NASA's Cassini spacecraft has orbited Saturn since 2004, revealing all kinds of valuable insights about the gas giant and its iconic ring system. But in some ways, the mission's final phase that kicks off later this month could prove even more fruitful, with the deep-space probe making a series of daring passes through the gap between Saturn and its rings, where scientists expect it to make some of its most extraordinary discoveries before burning up in the atmosphere.
Cassini lifted off from Earth way back in 1997 and slipped into Saturn's orbit after a seven-year, 2.2 billion-mile journey. Over the last 13 years it has treated us to glorious images of the planet's rings and polar storms, along with a raft of invaluable scientific tidbits that include evidence of methane-filled canyons, fizzy lakes and global oceans on Saturn's moons.
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And the expertise gained from the probe's orbit of Saturn has also helped engineers devise a flight path that will make the most of its final moments. With fuel running low, Cassini will plunge into Saturn's atmosphere on September 15, but not before it makes a series of tighter orbits that scientists hope will unlock even more of the system's secrets.
"No spacecraft has ever gone through the unique region that we'll attempt to boldly cross 22 times," says Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "What we learn from Cassini's daring final orbits will further our understanding of how giant planets, and planetary systems everywhere, form and evolve. This is truly discovery in action to the very end."
The first of these 22 dives through the 1,500 mile wide (2,400 km) gap between the planet and its rings will take place on April 26, following a final close flyby of Saturn's giant moon Titan. Scientists are hoping to learn more about Saturn's internal structure throughout these crucial final months, along with insights into how its rings were formed.
The period will also yield the first-ever samples of the planet's atmosphere and particles coming from the main rings, and the closest-ever views of Saturn's clouds and inner rings. Cassini will continue sending data back from several instruments right up until its signal is lost on September 15.
"Cassini's grand finale is so much more than a final plunge," said Linda Spilker, Cassini project scientist. "It's a thrilling final chapter for our intrepid spacecraft, and so scientifically rich that it was the clear and obvious choice for how to end the mission."
The animation below offers an overview of how Cassini's final months will play out.