 Today is the Cassini spacecraft's last full day in space. That's because early tomorrow morning, the NASA probe will plunge into Saturn's atmosphere where it will burn up and break apart. But don't worry, this is supposed to happen. Three, two, one, and liftoff of the Cassini spacecraft on a billion mile trek to Saturn. Cassini has been whirling around Saturn and its many icy moons for 13 years now. Launched in 1997, the probe traveled through space for seven years before reaching Saturn in 2004. Since then, Cassini has taken various paths around the planet, shifting orbits numerous times to fly close by certain targets. Its flight path looks kind of like a big ball of yarn. But that complicated route has enabled Cassini to make some big discoveries. We now know there's an ocean under the crust of Saturn's moon Enceladus, and that those waters may even be habitable. We also know that Earth-like processes happen on the moon Titan, such as methane rainfall that creates lakes and rivers. And there are the photos. Stunning, iconic views of Saturn and its rings, taken in vivid detail by the Cassini's onboard camera. There's even a shot of Earth from Saturn's perspective. But Cassini's time at Saturn was never meant to last. The spacecraft has limited fuel onboard, and eventually the mission team was always going to lose the ability to maneuver the vehicle in space. And NASA doesn't want to risk Cassini contaminating the Saturn system. Both Enceladus and Titan could harbor life. But we'd never know for sure if the probe accidentally wandered too close and exposed one of the moon's to Earth microbes. So the Cassini team came up with a unique way to dispose of the vehicle. The grand finale. In April, the engineers maneuvered Cassini into a new orbit that took the vehicle into the gap between Saturn and its famous rings. It's an area the vehicle had never been before, and it allowed NASA to get some up-close measurements of Saturn and its atmosphere. Cassini has completed 22 of these grand finale orbits so far, and with each orbit, the spacecraft has gotten a little gravitational nudge from Saturn's moon Titan. Then on Monday, Cassini passed by Titan one final time, getting a gravitational goodbye kiss that put the vehicle on a crash course with Saturn. Now Cassini is headed for Saturn's atmosphere no matter what. But NASA is going to get as much as it can out of the spacecraft before it's lost. Just before the dive, the mission team is going to roll the vehicle so that its instruments point toward Saturn's atmosphere, while its antenna points toward Earth. That way, Cassini can send back its data on Saturn's atmosphere in real time before it finally, inevitably, burns up on entry. After it's gone, though, there's going to be a lot of data to process. Heck, it may even take years for scientists to fully decode all the information Cassini captures during its last orbits and dive into Saturn's atmosphere. So the work isn't done yet. Still, tomorrow's going to be a bittersweet moment for the mission team, which has been working with this spacecraft for over a decade. I, for one, am not ready to say goodbye.