��ݮ����Ƶ����

Most people are familiar with the aurora borealis, or “Northern Lights,” with its spectacular curtains of light rippling across the night sky.

But there’s another type of aurora called a “patchy pulsating aurora” with irregular shapes and pulses – turning on and off – every few seconds or so, like a lava lamp.

Like all aurora, pulsating aurora are emissions of light caused by electrons and other particles coming from near-Earth space. These particles plunge into the ionosphere (Earth’s upper atmosphere) and collide with atoms and molecules, causing them to glow in distinctive colours.

“But the physical process that creates the pulsating aurora is very different than the process that creates the curtain-type of auroral arcs,” says Dr. Emma Spanswick, PhD, assistant professor in the Department of Physics and Astronomy in the Faculty of Science, and a member of ��ݮ����Ƶ����’s Auroral Imaging Group.

Scientists know that high-energy particles coming from sub-storms, a type of energy release in the geospace environment, are involved in pulsating aurora – as are waves in Earth’s magnetic field.

“We know a lot of the pieces of what’s involved. But no one has really stitched it all together into a coherent, detailed picture,” says Spanswick, who holds a Canada Research Chair in Geospace Dynamics and Space Plasma Physics.

The international , led by U.S. National Aeronautics and Space Administration (NASA), aims to determine whether the pulsating aurora is connected to another phenomenon called “microbursts” – higher-energy electrons from Earth’s magnetic field that occur in bursts lasting about one-tenth of a second.

On March 5, 2022, a NASA Black Brant IX sounding rocket launched from the Poker Flat Research Range north of Fairbanks, Alaska. The rocket flew directly through a  pulsating aurora, measuring particles and magnetic fields, before falling back to Earth.

Many kilometres below, two new ground-based radio instruments listened carefully for any disturbance caused in the ionosphere by high-energy particles in the pulsating aurora.

It was the first test for these protype instruments, built at ��ݮ����Ƶ���� and designed in collaboration with Merrimack College near Boston.

Next-generation instruments supported by Canada Foundation for Innovation

��ݮ����Ƶ���� wasn’t originally part of the LAMP mission. However, the mission leaders learned about Spanswick’s work on the radio instruments from collaborators in the U.S.

“So they contacted me and asked if we could supply support for the launch,” she says.

Spanswick’s success in securing a Canada Research Chair enabled her to apply for and receive a Canadian Foundation for Innovation-John R. Evans Leaders Fund (CFI-JELF) grant, to develop and deploy 15 of the new instruments, called “riometers.”

The next-generation instruments will replace the ��ݮ����Ƶ���� Auroral Imaging Group’s 11 riometers across a network in northern Canada. These older instruments operate only on a single radio frequency, which limits their capability.

A riometer is essentially a radio receiver used to monitor the radio signal emanating from the cosmos – the stars and galaxies. Whenever the near-Earth geospace system is active and high-energy particles are driving deep into the ionosphere, the radio signal from the cosmos starts to disappear.

“We can use the dropout in radio signal from the cosmic background as an indicator that the ionosphere is disturbed,” Spanswick says.

Spanswick’s next-generation riometers employ multiple radio frequencies to indicate at what altitude the ionosphere is disturbed. By incorporating models with the riometer data, researchers can show what the electron density looks like at certain altitudes, which can help identify the process driving the pulsating aurora.

International collaboration enhances auroral science

When Spanswick got the call from the LAMP mission leaders, she and her ��ݮ����Ƶ���� team installed and field-tested one of three riometers they’d built, deploying it at Meanook, a hamlet north of Edmonton. They then shipped the other two instruments to Fairbanks, Alaska.

Lukas Vollmerahus, instrument design and maintenance engineer, built and tested the riometers. Brenden Bickner, software and electrical engineering technician, developed a real-time dashboard used to view and assess data in support of the launch mission.

Due to COVID travel restrictions, the two riometers shipped to Alaska were installed by collaborators from the New Jersey Institute of Technology, University of Alaska Geophysical Institute, and Merrimack College.

One riometer was installed at the Poker Flat Research Range where the sounding rocket was launched. The other unit was deployed north of Fairbanks in Venetie, a town located directly below where the rocket reached its peak altitude.

Spanswick and her team are now involved with LAMP mission scientists in analyzing the data. “From what I’ve seen, this data is going to provide lots of discussion on mechanisms for the pulsating aurora, and it’s certainly going to drive more active research in this area,” she says.

“Being able to collaborate with new instrumentation and the experts who have developed it provides us additional ways to look at the space environment and see what is going on,” says Dr. Alexa Halford, PhD, LAMP’s principal investigator from  NASA’s Goddard Space Flight Center.

 “When we can find these partnerships, we end up with better results providing new insights into the physics of the aurora than we would have if it was only our own experiment – and we’re able to ask additional science questions,” Halford says.

��ݮ����Ƶ����’s long-standing international reputation for auroral research and innovation opened the door to participating in the LAMP mission, Spanswick notes. “We have world-leading programs here for remote sensing the space environment and studying the aurora.”