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A selection of photographs taken by Cassini. Photos: NASA/JPL-Caltech/Space Science Institute

The Cassini spacecraft has been in orbit around Saturn for 13 years, beaming data and photographs back to Earth. When it deliberately dove into Saturn's atmosphere today, it marked the end of one of our most in-depth looks at an alien planet to date and our only link to the Saturnian system. There are no plans to return.

The mission might be over, but there are discoveries yet to come as scientists sift through over 635 gigabytes of data sent back to Earth. Although we're certainly leaving out some (shoutout to Pan, the ravioli-shaped moon that took the internet by storm), here are three top findings so far.

1. Moons that could harbor life

Enceladus, the icy ocean moon. Cassini revealed that under Enceladus' icy surface there is a vast salty ocean, and plumes of it erupt from the South Pole like geysers. This discovery "changed almost the entire focus of the mission," writes JoAnna Wendel for Eos, because liquid water could mean life.

Titan, the gassy moon. A previous flyby from the Voyager spacecraft had shown that Titan had an atmosphere, so European Space Agency scientists created Huygens, a probe delivered by Cassini and dropped on Titan to sample the surroundings. It found vinyl cyanide, a complex molecule that some think could be a building block for alien life, as well as methane clouds, lakes and rivers: something akin to the water cycle on earth, but with methane instead of water.

And possibly more. Not all of Cassini's data has been analyzed, but there's some evidence that the tiny moon Dione has an internal ocean.

Why it matters: Along with Jupiter's Europa, Titan and Enceladus have redefined where we might find life beyond Earth.

2. Details about Saturn's rings

Once thought to be flat, Cassini's pictures revealed the dynamic landscape of Saturn's rings. There are dramatic spikes a mile and a half tall. Density waves form ripples in the rings, which come from the same processes that make the spirals in our own galaxy. And there's an empty gap between the rings and Saturn that Cassini dove through to record what it sounds like.

Why it matters: Tiny, propeller-like moons-to-be are scattered throughout these structures. They provide a glimpse into the early days of our solar system, when planets may have been propellers in a dustcloud around our Sun.

3. Some mind-blowing pictures

What's next: As Cassini falls towards Saturn, it'll sample the planet's atmosphere and take a few key readings. So far, scientists have struggled to get the magnetic measurements necessary to determine the length of a Saturnian day — but Cassini's last transmissions might contain that key data.

Go deeper:

  • Shannon Stirone explains what it takes to kill a spacecraft for The Atlantic. "Thousands will gather at JPL and wait until the early morning hours for Cassini's final orbit to begin. They'll share stories of a lifetime of work, as that effort culminates in fireworks 800 million miles away."
  • At the LA Times, Linda Netburn writes about how Cassini came to be. "This is the story of how it got off the ground, told by the people who were there."
  • Science News' Lisa Grossman highlights some of the best 'postcards' Cassini sent back to Earth: "After all this time, we've witnessed only the transitions to Saturnian spring and summer, the equivalent of January to June on Earth. And yet we've seen so much."

Go deeper

Mike Allen, author of AM
1 hour ago - Politics & Policy

Biden's "overwhelming force" doctrine

President-elect Biden arrives to introduce his science team in Wilmington yesterday. Photo: Kevin Lamarque/Reuters

President-elect Biden has ordered up a shock-and-awe campaign for his first days in office to signal, as dramatically as possible, the radical shift coming to America and global affairs, his advisers tell us. 

The plan, Part 1 ... Biden, as detailed in a "First Ten Days" memo from incoming chief of staff Ron Klain, plans to unleash executive orders, federal powers and speeches to shift to a stark, national plan for "100 million shots" in three months.

Off the Rails

Episode 2: Barbarians at the Oval

Photo illustration: Sarah Grillo/Axios. Photo: Jim Watson/AFP/Getty Images

Beginning on election night 2020 and continuing through his final days in office, Donald Trump unraveled and dragged America with him, to the point that his followers sacked the U.S. Capitol with two weeks left in his term. This Axios series takes you inside the collapse of a president.

Episode 2: Trump stops buying what his professional staff are telling him, and increasingly turns to radical voices telling him what he wants to hear. Read episode 1.

President Trump plunked down in an armchair in the White House residence, still dressed from his golf game — navy fleece, black pants, white MAGA cap. It was Saturday, Nov. 7. The networks had just called the election for Joe Biden.

Fringe right plots new attacks out of sight

Illustration: Aïda Amer/Axios

Domestic extremists are using obscure and private corners of the internet to plot new attacks ahead of Inauguration Day. Their plans are also hidden in plain sight, buried in podcasts and online video platforms.

Why it matters: Because law enforcement was caught flat-footed during last week's Capitol siege, researchers and intelligence agencies are paying more attention to online threats that could turn into real-world violence.

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