Scientists at both NASA and Australia's own Deep Space Communication Complex are preparing for the difficult and emotional end.
As Saturn's crushing atmosphere smashes Cassini into hundreds of pieces, Australian scientists in Canberra will be tuning in to its final throes.
The Canberra Deep Space Communication Complex will receive photos and atmospheric data from the satellite until the very end, just as it has for the last 20 years.
The Complex's Glen Nagle says the Canberra base was the first station to make contact with Cassini after its launch from Cape Canaveral in the United States in 1997.
"Then we tracked it throughout its seven-year journey to get all the way to Saturn. We actually, in 2004, provided the communication for NASA to get the first signals as the spacecraft arrived in orbit around that planet. We handled the landing of its Huygens probe on Saturn's largest moon, Titan. And now, of course, we're going to be getting the very last signals, what we're saying is Cassini's last breath of data."
It is one of the most ambitious planetary-exploration missions.
In 13 years orbiting the gas giant and its gigantic moons, Cassini has made groundbreaking discoveries.
Among them are seasonal changes on Saturn and a salty ocean on the moon Enceladus containing simple organisms.
Cassini project scientist Linda Spilker says the mission has been about asking what she calls "grand" questions.
"So the first grand question is, 'Are we alone in the universe?' Has life originated somewhere other than Earth, perhaps in our own solar system? And how did life originate on the Earth? Another grand question is, 'How did the solar system and the Earth within it come to be?' How is it evolving, and where is it headed?"
Cassini's discoveries have led scientists to believe Enceladus and Titan could potentially sustain life, although very different to life as we know it.
NASA's director of planetary science, Dr James Green, says that is why Cassini must be destroyed in a way that leaves no trace.
"Because of planetary protection and our desire to go back to Enceladus and go back to Titan, go back to the Saturn system, we must protect those bodies for future exploration."
The Canberra communication complex will play a crucial role in the final descent, sending a signal with timing codes to control Cassini's final actions.
The probe will hit Saturn's atmosphere at 111,000 kilometres per hour.
The turbulence will tear it apart before each part melts.
At NASA, the Jet Propulsion Laboratory's Earl Maize says it will be quick.
"We won't watch Cassini burn up. What we'll watch it do is slowly turn away from us, and we'll watch the indicator on the radio-science displays that will go down flat, an essentially lost signal. The mission will be over within a minute later."
Glen Nagle says it will be a bittersweet moment for Canberra scientists, too.
"It won't be like losing a friend or a family member. It's actually going to be more, I think, like the end of your favourite TV show, something you've watched for 20 years, great stories and characters. It's just not going to be on again next week. But, fortunately, Cassini's wealth of data that it's sent back -- over 450,000 images, 635 gigabytes of data -- that, we'll be able to go through as re-runs, binge watch it for decades to come."
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