Observations under the sun Flare Genesis: $16 million project is designed to unlock mysteries of solar flares and gigantic magnetic storms that erupt from sun's surface.

November 15, 1995|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

On Dec. 20, Johns Hopkins University astro-geophysicist David M. Rust plans to step out onto the Antarctic ice and launch the longest, most detailed observation of the sun ever attempted.

Dr. Rust and five colleagues from the Johns Hopkins Applied Physics Laboratory in Laurel are preparing to loft a converted "star wars" telescope 23 miles into the air beneath a giant helium balloon.

Called the Flare Genesis Solar Observatory, the $16 million project is designed to unlock the mysteries of solar flares and gigantic magnetic storms that sometimes erupt from the sun's surface into interplanetary space.

When they sweep over the Earth, the storms can trigger harmless northern lights displays or they can disrupt communications, overload electrical distribution systems and threaten the lives of astronauts venturing beyond the Earth's own sheltering magnetic field.

A magnetic storm in 1989 caused a nine-hour blackout in Canada and parts of New York state.

With its 32-inch mirror, the Flare Genesis telescope could record as many as 120,000 images of the sun's surface -- one every 10 seconds during a single, 10- to 14-day flight around the pole.

That would produce the longest continuous record ever made of the sun's surface. The best previous observation was 41 minutes, on a shuttle flight.

The photos should reveal details as small as 100 miles across, which is 50 times better than any previous view.

Astronomers had proposed an $850 million orbiting solar observatory. But budget cuts and launch uncertainties shrank the effort to a borrowed telescope and an Antarctic balloon.

"The Antarctic has just irresistible advantages for doing this work," Dr. Rust said. First, the sun shines 24 hours a day during the brief polar summer. The telescope -- steadied by an APL-invented system of star sensors and solar-powered, computer-driven electric motors -- will get a view uninterrupted by clouds or night.

Second, in the south polar atmosphere, the balloon's planned altitude of 125,000 feet, or 23 miles, will place it above 99 percent of the Earth's shimmering atmosphere, which blurs the view from the ground.

Finally, the high-altitude winds over Antarctica are circular. They'll carry the telescope from its McMurdo Station launch on a predictable path around the pole at the 78th parallel, bringing it back over McMurdo, where it will parachute to the ice for recovery if all goes well.

Recovery is crucial. The balloon will fly mostly out of radio contact with the ground, and most images will be recorded only on-board. So the tapes must be retrieved. Scientists also hope to fly the 3,000-pound telescope three or four more times before the sun reaches its next activity peak in 2000.

The APL team will be assisted by a crew from NASA's Scientific Ballooning Facility. The project is supported by $4 million contributed by APL, the National Science Foundation, NASA and the U.S. Air Force. Add to that the $12 million telescope. The instrument is on loan from the Pentagon's Star Wars missile defense project, which built it, but never used it.

The astronomers' goal is an understanding of forces on the sun )) that create magnetic storms. With that in hand, they hope to be able to use observations of the sun's surface to deduce what is going on deep in the sun's interior. They also hope to make more reliable interplanetary "weather" forecasts.

With the right scientific tools, Dr. Rust said, "you can predict how large a force will whack into the Earth when one of these clouds hits us. And that's thrilling."

Dr. Rust has argued that the secret of these eruptions may lie in the "twisting" of magnetic fields like rubber bands on the turbulent surface of the sun.

The sun's 15 million-degree nuclear fires, and its eastward rotation, create the magnetic fields among highly ionized gas atoms, which organize themselves like iron filings around a magnet.

X-ray movies of the sun's surface show the gases roiling like a pot of hot oatmeal. In this turbulence, Dr. Rust believes, the magnetic fields get "pushed around and twisted up." And, like rubber bands twisted too far, he says, they sometimes "kink up" and erupt into the solar atmosphere.

Several times a day -- more often during periods of high solar activity -- huge flares brighten somewhere on the sun's disk, and violent, 1 million-degree bursts of charged particles called "coronal mass ejections" erupt from the surface and fly off into interplanetary space.

Sometimes, Dr. Rust said, "a whole quadrant of the sun blows open. The mystery I'm interested in is to understand the generation of these magnetic fields, and what makes them unstable."

But "nobody has been able to make movies of the process from the ground. The things you're trying to photograph are too small. And because of changing atmospheric conditions, they come and go in your telescope. It's very frustrating."

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