By any definition, NASA’s Cassini spacecraft has been a massive success. The 20-year-old planetary probe has studied Saturn, its moon system, and its rings, since 2004. The mission was originally slated to last only four years, but it’s been extended twice, and the damn thing is still going.

Cassini is finally running out of gas, and it will meet its doom in Saturn’s atmosphere in September of 2017. But before then, it may uncover a few more mysteries.

A couple of weeks ago Cassini began a series of maneuvers that will take it very close to Saturn’s outer rings, just barely grazing them to take measurements of their densities and that of some of Saturn’s moons.

But next April, Cassini will go where no spacecraft has gone before — in between the planet and its inner rings. There, it may solve a big mystery: the mass of Saturn.

Scientists have known the mass of Saturn and its rings, but Cassini will solve the mystery of the mass of the rings themselves and that of Saturn minus the rings. Here’s what Cassini’s daredevil orbit will look like from its point of view:


Then, in September, Cassini’s final suicide mission will end in the planet’s atmosphere, once again going where no space probe has gone before. On its way down, it will take readings and attempt to send them back to earth. However, NASA scientists caution that the spacecraft’s thrusters weren’t designed for that maneuver, so it’s unclear if any data will get back to us.

But we’ve already received a treasure trove of information: We’ve seen Saturn’s hexagon-shaped south pole up close:


Cassini also found evidence of an underground ocean on Enceladus, one of Saturn’s many moons. We learned how new moons could form out of Saturn’s rings. Cassini found surprisingly Earth-like geographic features on Titan, including great lakes of liquid natural gas that outweigh all the oil and gas reserves here at home.

The probe has lasted far longer than scientists and JPL mission specialists had expected, but these final maneuvers may end it before its suicide plunge into Saturn. Rocks and debris from near the rings may destroy the craft or damage it enough to disable its ability to gather information or send it back to Earth.

But even if that happens, we’ve learned a few lifetimes’ worth of lessons from the ringed planet and its moons. Here’s hoping that humankind one day gets to see them with its own eyes.