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measuring the wavelength down to one part in a billion. This helps scientists solve very complicated problems." Among the FTS's advantages is that it uses more of the available light than other similar types of instruments, he said. The FTS can handle more than a hundred times the light a monochromater uses, for example. The FTS also continuously uses all the light, while a monochromater uses only a small amount of it at any given time. "We are pushing technology in most of the construction of this instrument," Palmer said. The two main mirrors, which cost $15,000 each, are precisely controlled by a computer to positions that are less than 10-billionths of an inch, or three times the diameter of the smallest atom. "Development of this powerful FTS was made possible by the advent of digital computers and advancements in optics and mechanics," said Palmer.

First Identification of a Polymer in Space A polymer has been identified in the dust cloud surrounding Halley's comet. Walter Huebner, a scientist on leave from Los Alamos National Laboratory and now at the Southwest Research Institute in San Antonio (Texas), identified the molecule from data obtained during the 1986 encounter with the comet. The polymer, called polyoxymethylene or POM, consists of hydrogen, carbon, and oxygen, three of the most abundant elements in space. It was one of the first polymers identified on Earth and was produced synthetically about the turn of the century.

Huebner identified POM by analyzing the masses of ions detected by a positive ion cluster composition analyzer (PICCA) aboard the Giotto spacecraft. PICCA detected an ion mass spectrum that Huebner says is a characteristic signature of POM and its decay products. The presence of a significant amount of POM in the comet's inner coma indicates that the polymer remains an important component of the nucleus, even though the comet's outer layer eroded away during successive revolutions around the sun. "So it must have been present in the solar nebula when the sun and planets were formed 4-5 billion years ago," Huebner said. "Therefore, POM is an important tracer for the early history of the solar system." The presence of POM in and around Halley's comet also helps explain unexpected data (such as the comet's extreme darkness and the distribution of its dust particles by composition and size) that were obtained by other instruments. Huebner said POM attaches itself to grains of carbon and silica, creating "clumps" of materials with tiny p r o t r u s i o n s , or "whiskers." Some of these grains fall back to the comet's surface, he said, creating a porous mantle that absorbs and traps light. The POM attached to the grains breaks up when the temperature rises, releasing smaller particles. Huebner said this could be one reason why other instruments found larger dust particles close to the nucleus and smaller ones farther away. The apparent presence of POM in the nebula from which the solar system was created means the polymer should also exist in interstellar clouds that astrophysicists ar