Updated at 12:57 pm ET: Today, Sept. 15, NASA's Cassini spacecraft wrapped up 20 historic years in space, and collected data as it crashed into Saturn's atmosphere and burned up like a meteor. Read our parent company Purch's interview on Cassini's death with managing editor Tariq Malik. Read on for our complete coverage:
Parting Views: In Photos: Cassini's Last Views from Saturn
Scientists React: Tears and Applause: Cassini Team Reflects on Saturn Plunge
- NASA's Cassini Mission to Saturn: By the Numbers
- Cassini's Last-Ever Photos Come Down to Earth
- Cassini Dives Into Saturn Today: Here's When and How to Watch
Why did NASA let Cassini hit Saturn?
The $3.2 billion Cassini-Huygens mission — a joint effort of NASA, the European Space Agency and the Italian Space Agency — launched in October 1997 and arrived in the Saturn system on June 30, 2004 (PDT).
Huygens was a piggyback probe that touched down on Saturn’s largest moon, Titan, in January 2005, pulling off the first-ever soft landing on a body in the outer solar system. The Cassini orbiter, meanwhile, kept circling Saturn, making a number of important discoveries in its 13-plus years at the ringed planet.
For example, the spacecraft spotted geysers of water vapor and other material blasting from the south pole of the icy moon Enceladus. Mission scientists have determined that this stuff is coming from a huge ocean of liquid water beneath the satellite’s shell — and that this ocean may be capable of supporting life as we know it.
Cassini also detected lakes and seas of liquid hydrocarbons on Titan — the first stable bodies of liquid ever discovered on the surface of a world beyond Earth. Scientists think Titan may also be able to support microbial life (though if that life teems in the hydrocarbon seas, it will be very different than organisms here on Earth).
But nothing lasts forever. Cassini is nearly out of fuel; if it runs out completely, the probe’s handlers won’t be able to control it anymore. So they want to dispose of Cassini before things get to that point, which is why they’re sending the spacecraft on a death dive into Saturn on Sept. 15. [Cassini's 'Grand Finale' at Saturn: NASA's Plan in Pictures]
This main goal of this final maneuver is protecting Titan and Enceladus — keeping them clean and pristine.
“In order to avoid the unlikely possibility of Cassini someday colliding with one of these moons, NASA has chosen to safely dispose of the spacecraft in the atmosphere of Saturn,” NASA officials wrote in a statement. “This will ensure that Cassini cannot contaminate any future studies of habitability and potential life on those moons."
Space.com coverage of Cassini's final days
We’ve written a lot about Cassini's Grand Finale — the last phase of its mission, which consists of 22 dives Cassini is making between Saturn’s cloud tops and its innermost rings — and the spacecraft’s impending death.
See our full coverage of Cassini's final days below.
- Cassini's 13 Greatest Discoveries During Its 13 Years at Saturn
- Cassini’s Greatest Hits: The Spacecraft’s Best Images of Saturn
- Cassini Spacecraft Photos Reveal the Secrets of Saturn's Strangest Moons
- Cassini's 'Grand Finale' at Saturn: NASA's Plan in Pictures
- 'Grand Finale' at Saturn Begins: Cassini Spacecraft's 1st Ring Dive in Pictures
- Latest Saturn Photos from NASA's Cassini Orbiter
- Wave at Saturn: Images from NASA's Cosmic Photo Bomb by Cassini Probe
- Photos: Saturn's Glorious Rings Up Close
- Photos: Monster Storm Rages on Saturn
- Photos: Spectacular Color Maps of Saturn's Moons by Cassini
- Stunning Photos: Saturn's Weird Hexagon Vortex Storms
- Landing on Titan: Pictures from Huygens Probe on Saturn Moon
- Photos: Enceladus, Saturn's Cold, Bright Moon
- Amazing Photos: Titan, Saturn's Largest Moon
- Icy Rhea: Photos of Saturn's Second-Largest Moon
- Saturn's Moon Dione: Photos from Cassini's Final Close Flyby
- Meet Mimas: Saturn's Death Star Moon
- Photos: The Rings and Moons of Saturn in Pictures
Rings Revealed: How Cassini's Saturn Odyssey Exceeds Expectations: As NASA's Cassini mission to Saturn heads toward its dramatic dive into the planet's atmosphere, scientists are reflecting on all that the mission has taught us about the ringed planet and its fascinating moons.
Cassini Spacecraft Photos Reveal the Secrets of Saturn's Strangest Moons: The weird and wonderful Saturn system is home to some truly strange moons. Here's an image gallery of some of the strangest satellites in the bunch.
Cassini Headed for Saturn Plunge After Titan 'Goodbye Kiss': After a "goodbye kiss" with Saturn's huge moon Titan, NASA's Cassini spacecraft should now be on course for its suicide dive into the ringed planet Friday (Sept. 15).
Wild! Cassini Probe Spots Weird Waves in Saturn's Rings : NASA's Cassini spacecraft captured a spectacular photo of a perplexing wave structure in one of Saturn's rings as the probe headed into its final days at the gas giant.
Saturn's Icy Moons Are a Little Less Mysterious Thanks to Cassini's Long Mission: Perhaps its greatest contribution to science is helping us learn about the many icy moons circling Saturn and its elegant rings.
1 Week Until Cassini's Fatal Saturn Dive: Here's How the Probe Will Spend Its Final Days : The one-week countdown has begun for the Cassini spacecraft's fatal plunge into Saturn's atmosphere, and the probe has a busy week ahead.
Saturn Moon Enceladus Shows Off Its Moves for Cassini : Saturn's possibly habitable moon Enceladus seems to dance in a gorgeous new video captured by NASA's Cassini spacecraft.
No End to Saturn's Mysteries in Cassini's Closing Days: Scientists are preparing for a bountiful harvest of science data when the Cassini probe makes its final death plunge into Saturn's atmosphere.
Cassini Snaps Saturn's Strange Polar Vortex During Daring Dive: The bizarre vortex spinning at Saturn's north pole takes center stage in a newly released photo by NASA's Cassini spacecraft.
Cassini Saturn Probe Preps for Last Hurrah: On Aug. 14, NASA's Cassini spacecraft made the first of five passes through Saturn's upper atmosphere, kicking off the last phase of the mission's "Grand Finale." The probe will end its life with a plunge into Saturn's atmosphere on Sept. 15.
Cassini Probes Last Saturn Mysteries 1 Month from Demise: The end is nigh for NASA's trailblazing Cassini mission to Saturn as the veteran spacecraft enters its final month in orbit. The probe will burn up like an artificial meteor in the gas giant's upper atmosphere on Sept. 15.
Life in the Saturn System? Cassini Has Shown It's Possible: The European-American Cassini spacecraft has found that three of Saturn's many moons likely host subsurface oceans and may be capable of supporting life.
Saturn's Surprising Rings: The Fascinating Mysteries Cassini Has Solved: Before the Cassini-Huygens mission, scientists weren't sure how old Saturn's rings are, what they're made of, how they change, how thick they are, how fast they move, how big the ring particles are, or how Saturn's moons its rings. Now, we know.
How Long Is a Day on Saturn? Cassini Is Racing to Find Out in Its Final Months: How long is a day on Saturn? The answer is still unclear as the Cassini spacecraft approaches its "Grand Finale" plunge into the ringed planet's atmosphere.
Why Kill Cassini? Saturn Probe's Fate Carefully Considered: On Sept. 15, the Cassini spacecraft will destroy itself by burning up in Saturn's atmosphere in order to protect the ringed planet's moons from biological contamination by bacteria from Earth. But there were other possible fates for Cassini.
'Kingdom of Saturn': New Documentary Dives Deep into NASA's Amazing Cassini Mission: A new documentary look backs at the triumphs of the Cassini probe ahead of the spacecraft's scheduled death dive into the ringed planet.
Happy Anniversary, Cassini! NASA Probe Marks 13 Years at Saturn: Cassini arrived in orbit around the ringed planet on June 30, 2004, after a nearly seven-year journey through deep space.
Cassini Makes 8th Dive Through Saturn's Rings: The Cassini spacecraft has made its eighth dive between Saturn and its rings, documenting the planetary system up close as it prepares for its Grand Finale plunge into the gas giant on Sept. 15.
Cassini Takes Most Dangerous Saturn Ring Dive Yet: The Cassini spacecraft completes its sixth dive between Saturn and its rings today (May 28), and this is the most dangerous dive yet through the inner edge of Saturn's D ring.
Cassini's 'Grand Finale' Dives Could Show How Quickly Saturn's Rings Will Fade: New research suggests Saturn's rings may last a billion years before fading away — and Cassini's ring dives will help test the theory.
Wow! Cassini's Bird's-Eye View of Saturn Plunge Astonishes in New Video: An amazing new video shows just what NASA's Cassini spacecraft saw during its first "Grand Finale" dive between Saturn's cloud tops and the gas giant's rings last week.
Cassini Saturn Probe Survives 1st 'Grand Finale' Dive: NASA's Cassini spacecraft has survived its first plunge between Saturn's cloud tops and the giant planet's innermost rings, a region that no probe had ever explored before.
'Giant Hurricane' on Saturn: 1st Images Back from Cassini's Epic Ring Dive: NASA's Cassini spacecraft dove between Saturn and its rings yesterday (April 26), snapping the closest-ever views of Saturn's atmosphere.
Cassini Spacecraft's Ring Dive Yields Saturn Surprises: The Cassini spacecraft spotted strange atmospheric structures during the first of its 22 dives between the rings and gas body of Saturn, the planet it has studied up close since 2004.
Google Doodle Celebrates Cassini Probe's 'Grand Finale' Saturn Dive: Today, Google is honoring NASA's Cassini mission to Saturn with an adorable Google Doodle featuring the spacecraft swooping between the planet and its rings.
Cassini's Grand Finale Is Saving the Best Saturn Science for Last: As Cassini wraps up its 13-year mission in Saturn's system, scientists are preparing for the spacecraft's final burst of observations in the never-before-explored region between the planet and its inner rings.
No Turning Back: Titan Flyby Assures Cassini's Crash Into Saturn: There's no turning back now. The Cassini probe's most recent flyby of Saturn's moon Titan puts the spacecraft on a path to crash into the ringed planet.
As Cassini Makes 1st 'Grand Finale' Dive, More Saturn Mysteries Remain: Running low on fuel, NASA's Cassini spacecraft has begun the final (and most daring) phase of its epic mission to Saturn.
Cassini's Final Chapter: 1 More Titan Flyby Before 'Grand Finale' at Saturn: NASA's Cassini spacecraft will make its final close flyby of Saturn's moon Titan this weekend in preparation for the mission's grand finale, when it dives down into the planet itself.
Epic Cassini Saturn Mission Begins 'Grand Finale' This Month: NASA's veteran Cassini mission will officially kick off its farewell tour of the Saturn system on April 22 with a final close encounter of the ringed planet's largest moon, Titan. Then, on Sept. 15, Cassini will burn up in Saturn's atmosphere.
One Last Year at Saturn: Cassini Heads for Grand Finale: The Cassini spacecraft has studied Saturn for 12 years, and the probe has just one more year to go before its final dive into the planet itself.
At Saturn, Cassini Spacecraft Adjusts Orbit for Titan-ic 'Grand Finale': NASA's Cassini Saturn probe has begun reshaping its orbit in preparation for the spacecraft's "grand finale" at the ringed planet next year. The spacecraft performed an engine burn Jan. 23 to set up a Feb. 1 flyby of Saturn's huge moon Titan.
NASA Saturn Probe Will End Mission in Epic 'Grand Finale': Starting in late 2016, Cassini will zip between Saturn and its innermost ring a total of 22 times in a mission phase now known as the "Cassini Grand Finale," which will end when the probe intentionally dives into Saturn's atmosphere in September 2017.