Summary

  • Nasa's Cassini spacecraft was destroyed at 12:55 BST (04:55 PDT) as it plunged into Saturn's atmosphere

  • The plan prevented it crashing into and contaminating the moons Titan or Enceladus, which could host alien microbial life

  • The spacecraft was torn apart and will now become part of the planet it has been studying

  • Cassini reached Saturn in 2004. Shortly after arrival, it released the Huygens lander to Saturn's moon Titan

  • The Cassini-Huygens mission has revealed seas of liquid methane on Titan and an ocean of water beneath Enceladus

  1. An ending and a beginningpublished at 15:58 British Summer Time 15 September 2017

    It was a sombre event. Cassini has been sending back data from the Saturn system for 13 years now, and for those who’ve followed the mission for so long, the end is hard to take. The Cassini-Huygens mission has left an indelible mark on human knowledge, enriching our understanding of the Solar System.

    So as we sign off, we’ll leave it to Cassini’s project scientist Dr Linda Spilker to explain why we shouldn’t be glum: “What's happening is both an ending and a beginning. It's the end of data collection. But it's the beginning of a legacy where the scientists and engineers will go out and become a part of other missions, taking what they've learned from Cassini with them.”

    CassiniImage source, Nasa
  2. The Cassini-Huygens storypublished at 15:39 British Summer Time 15 September 2017

    Cassini may be gone, but you can re-visit the key events of the mission, through the stories of the people who made it happen.

    "Our Saturn years" - The story of Cassini-Huygens

    Saturn
  3. New places to look for lifepublished at 15:23 British Summer Time 15 September 2017

    The discovery that there are ocean worlds not just around Jupiter but around Saturn too was perhaps the Cassini mission's most important discovery, Linda Spilker said.

    "It's opening up our view of where we could find life in the solar system. Maybe it doesn't have to be restricted to the so-called Goldilocks zone where the Earth is," she said.

  4. Anti-social routinepublished at 15:23 British Summer Time 15 September 2017

    Now the mission was over, Julie Webster, spacecraft operations manager, wondered whether Cassini team family members might be relieved that their relatives' pagers wouldn't be going off all the time at inopportune moments.

    "We stomped on every Christmas, every thanksgiving," she says.

  5. New areas for explorationpublished at 15:11 British Summer Time 15 September 2017

    Linda Spilker said the new information from the Cassini mission had raised new areas for exploration, including:

    Enceladus moon - investigate the potential for life in its global ocean

    Titan moon - examine the astrobiology of the oceans and figure out the source of methane that keeps the atmosphere so extensive

    Hexagon jet stream at Saturn's north pole - look at what keeps it going "like a Duracell bunny"

    Saturn's rings - can we get even closer?

  6. 'Thanks for the ringside seat'published at 15:05 British Summer Time 15 September 2017

    Spacecraft operations manager Julie Webster and project scientist Linda Spilker have been speaking.

    The BBC's Rebecca Morelle is at the Jet Propulsion Laboratory in California and has been tweeting some of what they have been saying.

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  7. Cassini's final resting placepublished at 14:58 British Summer Time 15 September 2017

    Dr Linda Spilker presented an image from the Visible and Infrared Mapping Spectrometer showing where scientists think Cassini plunged into Saturn.

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  8. Legacypublished at 14:49 British Summer Time 15 September 2017

    Cassini programme manager Earl Maize has been speaking about the end of the mission.

    "There are times when things just line up - a child's laugh, a desert sunset and this morning. It just couldn't have been better," he said.

    Mr Maize described the probe as a "superb machine" that "to the very end did everything we asked".

    And he said the Cassini mission had set a blueprint for future space missions thanks to the technological improvements achieved and the successful collaboration between different scientists and engineers.

    "Cassini has ended its mission high over the clouds of Saturn," Mr Maize said.

    "Thanks and farewell, faithful explorer."

  9. Nature is beautifulpublished at 14:42 British Summer Time 15 September 2017

    There's a press conference happening at the Jet Propulsion Laboratory in California now. Nasa science director Thomas Zurbuchen presents a picture of Saturn and its amazing arrangement of rings taken a year ago: "People say: Is this how nature is? Yes it is."

  10. Cassini noooo.....published at 14:21 British Summer Time 15 September 2017

    Launched in 1997, Cassini is too old to have its own social media account - unlike more recent probes such as the Philae lander, external, which was part of the Rosetta mission and landed on the surface of comet 67P/Churyumov-Gerasimenko.

    But a group of Cassini-watchers created an unofficial account counting down the days to the craft's fiery end. Here are a few of its last tweets...

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  11. But... but...published at 14:08 British Summer Time 15 September 2017

    ...we thought it was gone.

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  12. A graphic talepublished at 14:04 British Summer Time 15 September 2017

    The BBC has put together a fun, interactive guide to Cassini's greatest discoveries. You can view it here.

    Enceladus
  13. 'Ah, but here Cassini's heart leaps...'published at 13:56 British Summer Time 15 September 2017

    Nasa's team have also been moved to poetry - on Nasa TV astrobiologist Jonathan Lunine read out a subtly altered verse from the poem "On the Verge" by Algernon Charles Swinburne.

    It brought a tear to the interviewer's eye.

    "This was a moment of transition. It's not the end," Mr Lunine added.

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  14. The moment the mission endedpublished at 13:18 British Summer Time 15 September 2017

    Nasa has tweeted a video of the moment the signal was lost. The footage contains audio of the programme manager Earl Maize calling the mission's end.

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  15. Saturn: The returnpublished at 13:13 British Summer Time 15 September 2017

    Asked what he would like to see next on Nasa TV, astrobiologist Jonathan Lunine said: "What I would like to see is that we go back there [to Saturn]." Saturn's moons Titan and Enceladus are considered the prime targets for follow-up missions.

    Titan's atmosphere is thought to be very similar to the one that nurtured life on the early Earth. Enceladus has a liquid water ocean that seems to have many of the conditions needed for microbial life to thrive in.

    There are already several mission concepts out there for a return mission to both moons.

    Prof Lunine added: "We need to go back to Saturn, to Neptune. We need to do the whole outer Solar System."

    BalloonImage source, NASA
    Image caption,

    Artwork showing a future balloon and drone mission to Titan

  16. 'Goodnight, sweet spacecraft'published at 13:13 British Summer Time 15 September 2017

    Cassini-watchers have been describing their feelings on social media after the probe's final signal was received.

    There were tears, poetry and sombre photographs of clouds covering the night sky.

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  17. Applause at final signalpublished at 13:05 British Summer Time 15 September 2017

    The team behind the Cassini mission at the Jet Propulsion Laboratory in Pasadena, California have applauded and hugged one another after the final signal was received at 11:55 and 46 seconds GMT (12:55:46 BST).

    "This has been an incredible mission, an incredible spacecraft, you're an incredible team," said Earl Maize, Cassini programme manager.

    applauseImage source, NASA
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  18. Cassini mission endspublished at 12:57 British Summer Time 15 September 2017
    Breaking

    The American-led Cassini space mission to Saturn has just come to a spectacular end.

    Controllers had commanded the probe to destroy itself by plunging into the planet's atmosphere.

    It survived for about a minute before being broken apart.

    Cassini had run out of fuel and Nasa had determined that the probe should not be allowed to simply wander uncontrolled among Saturn and its moons.

  19. How much did the mission cost?published at 12:51 British Summer Time 15 September 2017

    The total bill comes to $3.9bn (£2.9bn) according to Scienceogram, which tracks spending on science.

    The Nasa contribution of $3.2bn works out at $11 or three Big Mac burgers per American. Europe's $500m works out at $1 per European or the price of a French baguette. And Italy's $200m comes to $3 per Italian, the price of an ice cream in Rome.

    Andrew Steele from Scienceogram says the cost of such missions is "ludicrously cheap".

    "Big days in spaceflight like today are an important time to celebrate what we have achieved, but it’s all too easy to forget how little we care about space in the grand economic scheme of things," he says.

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  20. A few minutes leftpublished at 12:50 British Summer Time 15 September 2017

    Jonathan Amos
    Science correspondent, BBC News, in Pasadena

    Control reports Cassini to have passed 20 degrees North latitude. When it gets to 10 degrees - that will be it.