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The world's first "space weather" satellite captures the once invisible interactions between the solar wind and the Earth's magnetosphere.

Spectacular real-time photographs of geomagnetic substorms and associated coronas thousands of miles wide are among the first dramatic images of Earth's previously invisible plasma shield being sent to Earth, courtesy of a new polar-orbiting satellite. Called IMAGE, for Imager for Magnetopause-to-Aurora Global Exploration, the spacecraft enables scientists and laymen alike to see the planet's space weather in panoramic splendor, as clearly and instantly as the storm systems on televised weathercasts. 

Highly detailed images from space of Earth's dynamic aurora are being obtained with the far ultraviolet imager on the IMAGE spacecraft. The aurora borealis and aurora australis, commonly known as the Northern and Southern Lights, are ghostly light shows seen most often at the high latitudes of Earth. The light visible from the ground is caused by electrons striking and lighting up the atmosphere much like electricity lights up a television screen. 

The magnetosphere is the outermost edge of Earth's protective shield - a tenuous, dynamic plasma of electrified gas extending beyond the moon on Earth's dark side and stretching over 40,000 miles on the planet's light side. This vitally important protective force field - a shelter from the space storm, so to speak - provides Earth's last line of defense from the solar winds that continually pummel our planet at supersonic speeds. 

"Disturbances caused by these solar storms can play havoc with satellite, telephone, and radio signals and can overload power systems on the ground, among other negative effects," explains Dr. James L. Burch, IMAGE principal investigator at Southwest Research Institute (SwRI), which has overall responsibility for the spacecraft and for the mission. 

Since the March 25 launch, all spacecraft systems have been successfully deployed and are operating normally. The science instruments use all known magnetosphere imaging techniques and are operating even better than expected. 

"The IMAGE spacecraft is the first weather satellite for space storms, and makes them visible through a variety of imaging techniques," he adds. "In a sense, IMAGE becomes a 'seeing eye' of the storm that allows us to view the Earth through plasma-colored glasses." 

Before IMAGE, spacecraft explored the turbulent field around Earth by detecting particles and fields as the craft passed through. As a result, researchers were limited to data only at individual points of this vast and dynamic region. Combining those individual points to get a more complete picture was rarely more precise than a child's connect-the-dots exercise. 

"The old way of tracking magnetic storms is like trying to understand severe thunderstorms in the Midwest by driving around with a rain gauge out the window," says Dr. Thomas Moore, mission project scientist at the Goddard Space Flight Center in Greenbelt, Maryland. "With IMAGE, we are seeing the big picture." 

The big picture promises to be a spectacular one on Earth as the sun enters "solar maximum," a period of intense solar activity that occurs every 11 years. IMAGE's two-year mission coincidentally comes at the height of this period, which will enable the spacecraft to study the colossal cosmic turbulence of solar flares and coronal mass ejections that agitate the magnetosphere, producing unusually spectacular displays of Northern and Southern Lights. In March 1989, for example, the same severe solar storm that knocked out electricity in the Northeastern U.S. so intensified the aurora borealis that the light could be seen as far south as Texas. 

As part of the mission's open data policy, the once-invisible images returned by the spacecraft will be accessible on the internet to amateurs and professionals alike, at image/ image_main.html. The science instruments will provide movies that show real-time space weather. In addition, the data is being held online at the National Space Science Data Center at Goddard. Data processing and analysis software is available for download along with the data, giving the space science community the same access to data as the IMAGE science team. 

The extreme ultraviolet imager is capturing the first global images of the plasmasphere, the tenuous extension of the Earth's electrically charged upper atmosphere. The plasmasphere appears in the image above as a ragged reddish-orange cloud surrounding the Earth. The bright yellow-orange crescent on the Earth's day side - the sun is at upper left - is sunlight reflected from the higher-density atmospheric gases closer to the Earth.

"By allowing us to view large areas of the magnetosphere simultaneously, IMAGE is already greatly enhancing our understanding of how this region responds to solar storms," says Burch. "Whether viewing the space storms directly or witnessing the spectacular effects of those storms here on Earth, it's an enlightening cosmic light show no one will want to miss." 

For more information, read "To See the Invisible" in the Fall 1999 issue of Technology Today® at, or visit the IMAGE web site at Contact Burch at (210) 522-2526 or


Technics Summer 2000 Technology Today
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