camera array turns substorm into a grand mosaic

By Erling Friis-Baastad The first time Your Yukon checked in with the THEMIS team, back in 2005, their five satellites hadn't gone up and the coast-to-coast array of ground-based cameras was only beginning to be installed and prepped.

By Erling Friis-Baastad

The first time Your Yukon checked in with the THEMIS team, back in 2005, their five satellites hadn’t gone up and the coast-to-coast array of ground-based cameras was only beginning to be installed and prepped. But there was plenty of thrilled anticipation: if the Time History of Events and Macroscale Interactions During Substorms project worked, scientists believed they would be able to understand the processes behind the huge storms we see here in the North as brilliant displays of northern lights.

Post-doctoral fellow Emma Spanswick, a member of the THEMIS team based at the University of Calgary, explains what the cameras and satellites were seeking: “The Earth is protected by its magnetic field. The solar wind pushes on that field and produces a wind-sock like shape streaming away from the sun.

“The more the sun pushes, the more stretched the magnetic field becomes … as you stretch the field you are storing energy in there and at some point, just like a rubber band, it’s going to snap, and when it snaps, you get this dramatic reconfiguration of the Earth’s magnetic field that energizes particles and pushes them in towards the atmosphere, causing the dramatic release … the aurora light up.”

The THEMIS satellites have had two successful “tail seasons” since they were launched early in 2007, stacked up like layers of a wedding cake atop a rocket, from Cape Canaveral, Florida. A tail season refers to those months during our dark northern winter when the five satellites line up behind the Earth, opposite from the sun, in the wind sock – the “tail.”

Meanwhile, to coincide with data coming in from the satellites, 20 cameras (16 in Canada) take perfectly synchronized photographs of the sky from the ground every three seconds. Scientists have stitched images from the camera into an impressive mosaic of an auroral band stretching clear across the Canadian North.

The logistics were awesome, but on the whole all systems have worked marvelously – so marvelously that so far there is no absolutely definitive single answer to the big question: “What initiates the snap?” THEMIS was designed to end the controversy between two competing theories, says Spanswick. “We have observed more than we thought we would and it appears multiple things cause the snap.

“THEMIS put more fuel on the fire.”

There have been some other surprises over the two tail seasons. Among them are very faint bands of fluctuation within the lights, now called arc waves, which had never been seen before. (See Canadian Space Agency site for more on these waves.)

Spanswick is a member of the team charged with maintaining the ground-based Canadian cameras at sites which include Whitehorse, YT, Fort Smith and Inuvik in the NWT, Taloyoak in Nunavut, and so on all the way to Goose Bay, Labrador. The array produces about 20 gigabytes of data a night. “Our archives right now contain 16 terabytes of data,” she adds. That’s far too much for a mere human to comprehend, so new computer systems are being developed to summarize the data.

Meanwhile, lower-resolution images can make their way to southern observers from the ground-based observatories over the internet, but the high-resolution images are just too full of data to travel that route, so the USB drives from the camera are periodically shipped south via Canada Post!

Throughout this elaborate astro-ballet, amateurs have played a vital role. In every community hosting a camera, the THEMIS scientists can count on a local to maintain infrastructure and instruments. They are basically high-tech custodians and come from many walks of life. One custodian in northern Manitoba works on a local hydro dam; another in Yellowknife is employed by Indian and Northern Affairs. These dedicated amateurs trouble-shoot, reboot and perform minor repairs on the system, saving southern scientists many expensive trips north.

There have been a few problems; no such elaborate and innovative system would be complete without them. Not surprisingly, equipment in a ground-based observatory can freeze in the cold Arctic. But overheating has been a problem too, maybe a bigger one, as air-conditioning units that protect delicate circuitry, such as the one in Fort Smith, have briefly failed.

The THEMIS project has one more year to go, but aboard two of the satellites, P1 and P2, small burners have been briefly reignited to begin the process of sending the craft deeper into the moon’s gravity, and eventually into lunar orbit. From there the two P’s will provide another perspective on the Earth’s magnetosphere for a project called ARTEMIS, but that’s another story.

When asked why the Alberta scientists, NASA and the Canadian Space Agency have undertaken the THEMIS challenge, Spanswick says, “Our motivation is entirely science, entirely understanding the Earth’s environment.” Of course, the history of scientific research has been a history of surprises, of answers to old questions suddenly creating new questions, and of unforeseen developments.

Meanwhile, in Calgary, there’s a team of researchers who have, in Spanswick’s words, “developed expertise in deploying remote instrumentation and developed technologies for retrieving real-time data from remote systems.” That bodes well for Canada’s role in the future of space exploration.

For more information on THEMIS, see Your Yukon 433, “Light Storms Rage Above the Sky,” July 29, 2005.

This column is co-ordinated by the Northern Research Institute at Yukon College with financial support

from Environment Yukon and

Yukon College. The articles are

archived at