The Eye of Space Storms
Artist’s conception of a blast of magnetic waves arriving from space at the eye of a storm and then launching a series of concentric outward propagating ripples.
Credit: Any Kale/Univ. of Alberta
Using data from NASA’s THEMIS mission, a team of University of Alberta researchers has pinpointed the impact epicenter of an Earth-bound space storm as it crashes into the atmosphere, and given an advance warning of its arrival.
The team’s study reveals that magnetic blast waves can be used to pinpoint and predict the location where space storms dissipate their massive amounts of energy. These storms can dump the equivalent of 50 gigawatts of power, or the output of 10 of the world’s largest power stations, into Earth’s atmosphere.
The energy that drives space storms originates on the sun. The stream of electrically charged particles in the solar wind carries this energy toward Earth. The solar wind interacts with Earth’s magnetic field. Scientists call the process that begins with Earth’s magnetic field capturing energy and ends with its release into the atmosphere a geomagnetic substorm.
“Substorm onset occurs when Earth’s magnetic field suddenly and dramatically releases energy previously captured by the solar wind,” said David Sibeck, project scientist for the Time History of Events and Macroscale Interactions During Substorms (THEMIS) mission at NASA Goddard Spaceflight Center in Greenbelt, Md.
Solar flares issue strong electromagnetic bursts.
Physicists Jonathan Rae and Ian Mann lead the University of Alberta research team that recently located a substorm’s epicenter of the impact. The team uses ground-based observatories spread across northern Canada and the five satellites of the THEMIS mission to detect magnetic disturbances as storms crash into the atmosphere. Using a technique the researchers call “space seismology,” they look for the eye of the storm hundreds of thousands of miles above Earth.
“We see the benevolent side of space storms in the form of the Northern Lights,” said Mann. “When electrically charged particles speed toward Earth and buffet the atmosphere, the result is often a dancing, shimmering light over the polar region.” But there is also a hazardous side. Earth’s atmosphere protects us from the damaging direct effects of the radiation from space storms, but in space there is nowhere to hide. High-energy, electrically charged particles released by space storms can damage spacecraft. On Earth, disturbances caused by the particles and the electrical currents they carry can interrupt radio communications and global positioning system (GPS) navigation, and damage electric power grids.
Rae and Mann’s team has also determined that the magnetic tremors show that the space storm impact into the atmosphere has a unique epicenter, with the eye of the storm located in space beyond the low-Earth orbits of most communication satellites.
Guided by Earth’s magnetic field, the magnetic tremors rocket through space toward Earth. These geomagnetic substorms trigger magnetic sensors on the ground as they impact the atmosphere. The effects of these storms, and the most spectacular displays of the Northern Lights, follow a few minutes later.
Artist’s concept of THEMIS in orbit. THEMIS is a 2-year mission consisting of 5 identical probes that are designed to study the violent eruptions of Auroras.
The objective of NASA’s pioneering multi-spacecraft THEMIS mission is to determine what causes geomagnetic substorms. In addition to a well-instrumented fleet of five spacecraft, THEMIS operates a network of ground observatories stretching across Canada and the United States to place the spacecraft observations in their global context. All night long, every night, the observatories take 3-second time resolution snapshots of the aurora and measure corresponding variations in Earth’s magnetic field strength and direction every half second.
An analysis of the auroral movies and magnetic variations by Dr. Jonathan Rae from the University of Alberta pinpointed just when and where one substorm explosively released its magnetic energy. “Undulating auroral features and ripples in Earth’s magnetic field began at the same time and propagated away from Sanikulaq, Nunavut, Canada at speeds on the order of 60,000 miles per hour, much like the blast wave from a gigantic explosion,” said Sibeck. Dr. Rae and his team presented the results on May 25 at the American Geophysical Union meeting in Toronto.
Studying space weather is important for astrobiologists seeking to understand how the Earth interacts with the solar system environment and how these interactions can affect life on our planet. The sun provides most of the energy that fuels the Earth’s biosphere, and the interactions between the sun and the Earth have had a profound influence on the evolution of life through time.
Advance warning of approaching space storms could also ensure the safety of future human explorers on missions in orbit, to the moon and beyond. When humans travel beyond the protection of Earth, space weather can expose them to harmful amounts of radiation. A better understanding of space weather can help scientists develop methods of protecting astronauts on future long-duration missions.