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Spacecraft Down: Cassini is Gone


It’s official: Cassini’s mission at Saturn is over. Today, at 6:31 a.m. EDT (10:31 UTC), Cassini entered the atmosphere of Saturn. A little over a minute later it sent its final transmission back to Earth before succumbing to the physical forces of entry. That signal, Cassini’s last piece of data, ended at 7:55 a.m. EDT (11:55 UTC). After over thirteen years in orbit Cassini is now a part of Saturn; its work is done.

Mission accomplished.

About 14 hours earlier Cassini transmitted its final images of Saturn to Earth. You can see some of those below: Read the rest of this entry

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It’s Time to Say Goodbye to Cassini

Artist’s rendering of Cassini at Saturn. Credit: NASA/JPL

Well, the day has come. Today is the last full day that NASA’s Cassini spacecraft will exist, and in fact right now it is on its final path—a grand soaring arc that will send it down into the atmosphere of Saturn itself on the morning of Friday, Sept. 15. It will be the closest to the ringed planet any spacecraft will have ever gotten, but it’s a trip that Cassini will not long survive. It’s the long-planned end of a glorious mission of exploration and discovery—not to mention beauty, art, and inspiration—and while Cassini itself will soon be gone, the enormous amount of data it has gathered in the twenty years since its launch will continue to drive discovery for many, many years to come.

(At least that’s what we’re all telling ourselves to make the loss a bit easier to bear.)

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It’s Cassini’s Final Month.

Cassini is completing its 13-year tour of Saturn with dives between the planet and its rings. Credit: NASA/JPL

Yes, it’s true. As of today, August 15, NASA’s Cassini spacecraft has less than 31 days—one full month—left in operation and, sadly, its existence. On September 15, 2017, Cassini will end its mission with a controlled dive into Saturn’s atmosphere…a journey that it will not long survive. But up until the very end Cassini, which has been exploring the majestic ringed planet and its family of moons since it arrived in the summer of 2004, will be making scientific observations and sending the data back to us here on Earth—at least as long as it possibly can. That data, in fact, will still be en route across the 900 million miles of space between us and Saturn for almost an hour after the spacecraft will have succumbed to the forces of atmospheric entry.

When Cassini’s final signal is received on Earth it will be a ghost message, sent from a ship that no longer exists.

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This Toxic Compound on Titan Could Support Life “Not as We Know It”

Illustration of a sunrise over a liquid methane lake on Titan. © Ron Miller. All rights reserved.

Saturn’s largest moon Titan is often called an analogy to early Earth, with its thick, chemical-rich atmosphere and widespread system of flowing rivers and north polar lakes. But located almost a billion miles away from the Sun, everything on Titan is shifted into a completely different—and frigid—level of existence from that found on Earth. With surface temperatures of 300 degrees below zero F, the lakes are filled with liquid methane and what’s life-giving water here is literally solid rock there. Even the rain on Titan falls as oversized drops of ethane.

But even in this extreme cryo-environment it’s possible that life may right now exist…life relying on an entirely different chemistry than what’s possible on our planet.

Recently scientists have identified a molecule on Titan called vinyl cyanide, or acrylonitrile. To Earthly life acrylonitrile is toxic and carcinogenic; luckily for us it isn’t naturally-occurring here. But on Titan it is and apparently in quantity; it’s possible that vinyl cyanide, raining down from Titan’s atmosphere into its vast hydrocarbon lakes, could even help form methane-based cell structures in much the same way phospholipids do here.

The molecule (C2H3CN) has the ability to form membranes and, if found in liquid pools of hydrocarbons on Titan’s surface, it could form a kind of lipid-based cell membrane analog of living organisms on Earth. In other words, this molecule could stew in primordial pools of hydrocarbons and arrange itself in such a way to create a “protocell” that is “stable and flexible in liquid methane,” said Jonathan Lunine (Cornell University) who, in 2015, was a member of the team who modeled vinyl cyanide and found that it might form cell membranes.

Further evidence of life “not as we know it?” Read more on Ian O’Neill’s Astroengine blog here: Vinyl Cyanide Confirmed: Weird Form of Alien Life May Be Possible on Saturn’s Moon Titan and in a Gizmodo article by Maddie Stone here: Potential Building Block of Alien Life Spotted in Titan’s Atmosphere

A Departing View From Cassini After Clearing the Gap

Animation of raw uncalibrated images acquired by Cassini on May 3, 2017 (Credits: NASA/JPL-Caltech/SSI. Animation by Jason Major.)

Cassini did it again! On May 2-3, 2017 the spacecraft made its second “ring dive” pass of Saturn, passing through the clear space between the innermost edge of the ring system and the planet itself. The animation above shows a view from Cassini looking back toward Saturn on its outbound flight on May 3, just a few hours after the ringplane crossing. Saturn’s limb is visible at upper left.

What’s more, NASA has released a detailed video from the first ring dive on April 26, showing all of the images that were captured and where on Saturn Cassini’s cameras were pointed. Check it out below.

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