NASA enlists tiny satellites in fight against solar storms


GREENBELT -- Scientists at NASA's Goddard Space Flight Center unveiled new satellites yesterday that may represent the future of space science - and they're about the size of your microwave oven.

The agency's Space Technology 5 mission will test three micro-satellites designed to measure Earth's magnetic field, track the solar storms that batter it and serve as prototypes for probes that can predict solar hurricanes the way forecasters predict the weather on Earth.

It's an increasingly important job in a world that relies on global positioning technology for navigation and communication - systems that can be dangerously disrupted by solar storms.

The probes also represent the kind of practical NASA projects that get far less attention than the space shuttle program, the International Space Station, the Hubble Space Telescope and other more-glamorous missions.

In February, a single rocket will launch the micro-satellites into polar orbits up to 2,800 miles, where they will take measurements for 90 days before eventually burning up.

$130 million mission

The $130 million mission, planned since 1999, will test the miniaturized monitoring and communications technology that NASA hopes to use for years to come in instruments ranging from weather satellites to space telescopes.

"The first priority is validating the technology we've developed," said Candace Carlisle, the mission's deputy project manager. Carlisle said the satellites' diminutive size sets them apart from other probes: Smaller devices mean smaller, more-efficient payloads, she said.

The ultimate goal is to send dozens of such satellites into space, at a cost of $1.5 million each, to keep an eye out for solar storms. "We want to show that these small systems can do useful science," she said. "We think that's where the future is."

Everything on ST5 is as small as possible, with equipment squeezed down to as little as 25 percent of its normal size, Carlisle said.

The transponder, a communications system that relays data to Earth, is about the size of an egg. The magnetometer, which will measure the intensity of magnetic fields above the North and South poles, is a 2-inch-thick pancake with the circumference of a tennis ball. It extends outward from the main satellite on a small arm.

Weighing only 55 pounds, the octagonal cylinders are about 19 inches tall and 20 inches wide. By comparison, the average NASA spacecraft weighs 1,000 to 2,000 pounds (they come in a variety of shapes and sizes).

Once launched on a Pegasus XL rocket, the new satellites will be flung Frisbee-style from the rocket, and will orbit about 50 miles apart.

The mission is called Space Technology 5 because it's the fifth mission in NASA's New Millennium Program, an initiative created to develop and test new technologies.

NASA hopes the probes will eventually provide earlier warning and minimize the threats posed by solar hurricanes, which can disrupt radio communications and knock out Global Position System satellites and power grids.

The early warning would allow operators of electronics systems to temporarily shut down vulnerable equipment and carry out contingency plans to minimize danger and disruption.

Earlier efforts

NASA launched several earlier probes that monitor for solar storms and the forces that create them.

The Advanced Composition Explorer, launched in 1997, studies energetic particles from the sun. The Transition Region and Coronal Explorer, launched in 1998, studies the links between the sun's magnetic fields and the heating of the sun's corona.

But solar storms are still hard to predict, and ST5 will test technologies that should be able to provide the best measurements yet of the Earth's magnetic field and track the storms that enter it, said project scientist James A. Slavin.

"We'll be able to measure these structures as they occur, in the solar winds, so we can predict when they will occur and where they will hit," Slavin said.

The probes will depart from Vandenberg Air Force Base in California on Feb. 28 and head for polar orbits so they can measure the electromagnetic field in the currents of the aurora borealis, where the field is most evident.

Auroral displays are common in far northern latitudes. But unusual solar storms - such as some last November - have been known to push them farther south.

Solar assault

The sun is constantly hurling solar flares, creating solar hurricanes or assembling coronal mass ejections - which disrupt the flow of solar wind - in space.

The storms can send bolts of magnetic energy and billions of tons of electrically charged particles into the magnetic field that surrounds and protects the Earth from solar radiation.

Such blasts can rattle the magnetic field, causing geomagnetic storms that trigger electrical surges in long-distance transmission lines and disrupt high-frequency radio and navigation systems.

A solar hurricane in 1989 blacked out much of Canada and the Upper Midwest. One on Halloween 2003 knocked out GPS systems and power grids.

In January, NASA warned utilities and airlines that a sunspot complex was creating solar flares that could lead to threatening storms.

The storms could have caused electrical surges on power grids and disrupted radio communications and navigational systems on some aircraft.

A storm's high-speed particles also can trigger glitches and failures in communications satellites in high Earth orbits.

NASA sometimes tells Space Station crews to stay in one of the better-shielded Russian modules when sunspots appear to be forming into solar storms.

"These solar hurricanes are something that really need to be addressed," Slavin said.

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