NASA’s $3.9 billion Cassini spacecraft today ended its 20-year-long groundbreaking journey with a fiery plunge into the Saturn’s crushing atmosphere, beaming back never-before-seen images of the ringed planet and its mysterious moons until the last moment.

Operators deliberately made Cassini, the first spacecraft to orbit Saturn, dive into the gas giant to ensure that the planet’s moons – in particular Enceladus, with its subsurface ocean and signs of hydrothermal activity – remain pristine for future exploration. “Our spacecraft has entered Saturn’s atmosphere, and we have received its final transmission,” NASA said in a tweet. “Every time we see Saturn in the night sky, we’ll remember. We’ll smile. And we’ll want to go back,” the US space agency said.

 No spacecraft has ever ventured so close to the planet before, NASA said. “I hope you are all as deeply proud of this amazing accomplishment. Congratulations to you all. This has been an incredible mission, incredible spacecraft and you were all incredible team,” Earl Maize, Cassini mission manager, said while announcing the end of the mission at IST 5:25 pm.

The $3.9 billion mission continued to transmit data back to the Earth till the last minute before it came apart and was burned up like a meteor in Saturn’s atmosphere. The unmanned orbiter tore through the atmosphere at the speed of 113,000 kilometres per hour.Contact was lost with the Cassini spacecraft a minute after it reached an altitude of about 1,500 kilometres above the planet’s estimated cloud tops. Within about 30 seconds following loss of signal, the spacecraft came apart; and within a couple of minutes, all remnants of the spacecraft were consumed in the atmosphere of Saturn, NASA said.

“Earth received CassiniSaturn’s final signal at 7:55 am ET. Cassini is now part of the planet it studied. Thanks for the science,” NASA tweeted.

The Cassini mission gave scientists an unprecedented view of the sixth planet from the Sun. The probe discovered seasonal changes on Saturn, a hexagon-shaped pattern on the north pole and the moon Titan’s resemblance to a primordial Earth. Scientists found deep, liquid-filled canyons on Saturn’s moon Titan for the first time. They also found a global ocean on the moon Enceladus, with ice plumes spouting from its surface.

The spacecraft has produced 450,000 images and 635 gigabytes of data since it began probing Saturn and its 62 known moons in July 2004. Cassini also carried a probe called Huygens, which parachuted to the surface of Saturn’s largest moon, Titan, in January 2005 and returned spectacular results.

Launched in October 1997, Cassini completed its initial four-year mission to explore the Saturn system in June 2008, and the first extension, called the Cassini Equinox Mission, in September 2010. In a second extension called the Cassini Solstice Mission, the spacecraft made new exciting discoveries.