The Cassini–Huygens mission, commonly called Cassini, was a collaboration between NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a probe to study the planet Saturn and its system, including its rings and natural satellites. Cassini was active in space for nearly 20 years, with 13 years spent orbiting Saturn, studying the planet and its system after entering orbit on July 1, 2004.[8] The voyage to Saturn included flybys of Venus (April 1998 and July 1999), Earth (August 1999), the asteroid 2685 Masursky, and Jupiter (December 2000). Its mission ended on September 15, 2017, when Cassini’s trajectory took it into Saturn’s upper atmosphere and it burned up[9][10] in order to prevent any risk of contaminating Saturn’s moons, which might have offered habitable environments to stowaway terrestrial microbes on the spacecraft