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The Terrestrial Planet Finder Coronagraph (TPF-C) is conducting pre-formulation design and analysis studies based on a 8x3.5m elliptical aperture, light-weight primary mirror feeding an internally occulted (Lyot) coronagraph. The primary mirror has challenging static and dynamic performance requirements. We report on recent trade studies and concepts including open- and closed-back mirror blank designs and comparisons of thermal and mechanical performance; aperture shape alternatives to better match the coronagraph application with weight, packaging, and fabrication constraints; and mirror material trades.

Upcoming major NASA missions such as the Einstein Inflation Probe and the Single Aperture Far-Infrared Observatory require arrays of detectors with thousands of elements, operating at temperatures near l00 mK and sensitive to wavelengths from approx. 100 microns to approx. 3 mm. Such detectors represent a substantial enabling technology for these missions, and must be demonstrated soon in order for them to proceed. In order to make rapid progress on detector development, the cryogenic testing cycle must be made convenient and quick. We have developed a cryogenic detector characterization system capable of testing superconducting detector arrays in formats up to 8 x 32, read out by SQUID multiplexers. The system relies on the cooling of a two-stage adiabatic demagnetization refrigerator immersed in a liquid helium bath. This approach permits a detector to be cooled from 300K to 50 mK in about 4 hours, so that a test cycle begun in the morning will be over by the end of the day. Tine system is modular, with two identical immersible units, so that while one unit is cooling, the second can be reconfigured for the next battery of tests. We describe the design, construction, and performance of this cryogenic detector testing facility.

The twin composite structure telescopes aboard the Microwave Anisotropy Probe were selectivity roughened to reduce focused solar radiance. They were then overcoated with evaporated A1 + reactively evaporated silicon oxide films whose respective thicknesses were sufficient to achieve the high reflectance of bulk aluminum at the microwave operating frequencies; high emittance in the thermal emittance region; and moderately low solar absorptance for a resultant (alpha) /(epsilon) < 0.9. This report will discuss the experimental techniques used to prepare the telescope reflector surfaces and to evaluate their resultant properties.

The FeIII-TAML (tetra-amido macrocyclic ligand) activators 1 (Y = Cl) and 2 (Y = H2O), a (R = Me, X = H), b (Me, Cl), c (Me, MeO), d (Et, Cl), e (F, H), f (F, Cl), are five-coordinated in the solid state (X-ray crystallography) but are six-coordinated species in water with two H2O axial ligands. The first pKa's of aqueous ligands are in the range of 9.5-10.5. The acid-induced demetalation of 2 follows the equation kobs = k1*[H+] + k3*[H+]3. The rate constants k1* and k3* vary by 5 and 11 orders of magnitude depending on the nature of substituents R. The highest stabilization against the demetalation is achieved for R = F.