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K. J. Johnston (U. S. Naval Observatory)
The FAME project team has pursued several studies in order to resolve technical, schedule, and mission cost concerns and to investigate requirements for future space astrometry missions. Two CCD fabrication runs have been completed with good yields of operating CCDs. The first fabrication run, using a mixture of 37 and 100 ohm cm substrate, produced 100 ohm cm devices with a reduced CTE. Thus, only 37 ohm cm substrate was used in the second run. To mitigate the effects of on-orbit radiation damage, FAME CCDs are designed with charge injection capabilities. The current FAME CCDs have a reduced yield of devices with good operating charge injection. The CCDs are currently being tested for image centroiding accuracy and operating characteristics, both before and after laboratory irradiation. The intent is to learn more about the radiation effects on the CCDs and the methods of mitigating the effects of charge transfer inefficiency. Results of these tests will be given.
The requirements for very accurate centroiding of images places strict requirements on the optical design, distortions, and the tolerances on the alignment and thermal variations of the optical components of the instrument. The exact requirements necessary to reach the measurement accuracy have a large effect on the schedule and cost of manufacturing and installing the optics. Therefore, special studies have been conducted to determine the exact requirements for the optical design.
The science that would result from the FAME observations remains compelling, which is the reason for the efforts to continue to develop the project. The latest status and future plans for FAME will be included.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.