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Innovations: Dramatic Technology DevelopmentsApart from the compelling scientific motivations behind infrared astronomy, there is a dramatic technology revolution -- still ongoing -- that has done much to open the vistas of the IR universe. This point is spectacularly illustrated in the Figure below, where a pair of observations of infrared emission from the center of our Galaxy, separated by three decades, is shown.
The inset displays a strip-chart recording made by Gerry Neugebauer and Eric Becklin, obtained with a single-element PbS (lead sulfide) detector and the Palomar 200-inch telescope in 1967. The larger near-infrared mosaic of the Galactic Center was created in the early 1990s by Ian Gatley at Kitt Peak National Observatory, from observations with a modern infrared camera using PtSi (platinum silicon) detector arrays. The breathtaking progress made in developing infrared detector technologies has resulted in large part from a synergistic relationship between science and technology -- and between industry and universities. The genesis of this revolution was an investment of hundreds of millions of dollars in infrared detector array technology by the U.S. Department of Defense throughout the 1980s. Military interests in this technology concentrated on high-background temperature environments and on wavelengths shorter than about 30 microns. As the accumulated technical knowledge migrated to the civilian world, astronomers re-directed the focus of development towards the goal of low-background, high-sensitivity applications. Moreover, impressive progress has been made in array technology at all wavelengths stretching from the near- to the far-infrared. In the span of fifteen years, infrared astronomers have gone from using a handful of individual detector elements to routinely working with large-format arrays of many thousands of picture elements (pixels). The "million pixel era" of IR astronomy dawned in 1995. One looks back with a mixture of amazement and amusement when recognizing that the enormous legacy of the path-breaking Infrared Astronomical Satellite was the result of only 62 detector elements! A dramatic application of the continued improvements in detector technologies are these mosaics of the Galactic Center, each featuring near-infrared data obtained from the Two-Micron All-Sky Survey (2MASS).
The progress made in infrared detector technologies for astronomical applications is a direct result of a beneficial partnership between scientists and industry. While scientists owe a debt of gratitude to the design and fabrication efforts of industry, many of these firms have also obtained benefits from the rigorous testing performed by university-based astronomical research groups. It is this revolution in infrared detector technology that will be at the core of the scientific discoveries made by Spitzer. Another important technical development that reduces the mass of the Observatory, and thereby the launch costs, is lightweight optics. The Spitzer primary and secondary mirrors, and the supporting structures, are fabricated almost entirely with lightweight beryllium. This material features a high stiffness-to-density ratio, high thermal conductivity, and low cryogenic specific heat. The total mass of the Spitzer telescope is less than 50 kg. The beryllium telescope assembly is not subject to the complications of thermal expansion variations, and has extremely good dimensional stability.
The 85-cm diameter primary mirror is designed to operate at temperatures of 5.5 K with a wavefront error of less than 0.07 waves. The Spitzer telescope is of Ritchey-Chretien design and will deliver diffraction-limited performance at wavelengths of 6.5 microns and longer.
More InnovationsThe Spitzer Space Telescope is a NASA mission managed by the Jet Propulsion Laboratory. This website is maintained by the Spitzer Science Center, located on the campus of the California Institute of Technology and part of NASA's Infrared Processing and Analysis Center. Privacy Policy |
