Nav: Home

A new way to create Saturn's radiation belts

November 29, 2018

A team of international scientists from BAS, University of Iowa and GFZ German Research Centre for Geosciences has discovered a new method to explain how radiation belts are formed around the planet Saturn.

Around Saturn, and other planets including the Earth, energetic charged particles are trapped in the magnetic field. Here they form doughnut-shaped zones near the planet, known as radiation belts, such as the Van Allen belts around the Earth where electrons travel close to the speed of light.

Data collected by the NASA Cassini spacecraft, which orbited Saturn for 13 years, combined with a BAS computer model have provided new insights into the behaviour of these rapidly-moving electrons. The discovery overturns the accepted view among space scientists about the mechanisms responsible for accelerating the electrons to such extreme energies in Saturn's radiation belts. The team's results are published in the journal Nature Communications this week (Thursday 29 November).

It has always been assumed that around Saturn, electrons are accelerated to extremely high energies by a process called radial diffusion, where electrons are repeatedly nudged towards the planet, increasing their energy. An alternative way of accelerating electrons is their interaction with plasma waves as happens around the Earth and Jupiter with Chorus waves. Around Saturn, Chorus waves have been dismissed as ineffective; however, the authors discovered that in Saturn's unique environment, it is another form of plasma wave called the Z-mode wave that is critical.

According to lead author, Dr Emma Woodfield from British Antarctic Survey:

"This research is really exciting because the high energy electrons in the radiation belt around Saturn have always been assumed to come from radial diffusion. We've identified a different way to create a radiation belt that no one knew of before.

"This study provides us with a better understanding of how radiation belts work across the Solar system and will help modellers forecast space weather more accurately at the Earth, which in turn will protect both astronauts and satellites from radiation hazards."

Dr Emma Woodfield continues:

"Saturn gave us the opportunity of abundant Z-mode waves, to really test what these waves can do to the electrons on a large scale.

"Some people think that planets are just cold chunks of rock travelling through empty space, but the way each planet interacts with the particles in space is complex, unique and exquisite, and studying them can tell us about our own planet and the rare extreme events that occasionally do occur".

Prof Yuri Shprits from GFZ German Research Centre for Geosciences says:

"I think it's most critical to understand the extreme radiation environments of the outer planets. These studies provide us with a unique opportunity to evaluate the potential extremes of terrestrial space weather and to understand what space weather conditions may be around planets beyond our Solar system (exoplanets)".

The team concludes that electron acceleration by Z-mode waves is more rapid at energising electrons in Saturn's radiation belt than radial diffusion and both mechanisms will work together to maintain the radiation belt at Saturn.
-end-
Formation of electron radiation belts at Saturn by Z-mode wave acceleration by E.E. Woodfield, R.B.Horne, S.A Glauert, J.D. Menietti, Y.Y. Shprits and W.S. Kurth is published in Nature Communications here

Issued by the British Antarctic Survey Press Office:

Athena Dinar, Senior PR & Communications Manager, British Antarctic Survey, tel: +44 (0)1223 221 441; mobile: +44 (0)7909 008516; email: amdi@bas.ac.uk

Layla Batchellier, Communications Officer, British Antarctic Survey, tel: +44 (0) 1223 221506; email: laytch@bas.ac.uk

Notes for Editors:

Van Allen radiation belts


The Van Allen radiation belts were detected by the first US satellite Explorer I, which was launched during the International Geophysical Year of 1957-58. They are composed of energetic charged particles trapped inside the Earth's magnetic field, which surrounds the Earth like a ring doughnut. Energetic electrons in the Earth's Van Allen radiation belts occupy two distinct regions.

Solar system radiation belts - Jupiter, Saturn, Uranus and Neptune all have strong magnetic fields and radiation belts. It is thought Mercury may have transient radiation belts.

Radial diffusion - lots of little nudges which push electrons towards or away from the planet, motion towards the planet results in an increase in electron energy.

Wave-particle interaction - the way in which energy is transferred to or from a plasma wave to a charged particle (e.g. electron)

Chorus - Whistler mode chorus waves - a type of plasma wave in a magnetised plasma, these radio waves are converted to sound they sound like the dawn chorus.

Z-mode waves - a type of plasma wave present in a magnetised plasma, so-called because of the shape seen in observations of this wave from instruments on the ground at Earth - a "Z" shape.

British Antarctic Survey (BAS) delivers and enables world-leading interdisciplinary research in the Polar Regions. Its skilled science and support staff based in Cambridge, Antarctica and the Arctic, work together to deliver research that uses the Polar Regions to advance our understanding of Earth as a sustainable planet. Through its extensive logistic capability and know how BAS facilitates access for the British and international science community to the UK polar research operation. Numerous national and international collaborations, combined with an excellent infrastructure help sustain a world leading position for the UK in Antarctic affairs.

British Antarctic Survey is a component of the Natural Environment Research Council (NERC). NERC is part of UK Research and Innovation http://www.ukri.org

For more information visit http://www.bas.ac.uk @basnews

British Antarctic Survey

Related Solar System Articles:

From rocks in Colorado, evidence of a 'chaotic solar system'
Plumbing a 90 million-year-old layer cake of sedimentary rock in Colorado, a team of scientists from the University of Wisconsin-Madison and Northwestern University has found evidence confirming a critical theory of how the planets in our solar system behave in their orbits around the sun.
Why are there different 'flavors' of iron around the Solar System?
New work from Carnegie's Stephen Elardo and Anat Shahar shows that interactions between iron and nickel under the extreme pressures and temperatures similar to a planetary interior can help scientists understand the period in our Solar System's youth when planets were forming and their cores were created.
Does our solar system have an undiscovered planet? You can help astronomers find out
ASU's Adam Schneider and colleagues are hunting for runaway worlds in the space between stars, and citizen scientists can join the search with a new NASA-funded website.
Rare meteorites challenge our understanding of the solar system
Researchers have discovered minerals from 43 meteorites that landed on Earth 470 million years ago.
New evidence on the formation of the solar system
International research involving a Monash University scientist is using new computer models and evidence from meteorites to show that a low-mass supernova triggered the formation of our solar system.
Planet Nine could spell doom for solar system
The solar system could be thrown into disaster when the sun dies if the mysterious 'Planet Nine' exists, according to research from the University of Warwick.
Theft behind Planet 9 in our solar system
Through a computer-simulated study, astronomers at Lund University in Sweden show that it is highly likely that the so-called Planet 9 is an exoplanet.
Studying the solar system with NASA's Webb Telescope
NASA's James Webb Space Telescope will look across vast distances to find the earliest stars and galaxies and study the atmospheres of mysterious worlds orbiting other stars.
'This solar system isn't big enough for the both of us.' -- Jupiter
It's like something out of an interplanetary chess game. Astrophysicists at the University of Toronto have found that a close encounter with Jupiter about four billion years ago may have resulted in another planet's ejection from the Solar System altogether.
IBEX sheds new light on solar system boundary
In 14 papers published in the October 2015 Astrophysical Journal Supplement, scientists present findings from NASA's Interstellar Boundary Explorer, or IBEX, mission providing the most definitive analyses, theories and results about local interstellar space to date.

Related Solar System Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Changing The World
What does it take to change the world for the better? This hour, TED speakers explore ideas on activism—what motivates it, why it matters, and how each of us can make a difference. Guests include civil rights activist Ruby Sales, labor leader and civil rights activist Dolores Huerta, author Jeremy Heimans, "craftivist" Sarah Corbett, and designer and futurist Angela Oguntala.
Now Playing: Science for the People

#521 The Curious Life of Krill
Krill may be one of the most abundant forms of life on our planet... but it turns out we don't know that much about them. For a create that underpins a massive ocean ecosystem and lives in our oceans in massive numbers, they're surprisingly difficult to study. We sit down and shine some light on these underappreciated crustaceans with Stephen Nicol, Adjunct Professor at the University of Tasmania, Scientific Advisor to the Association of Responsible Krill Harvesting Companies, and author of the book "The Curious Life of Krill: A Conservation Story from the Bottom of the World".