It's been just under 20 years since NASA's Cassini spacecraft left Earth for its mission to Saturn - but in just a few days, it will undertake its Grand Finale, intentionally plummeting into Saturn's atmosphere to be pressurized into oblivion.
Its mission extended twice, Cassini's findings transformed scientists' understanding of Saturn, its rings and its moons.
Funded with $3.9B from NASA, the European Space Agency, and the Italian Space Agency, the mission honors Giovanni Cassini, the 17th century Italian astronomer who spotted four of Saturn's moons, and Christiaan Huygens, his Dutch contemporary who discovered Titan and was first to propose that Saturn had rings. "Cassini's final weak radio signals will have travelled 1.5 billion km at the speed of light to reach Canberra".
Cassini has spent the past 13 years exploring Saturn, its dramatic rings and its icy moons.
Cassini is on course to dive into Saturn to ensure that the planet's moons - in particular, Enceladus, with its subsurface ocean and signs of hydrothermal activity - remain pristine for future exploration.
Moving closer to Titan, the spacecraft took advantage of the massive moon's gravitational push to make the first of 22 weekly dives between Saturn and its rings - venturing for the first time into the uncharted 1,700-mile (2,700-kilometer) space.
"In Cassini's final orbit, plunging into Saturn's atmosphere, sending back science until the very last second ... we'll continue to learn from Cassini long after the end of the mission", said Spilker.
It also found seven new moons, six of which have been named, carried out detailed studies of Saturn's rings, and spotted raging hurricanes at both of Saturn's poles.
If you could magically teleport across the solar system, Saturn would be a great place to swing by on Friday morning.
The final pictures taken by Cassini will have been transmitted several hours earlier.
Right up until it beams its final signals to Earth eight of the spacecraft's 12 scientific instruments will be gathering data from the top of Saturn's atmosphere and transmitting information about its structure and composition.
During many flybys, Cassini monitored the dynamic Titan using its camera suite and an instrument called VIMS, a Visual and Infrared Mapping Spectrometer.
Cassini gazed toward the northern hemisphere of Saturn to spy subtle, multi-hued bands in the clouds there.
Still, "this mission has been going for so long, it's a little hard to believe that it's over", he says. It arrived six years later, having navigated the risky asteroid-belt that lies between us and Saturn, but with only basic instrumentation on board it wasn't able to gather much scientific data.
As the spacecraft is once again back online, it also began streaming back the data it gathered during its latest encounter with the moon. Among Cassini's objectives is the study of Saturn's rings, Titan's atmosphere, and the behavior of Saturn's magnetosphere. This time may change as Saturn's atmosphere slows Cassini during each of the final orbits.
One of Cassini's last looks at Saturn and its main rings from a distance.
"Its true legacy is how NASA responds to the observations it made and then make decisions on how to utilize those in another series of missions", stated Green.