When Cassini arrived at Saturn, where one "year" lasts 29.5 Earth years, the gas giant went through northern winter, and Cassini was there to witness the planet's change of seasons. "The haze has cleared remarkably as the summer solstice has approached", Cassini Project Scientist Linda Spilker said in a news conference September 13.
"That will enable sampling instruments, particularly the ion and neutral mass spectrometer, to get data as deep into the atmosphere as Cassini will permit it", he said. The ice was feeding into the rings of the planet. That's why, on Friday, it will slam itself into Saturn's atmosphere.
Cassini's last five orbits will take it through Saturn's uppermost atmosphere, before a final plunge directly into the planet on September 15.
This will likely happen around 6:30 a.m. "It will radiate across the solar system for almost an hour and a half after Cassini itself has gone", Cassini project manager at Nasa's Jet Propulsion Laboratory in Pasadena, California, Earl Maize said.
Along its way, Cassini (and its Titan-bound companion, the atmospheric entry probe Huygens) captured hundreds of thousands of images and taught us more about Saturn, its rings and many moons.
To mark the impending end of the mission, The Planetary Society released a video of its board member, "Star Trek" actor Robert Picardo, performing the "Le Cassini Opera," a humorous, musical farewell to the spacecraft.
Via an worldwide collaboration, Cassini brought Europe's Huygens lander to the Saturn system and dropped it down on Titan, giving Earthlings a stunning view of the moon's liquid oceans and complex organic atmosphere.
Cassini data and observations revealed that while seemingly inhospitable to us, two of Saturn's moons, Enceladus and Titan, could be potentially habitable for some form of life.
By destroying Cassini, NASA ensures that spacecraft doesn't inadvertently contaminate either moon with microbes carried billions of miles from Earth.
The long-lived spacecraft's fateful dive was the final beat in the mission's Grand Finale, which began in late April, through the gap between Saturn and its rings.
While the crash of Cassini has been planned for months, the expressions of grief over the upcoming end of the mission are still overflowing.
"We've had exceptional performance, and we couldn't have asked for much more", said Earl Maize, Cassini's project manager at the NASA Jet Propulsion Laboratory, per Scientific American.
Esposito says Cassini has helped scientists better understand Saturn.
In the end, Cassini will have witnessed half of a Saturn year. It was the first mission that was launched to specifically study Saturn and was the first to go near enough to the planet to take detailed images since the Pioneer and Voyager crafts flew by it, several decades before it.
But as with all things involving spaceflight, the reason for Cassini's collision course with Saturn is nothing if not practical.
NASA recreated a Cassini image of a backlit Saturn using a collage of about 1,600 photos of people waving at the ringed planet as part of social media campaign in 2013.
During the dive there is also a concern that Cassini might impact with ring material - space stuff the size of a grain-of-sand that could damage an instrument or the entire spacecraft.