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Lynx is a concept under study for prioritization in the 2020 Astrophysics Decadal Survey. Providing orders of magnitude increase in sensitivity over Chandra, Lynx will examine the first black holes and their galaxies, map the large-scale structure and galactic halos, and shed new light on the environments of young stars and their planetary systems. In order to meet the Lynx science goals, the telescope consists of a high-angular resolution optical assembly complemented by an instrument suite that may include a High Definition X-ray Imager, X-ray Microcalorimeter and an X-ray Grating Spectrometer. The telescope is integrated onto the spacecraft to form a comprehensive observatory concept. Progress on the formulation of the Lynx telescope and observatory configuration is reported in this paper.

The JWST Optical Telescope Element (OTE) assembly is the largest optically stable infrared-optimized telescope currently being manufactured and assembled, and is scheduled for launch in 2018. The JWST OTE, including the 18 segment primary mirror, secondary mirror, and the Aft Optics Subsystem (AOS) are designed to be passively cooled and operate near 45K. These optical elements are supported by a complex composite backplane structure. As a part of the structural distortion model validation efforts, a series of tests are planned during the cryogenic vacuum test of the fully integrated flight hardware at NASA JSC Chamber A. The successful ends to the thermal-distortion phases are heavily dependent on the accurate temperature knowledge of the OTE structural members. However, the current temperature sensor allocations during the cryo-vac test may not have sufficient fidelity to provide accurate knowledge of the temperature distributions within the composite structure. A method based on an inverse distance relationship among the sensors and thermal model nodes was developed to improve the thermal data provided for the nanometer scale WaveFront Error (WFE) predictions. The Linear Distance Weighted Interpolation (LDWI) method was developed to augment the thermal model predictions based on the sparse sensor information. This paper will encompass the development of the LDWI method using the test data from the earlier pathfinder cryo-vac tests, and the results of the notional and as tested WFE predictions from the structural finite element model cases to characterize the accuracies of this LDWI method.

Analysis of impacts on fused silica was motivated by the design of the mirror for the James Webb Space Telescope (JWST). The JWST is expected to have a large-diameter mirror shaded from sunlight but open to space. One of the candidate mirror materials is fused silica; the other candidate materials are ultra-low expansion (ULE) glass and O-30 beryllium. Historically, most meteoroid tests have concerned themselves with the degraded strength of the substrate; JWST is primarily concerned with maintaining its precise optical figure. Micrometeoroids can have velocities of 50 km/s or higher. Although the velocity in the analysis did not exceed 10 km/s, the computer model included a fit to shock Hugoniot data for fused silica with pressures as high as 700 GPa, typical of impacts at velocities higher than 10 km/s. The computer model also included the first-order phase transformation observed in fused silica. The calculations were made with the AUTODYN hydrocode [1], which includes smooth particle hydrodynamic (SPH) and Lagrange solvers with other modules and features for coupling them together. For the analysis of impact, both SPH and Lagrange methods were used. Using the static relaxation option, the analysis continued from crater formation to a late-time static solution from which the effect of the impact on the optics could be determined. Both low and high energy impacts were computed using the fused silica model. For the low energy impact, the computed crater depth, crater diameter, and spall diameter closely matched both historical data for fused silica and values measured by Auburn University/ Hypervelocity Impact Facility (AU/HIF) for two typical fused silica sites and one ULE site. For the high energy impact, the computed values matched historical data for fused silica but not the data measured by AU/HIF for three typical ULE sites. The discrepancy can be explained by the difference in the response of fused silica and ULE under impact, as seen in historical trends and as observed by AU/HIF. Optical interferometry of the surfaces of one of the mirrors revealed deformation in the vicinity of particle impacts that matched that estimated with a static model, and the deformation was consistent with that computed by AUTODYN.

2014 marks the crystal (15 th ) anniversary of the launch of the Chandra X-ray Observatory, which began its existence as the Advanced X-ray Astrophysics Facility (AXAF). This paper offers some of the major lessons learned by some of the key members of the Chandra Telescope team. We offer some of the lessons gleaned from our experiences developing, designing, building and testing the telescope and its subsystems, with 15 years of hindsight. Among the topics to be discussed are the early developmental tests, known as VETA-I and VETA-II, requirements derivation, the impact of late requirements and reflection on the conservatism in the design process.

Nested flat plates bent into the Kirkpatrick-Baez parabolic geometry and supported at discrete points are one means of obtaining large area grazing incidence x-ray optics with good angular resolution. A method for optimizing the on-axis resolution combining finite element and ray trace techniques with selective masking is presented. The optimally determined supported point location technique can lead to greatly reduced in situ labor costs.