This mission was the first of its kind as no other Spacecraft had ever ventured so close to the planet before Cassini. ESA's Huygens probe to the surface of Titan flew to Saturn mounted to Cassini and the agency was a partner with NASA and the Italian Space Agency, ASI, on the mission.
Within a year of arriving at Saturn, Cassini captured images of plumes of water vapor jetting out from near the moon's south pole.
The Ion and Neutral Mass Spectrometer will act as the "nose" of the spacecraft, directly sampling the composition and structure of the atmosphere - something that can't be done from orbit, said Hunter Waite, team lead for the spectrometer. The ice was feeding into the rings of the planet.
By 3:30 a.m., Cassini will be gone.
Cassini's team is reconfiguring the spacecraft to send back scientific data in "near real time". "It will radiate across the solar system for almost an hour and a half after Cassini itself has gone", Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory in Pasadena, Cal., said in a news release. A joint mission with the European Space Agency, a single rocket sent Cassini and Huygens on a meandering path through the Solar System. A flyby of Saturn's largest moon, Titan, on September 11 put Cassini on an irreversible trajectory for that final encounter with the planet. It's information that will be studied and analyzed by scientists long after the end of Cassini.
RINGS: Cassini discovered swarms of moonlets in Saturn's rings, including one called Peggy that made the short list for final picture-taking.
Titan - a moon of Saturn the size of planet Mercury - may also have a liquid ocean. So instead of letting the spacecraft orbit around Saturn, operators have used its last fumes of fuel to purposely crash it instead of running the risk of letting it hit a moon and potentially contaminate it, according to NASA's Jet Propulsion Laboratory.
"To find that there's an ocean world so tiny with a possibility of life, so far from the sun - 10 times farther from the sun than the Earth - has opened up our paradigm of where you might look for life, both within our own solar system, and in the exoplanet systems beyond", Linda Spilker, a Cassini project scientist and a planetary scientist at NASA JPL, said of Enceladus during the press conference. And surely that will continue with its final dive, she said.
NASA scientists at mission control expect to lose contact with Cassini at 7:55 a.m. EDT. The mission launched in 1997, and has essentially revolutionized our understanding of how Saturn and its complex system of 53 official moons works.
In the end, Cassini will have witnessed half of a Saturn year. During the same era, Dutch mathematician Christiaan Huygens found that Saturn had rings. A set of planet-themed stamps issued in May 2016 chose a Hubble Space Telescope image of Saturn over one of Cassini's images.
The 20-year mission to get up close and personal with Saturn and its moons will end when the 22-foot robot burns up in the ringed planet's cloud tops. Cassini has collected 450,000 images using a visible light camera. "It's one of the things we expected to learn, but have not".
And the spacecraft itself, as well as its instruments, are informing future missions that NASA has planned, like NASA's Europa Clipper mission to explore Jupiter's icy moon, launching in the 2020s.