After 11 years exploring the Saturn system, NASA’s Cassini spacecraft is saying goodbye to the moon Enceladus after a final approach this weekend.

The Cassini mission will end formally in September 2017, and over the course of its time in the Saturn system it has resulted in some pretty amazing discoveries and a better understanding of our solar system, according to a Discovery News report.

The Cassini mission has been looking more closely at plumes of vapor from Enceladus filled with organics that could lead to the creation of life. Enceladus is an icy moon but it has oceans beneath the surface.

Cassini was scheduled to come just 3,106 miles from Enceladus in order to determine how much heat was coming from the moon’s interior and better understand what kind of geologic activity is happening deep underneath its shell of ice, and perhaps causing these plumes.

Cassini will make further observations of Enceladus, but from a much farther distance than this approach. It’s not the closest the spacecraft has been: it once came just 16 miles from the surface back in October 2008. It’s the 22nd time the spacecraft has been near the intriguing moon.

Enceladus is the sixth largest moon in the Saturn system, measuring about 310 miles in diameter, which is just a tenth of the size of Titan, the largest moon of Saturn.

The moon was discovered back in 1789 by William Herschel, and was first visited by two Voyager spacecraft in the early 1980s. But it wasn’t until Cassini arrived in 2005 that we started to get much greater detail on the surface and environment of Enceladus, which is covered in a shell of fresh, clean ice that reflects most sunlight. Its surface temperature at its highest point during the day reaches a frigid -324.4 degrees Fahrenheit.