NASA’s Cassini spacecraft has met its fiery death as the ‘Grand Finale’ brings its mission to an end

The time has come. NASA’s Cassini spacecraft has taken its final mission-ending plunge into Saturn’s atmosphere following an epic 13-year tour of the giant planet. 

At 12.30pm BST, NASA’s JPL tweeted there had been an expected loss of signal, and that Cassini had crashed into the planet.

Earlier this week, the spacecraft passed Saturn’s largest moon, Titan, 73,974 miles (119,049 kilometres) above its surface, in a symbolic ‘goodbye kiss’ flyby that gave the spacecraft one last nudge of gravitational energy to send it to its end.

Watch Cassini’s Grand Finale online

NASA is live streaming Cassini’s Grand Finale and post-plunge press conferences on its NASA TV channel and via the JPL YouTube channel, but there will be an 80-minute delay between the action and the stream due to the length of time it takes for data to reach Earth.

The probe sent back its last pictures and data at around 4am EDT (9am BST) before the radio waves went silent. An uninterrupted feed then begin streaming at 6.30am EDT (11.30am BST). The Grand Finale took place at around 8.30am EDT (1.30pm BST).

“The Cassini mission has been packed full of scientific firsts, and our unique planetary revelations will continue to the very end of the mission as Cassini becomes Saturn’s first planetary probe, sampling Saturn’s atmosphere up until the last second,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory (JPL). “We’ll be sending data in near real time as we rush headlong into the atmosphere – it’s truly a first-of-its-kind event at Saturn.”

But what is the Cassini mission and why is it so important? Here’s everything you need to know.

What is Cassini?

The Cassini spacecraft was named after 17th-century Italian-French astronomer Giovanni Cassini and launched on 15 October 1997. A joint project between NASA, the European Space Agency (ESA) and the Italian Space Agency (Agenzia Spaziale Italiana or ASI), it was part of the Cassini-Huygens mission, along with the Huygens moon lander, named after Dutch astronomer Christiaan Huygens.

The most distant planetary orbiter ever launched, Cassini was the first space probe to make it into Saturn’s orbit and is packed with 12 science instruments to gather vital data from its surroundings.

What is Cassini’s mission?

In December 2000, three years after launch, the Cassini spacecraft made a six-month detour at Jupiter to pick up speed for its journey to Saturn. It reached Saturn in 2004 when the ESA-built Huygens lander was released. A few weeks later, in January 2005, Huygens made it through the atmosphere of Saturn’s largest moon, Titan, in order to sample the chemical composition and explore the terrain.

In 2008, with the mission to explore Saturn’s system completed, the Cassini probe was given an extension in the form of the Cassini Equinox Mission involving a series of flybys of Saturn and its moons. Once this two-year project was finished Cassini was given yet another extension – the Cassini Solstice Mission – which carried it through until 2017 and involved yet more flybys of Saturn’s moons to observe seasonal changes. The plan was always to safely dispose of the spacecraft in Saturn’s atmosphere.

Why is Cassini so important?

Cassini’s missions have revolutionised our understanding of Saturn, giving us a portal to look at the processes that shaped the development of our solar system, as well as planetary systems around other stars.

The extraordinary undertaking showed us that moons can be worlds in their own right, rather than mere satellites. It showed Titan to be one of the most Earth-like worlds we’ve seen so far, with the weather, climate and geology that could help us to understand more about our own planet.

What’s more, the length of the mission has enabled scientists to observe seasonal changes, while the numerous planetary flybys have told us more about the complexity of Saturn’s rings and given us some of the most detailed images ever. The final stages of the mission will help to improve our understanding of how giant planets like Saturn form and evolve.

During its various missions, Cassini has collected more than 635 GB of scientific data, taken more than 450,000 images and completed nearly 300 orbits of Saturn. It has also made astonishing discoveries including hydrocarbon lakes and seas on Titan and an underground ocean on the icy moon Enceladus.

Why end the mission?

The fuel used for adjusting the Cassini spacecraft’s course is running low and, if it was all used up, mission controllers on the ground would no longer be able to alter its course. It’s preferable for the probe to safely burn up in Saturn’s atmosphere after a controlled descent, rather than drifting as potentially hazardous space junk.

Ending the mission prevents any possible collision with Enceladus and Titan. This will avoid any contamination of future studies on the two moons.

The Cassini Grand Finale

 Cassini began its final plunge – dubbed ‘The Cassini Grand Finale’ by NASA – in April following its closest flyby of Titan. On 9 September, Cassini will make the last of 22 passes between the planet and its rings followed by a distant flyby of Titan on the 11 September before a final look around the Saturn system on the 14th. On 15 September, the final plunge begins, with thrusters helping the Cassini spacecraft to maintain its course so that its antenna is pointed at Earth for as long as possible for beaming back vital data.

Around 940 miles (1,510 kilometers) above Saturn’s cloud tops, communication with Earth will cease, and the spacecraft will break up like a meteor moments later. This is expected to take place at 7:54 a.m. EDT (12:44 p.m. BST).

During its final days, Cassini will collect vital data that was too risky to obtain earlier in the mission including detailed maps of Saturn’s gravity and magnetic fields and extreme close-ups of Saturn’s rings and clouds.

Because Saturn is so far from Earth – approximately 746 million miles (1.2 billion kilometers) away – Cassini will have been destroyed for about 83 minutes before its final signal reaches NASA’s Deep Space Network’s Canberra station in Australia.

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