Silicon micromachining is used extensively for the microfabrication of integrated circuits, microsensors and microactuator devices. We address both calculations of the surface free energy of the crystal planes of silicon and the results of etching single-crystal silicon spheres in KOH and CsOH under controlled conditions. The silicon spheres were prepared by the cup-grinding method. They were etched in a constant temperature bath at 50 and 75~ and inspected under the SEM. An optical reflectance technique was used to determine the angle of inclination of the etch facets. The order of etch rates for the crystal planes was {311}, {522} > {100} > {111}. The fastest etching planes in KOH were {320} and in CsOH were CII0}. Also, with KOH etching, the high index plane {432} was observed. The surface free energy of the crystal planes was calculated based upon the number of bonds on the surface. A minimum in surface free energy occurred for all the low index planes i.e., {100}, {110}, and {111}. There was also a minimum near the {522} planes in agreement with the experimental observations that these planes show anisotropic etching behavior. The {110} and {522} planes had a significant number of in-plane bonds. Whenthe in-plane bond density was added to the surface bond density a good fit with the observed hierarchy of etch rates was obtained for the slower etching planes: {311}, {522} > {100} > {111}.

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There is an urgent need to increase the capacity of developing countries to take part in the study and monitoring of their environments through remote sensing and spacebased Earth observation technologies. The Open Data Cube (ODC) provides a mechanism for efficient storage and a powerful framework for processing and analyzing satellite data. While this is ideal for scientific research, the expansive feature space can also be daunting for end-users and decision-makers who simply require a solution which provides easy exploration, analysis, and visualization of Analysis Ready Data (ARD). Utilizing innovative webdesign and a modular architecture, the Committee on Earth Observation Satellites (CEOS) has created a web-based user interface (UI) which harnesses the power of the ODC yet provides a simple and familiar user experience: the CEOS Data Cube (CDC). This paper presents an overview of the CDC architecture and the salient features of the UI. In order to provide adaptability, flexibility, scalability, and robustness, we leverage widely-adopted and well-supported technologies such as the Django web framework and the AWS Cloud platform. The fully-customizable source code of the UI is available at our public repository. Interested parties can download the source and build their own UIs. The UI empowers users by providing features that assist with streamlining data preparation, data processing, data visualization, and sub-setting ARD products in order to achieve a wide variety of Earth imaging objectives through an easy to use web interface.

The Open Data Cube (ODC) initiative, with support from the Committee on Earth Observation Satellites (CEOS) System Engineering Office (SEO) has developed a state-ofthe-art suite of software tools and products to facilitate the analysis of Earth Observation data. This paper presents a short summary and cost analysis of our experience using Amazon Web Services (AWS) to host one such software product, the CEOS Data Cube (CDC) web-based User Interface (UI). In order to provide adaptability, flexibility, scalability, and robustness, we leverage widely-adopted and well-supported technologies such as the Django web framework and the AWS Cloud platform. The UI has empowered users by providing features that assist with streamlining data preparation, data processing, data visualization, and the sub-setting of Analysis Ready Data (ARD) products in order to achieve a wide variety of Earth imaging objectives.

The requirements development process for the Advanced Engineering Environment (AEE) is presented. This environment has been developed to allow NASA to perform independent analysis and design of space transportation architectures and technologies. Given the highly collaborative and distributed nature of AEE, a variety of organizations are involved in the development, operations and management of the system. Furthermore, there are additional organizations involved representing external customers and stakeholders. Thorough coordination and effective communication is essential to translate desired expectations of the system into requirements. Functional, verifiable requirements for this (and indeed any) system are necessary to fulfill several roles. Requirements serve as a contractual tool, configuration management tool, and as an engineering tool, sometimes simultaneously. The role of requirements as an engineering tool is particularly important because a stable set of requirements for a system provides a common framework of system scope and characterization among team members. Furthermore, the requirements provide the basis for checking completion of system elements and form the basis for system verification. Requirements are at the core of systems engineering. The AEE Project has undertaken a thorough process to translate the desires and expectations of external customers and stakeholders into functional system-level requirements that are captured with sufficient rigor to allow development planning, resource allocation and system-level design, development, implementation and verification. These requirements are maintained in an integrated, relational database that provides traceability to governing Program requirements and also to verification methods and subsystem-level requirements.