X-ray Mirror Assembly Research Articles

Formulation of the production time and cost of the Lynx x-ray mirror assembly based on queuing theory

The timely and predictable cost of the Lynx x-ray mirror assembly (XMA) is an essential element of the mission concept. We present an analytic model for the cost, schedule, and risk for the manufacture of a generalized system of many parts, and apply it to preliminary data of the manufacturing process for the XMA. The manufacturing process is modeled as a series of G / G / w queues. The optimization of the manufacturing process, to minimize total process time, comes from the selection of the value of w, the number of servers performing each step in the manufacturing process, to avoid bottlenecks and minimizing idle servers. This analysis also includes the effects of finite process yield on cost and schedule. The cost model is parameterized by the various elements of cost, including the production time, thus linking the cost and schedule models. The system of coupled equations is the cost and schedule model. The process data that must be collected on the manufacturing process during the ongoing technology development process such as process times, yields, and distributions is identified. We conclude with the next steps that will be taken to make this analysis more complete.

High-resolution, lightweight, and low-cost x-ray optics for the Lynx observatory

We describe an approach to build an x-ray mirror assembly that can meet Lynx’s requirements of high-angular resolution, large effective area, light weight, short production schedule, and low-production cost. Adopting a modular hierarchy, the assembly is composed of 37,492 mirror segments, each of which measures ∼100 mm × 100 mm × 0.5 mm. These segments are integrated into 611 modules, which are individually tested and qualified to meet both science performance and spaceflight environment requirements before they in turn are integrated into 12 metashells. The 12 metashells are then integrated to form the mirror assembly. This approach combines the latest precision polishing technology and the monocrystalline silicon material to fabricate the thin and lightweight mirror segments. Because of the use of commercially available equipment and material and because of its highly modular and hierarchical building-up process, this approach is highly amenable to automation and mass production to maximize production throughput and to minimize production schedule and cost. As of fall 2018, the basic elements of this approach, including substrate fabrication, coating, alignment, and bonding, have been validated by the successful building and testing of single-pair mirror modules. In the next few years, the many steps of the approach will be refined and perfected by repeatedly building and testing mirror modules containing progressively more mirror segments to fully meet science performance, spaceflight environments, as well as programmatic requirements of the Lynx mission and other proposed missions, such as AXIS.

Resolve Instrument on X-ray Astronomy Recovery Mission (XARM)

The X-ray Astronomy Recovery Mission (XARM) is a recovery mission of ASTRO-H/Hitomi, which is expected to be launched in Japanese Fiscal Year of 2020 at the earliest. The Resolve instrument on XARM consists of an array of 6 × 6 silicon-thermistor microcalorimeters cooled down to 50 mK and a high-throughput X-ray mirror assembly with the focal length of 5.6 m. Hitomi was launched into orbit in February 2016 and observed several celestial objects, although the operation of Hitomi was terminated in April 2016. The soft X-ray spectrometer (SXS) on Hitomi demonstrated high-resolution X-ray spectroscopy of ~ 5 eV FWHM in orbit for most of the pixels. The Resolve instrument is planned to mostly be a copy of the Hitomi SXS and soft X-ray telescope designs, though several changes are planned based on the lessons learned from Hitomi. We report a brief summary of the SXS performance and the status of the Resolve instrument.

Design, construction, and performance of the ROSAT high-resolution x-ray mirror assembly

A grazing incidence telescope has been developed for the x-ray astronomy satellite ROSAT including a verification model and a flight model. The telescope consists of a fourfold nested Wolter type I mirror assembly of 84-cm front aperture and 240-cm focal length. The verification model has been built and fully assembled to a telescope. Full aperture x-ray measurements performed in our 130-m long-beam facility are pesented and successfully compared with model predictions based on mirror metrology data. An energy independent angular resolution of 4-sec of arc half-energy width for the encircled point spread function and a mirror surface microroughness of <3 A have been achieved. Metrology of the actual flight mirrors (although not yet assembled to a telescope) indicates an even better performance.