Arizona Reporter - Sci-Tech - 04/03
UA Receives Contracts to Support Quest for Dark Energy
Two University of Arizona research and development groups were selected to develop and manufacture key technology for the first major undertaking to investigate the mystery of dark energy in the universe.
UA's Imaging Technology Laboratory, a research group within Steward Observatory, and the Optical Fabrication and Engineering Facility at the College of Optical Sciences will provide image recording devices and the heart of the optical system used for imaging, respectively, for the Hobby-Eberly Telescope at the McDonald Observatory, which is operated by the University of Texas, Austin.
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The additions are part of outfitting the world's fourth largest optical telescope with an array of new instruments to analyze the light from distant galaxies in an effort to understand the nature of dark energy. Scientists have known for a while that dark energy exists, but so far, nobody has been able to come up with an explanation of what it is.
During the Hobby-Eberly Telescope Dark Energy Experiment, or HETDEX, the telescope will search a large area of the sky that encompasses most of the Big Dipper constellation. This region is far above the plane of the Milky Way galaxy, which is filled with clouds of gas and dust that block the view of distant galaxies. During three years of observations, UA's imaging sensors will collect the faint light from at least one million galaxies that are between nine billion and eleven billion light-years away. The data about their movement, size and precise locations with respect to one another will then be computed into the largest three-dimensional map of the universe ever produced.
The Optical Fabrication and Engineering Facility at the College of Optical Sciences was awarded a $4 million contract to devise and build an extremely complex optical device known as a wide field corrector.
"The wide field corrector broadens the telescope's view into space," explained Martin Valente, who directs the facility, "enabling it to survey vast swaths of the sky in a relatively short amount of time."
Ever since the Big Bang, the universe has been expanding and galaxies are moving away from each other. Galaxies attract each other through their immense gravitational forces, which should slow down the expansion of the universe. Instead, the expansion of the universe has sped up over time. This acceleration is attributed to some unknown force - dark energy - counteracting the galaxies' gravitational pull, causing them to spread out deeper into space.
The map of galaxies produced by the HETDEX survey will allow astronomers to measure how fast the universe was expanding at different times in its history. Changes in the expansion rate will reveal the role of dark energy at different epochs. Various explanations for dark energy predict different changes in the expansion rate, so by providing exact measurements of the expansion, the HETDEX map will eliminate some of the competing ideas.
Jim Burge, a professor with joint appointments in the College of Optical Sciences and the College of Science, pointed out that in addition to venturing into uncharted territory by developing innovative optical solutions and devices, education is an important by-product of the process.
"We have students work side by side with faculty and technicians on projects like this one," he said. "They come up with their own solutions to scientific and design challenges, put the systems together and run the tests."
The hands-on experience provides these optical sciences engineers in the making with practical experience, giving them a head start once they enter the engineering workforce.
"Because of the talent and motivation of our students, we are capable of attracting such contracts that bring money to the state, provide opportunities for students, and advance technology," Burge said. "It's a win-win-win situation for Arizona."
The second UA contractor, the Imaging Technology Laboratory, or ITL, has won a $2 million contract with Astronomical Research Cameras, Inc., a small business in California providing the camera electronics, to manufacture about 200 exceptionally sensitive detectors. The devices will be fitted into the telescope's custom-made assemblies (spectrographs) that will record and analyze the light from distant galaxies.
"Our laboratory was selected because of our ability to make highly sensitive sensors," said ITL Director Michael Lesser, a senior research scientist at Steward Observatory. Lesser and his colleagues came up with a unique process to overcome the challenge of producing highly sensitive light detectors. "The way we mount them makes it possible for the light to enter the sensor from the back side and, coupled with optimized thin film coatings, convert 90 percent of the light into image data."
Each spectrograph unit will be identical to all the others, making it possible to mass-produce them in less time and for less money than a single giant spectrograph with the same capabilities.
"It is very special for a university to be involved in a high-volume production process like that," Lesser said. "The typical scale for an academic institution is to make only one or a few prototypes of a given instrument."
The Hobby-Eberly Telescope is a partnership of the University of Texas at Austin, Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität and Georg-August-Universität. The HETDEX project is a collaboration of the University of Texas at Austin, Pennsylvania State University, Texas A&M University, Universitäts-Sternwarte Munich, Astrophysical Institute Potsdam and the Max-Planck-Institut fuer Extraterrestrische Physik.
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