NASA is preparing to launch five identical satellites on Feb. 15 in hopes of solving the mystery of why the Northern Lights sometimes shimmer and dance.
From Earth, the aurora borealis looks like a steady band of pale green. But sometimes it suddenly leaps across the sky, and turns violet or red.
This burst of energy is what the satellites will be looking for from space.
The data from above will be augmented by measurements taken on the ground at 20 automated observatories, including 16 set up across Northern Canada by the University of Calgary and the University of California at Berkeley. Four are in Alaska.
The mission is about more than understanding the Northern Lights at their most strange and beautiful. For when the aurora borealis moves and changes colour, it is a sign that a geomagnetic substorm has begun. These substorms release radiation that can damage satellites and power grids.
In 1994, two Canadian satellites, Anik E1 and Anik E2, were damaged in a substorm, says John Manuel, at scientist at the Canadian Space Agency.
In March, 1989, one knocked out power in Eastern Canada for nine hours, he says.
The goal of the U.S. National Aeronautics and Space Administration's mission is to understand why a blast of charged particles from the sun can sometimes trigger these damaging and powerful bursts of energy in the Earth's atmosphere. NASA scientists say they hope to monitor at least 30 substorms during the two-year mission and pinpoint when and where they begin.
The mission is called THEMIS, for Time History of Events and Macroscale Interactions during Substorms, and will cost $200-million (U.S.). “For more than 30 years the source location of these explosive energy releases has been sought after with great fervour. It is a question almost as old as space physics itself,” said Vassilis Angelopoulos, a researcher at UC Berkeley's Space Sciences Laboratory, and the principal investigator of the THEMIS mission.
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The magnetosphere
The sun produces electrically charged flow known as the solar wind, explains Dr. John Manuel, a scientist at the Canadian Space Agency.
The Earth's magnetic field largely deflects the blast around the planet. The area of space dominated by the Earth's magnetic field is called the magnetosphere.
The THEMIS mission will help scientists learn more about when, where and why the solar wind energy stored within the Earth's magnetosphere is explosively released. It is this release of energy that causes the sudden brightening of the Northern Lights, which can damage satellites and power grids.
Five in One
This is the first time NASA has launched five satellites on one rocket.
They have propellants to get them into different orbits and will line up over northern Canada every four days. Three will be at almost 80,000 km above the Earth, a fourth at almost 130,000 km and fifth at a little more than 190,000 km. (That's roughly halfway to the moon.) They are carrying electric, magnetic and particle detectors.
The view from the ground
Canada has helped build 16 automated observatories that will monitor the sky for bursts of Northern Lights activity. Each is equipped with a camera that can take an image of the entire sky and an instrument to measure the Earth's magnetic field. Canada's contribution cost $1.4-million.
1. Gakona
2. McGrath
3. Kiana
4. Fort Yukon
5. Inuvik
6. White Horse
7. Ekatl
8. Fort Simpson
9. Prince George
10. Rankin Inlet
11. Fort Smith
12. Athabasca
13. Gilam
14. The Pas
15. Pinawa
16. PBQ
17. Kapuskasing
18. Hebron
19. Gangon
20. Goose Bay
SOURCES: NASA, CANADIAN SPACE AGENCY
