Astro Confirms Graphite Theory : Space: A telescope shows that the material absorbs light at a certain wavelength and may play a role in star formation.

The first discovery by any of the four telescopes aboard the space shuttle Columbia has confirmed a 25-year-old pet theory developed by the chief scientist for one of the other telescopes on the mission.

That was one of the bright spots Wednesday as the Astro observatory continued to struggle against problems that are robbing it of irreplaceable viewing time.

Even the crew became a little testy, suggesting that NASA quit trying to make a balky automatic pointing system work properly and use that time instead to carry out some of the scientific objectives of the mission by allowing the crew to guide the telescopes manually.

“We’re up here to do science,” a feisty Vance Brand, skipper of the Columbia, told Mission Control. He was overruled and NASA continued to use precious time to work out some of the bugs.

Scientists were only getting about 35% of their viewing time, a considerable improvement over Tuesday but still far below expectations.

But at least Theodore P. Stecher, principal investigator for Goddard Space Flight Center’s ultraviolet imaging telescope, had something to crow about.

In 1965, Stecher pioneered the field of ultraviolet astronomy when he used small rockets to send instruments above the Earth’s atmosphere, which absorbs ultraviolet light. Stecher discovered that light at a certain wavelength died out as it traveled through the interstellar medium--the gas, dust and subatomic particles that flow though the vast regions among the stars.

Stecher theorized that graphite must be present in the interstellar medium and it was absorbing the light at that wavelength.

Scientists believe that stars are formed when tiny particles in space collapse together, but that process also produces heat, and if the heat is too great it will cause the material to blow apart.

Graphite would also absorb some of the heat from colliding dust particles, thus playing a role in star formation.

But other scientists argued that the dust was simply scattering the light in the same process that makes it difficult to see through a dirty windshield when driving into the sun.

Scientists knew that they could find out which side was right by studying something called polarized light. Usually, waves of light move randomly, up and down, back and forward and diagonally. But when it is polarized, like sunlight reflecting off water, all the waves oscillate in a single plane.

By studying polarized light, scientists can learn much about the geometry of the source as well as the nature of the material through which the light pases, in this case the interstellar medium.

If dust in the interstellar medium scatters the light, that should also produce polarization, so if Stecher’s early opponents are right, the amount of polarized light should increase as it passes through the medium.

The only way to test the theory was to measure the polarized light from a distant star, but there was no way to do that until the Astro mission. So Stecher had to wait a quarter of a century to find out if he was right.

The answer came from the University of Wisconsin’s ultraviolet photo-polarimeter telescope aboard Columbia. That telescope studies light from space that has been polarized, and it is the first space-borne telescope to do that.

If the disappearance of light waves detected by Stecher 25 years ago resulted from scattering, the Wisconsin instrument should have measured an increase in the amount of polarized light.

But no such change was found, confirming Stecher’s theory that the dust was not scattering the light, and the drop at 2200 angstroms was caused by graphite absorption.

“It’s wonderful,” Stecher said Wednesday. “It confirms the suggestion I made 25 years ago.”

Not everybody associated with Astro was happy, however.

The system that points the telescopes and locks them on target was still causing problems for engineers. They also had problems with a small thruster used to position the Columbia, which robbed scientists of a couple of precious hours Wednesday.

The pointing system is supposed to point the telescopes at selected targets automatically, but in most cases the astronauts aboard the Columbia are having to do that manually. Although that takes longer, at least it is getting results.