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Abstract-Advances in earth and space instrumentation will come from future optical systems that can provide large, collecting areas of low areal mass density (< 10 kg/sq meter) at a cost much lower than current practice. Launch cost and volume constraints require mass and volume both be reduced to permit affordable systems using large apertures. Composite optics show promise for light-weight, stiff optical substrates, but surface finish has not been adequate for many applications. Electroplated, replicated optical surfaces of nickel have been used for producing smooth, accurate optical surfaces primarily for X-ray optics, but require high mass to be self-supporting. Combining a light-weight and stiff composite substrate with a high quality replicated metal optical surface combines the best properties of these disparate materials. Recent developments in polymer chemistry have led to development of resins that can be formed into structures with shape memory properties. The unique properties of shape memory resins in the composite provide a larger range of design parameters for production of usable optics, allowing repeated deployability and accurate recovery to replicated shapes, selective shaping of optical surfaces, and management of interface stresses. Results are presented from optical and structural tests of various mirror constructions that show progress towards a laminated, deployable optic. Key issues for successful space applications are interface stress control of the disparate materials, strain recovery of the resins for accurate deployment, and stability over the operating conditions of temperature and moisture loss. Initial requirements analysis and material properties measurements for both system and individual material target performance are presented with current status and goals for future development.

We have been working on 3 separate projects that together will give us the ability to make 1 arc second, light weight Wolter I optics that work above 40 keV. The three separate tasks are: (a) plasma spraying of metal-coated micro-balloons; (b) coating of the inside of Wolter I mirrors, (c) actuator designs for improving figure quality. We give a progress report on our work on all three areas.

Deployable optics comprised of an electroformed, replicated nickel optical surface supported by a reinforced shape memory resin composite substrate have the potential to meet the requirements for rapid fabrication of lightweight, monolithic, deployable, large optics. Evaluation has been completed for various composite constructions including shape memory resin, carbon fiber reinforcement and syntactic fillers bonded to the electroformed nickel surface. Results from optical and structural performance tests on the 0.5 meter aperture deployable test items are also applicable to non-deployable replicated composite optics.

Dark Energy dominates the mass-energy content of the universe (about 73%) but we do not understand it. Most of the remainder of the Universe consists of Dark Matter (23%), made of an unknown particle. The problem of the origin of Dark Energy has become the biggest problem in astrophysics and one of the biggest problems in all of science. The major extant X-ray observatories, the Chandra X-ray Observatory and XMM-Newton, do not have the ability to perform large-area surveys of the sky. But Dark Energy is smoothly distributed throughout the universe and the whole universe is needed to study it. There are two basic methods to explore the properties of Dark Energy, viz. geometrical tests (supernovae) and studies of the way in which Dark Energy has influenced the large scale structure of the universe and its evolution. DUO will use the latter method, employing the copious X-ray emission from clusters of galaxies. Clusters of galaxies offer an ideal probe of cosmology because they are the best tracers of Dark Matter and their distribution on very large scales is dominated by the Dark Energy. In order to take the next step in understanding Dark Energy, viz. the measurement of the 'equation of state' parameter 'w', an X-ray telescope following the design of ABRIXAS will be accommodated into a Small Explorer mission in lowearth orbit. The telescope will perform a scan of 6,000 sq. degs. in the area of sky covered by the Sloan Digital Sky Survey (North), together with a deeper, smaller survey in the Southern hemisphere. DUO will detect 10.000 clusters of galaxies, measure the number density of clusters as a function of cosmic time, and the power spectrum of density fluctuations out to a redshift exceeding one. When combined with the spectrum of density fluctuations in the Cosmic Microwave Background from a redshift of 1100, this will provide a powerful lever arm for the crucial measurement of cosmological parameters.