The northern lights are one of nature’s most exquisite light shows, splashing shimmering arrays of colour across the night sky. But to this day, they are not fully understood. Now, NASA and the Canadian Space Agency are working to unravel the mystery.
The program, dubbed THEMIS, aims to gain a better understanding of the immense energy releases — called substorms — that cause the aurora borealis.
As part of the US$180-million program, NASA is launching five satellites Feb. 15 – the largest number of scientific satellites ever sent into orbit aboard a single rocket.
They will orbit above the Earth, aligning themselves once every four days above northern Canada to send back measurements of magnetic and electrical energy at the outermost layers of the Earth’s atmosphere.
The Canadian team will be responsible for information from 13 magnetic ground stations across the North.
Canada is involved because our country is the most geographically accessible region to study the aurora.
Eric Donovan, University of Calgary, tells Canada AM that scientists understand a lot about the northern lights and yet many aspects remain a mystery.
“We actually know quite a bit about the aurora. People have been intensively studying it for more than 40 years now,” he says.
“We know it comes from the wind that blows off the solar surface and goes by the Earth and interacts with the Earth’s magnetic field. That sets up electric currents — charged particles collide with the Earth’s upper atmosphere and cause it to glow.
“So a lot of the mechanics we understand. But there are still a lot of physical processes that are involved in the aurora itself that we’re very interested in studying and better understanding. ”
In particular, the mission wants to understand the trigger mechanism for magnetospheric substorms.
“A magnetic substorm involves loading energy in slowly over the course of maybe an hour and then it’s explosively released in a matter of seconds. This is something that happens two or three times a day on the Earth. It happens always on the night side — or almost always on the night side — and it’s the substorm itself that we’re going after.”
The storms cause a huge release of energy and radiation that create strong electrical charges that can damage telecommunications satellites or even affect astronauts working on the International Space Station.
“What we’re really getting at it is to understand the way energy makes its way from the solar wind around the Earth and affects charged particle population around the Earth and affects the aurora which then affects the Earth’s atmosphere in interesting ways,” says Donovan. “So really we’re looking at that whole chain of events.”
By understanding substorms, scientists will be able to understand space weather and how it affects satellites and humans in the magnetosphere, thereby one day making space travel safer.
The area around the South Pole also experiences “northern lights”, called aurora australis. The auroras coincide with periods of greatest sunspot activity and with magnetic storms and are seen most frequently at the time of the equinoxes.