NASA’s Cassini spacecraft has been vaporized. The probe dove into Saturn’s upper atmosphere this morning, and NASA lost the vehicle’s signal at 7:55AM ET, indicating it had broken apart irrevocably during its rapid descent toward the planet. Cassini’s demise officially puts an end to the probe’s 13-year mission at Saturn and wraps up a 20-year tour traveling through space.
It all went more or less like NASA had intended. The mission team behind Cassini has planned to send the spacecraft into Saturn for many years now, in order to protect the planetary system the vehicle has been exploring. Two of Saturn’s moons — Enceladus and Titan — are considered tantalizing places that could potentially host life, and NASA wants to continue studying these worlds in the future. But the agency didn’t want to risk Cassini accidentally crashing into one of these moons and spreading around Earth microbes. So the team decided to bring Cassini closer to Saturn than ever before to do some final science, before sending the probe into the planet to meet its fiery end.
Still, it was an emotional time for everyone involved, as many have been working with this spacecraft for decades. Launched in 1997, Cassini traveled seven years through and across 2.2 billion miles of space to reach Saturn. It then spent more than a decade whirling around the planet and flying close by the many moons in the system, gathering data and making discoveries that many at NASA never even expected. Perhaps Cassini’s biggest revelation was the fact that Enceladus has a global ocean underneath its crust, one that could be habitable. The vehicle has also taught us much about the unique nature of Titan, showing that the moon has lakes and rivers of methane on its surface.
“This has been an incredible mission, an incredible team,” Earl Maize, Cassini’s program manager, said in mission control at NASA’s Jet Propulsion Laboratory once the signal had been lost. “I’m going to call this ‘end of mission.’” His statement was met with applause in the control center.
Even in its final months, Cassini got to collect some of its juiciest data. In April, the mission team maneuvered the spacecraft into its final orbital path around Saturn, known as the “Grand Finale.” This last route took Cassini in the gap between Saturn and its rings, the closest the vehicle has ever come to the planet. The vehicle completed 22 of these orbits, but during each pass, it flew by Titan where it got a little gravitational nudge that pushed the spacecraft closer and closer to the planet. Then on its final pass by Titan this week, the moon gave Cassini just enough of a “goodbye kiss” to send the vehicle on its crash course with Saturn.
But Cassini still made the most of its final descent. Yesterday, the spacecraft took its last images at Saturn, snapping photos of Enceladus as it fell behind the planet. It also captured some final images of Titan and close-ups of Saturn’s rings. Cassini’s last image, taken at 3:59PM ET on Thursday, shows the general area where the spacecraft impacted Saturn.
Here is Enceladus setting, with all the animation frames aligned on Enceladus. pic.twitter.com/1JfJ0FWino— Emily Lakdawalla (@elakdawalla) September 15, 2017
Plus, the spacecraft captured as much data as it could up until the very end. Just a few hours before it entered Saturn’s atmosphere, the mission team made Cassini roll a bit, positioning the vehicle’s instruments toward the planet while pointing its radio antenna at Earth. That way, Cassini could collect detailed data about the atmosphere and then send it back to researchers as quickly as possible.
Cassini’s atmospheric dive started around 6:31AM ET, but researchers didn’t receive word of the vehicle’s destruction until about 83 minutes later. That’s because of the distance between Saturn and Earth, which spans nearly a billion miles. It took a while for Cassini’s last signal from Saturn to travel the vast distance through space and then get picked up by giant receiving antennas in Australia. NASA predicted it would receive the final signal at 7:55AM ET, and wound up getting it about half a minute later than expected.
Just because Cassini no longer exists doesn’t mean the work is over. Scientists still need to decode the last bits of data the vehicle gathered during its plunge, as well as all of the information the probe has received during its journey at Saturn. It could be years before researchers truly understand what Cassini saw during its final descent.
Updated September 15th, 8:45AM ET: This article was updated to include Cassini’s last image ever taken.