Posted on by Elizabeth Howell

How Saturn’s Magnetic Activity Could Help us Pinpoint Time on the Ringed Planet

Image of Saturn’s aurora seen at ultraviolet wavelengths. The spiral shape seen here is similar to the distorted radio aurora visualised by the team and also indicates enhanced auroral activity. Credit: ESA/NASA/Hubble

He’s not even finished his first university degree yet, but Tim Kennelly is already part of a team that is altering our perception of time on Saturn.

The University of Iowa undergrad — in junior year, yet — led a paper describing activity in Saturn’s magnetosphere, where charged particles collect and sometimes form auroras. The process changes with the Saturnian seasons and could, the university stated, help scientists better understand how long a Saturn day lasts.

The  researchers used information from NASA’s Cassini spacecraft, which has been orbiting the planet and its moons since 2004. The research challenge: Saturn is a gas giant full of layers that each have their own rotational speed. That makes it hard to figure out how long Saturn’s day is. (It’s about 10 hours, but varies by latitude.)

Kennelly made direct observations of seasonal changes in a phenomenon known as Saturn kilometric radiation (SKR). This robust radio signal was first discovered several decades ago and is being examined more closely by Cassini.

“UI space physicist Donald Gurnett and other scientists showed that the north and south poles have their own SKR ‘days’ that vary over periods of weeks and years,” the university stated. “How these different periods arise and are driven through the magnetosphere has become a central question of the Cassini mission, according to NASA officials.”

Kennelly observed, from looking at data collected between 2004 and 2011, that SKAs are linked with “flux tubes” that are made up of plasma, or superhot gas. These tubes happen around the same time of instances of SKAs in the northern and southern hemisphere, which changes seasonally.

It’s possible that this understanding could be carried over to other planets, the university stated, including our own.

“This finding may alter how scientists look at the Earth’s magnetosphere and the Van Allen radiation belts that affect a variety of activities at Earth ranging from space flight safety to satellite and cell phone communications,” it added.

This won’t be Kennelly’s only degree. He is about to apply to graduate schools, and he has aims to earn a doctorate in plasma physics.

“I’m pleased to have contributed to our understanding of Saturn’s magnetosphere so early in my career,” stated Kennelly. “I hope this trend continues.”

The research is described in the American Geophysical Union’s Journal of Geophysical Research.

Source: University of Iowa

Posted on by Jason Major

NASA Probes Play the Music of Earth’s Magnetosphere

Launched on August 30, 2012, NASA’s twin Radiation Belt Storm Probe (RBSP) satellites have captured recordings of audible-range radio waves emitted by Earth’s magnetosphere. The stream of chirps and whistles heard in the video above consist of 5 separate occurrences captured on September 5 by RBSP’s Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument.

The events are presented as a single continuous recording, assembled by the (EMFISIS) team at the University of Iowa and NASA’s Goddard Space Flight Center.

Called a “chorus”, this phenomenon has been known for quite some time.

“People have known about chorus for decades,” says EMFISIS principal investigator Craig Kletzing of the University of Iowa. “Radio receivers are used to pick it up, and it sounds a lot like birds chirping. It was often more easily picked up in the mornings, which along with the chirping sound is why it’s sometimes referred to as ‘dawn chorus.’”

The radio waves, which are at frequencies that are audible to the human ear, are emitted by energetic particles within Earth’s magnetosphere, which in turn affects (and is affected by) the radiation belts.

The RBSP mission placed a pair of identical satellites into eccentric orbits that will take them from as low as 375 miles (603 km) to as far out as 20,000 miles (32,186 km). During their orbits the satellites will pass through both the stable inner and more variable outer Van Allen belts, one trailing the other. Along the way they’ll investigate the many particles that make up the belts and identify what sort of activity occurs in isolated locations — as well as across larger areas.

Read: New Satellites Will Tighten Knowledge of Earth’s Radiation Belts

Audio Credit: University of Iowa. Visualisation Credit: NASA/Goddard Space Flight Center. (H/T to Peter Sinclair at climatecrocks.com.)