Novel technologies for space x-ray optics

The future space X-ray astronomy imaging missions require very large collecting areas at still fine angular resolution and reasonable weight. The novel substrates for X-ray mirrors such as Silicon wafers and thin thermally formed glass enable wide applications of precise and very light weight (volume densities 2.3 to 2.5 gcm-3) optics. The recent status of novel technologies as well as developed test samples with emphasis on precise optical surfaces based on novel materials and their space applications is presented and discussed.

The HESSI mission proposes to perform high resolution imaging and spectroscopy observations in the soft X-ray, hard X-ray, and gamma-ray regimes, with finer angular resolution (nearly 2 arcseconds) and finer energy resolution (approximately 1 keV) than has been previously possible. This combination of imaging and spectroscopy is achieved with a set of Rotating Modulation Collimators placed in front of an array of cooled germanium and silicon detectors. A set of 12 bi-grid collimators, each of which consists of a pair of identically pitched, widely-separated grids, is used to provide the imaging. Each grid consists of a planar array of equally-spaced, parallel, X-ray opaque slats separated by X-ray transparent slits. If the slits of each grid are parallel to each other and the pitch is identical for the two grids, then the transmission through the grid pair depends on the direction of incidence of the incoming X-rays. For slits and slats of equal width, the transmission varies between zero and 50% depending on whether the shadows of the slats in the top grid fall on the slits or slats of the lower grid. A complete transmission cycle from zero to 50% and back to zero corresponds to a change in source direction that is given by p/L, where L is the separation between the grids. The authors describe a deep etch lithography technique developed to fabricate the grids which have pitches below 100 {micro}m. They use a free standing sheet of PMMA as a base for the process, and use the ALS facility to perform the exposures of the PMMA.

Naturally occurring water vapor maser emission at 1.35 cm wavelength provides an accurate probe for the study of accretion disks around highly compact objects, thought to be black holes, in the centers of active galaxies. Because of the exceptionally fine angular resolution, 200 microarcseconds, obtainable with very long baseline interferometry, accompanied by high spectral resolution, <0.1 km s-1, the dynamics and structures of these disks can be probed with exceptional clarity. The data on the galaxy NGC 4258 are discussed here in detail. The mass of the black hole binding the accretion disk is 3·9 × 107 M⊙. Although the accretion disk has a rotational period of about 800 years, the physical motions of the masers have been directly measured with VLBI over a period of a few years. These measurements also allow the distance from the earth to the black hole to be estimated to an accuracy of 4 per cent. The status of the search for other maser/black hole candidates is also discussed.

If a collector is very large - square kilometers in size - it may be easier to fabricate flat optics than curved optics. If the primary objective is a flat diffraction grating, microscopic grooves would reshape the incident wave front rather than the 3D surface of a conventional parabolic reflector. I discuss diffractive optics that potentially can cover areas of square kilometers. The geometry of grazing incidence and evanescence allows for very large grating surfaces in ribbons or aggregated segmented modules. Diffraction grating primaries are attractive in that they are well suited for spectrographic astronomy, particularly the Doppler shift studies that have recently been useful in extra-solar planet detection. I propose a unique static mount for ground-based observations where the only moving part is the earth itself. For space-based installations, a new type of membrane telescope is disclosed that can be orbited as a roll of plastic and unfurled over multiple kilometer lengths. Holographic gratings are capable of very fine angular resolution, and only their extreme chromatic dispersion has inhibited their use. The bug is a feature. When taking spectra, chromatic dispersion is useful.

Angular resolution study of a combined gamma-neutron coded aperture imager for standoff detection

In a recent publication, an aperture mass statistic for gravitational flexion was derived and shown to be effective, at least with simulated data, in detecting massive structures and substructures within clusters of galaxies. Further, it was suggested that the radius at which the flexion aperture mass signal falls to zero might allow for estimation of the mass or density profile of the structures detected. In this paper, we more fully explore this possibility, considering the behaviour both of the peak signal and the zero-signal contours for two mass models – the singular isothermal sphere and Navarro–Frenk–White profiles – under varying aperture size, filter shape and mass concentration parameter. We demonstrate the effectiveness of the flexion aperture mass statistic in discriminating between mass profiles and concentration parameters, and in providing an accurate estimate of the mass of the lens, to within a factor of 1.5 or better. In addition, we compare the aperture mass method to a direct non-parametric reconstruction of the convergence from flexion measurements. We demonstrate that the aperture mass technique is much better able to constrain the shape of the central density profile, obtains much finer angular resolution in reconstructions, and does not suffer from ambiguity in the normalization of the signal, in contrast to the direct method.

Using millimeter-wave radars as a perception sensor provides self-driving cars with robust sensing capability in adverse weather. However, mmWave radars currently lack sufficient spatial resolution for semantic scene understanding. This paper introduces Radatron++, a system leverages cascaded MIMO (Multiple-Input Multiple-Output) radar to achieve accurate vehicle detection for self-driving cars. We develop a novel hybrid radar processing and deep learning approach to leverage the 10× finer angular resolution while combating unique challenges of cascaded MIMO radars. We train and evaluate Radatron++ with a novel cascaded radar dataset. Radatron++ achieves 93.9% and 58.5% Average Precisions with 0.5 and 0.75 Intersection over Union thresholds respectively in 2D bounding box detection, outperforming prior work using low-resolution radars by 9.3% and 18.1% respectively.

Integrated system health management (ISHM) technologies have been developed to address safety, replace time-based maintenance with condition-based maintenance, and to reduce life cycle costs. Traditional space system designs have focused on safety to minimize the risk to crew and to protect the public, astronauts and pilots, the NASA workforce, and high-value equipment and property. Systems have relied on high reliability components to provide the necessary safety margins and avoid operational mission failures. The current vision for future manned and unmanned space missions to the International Space Station, the Moon, Mars, and beyond, will require longer duration missions and will rely on complex assemblages of components. Increased mission duration and complexity increase the probability of operational mission failures that must be mitigated without jeopardizing safety or the objectives of the current or future missions that might reuse critical mission components. ISHM technology will be essential for providing near-real-time assessments of system capability, safety margins, and maintenance and sustainment requirements. The Applied Research Lab has conducted a series of workshops for NASA which focused on defining requirements for integrated system health monitoring and for the integration of health monitoring and control to provide intelligent self situational awareness (ISSA). The results of these workshops indicate that the benefits of ISHM and greater integration between ISHM and control include increased safety and mission assurance, the ability to rapidly respond to system failures, and decreased operator workload. Emerging open system standards such as OSA-EAI provide a framework for integrating system health monitoring with control functionality in spacecraft avionics systems. The purpose of this paper is to describe areas where system health monitoring can impact safety, reliability and sustainment in space applications and present the results of workshops conducted for NASA to identify requirements for the integration of health monitoring and control in future space systems

Nuclear propulsion

Flexible photovoltaics are covering the way to low-cost electricity. The build-up of organic, inorganic and organic–inorganic solar cells on flexible substrates by printing technologies is to provide lightweight and economic solar modules that can be incorporated in various surfaces. Progress of flexible and lightweight solar cell is interesting for many terrestrial and space applications that require a very high specific power. Thin-film solar cells on polymer films can produce more than 2KW\\Kg specific power. Flexible solar cells are proposed to open up a numerous of possibilities for enabling new applications in consumer electronics and space satellites. Recent research in thin-film electronics has been concentrated on the replacement of the traditional rigid glass plate substrate with plastic or metallic foils. Organic materials bear the potential to develop a long-term technology that is economically viable for large-scale power generation based on environmentally safe materials with unlimited availability. Organic and organic-inorganic photovoltaics (PVs) (third generation solar cells) continue to attract great attention from the PV community, due to their promising features such as low organic–inorganic cost, flexibility and light weight. In this chapter, many of the possible materials for manufacturing of flexible solar cells are discussed.

The results of a survey of oil company experiences with Fiberglass Reinforced Plastic (FRP) products indicate good experiences both onshore and offshore for numerous facility applications. This report reviews the current state of FRP technology and highlights the experiences reported in the survey. The lower cost, corrosion resistance and lighter weight of FRP components make them very attractive for expanded application, especially in the North Sea where FRP use is currently very limited. INTRODUCTION Fiberglass Reinforced Plastics (FRP) had their beginning with a commercial venture in 1938 by Owens Corning to make glass fibers for use as insulation and acoustical isolation material. The development of plastic resins subsequently led to the development of structural uses for FRP. Over the past two decades FRP composites have been used throughout the world for a wide variety of oil industry applications. The lighter weight, fatigue and corrosion resistance and associated low life cycle costs (Figure 1) make FRP components very attractive for expanded oil industry application both onshore and offshore. Glass fibers are resistant to most chemicals and resin materials are available which are compatible with most environments experienced in the oil industry. FRP composites are approximately 66 percent lighter weight (weigh one-third as much) than equivalent steel components. FRP's lighter weight often permits FRP pipe to be installed by work crews unassisted by mechanical hoists. This convenience is especially helpful for installing pipe in tight locations. Complex spool assemblies can be made in the factory and assembled in the field saving valuable on-site installation time. FRP joints require no welding and the experience level required to make quality joints can be learned very quickly. Facility modifications are also easier and less expensive with FRP. FRP composites can offer significant cost savings relative to metal by providing lower initial installed cost, reduced maintenance and longer life. A survey was conducted recently to determine the experiences of the oil industry concerning FRP components. The survey was by no means comprehensive; however, it is believed to be representative of current experience. Overall, the results show strong approval for existing FRP pipe and tank components and include recommendations for expanded utilization. Many oil companies are very aggressive in their utilization of FRP. Operators off the coast of Africa, for example, use FRP extensively for water management systems including fire water lines. Conoco has used FRP tanks and pipe for approximately 20 years and currently uses considerable amounts offshore for low pressure waterflood systems. Limited amounts of FRP are used in the North Sea where operators and regulatory agencies have been much more conservative. In the last few years, however, this region has begun to give serious consideration to utilizing FRP products. This paper highlights the response of oil operations personnel concerning their experiences with FRP components. Discussions are presented on the current status of FRP technology and on issues which concern potential users of FRP products. In addition, cost comparisons between FRP and metal components are discussed as well as cost effective opportunities for expanded applications of FRP components.

Two power technologies, Photovoltaic (PV) and Organic Rankine Cycle (ORC), are presently used in utility scale renewable energy systems and were initially developed to power telecommunication applications in space and remote terrestrial sites. Today, the total installed capacity worldwide is 90 GW for PV and 2 GW for ORC (mainly through geothermal applications). This paper describes the particular characteristics of these technologies and how they overcame established power systems: batteries for satellites and diesel generators in remote sites. While the upgraded power technologies lower efficiency (main criteria for power conversion systems choice) and higher cost per kW, neither of these characteristics were the priority when first introduced. Rather, PV was crucial for satellites due to its light weight (reducing the cost of the launch) and the ORC eliminated maintenance and overhauls, and, in many cases, storage batteries, at remote locations in harsh environments. This paper further describes various original applications and how ever-changing market conditions enabled the now proven new technologies to be expanded from watt to MW plants for PV and from 1 kW to 25 MW ORC units The increased use of PV and ORC technologies are examples depicting how disruptive technologies, as described by Clayton Christensen (“The Innovator's Dilemma” and “The Innovator's Solution”), evolve from niche markets in the fast changing electronic industry to wider use in slower changing industries such as large scale energy production. In both cases it took more than a century to reach parity with established power solutions. By planning the phases ahead of time in may be possible to accelerate the introduction of new technologies into large established markets. A bibliography is presented at the end of the paper.

1 - Introduction to hydrogen and its properties

Optical elements, such as grating, holographic optical element and Fresnel lens, are made on the SiN membrane. The SiN film was deposited on the silicon wafer by low pressure chemical vapor deposition (LPCVD). Its advantages include the high transmission efficiency, light weight, and easy packaging for the Si-based optical pickup head.

Membranes have been of continuing interest to the petroleum and chemical industries for gas separations. While glassy, polymeric membranes have provided efficient performance to date, significant improvements over current membrane technology will likely require novel materials. This paper will review the development and status of a new technology based on composite membranes, termed mixed matrix membranes, of polymer matrices in which molecular sieves are dispersed to give enhanced separation of natural gas from its impurities compared to membranes of the polymer alone. The technology is particularly of interest to the separation of natural gas from its impurities, such as CO2 and H2S. In laboratory testing, the composite membranes, composed of molecular sieves in commercial membrane polymer matrices, showed significant improvement in both selectivity and flux compared to membranes of the polymers alone for the separation of CO2 from natural gas. Enhancements were obtained using both carbon molecular sieves and small pore zeolites. While membranes have been of interest due to their compactness, light weight, and ease of operation, there has not been widespread application due to low selectivity and flux, and limited robustness. This has led researchers to study molecular sieve membranes, including carbon molecular sieve and zeolitic materials. While these membranes offer very attractive properties, their cost, difficulty of commercial scale manufacture, and brittleness remain major challenges. Mixed matrix membrane technology, which combines the benefits of molecular sieves with the ease and low cost of processing polymer membranes, offers a potential solution to these challenges. Introduction With worldwide natural gas production at around 50 trillion standard cubic feet per year, there is continuing interest in improved technology for natural gas purification. A large fraction of natural gas resources is high in impurities (N2, H2S, and especially CO2), making production difficult or uneconomic. In the lower 48 United States, for example, 550 trillion SCF cannot be processed due to high CO2 content [1]. Since much of worldwide gas resources are offshore or in remote locations, membranes are becoming attractive for gas separations due to their light weight, compactness, and ease of operation. This makes membranes potentially more attractive than much larger and heavier amine units, especially for gas resources high in CO2 (&amp;gt;10%), where regeneration of the spent amine solutions is energy intensive and disposal of spent amine has environmental issues. Nevertheless, of the $5 billion/year market for natural gas separation equipment, membrane processing represents only about 1% [2]. Affecting the ability of membranes to compete against amine treating for natural gas has been low selectivity for removing the impurity gases and the low flux of current commercial membranes. Also detrimental to the greater use of membranes is poor reliability due to fouling and loss of selectivity (e.g., through plasticization), and inability to operate effectively at high temperature and high hydrocarbon partial pressure. The sensitivity of polymer membranes to impurities and high temperature has necessitated the use of extensive pretreatment equipment, in part offsetting the weight and space advantages of compact membranes. While improvements have been made in polymer membranes, further advances are needed to successfully commercialize a number of high impurity offshore and remote natural gas fields.