Cassini Archives

June 25, 2024June 25, 2024 by Mark Thompson

Saturn’s Energy is Out of Balance

Energy imbalance of Saturn (image credit: NASA/JPL)

Earth releases about as much energy out into space as it absorbs, arriving at a thermal equilibrium. This means it will reach an average temperature as is the case with most planets. Saturn however, is a little different as recent observations show the planet’s energy is out of balance. It seems that in addition to the energy it receives from the Sun, there must also be an internal source of heat, perhaps driven by its highly elliptical orbit.

June 17, 2024June 17, 2024 by Evan Gough

The Great Red Spot Probably Formed in the Early 1800s

"Great Red Spot from P7 Flyover". Credit: NASA / SwRI / MSSS / Jason Major © public domain

Jupiter’s Great Red Spot (GRS) is one of the Solar System’s defining features. It’s a massive storm that astronomers have observed since the 1600s. However, its date of formation and longevity are up for debate. Have we been seeing the same phenomenon all this time?

March 27, 2024March 27, 2024 by Evan Gough

A Single Grain of Ice Could Hold Evidence of Life on Europa and Enceladus

The Cassini spacecraft captured this image of cryovolcanic plumes erupting from Enceladus' ice-capped ocean. Image Credit: NASA/JPL/CalTech

The Solar System’s icy ocean moons are primary targets in our search for life. Missions to Europa and Enceladus will explore these moons from orbit, improving our understanding of them and their potential to support life. Both worlds emit plumes of water from their internal oceans, and the spacecraft sent to both worlds will examine those plumes and even sample them.

New research suggests that evidence of life in the moons’ oceans could be present in just a single grain of ice, and our spacecraft can detect it.

March 13, 2024March 16, 2024 by Matt Williams

What Can We Learn Flying Through the Plumes at Enceladus?

In the next decade, space agencies will expand the search for extraterrestrial life beyond Mars, where all of our astrobiology efforts are currently focused. This includes the ESA’s JUpiter ICy moon’s Explorer (JUICE) and NASA’s Europa Clipper, which will fly past Europa and Ganymede repeatedly to study their surfaces and interiors. There’s also NASA’s proposed Dragonfly mission that will fly to Titan and study its atmosphere, methane lakes, and the rich organic chemistry happening on its surface. But perhaps the most compelling destination is Enceladus and the lovely plumes emanating from its southern polar region.

Since the Cassini mission got a close-up look at these plumes, scientists have been aching to send a robotic mission there to sample them – which appear to have all the ingredients for life in them. This is not as easy as it sounds, and there’s no indication flying through plumes will yield intact samples. In a recent paper, researchers from the University of Kent examined how the velocity of a passing spacecraft (and the resulting shock of impact) could significantly affect its ability to sample water and ice within the plumes.

February 13, 2024February 13, 2024 by Laurence Tognetti

Saturn’s “Death Star Moon” Mimas Probably has an Ocean Too

Saturn's moon, Mimas, captured by NASA's Cassini spacecraft in 2010. (Credit: NASA/JPL-Caltech/Space Science Institute)

A recent study published in Nature presents a groundbreaking discovery that Saturn’s moon, Mimas, commonly known as the “Death Star” moon due to its similarities with the iconic Star Wars space station, possesses an internal ocean underneath its rocky crust. This study was conducted by an international team of researchers and holds the potential to help planetary geologists better understand the conditions for a planetary body to possess an internal ocean, which could also possess the conditions for life as we know it. While Mimas was photographed on several occasions by NASA’s Cassini spacecraft, including a close flyby in February 2010, what was the motivation behind this recent study regarding finding an internal ocean on Mimas?

January 6, 2024January 31, 2024 by Mark Thompson

Titan’s “Magic Islands” Could Be Floating Blobs of Organic Solids

A false-color image based on Cassini data shows Ligeia Mare on Titan. Credit: Howard Zebker / Stanford

When the Cassini spacecraft returned radar scans of the surface of Saturn’s moon Titan, the results were mindblowing. It revealed giant lakes or seas of liquid methane, a complete absence of waves and what seemed to be islands in the giant bodies of liquid. Now a team of scientists think they may be blobs of organic molecules that form in the atmosphere, collect in the lakes and float around!

December 18, 2023December 18, 2023 by Evan Gough

Toxic Gas is Leaking out of Enceladus. It’s also a Building Block of Life.

Enceladus’ status as a target in the search for life keeps rising. We’ve known for years that plumes erupting from the ocean under the moon’s icy shell contain important organic compounds related to life. Now, researchers have found another chemical in the plumes which is not only highly toxic but also critical in the appearance of life.

December 14, 2023December 14, 2023 by Mark Thompson

Dark Matter Could Cause Jupiter’s Night Side to Glow

One of the aspects of our study of the universe that fascinates me is the hunt for dark matter. That elusive material that doesn’t interact with much makes it difficult but not impossible to detect. Gravitational lenses are one such phenomena that point to its existence indeed it allows us to estimate how much there is in galaxy clusters. A paper now suggests that observations of Jupiter by Cassini in 2000 suggest we may be able to detect it using planets too.

December 7, 2023December 9, 2023 by Nancy Atkinson

Fly Slowly Through Enceladus' Plumes to Detect Life

The plumes of Enceladus have phosphate-rich ice grains entrained. Credit: NASA — A NASA illustrations of Cassini flying through the plumes of Enceladus. Credit: NASA.

Enceladus is blasting water into space from the jets at its southern pole. This makes it the ideal place to send a dedicated mission, flying the spacecraft through the plumes with life-detection instruments s. A new study suggests that a spacecraft must proceed carefully through the plumes, keeping its speed below 4.2 km/second (2,236 miles per hour). Using a specialized, custom-built aerosol impact spectrometer at these speeds will allow fragile amino acids to be captured by the spacecraft’s sample collector. Any faster, they’ll shatter, providing inclusive results.

November 21, 2023November 21, 2023 by Mark Thompson

In the Shadow of Saturn’s Rings

This image is a composite of observations made of Saturn in early 2018 in the optical and of the auroras on Saturn’s north pole region, made in 2017. Image from NASA/ESA Hubble Space Telescope — Composite image of Saturm from HST (Credit NASA/ESA)

I can remember it very well, although not actually sure when it was, back around 1995/1996 I think. I was, like most other keen stargazers very familiar with the sight of Saturn with rings and all. Indeed the view of Saturn with its rings was one of the first things I had ever seen through a telescope and it inspired me into a lifetime passion of exploring the night sky. Every 15 years though, the Earth passes through the plane of the rings and from Earth they seem to vanish. Now, an astronomer has used data taken during such ring plane crossings from the Cassini spacecraft to measure the transparency of the rings.