"Cassini has enabled those future missions to be possible", said Jim Green, NASA's director of planetary science. Following a gravity assist from Saturn's moon, Titan, the R-4D main engine was sacked to fine-tune the trajectory, during which Cassini passed just outside of Saturn's main rings 20 times.
A Vox report explains that keeping Cassini going could potentially risk contaminating one of Saturn's moons - such as Enceladus or Titan - with microbes from Earth. A few minutes before 8 am Eastern Time, Cassini hurtled to its end.
Since April 2017, NASA's Cassini spacecraft has been writing the final, thrilling chapter of its remarkable 20-year-long story of exploration, its Grand Finale. The probe spent about three and half hours analyzing Titan's atmosphere and surface until its battery died, leaving Cassini on its own.
Cassini's imaging camera will take a last look at the Saturn system on the day before the plunge and will be off during this final descent.
Though Cassini's life was extended twice with new missions, the spacecraft had a limited fuel supply.
During Cassini's thirteen years in orbit around Saturn, it danced among the moons and rings to study the world in unprecedented detail. The Australian team will be monitoring the last signals for information about the planet's atmosphere, fed from complex UV, infrared and particle monitoring equipment on-board.
'We'll raise a glass, or two, in the pub to Cassini on Friday lunchtime and will remember our involvement fondly and with great pride'. Cassini will make a final pass-by of Titan - Saturn's moon - which will put it on a collision course with Saturn, and then, there will be no way to stop the spacecraft from crashing.
Project manager Earl Maize said: "Congratulations to you all".
At NASA's Jet Propulsion Laboratory (JPL) in California, scientists and engineers, some of whom have been on the mission since its conception in the 1980s, will gather in the early hours of Friday morning to witness Cassini's final moments before joining other missions, perhaps to Jupiter or Mars.
No spacecraft has ever ventured so close to the planet before.
The odyssey "Cassini" will be completed.
Cassini, an global project that cost $3.9 billion and included scientists from 27 nations, has run out of rocket fuel as expected after a journey of some 7.9 billion kilometers. Among other things, the probe discovered water spewing from Enceladus, discovered that Hyperion has a statically charged surface and that Saturn's entire moon system - a virtual mini solar system in itself - exchanges dust and chunks of material with the planet's ring system.
However, there's another reason for ending the mission in such a spectacular fashion: "We have the opportunity to do some really cool science", Bittner says.
"This is the first time that we have found so numerous essential components for life in one place beyond our own planet", Perry said.
NASA now has no missions on the books to return to Cassini, although agency officials noted that both Saturn and its moons Enceladus and Titan are potential destinations for NASA's next New Frontiers medium-class mission, the competition for which is ongoing. And Titan not only has seas and lakes of liquid ethane and methane, it has an atmosphere of chemicals that rain down, forming a unique chemistry that could lead to life. "The mood of the team heading toward end of mission is a mix of joy and satisfaction, given the mission's enormous success, tinged with sadness at the impending loss of their stalwart spacecraft".