Space: Cassini-Huygens (spacecraft)

American spacecraft sent to the planet Saturn. It is a flagship-class NASA-ESA-ASI robotic spacecraft sent to the Saturn system. It has studied the planet and its many natural satellites since arriving there in 2004, also observing Jupiter and the heliosphere, and testing the theory of relativity.

Launched in 1997 after nearly two decades of development, it includes a Saturn orbiter and an atmospheric probe/lander for the moon Titan called Huygens, which entered and landed on Titan in 2005. Cassini is the fourth space probe to visit Saturn and the first to enter orbit, and its mission is ongoing as of 2014. The two-part spacecraft is named after astronomers Giovanni Cassini and Christiaan Huygens.

The spacecraft was launched 15 October 1997 aboard a Titan IVB/Centaur and entered orbit around Saturn on 1 July 2004, after an interplanetary voyage which included flybys of Earth, Venus, and Jupiter. On 25 December 2004, Huygens separated from the orbiter at approximately 02:00 UTC.

It reached Saturn's moon Titan on 14 January 2005, when it entered Titan's atmosphere and descended to the surface. It successfully returned data to Earth, using the orbiter as a relay. This was the first landing ever accomplished in the outer Solar System.

Nearly a decade after entering orbit, on 3 April 2014, NASA reported that evidence for a large underground ocean of liquid water on Enceladus, a moon of Saturn, had been found by Cassini. According to scientists, evidence of an underground ocean suggests that Enceladus is one of the most likely places in the solar system to "host microbial life".

On 30 June 2014, NASA celebrated ten years of Cassini exploring Saturn and its moons, highlighting the discovery of water activity on Enceladus among other findings.