Italian-French astronomer Giovanni Domenico Cassini (1625-1712).
• The Huygens probe, named after the Dutch astronomer, mathematician, and physicist Christiaan Huygens (1629-1695).

It is 6.8 m in length with a 4 m high gain antenna. At launch, the spacecraft had a mass of 5,655 kg. There are 12 instruments on the Cassini orbiter and six on the Huygens probe. The total cost of the Cassini–Huygens mission is about US$3.26 billion, including $1.4 billion for pre-launch development, $704 million for mission operations, $54 million for tracking and $422 million for the launch vehicle.

The principal objectives are to:

1. Determine the three-dimensional structure and dynamical behavior of the rings.
2. Determine the composition of the satellite surfaces and the geological history of each object.
3. Determine the nature and origin of the dark material on Iapetus’ leading hemisphere.
4. Study the planet’s magnetosphere – the region of space that’s influenced by Saturn’s magnetic field.
5. To analyze the composition and atmosphere of Saturn.
6. Study the time variability of Titan’s clouds and hazes.
7. Characterize Titan’s surface on a regional scale.

Cassini
Cassini is the largest interplanetary spacecraft ever constructed by NASA. Cassini carries two groups of complex instruments.

1. Remote sensing devices, including visible light and infrared cameras that can take pictures.
2. Radar to directly measure and analyze charged dust particles and magnetic fields.

Cassini has been sending back huge amounts of new information about Saturn, its rings, moons and its magnetic fields.

Cassini has made many discoveries, including:

• Four new moons, a new ring and various new structures in Saturn’s F-ring ·An equatorial ridge around Saturn’s moons Iapetus.
• The E ring acts as a source of plasma for the magnetosphere.
• Winds in Saturn’s atmosphere decrease rapidly with height.
• Enceladus vents water vapour and ice crystals from cracks at its south pole.
• Lightning on Saturn is roughly 1 million times stronger than lightning on Earth.
• Surface details of Saturn’s moon Hyperion.
• Details of cup-like craters filled with hydrocarbons.
• Saturn’s moons Tethys and Dione are flinging great streams of particles into space.

Cassini will continue to explore the moons and rings of Saturn until at least July 31, 2008.

Huygens
On 14th January 2005, the Huygens probe descended through Titan, the largest moon of the planet Saturn, a thick orange atmosphere. Huygens has sensitive instruments to study the atmosphere and surface of Titan. Its camera collected more than a thousand images of Titan’s surface and clouds. Another instrument used radio signals to measure Titan’s winds. Three sensors analyzed the moon’s atmosphere.

Huygens has transmitted atmospheric data during its descent and for 72 minutes on the surface showed:

• Titan has a varied surface with hills, drainage channels and shorelines.
• Titan’s atmosphere was more turbulent than expected.
• Titan’s surface shows processes of weathering and erosion occurring with ice and liquid methane.
• Geysers spewing water vapor and ice crystals high above the moon’s south pole.
• Titan is geologically active.
• There is a source of the eruptions: pockets of liquid water close to the satellite’s surface.

Titan

• Largest moon of the planet Saturn.
• Diameter of 5,150 km.
• Mean distance from Saturn of 1,222,000 km.
• Discovered in 1655 by Dutch mathematician and astronomer Christiaan Huygens.
• Only moon in the Solar System with a substantial atmosphere mostly nitrogen, topped with smoggy orange clouds, which may be covered with liquid ethane lakes.
• Its surface atmospheric pressure is greater than Earth’s.
• It has dry land as well as oceans.