Hopkins team designs hoist of sun telescope by balloon


September 15, 1992|By Douglas Birch | Douglas Birch,Staff Writer GR. COLOR PHOTO

A team of Johns Hopkins University scientists is designing what may become the largest, most powerful solar telescope ever flown above the Earth's blurring atmosphere.

But this state-of-the-art instrument, designed to help researchers find the cause of violent eruptions on the sun's surface, won't soar into orbit aboard a ground-shaking launcher. A NASA rocket or space shuttle flight might take a decade of planning and cost hundreds of millions of dollars, scientists say.

Instead, the telescope and its telephone-booth shaped gondola will fly economy class -- dragged 19 miles above Antarctica by a balloon.

The balloon, which can hold 28 million cubic feet of helium, would cover most of the playing field at Camden Yards and tower 35 stories above the pitcher's mound.

The Flare Genesis telescope could soar as early as December 1993, for a mere $4 million.

"That's the beauty of this. It's basement-of-the-physics-department kind of stuff," said Dr. David M. Rust, chief scientist for the Flare Genesis project. He heads the Center for Applied Solar Physics at Johns Hopkins Applied Physics Laboratory in Howard County.

Dr. Rust and his colleagues hope to use the telescope to pin down the precise cause of solar flares, eruptions of the sun's surface that can pack the power of 100 million 25-megaton nuclear warheads.

A solar flare in March 1989 knocked out the electrical grid across the province of Quebec, created an aurora borealis visible as far south as Florida and probably gave some airline passengers a dose of radiation equivalent to a chest X-ray.

Large flares would also threaten the lives of astronauts traveling to the moon, Mars or some other destination in deep space.

A leading theory that Dr. Rust wants to test holds that solar flares are triggered when magnetic fields, twisted like the strands in a cable, rise from the sun's interior and collide with a patchwork of fields that cover the star's roiling surface.

DTC Glowing gases are trapped in these upwelling fields like iron filings caught in the pull of a horseshoe magnet, creating rainbow-shaped prominences that can soar 100,000 miles above the surface. As sheared fields reconnect, they can generate heat of 100 million degrees centigrade.

"There is a sudden conversion of magnetic energy into heat and light and shock waves and energetic particles," Dr. Rust said. "It's just a bad accident. They sort of get slammed together."

Strong magnetic fields polarize some colors of light, causing the normally chaotic rays to vibrate in the same plane. Flare Genesis will map the sun's magnetic fields by recording the patterns of polarized light coming from the surface.

Solar physicists are anxious to get their hands on the Flare Genesis data.

"It's been harder than hell to catch it (the sun) from the ground," Dr. Rust said. "Clouds come over. Worse, the turbulence in the atmosphere is always changing. We just have fuzzy pictures from the ground."

The Flare Genesis telescope is designed to soar above more than 99 percent of the atmosphere, and make images 10 times sharper than any similar, ground-based instrument.

Now, the smallest solar features that astronomers can see clearly from Earth are about 700 miles across. Flare Genesis will produce sharp images of features just 100 miles across.

Solar astronomers have pushed for an orbiting observatory for ,, more than 25 years. But proposals for such a satellite have never made it past NASA planning committees. One $870 million plan was scrapped by a NASA advisory panel just last year, Dr. Rust said.

In the mid-1980s, Dr. Rust began tinkering with the idea of a simpler, space-based solar telescope. He thought about stripping one proposed satellite of everything but its telescope and support equipment.

"Looking at it, I said, 'Ah! That's a balloon mission,' " he said.

The National Science Foundation's Division of Polar Programs awarded the Flare Genesis project an initial $310,000 grant in May. The project has also won the support of NASA and the U.S. Air Force Office of Scientific Research.

Astronomers began using large balloons for long-duration research flights above Antarctica in 1988, said John T. Lynch, who manages astrophysics projects for the foundation's polar programs division. The year before, an exploding star, known as a supernova, came into view almost directly over the South Pole.

After launch, Flare Genesis will use its computer and sensors to point itself automatically at the sun and begin taking pictures at the rate of one every seven minutes. At the end of the mission, researchers will transmit a signal to a device that will puncture the skin of the balloon, deflating it.

The telescope's parachute is supposed to return it gently to the Antarctic ice, where researchers will retrieve 10 tape cassettes loaded with data.

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