Final images of the Cassini spacecraft

Final images of the Cassini spacecraft

Composed of a true color image of Saturn, observed by Cassini in 2016, superimposed with a false color representation of the ultraviolet aurora in the northern hemisphere as observed on August 20, 2017. Credit: NASA / JPL-Caltech / Space Science Institute / A. Bader (Lancaster University).

The researchers are busy analyzing some of the final data sent from the Cassini spacecraft that has been in orbit around Saturn for more than 13 years until the end of its mission in September 2017.


During the last leg of his trip, Cassini was placed in a particularly daring orbit that passed between Saturn and its rings, which brought her closer than ever to Saturn. This allowed scientists to obtain images of Saturn’s ultraviolet auroras in an unprecedented resolution.

The new observations are detailed in two new studies published in Geophysical Research Letters Y JGR: Space Physics.

Saturn’s auroras are generated by the interaction of the solar wind, a stream of energy particles emitted by the Sun, with Saturn’s fast-rotating magnetic field. They are located in the polar regions of the planet and are known to be highly dynamic, often pulsating and flickering as different dynamic processes occur in the plasma environment of the planet.

Ph.D. from Lancaster University Alexander Bader, a student and lead author of the research, said: “Surprisingly, many questions that revolve around Saturn’s auroras remain unanswered, even after the outstanding success of the Cassini mission.

“This latest set of close-up images gives us unique and highly detailed views of small-scale structures that could not be discerned in the previous observations of Cassini or the Hubble Space Telescope. We have some ideas on what their origin might be, but there is still a lot of analysis to do. “

The satellite images alone will barely be enough to unravel the mysteries of the aurora: the energy particles that cause the bright light shows around the poles of Saturn originate far away from the planet’s surface, where the magnetic field lines are they twist and the plasma clouds interact with each other. When it is in the correct region, Cassini sometimes embeds itself in the stream of particles that connects the auroras with the magnetosphere.

The first analysis of spacecraft particle measurements recorded during these times showed that Saturn’s auroras, such as Jupiter’s, are generated by particles much more energetic than Earth’s. However, the underlying physical mechanisms seem to show similarities between the three.

Although Cassini’s mission is over, the data he provided is still full of surprises and will continue to help researchers understand the operation of the auroras of giant planets, especially in combination with Juno’s observations of the Jupiter magnetosphere.


Image: overnight on Saturn’s rings


More information:
A. Bader et al, The morphology of Saturn’s auroras observed during the Cassini Grand Final, Geophysical Research Letters (2019) DOI: 10.1029 / 2019GL085800

A. Bader et al. Signatures of energy particles on Saturn’s auroras, JGR: Space Physics (2019) First published: December 22, 2019 doi.org/10.1029/2019JA027403

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Lancaster University

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Final images of the Cassini spacecraft (2020, January 14)
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