Aug. 20, 2017
How’s the weather up there? Space weather and how it impacts Earth
On Earth, we are delighted whenever we have the chance to gaze up at the aurora borealis – also known as the northern lights – dancing across the night sky. People visit the North, drive for miles or wake their children up late at night all for the opportunity to go outside, look up and be astounded by the rippling green, blue and red sheets of light.
The aurora’s spectacular displays, 100 to 500 kilometres above us, are caused by the solar wind streaming from the Sun and interacting with Earth’s magnetic field to generate huge electric currents. One consequence is that electrons trapped in the Earth's magnetic field are accelerated and collide with nitrogen and oxygen in the upper atmosphere, creating the colourful aurora borealis in the northern hemisphere and aurora australis in the southern hemisphere.
Aurora is a form of space weather
And while it is beautiful to behold from Earth, its effects on critical systems for our planet can be anything but pretty. Extreme space weather over vast regions of near-Earth space can knock out global navigation and communications satellites and short-circuit our electrical transmission grids, corrode petroleum pipelines and interfere with magnetically guided directional oil drilling.
Scientists at UCalgary are building our understanding of space weather and our near-Earth space environment—an area that extends about 60,000 kilometres toward the sun and more than 3.8 million kilometres on the night side away from the sun.
“This is part of our environment,” says Eric Donovan, professor in the Department of Physics and Astronomy and associate dean (research) in the Faculty of Science, and director of the Auroral Imaging Group. “It’s the cosmic shore.”
Decades of discovery about Earth's 'windsock'
In 1971, an innovative, UCalgary-led space instrument captured the first global images of the aurora. Since then researchers have participated in more than 20 national and international space missions, with instruments designed and built either in the university’s Science Workshop or with Canadian space industry partners.
The university also operates an extensive network of instruments that include more than 60 on the ground and several on satellites that observe the aurora—the hot, electrically charged gases that are interacting in the upper atmosphere, or ionosphere, and Earth’s magnetic field.
“Our work is all about understanding how these plasmas work, how these charged particle gases behave,” says David Knudsen, professor and interim department head of Physics and Astronomy. “It’s about having a deeper understanding of fundamental science and the mysteries of the aurora.”
Plasma gases in this environment are essentially giant electrical circuits of highly charged particles, or electrons, which are generated near Earth and driven by the Sun. Earth’s magnetic field funnels the flow of plasma toward high-latitude regions and around the planet.
“The near-space environment is basically throwing electrons down at the atmosphere,” says Emma Spanswick, adjunct assistant professor of physics and astronomy and associate director of the Auroral Imaging Group. “Every time the electrons hit something, it can excite them and give off light.” This can generate tens of thousands of volts of electricity. Plasma currents can carry up to one terawatt of electrical power – about 30 times the energy consumed in New York City during a heatwave.
“Imagine the near-Earth environment as the outer reaches of the upper atmosphere that spills into space,” says Spanswick. “It’s like a windsock that protects the Earth.” Exploring that windsock and building knowedge of extreme space weather is helping us understand how it affects technology and our lives — everything from the satellites in near-Earth-space, the Global Positioning Systems (GPS) we rely on every day and even communications with aircraft.
Collecting data worldwide
Anyone with an internet connection can tune in to see live, high-definition pictures of the aurora from a ground camera in Yellowknife for the Canadian Space Agency’s AuroraMax public outreach program. UCalgary’s AuroralZone encourages people to share their colour photos of the aurora and help space scientists classify auroral structures.
UCalgary space physicists and engineers are collaborating with colleagues around the world on a new auroral imaging project, TREx, a massive, ground-based network of optical and radio instruments across the prairie provinces and the Northwest Territories. “It will be the first active sensor web deployed for space weather research,” Spanswick says. “With TREx, we can target higher-quality science data that we would not be able to get otherwise.”
NASA’s THEMIS is a five-satellite mission studying what causes explosive sub-storms in the aurora. UCalgary scientists run 17 of the 22 missions’ ground-based observatories and take pictures every three seconds of the night sky. “Together with University of California, Berkeley, we have produced the highest-resolution, large-scale view of the aurora that anyone has ever produced,” Donovan says. THEMIS provided the first detailed ‘map’ of how auroral arcs in Earth’s ionosphere correspond to the planet’s magnetosphere and magnetic field lines.
The European Space Agency’s SWARM project involves three satellites, each carrying three different instruments, to precisely measure and generate accurate models of Earth’s magnetic field. Knudsen designed three of SWARM’s instruments, one for each satellite, for the first precision, multipoint measurements of the plasma’s combined magnetic and electric fields.
These instruments led to the discovery of supersonic plasma jets high in the atmosphere that can push temperatures to almost 10,000 degrees Celsius. Strong electric fields associated with “Birkeland currents” – which generate the auroral arcs’ green curtains of light – are driving the plasma jets. “These findings add knowledge of electric potential, and therefore voltage, to our understanding of the Birkeland current circuit,” Knudsen says.
The SWARM mission, with help from the Alberta Auroral Chasers, also confirmed “Steve,” a rarely seen, narrow strand of purplish light arcing in the aurora. The phenomenon’s appearance is associated with extremely fast flows in the ionized gas at altitudes of 200 to 500 kilometres. “I think we’ll find that there’s heating that causes the air to glow,” says Donovan. “But the cause of this will be in the magnetosphere.”
Nine new “redline” imagers have been deployed from the prairies to the Arctic to capture data and dynamic behaviour in the red spectrum of the aurora, information that provides context to the data collected at the UCalgary operated radar facility at Resolute Bay.
e-POP, part of the European Space Agency’s CASSIOPE mission, is measuring plasma material heated by the aurora in the ionosphere that partially escapes into space. Three of e-POP’s eight instruments were built at UCalgary, including an imaging plasma sensor which provides data on relatively low-energy or ‘cold’ plasma with temperatures of about 1,000 degrees Celsius.
UCalgary researchers have been invited to participate in SMILE, a joint European Space Agency and Chinese Academy of Sciences mission scheduled for launch in 2021-22. A satellite will measure the “magnetopause,” the boundary where the solar wind is on one side and the Earth’s magnetic field is on the other. If all goes well, the mission will provide images of how the sun is driving space weather on the day side, and the response of the system on the night side. “It will be the first time anyone has ever done that,” Spanswick says.
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ABOUT OUR EXPERTS
Eric Donovan studies the physical processes that occur in the near-Earth space environment. In particular, he uses observations of the northern lights, or Aurora Borealis, to ‘remote sense’ the outermost parts of the Earth’s environment — the ionosphere and magnetosphere. View Eric's publications
David Knudsen is a professor and department head in UCalgary's Department of Physics and Astronomy. His research interests include physics of the aurora, space plasma instrumentation, and space plasma physics. Read more about David
Emma Spanswick is an adjunct assistant professor in the Department of Physics and Astronomy at UCalgary and the associate director of the Auroral Imaging Group (AIG). Emma specializes in space physics and magnetospheric physics, and her research interests include electromagnetism, plasma physics, and geophysics. View Emma's publications