Largest, most intense storm observed on Saturn, captured on Feb. 25, 2011. Credit: NASA/JPL-Caltech/SSI
Among Cassini's many more achievements, the vertical structures in Saturn’s rings were imaged for the first time. New phenomena were observed in Saturn's rings which were revealed to be active and dynamic. At both of Saturn’s poles giant storms and hurricanes were discovered. Cassini studied Saturn’s great northern storm of 2010-2011, which encircled the entire planet for months. With Cassini’s help, the long-standing mystery of the dual, bright-dark surface of the moon Iapetus could be solved.
Though, some of Cassini’s most astonishing discoveries were made on Saturn’s moon Enceladus, an icy moon a tenth the size of Titan. On Enceladus, Cassini found a liquid-water ocean buried under an outer layer of ice escaping to the surface via geysers. More than 100 geysers were found to spout from the moon’s south polar region, creating a plume of tiny ice particles and vapor extending hundreds of kilometers above the surface, a fraction of the solid mass in this plume extending even farther to form Saturn's large E ring.
Cassini scientists found evidence suggesting the moon's global ocean hosts active hydrothermal vents which would be a hint to biological activity. Released from ice particles in the ejected plume on Enceladus, tiny bits of rock were analyzed and found to be silica, and among other findings pointed to hydrothermal activity.
South polar region of Enceladus with jets erupting from fractures in the moon's crust. Credit: NASA/JPL-Caltech/SSI
On earth, in 1977, scientists had discovered hydrothermal vents pouring hot, mineral-rich fluids from beneath the seafloor on the bottom of the Pacific Ocean. They later found the vents were inhabited by previously unknown organisms that thrived in the absence of sunlight. These discoveries fundamentally changed our understanding of Earth and life on it.
Confirming the presence of hydrothermal vents on another world is even more extraordinary, not simply because life can exist around them.
“A lot of origin-of-life scientists believe that this is the place where life could have started on Earth,” Morgan Cable, a research scientist who studies ocean worlds at NASA’s Jet Propulsion Laboratory said. “So that gets us very excited about finding a place where conditions might not only allow for life to exist, but conditions that might allow for an origin of life as well.”
Cassini's last images
Credit: NASA/JPL-Caltech/SSI
Cassini’s legacy is overwhelming. Even after the Cassini spacecraft has dissolved, its enormous collection of data including the outcome of the Grand Finale will continue to yield new discoveries for decades to come.
"Cassini may be gone, but its scientific bounty will keep us occupied for many years,” Linda Spilker, Cassini project scientist at JPL, said, “We've only scratched the surface of what we can learn from the mountain of data it has sent back over its lifetime."
Goodbye, Cassini, and thanks for all the incredible data.- Linda Spilker
And Carolyn Porco, imaging science team leader for the Cassini mission:
“I sign off now, grateful in knowing that Cassini’s legacy, and ours, will include our mutual roles as authors of a tale that humanity will tell for a very long time to come.”
Hear from the team behind the mission and its Grand Finale.
For more insights into the great mission, check out this free NASA e-Book celebrating Saturn as seen through the eyes of the Cassini spacecraft with lots of iconic images.
And here's a collection of stunning images of the mission
