UA scientists help test theory of relativity

Karen C. Tully Arizona Daily Wildcat Senior staff engineer Martin Valente (left) and senior optician Scot Sumner sit around their successfully polished quartz block. The block is projected to launch in October 2000 for a year-long orbit on a satellite 400 miles above the Earth's poles.

UA Senior Optician Scot Sumner and others at the Optical Sciences Optics Laboratory have recently spent more than 14 months on NASA's 40-year project, meticulously grinding and polishing a pair of precision-cast, 75-pound quartz blocks.

One block will house four ultra-sensitive quartz gyroscopes engineered to measure Earth's effects on space-time. The second block will be an emergency backup.

In October 2000, the quartz block and a telescope will be sent into a year-long orbit on a satellite 400 miles above Earth's poles.

Gyroscopes, which will be housed within the block, will detect space-time gravitational shifts as slight as .1 milliarc-seconds, a measurement equal to the width of a human hair seen from a distance of 100 miles.

The quartz block was delivered to scientists from Stanford University on Feb. 12 for the joint NASA/Stanford relativity experiment. Its backup counterpart was delivered Nov. 3.

"It's about time we steal some publicity away from Steward Observatory," said Sumner, a second-generation optician who has an artistic appreciation for his technical work.

"It (quartz) is such a beautiful medium to work in," he added.

One end of the cylindrical block will be attached to a compact, yet powerful, quartz telescope designed by Tucson Optical Research Corp. through a process called "optical contacting."

The process involves polishing quartz surfaces to such smoothness that when one surface touches another, the atoms begin to "share" a molecular bond, virtually fusing together, Sumner said.

To achieve near-perfect smoothness, Sumner used a variety of polishing tools, some as small as one-fourth of an inch in diameter, to level the telescope's mounting surface to within 2.5 millionths of an inch.

"The most interesting part was doing it all by hand," Sumner said.

The work was done manually because machines are not precise enough to work within the necessary specifications without damaging the block.

"I had never done anything to this degree of difficulty until now," Sumner said.

Stanford offered the UA the grinding and polishing jobs after two efforts at other facilities failed.

"This was a breakthrough project for us," said Martin Valente, UA optics shop manager and principal investigator for the project.

Valente said the challenge was trying to maintain 90-degree angles between the polished faces in two planes.

"There was a lot of planning in this project so we wouldn't give them (Stanford) something unusable," said Valente.

Scientists anticipate that in one year, the gyroscope's orbit plane will shift 6,600 milliarc-seconds, or the width of a human hair seen at a distance of about 40 miles.

Space-time is like a flexible grid, and Einstein believed massive celestial bodies simultaneously drag or twist space-time around as they rotate. This phenomenon is called "frame-dragging."

The more mass a celestial body has, the more distortion it makes in the grid. This distortion, or curving of space-time around a planet, is known as the geodetic effect.

Scientists hope to measure the frame-dragging effect by observing the total shift in gyroscope spin during the one-year mission.

The gyroscopes should detect a 42 milliarc-second directional shift, or the width of a single human hair seen from a quarter of a mile away.

This is the first time Einstein's general theory has directly been tested.

A report on the project stated that the mission's results may shed more light on the nature of matter and the structure of the universe.

Inspired by the project's success, Valente is trying to stimulate more interest in the optic sciences at college and high school levels.

"I see our role growing," said Valente about other space-borne projects currently on the table.

"We're filling niches that industry can't," he added.