Updated
The 7.9-billion-kilometre journey to explore the distant planet Saturn has come to a crashing end, having discovered moons that might hold the key ingredients for life.
Key points:
- Cassini probe will burned on entry to Saturn just before 10:00pm (AEST) last night
- The NASA mission started in 1997
- The probe has spent its final months diving in and out of Saturn's rings
It had been a 20-year mission through space that took less than a minute to come to a fiery end, with the Cassini probe burning up on entry to Saturn just before 10:00pm (AEST) on Friday.
Cassini's final transmission was met with a round of applause in NASA's Jet Propulsion Laboratory (JPL).
"Cassini showed us the beauty of Saturn. It revealed the best in us. Now it's up to us to keep exploring," a tweet from the official Cassini account read.
Our spacecraft has entered Saturn's atmosphere, and we have received its final transmission.
The Cassini mission discovered a global ocean on one of Saturn's moons — Enceladus — that contained geyser-like jets that spew water vapor and ice particles from beneath the icy crust.
According to NASA, before Cassini launched in 1997 it wasn't clear that anywhere beyond Mars contained liquid water, essential chemical elements, and energy — such as sunlight — thought to be required for life.
Our @CassiniSaturn spacecraft is now one with the planet it studied for so long. The rest is science. #GoodbyeCassini#GrandFinale
NASA believes that Enceladus "is now one of the most promising places in our solar system to search for present-day life beyond Earth".
The mission also carried a probe from the European Space Agency that landed on Saturn's largest moon, Titan.
That too found clear evidence of prebiotic chemicals in the atmosphere and a global ocean beneath the moon's icy crust.
Photo:
An artist's illustration of Cassini diving between Saturn and the planet's innermost rings. (NASA/JPL-Caltech)
Some researchers believe that ocean contains the hydrothermal chemistry that could provide energy for life.
On Saturn itself, NASA scientists discovered a massive 30,000km hexagonal jet stream on the planet's north pole.
No-one really knows what drives it — or why it has six sides — but scientists have been studying the vortex at its centre to get a better understanding of how hurricanes on Earth come about.
To avoid contaminating Enceladus or Titan with Cassini's plutonium-powered remnants, scientists decided to crash it into Saturn instead.
Saturn as a planet is more than 700 times the volume of Earth, and mostly filled with deep, dense and hot gas, and compressed metallic hydrogen, with some helium and other trace molecules thrown in as well.
With its final burst of fuel, the spacecraft spent its final few months diving in and out of Saturn's rings to give information about the gravity and the mass of the planet.
The more massive the rings, the older they're likely to be. Here's a sense of the scale of the rings alone:
Like so many missions before it, the Deep Space Communication Complex in Canberra tracked Cassini for every final second of its final mission.
It picked up signals from early this afternoon and locked on for as long as possible.
While Cassini has been travelling, scientists also discovered evidence of a salty global ocean beneath the icy crust of Jupiter's moon Europa.
The scientific discoveries on Saturn's Enceladus reinvigorated the desire to explore ocean worlds — with NASA aiming to get a spacecraft to Europa in the next decade.
Many of the lessons learnt from Cassini's journey to Saturn will greatly help that mission.
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