When NASA’s Cassini spacecraft took off from Earth for Saturn over 11 years ago, researchers never could have imagined what they would find on the ringed planet and its moons. According to a report from Discovery News, the Cassini mission is finally coming to a close, and it passed Saturn’s moon Enceladus, complete with an icy crust and an underground ocean, for the last time on Saturday.

NASA has learned some amazing things about Saturn and its moon Enceladus over the course of the Cassini mission. One of the most significant findings so far is that Enceladus emits plumes of vapor and ice full of organic molecules from a network of cracks along the southern polar region. Researchers suspect that these plumes come from a massive ocean that rests below the icy surface of Enceladus. They think the ocean also comes into direct contact with rock, which would, in theory, provide the chemical reactions necessary for creating some of the most basic building blocks of life.

Cassini came within just 3,106 miles of Enceladus at about 1pm EST on Saturday. Researchers were hoping to determine the amount of heat that is being released from the ice in the center of the moon, which would help them to find out the specific chemical makeup of the gas in the plumes.

“Understanding how much warmth Enceladus has in its heart provides insight into its remarkable geologic activity, says Linda Spilker, a scientist working on the Cassini project from NASA’s Jet Propulsion Laboratory in Pasadena, CA.

Cassini will continue to gather data about Enceladus as it carries out the rest of its mission, but it will be at least four times as far away as it completes its final orbits of Saturn. In October of 2008, the space probe came within just 16 miles of the moon. The flyby on Saturday marked Cassini’s 22^nd pass of the moon.

A NASA press release describing the final flyby of Saturn’s moon Cassini can be found here.