Cassini is an unpiloted spacecraft sent to the planet Saturn. It is a Flagship-class NASA–ESA–ASI robotic spacecraft. Cassini is the fourth space probe to visit Saturn and the first to enter orbit, and its mission is ongoing as of April 2017. It has studied the planet and its many natural satellites since arriving there in 2004.
Development started in the 1980s. Its design includes a Saturn orbiter (Cassini) and a lander (Huygens) for the moon Titan. The two spacecraft are named after astronomers Giovanni Cassini and Christiaan Huygens. The spacecraft launched on October 15, 1997 aboard a Titan IVB/Centaur and entered orbit around Saturn on July 1, 2004, after an interplanetary voyage that included flybys of Earth, Venus, and Jupiter. On December 25, 2004, Huygens separated from the orbiter, and it landed on Saturn's moon Titan on January 14, 2005. It successfully returned data to Earth, using the orbiter as a relay. This was the first landing ever accomplished in the outer Solar System.
Cassini continued to study the Saturn system in the following years, and continues to operate as of April 2017. However, since November 30, 2016, due to the spacecraft's dwindling fuel resources for further orbital corrections, Cassini entered the final phase of the project. Cassini will dive through the outer ring of Saturn 22 times, once every seven days. The spacecraft will enter areas that have been untouched up until this point, getting the closest look ever at Saturn's outer rings. The first pass of the rings took place on December 4, 2016.
Cassini is currently planned to be destroyed by diving into the planet's atmosphere on September 15, 2017, when it will beam its last batch of images. This method of disposal was chosen to avoid potential biological contamination of Saturn's moons.
Seventeen countries make up the team responsible for designing, building, flying and collecting data from the Cassini orbiter and Huygens probe. The mission is managed by NASA's Jet Propulsion Laboratory in the United States, where the orbiter was assembled. Huygens was developed by the European Space Research and Technology Centre. The Centre's prime contractor, Aérospatiale of France (now Thales Alenia Space), assembled the probe with equipment and instruments supplied by many European countries (Huygens' batteries and two scientific instruments by the United States). The Italian Space Agency (ASI) provided the Cassini orbiter's high-gain radio antenna, with the incorporation of a low-gain antenna (to ensure telecommunications with the Earth for the entire duration of the mission), a compact and lightweight radar, which also uses the high-gain antenna and serves as a synthetic aperture radar, a radar altimeter, a radiometer, the radio science subsystem (RSS), the visible channel portion VIMS-V of VIMS spectrometer. The VIMS infrared counterpart was provided by NASA, as well as Main Electronic Assembly, which includes electronic subassemblies provided by CNES of France.
On April 16, 2008, NASA announced a two-year extension of the funding for ground operations of this mission, at which point it was renamed the Cassini Equinox Mission.This was again extended in February 2010 with the Cassini Solstice Mission.