Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. The spacecraft consists of two main elements: the NASA Cassini orbiter, named in honor of the Italian-French astronomer Giovanni Domenico Cassini, and the ESA Huygens probe, named after the Dutch astronomer Christiaan Huygens. It was launched on October 15, 1997 on a Titan IV/Centaur launch vehicle, and entered into orbit around Saturn on July 1, 2004 after nearly seven years of interplanetary journey. On December 25, 2004 the Huygens probe separated from the orbiter at approximately 02:00 UTC, with deployment confirmed by the Jet Propulsion Laboratory. The probe arrived at Saturn's moon Titan on January 14, 2005, where it made an atmospheric descent to the surface and relayed scientific information. It is the first spacecraft to orbit Saturn and the fourth spacecraft to visit Saturn.


Cassini's principal objectives are to:

  1. Determine the three-dimensional structure and dynamic 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's leading hemisphere
  4. Measure the three-dimensional structure and dynamic behavior of the magnetosphere
  5. Study the dynamic behavior of Saturn's atmosphere at cloud level
  6. Study the time variability of Titan's clouds and hazes
  7. Characterize Titan's surface on a regional scale

The Cassini-Huygens spacecraft was launched on October 15, 1997 from Cape Canaveral Air Force Station's Launch Complex 40 using a U.S. Air Force Titan IV-B/Centaur launch vehicle. The launch vehicle was made up of a two-stage Titan IV booster rocket, two strap-on solid rocket motors, the Centaur upper stage, and a payload enclosure, or fairing. The complete Cassini flight system was composed of the launch vehicle and the spacecraft.

The spacecraft is composed of the Cassini orbiter and the Huygens probe. The Cassini orbiter is planned to orbit Saturn and its moons for four years, and the plan sees the Huygens probe dive into the atmosphere of Titan and land on its surface. Cassini-Huygens is an international collaboration between three space agencies. Seventeen nations contributed to building the spacecraft. The Cassini orbiter was built and managed by NASA/CalTech's Jet Propulsion Laboratory. The Huygens probe was built by the European Space Agency. The Italian Space Agency provided Cassini's high-gain communication antenna, and a revolutionary compact and light-weight multimode radar (synthetic aperture radar, radar altimeter, radiometer).

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 U.S. contributed $2.6 billion, the European Space Agency $500 million and the Italian Space Agency $160 million.


Cassini-Huygens's roots traces back to 1982, when the European Science Foundation and the American National Academy of Sciences formed a working group to investigate future cooperative missions. Two European scientists suggested a paired Saturn Orbiter and Titan Probe as a possible joint mission. In 1983, NASA's Solar System Exploration Committee recommended the same Orbiter and Probe pair as a core NASA project. NASA and the European Space Agency (ESA) performed a joint study of the potential mission from 1984 to 1985. ESA continued with its own study in 1986, while American astronaut Sally Ride, in her influential 1987 report "NASA Leadership and America's Future in Space," also examined and approved of the Cassini mission.

While Ride's report described the Saturn orbiter and probe as a NASA solo mission, in 1988 the Associate Administrator for Space Science and Applications of NASA Len Fisk returned to the idea of a joint NASA and ESA mission. He wrote to his counterpart at the ESA, Roger Bonnet, strongly suggesting that the ESA choose the Cassini mission from the three candidates at hand and promising that NASA would commit to the mission as soon as ESA did.

At the time, NASA was becoming more sensitive to the strain that had developed between the American and European space programs as a result of European perceptions that NASA had not treated it like an equal during previous collaborations. NASA officials and advisors involved in promoting and planning Cassini-Huygens attempted to correct this trend by stressing their desire to evenly share any scientific and technology benefits resulting from the mission. In part, this newfound spirit of cooperation with Europe was driven by a sense of competition with the Soviet Union, which had begun to cooperate more closely with Europe as the ESA drew further away from NASA.

The collaboration not only improved relations between the two space programs but also helped Cassini-Huygens survive congressional budget cuts in the US. Cassini-Huygens came under fire in both 1992 and 1994, but NASA successfully persuaded the U.S. Congress that it would be unwise to halt the project after the ESA had already poured funds into development because frustration on broken space exploration promises might spill over into other areas of foreign relations. The project proceeded politically smoothly after 1994, although, as noted below, citizens groups concerned about its potential environmental impact attempted to derail it through protests and lawsuits until and past its 1997 launch.

The Grand Finale

After 20 years in space, Cassini's spacecraft is running out of fuel. In order to preserve and protect moons of Saturn that could be suitable for life; a spectacular end has been planned for Cassini. After many years of exploration including the Huygens probe landing, Cassini is planned to begin its end.

The last assignment of Cassini, known as the Grand Finale, is a mission in its self. Performing 22 dives between Saturn and its rings. While performing these daring dives, it seeks the origins of Saturn's rings and the nature of the planet's interior. The first dive beginning on April 26, 2017.

On September 15, 2017, Cassini will complete its final dive; closest to Saturn, Cassini will plunge into Saturn while fighting to keep its antenna pointed at Earth as it transmits its farewell. In the sky's of Saturn, Cassini becomes part of the planet itself.

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