Kevin Dean Bell

The Development And Verification of a Cryogenic Phase Change Thermal Storage Unit For Spacecraft Applications

This paper presents a summary of the design, development, and ground verification of the BETSU (Brilliant Eyes Thermal Storage Unit) experiment. The BETSU utilizes 2-methyl pentane as a 120 K PCM (Phase Change Material) and will be flown on board the Shuttle in early 1994. There has been very limited experience with the space flight of cryogenic phase change materials. Space applications for a cryogenic TSU include the storage of energy for the cooling of temperature sensitive sensor components such as focal planes, optics, mirrors, and telescopes. Based on ground test data, trade studies were performed which show the significant weight and cost benefits of the BETSU technology.

Deployable optical telescope ground demonstration

The deployable optical telescope, the second project of the Air Force Research Laboratorys Integrated Ground Demonstration Laboratory, will demonstrate critical integration technologies associated with the next generation of beam expanders for space-based laser systems and large apertures for tactical surveillance systems. AFRLs development will be carried in cooperation with the contractor community and have direct ties to the future program offices that will utilize the DOT technologies. A flow down of total wavefront error acceptable for future operational systems has been used to derive DOT experiment requirements. The sub-scale DOT will demonstrate the initial deployment of a segmented primary and secondary tower in a 1-g laboratory environment.

Air force research laboratory's technology programs addressing deployable space optical systems

The US Air Force Research Lab (AFRL) has integrated several technology development efforts together to form a cohesive approach for enabling deployable optical systems in the future. Aperture size dominates the cost/architecture trades for space based laser systems for missile defense and tactical imaging system pursuing broad area coverage with local access. Larger apertures allow both systems to consider higher orbits, offering greater fields of regard. However, large monolithic apertures quickly run into launch vehicle faring volumetric and throw mass constraints. Several technologies may enable space deployable of optical segments to form a large primary mirror at a reduced mass, circumventing the launch vehicle constraints. However, to produce an optically phased wavefront, a combination of technologies, deployment mechanisms, lightweight structures and mirrors, mirror mount isolators and actuators, adaptive optics, and processing techniques, must be applied in concert. While this paper concentrates on the hardware development activities under the UltraLITE program, namely the Precision Deployable Optical Structure ground demonstration and the brassboard Deployable Space Telescope, it will also briefly cover and provide references to related technology programs on-going at the AFRL.

Ultralightweight optics for space applications

Lightweight, deployable space optics has been identified as a key technology for future cost-effective, space-based systems. The United States Department of Defense has partnered with the National Aeronautical Space Administration to implement a space mirror technology development activity known as the Advanced Mirror System Demonstrator (AMSD). The AMSD objectives are to advance technology in the production of low-mass primary mirror systems, reduce mirror system cost and shorten mirror- manufacturing time. The AMSD program will offer substantial weight, cost and production rate improvements over Hubble Space Telescope mirror technology. A brief history of optical component development and a review of optical component state-of-the-art technology will be given, and the AMSD program will be reviewed.

ADVANCED GUIDANCE, NAVIGATION, AND CONTROL FOR REMOTE SENSING

Guidance, navigation, and control (GNC the knowledge of the systems current location, orientation, or state; and the application of forces

Joint NASA and DoD deployable optics space experiment

The Air Force Research Lab is proposing a DoD partnership with NASA on NEXUS; a deployable optics flight demonstrator scheduled to launch in 2004. NEXUS is designed to demonstrate technologies for the Next Generation Space Telescope, primarily the deployment and wave front control of a 2.8 meter optical telescope in space.

Cost-engineering modeling to support rapid concept development of an advanced infrared satellite system

Current architectural and design trade techniques often carry unaffordable alternatives late into the decision process. Early decisions made during the concept exploration and development (CE&D) phase will drive the cost of a program more than any other phase of development; thus, designers must be able to assess both the performance and cost impacts of their early choices. The Space Based Infrared System (SBIRS) cost engineering model (CEM) described in this paper is an end-to-end process integrating engineering and cost expertise through commonly available spreadsheet software, allowing for concurrent design engineering and cost estimation to identify and balance system drives to reduce acquisition costs. The automated interconnectivity between subsystem models using spreadsheet software allows for the quick and consistent assessment of the system design impacts and relative cost impacts due to requirement changes. It is different from most CEM efforts attempted in the past as it incorporates more detailed spacecraft and sensor payload models, and has been applied to determine the cost drivers for an advanced infrared satellite system acquisition. The CEM is comprised of integrated detailed engineering and cost estimating relationships describing performance, design, and cost parameters. Detailed models have been developed to evaluate design parameters for the spacecraft bus and sensor; both step-starer and scanner sensor types incorporate models of focal plane array, optics, processing, thermal, communications, and mission performance. The current CEM effort has provided visibility to requirements, design, and cost drivers for system architects and decision makers to determine the configuration of an infrared satellite architecture that meets essential requirements cost effectively. In general, the methodology described in this paper consists of process building blocks that can be tailored to the needs of many applications. Descriptions of the spacecraft and payload subsystem models provide insight into The Aerospace Corporation expertise and scope of the SBIRS concept development effort.

Real Time Control of a Shuttle Phase Change Material Experiment Using Flight Correlated Algorithms

This paper presents a summary of the methods and algorithms used for the real time control of the Brilliant Eyes Thermal Storage Unit (BETSU) experiment. The BETSU utilized 2-methyl pentane as a 120 K Phase Change Material (PCM) and was flown on board the Shuttle STS-62 in March 1994 as part of the primary payload OAST-2 (Office of Aeronautics and Space Technology) bridge pallet. The BETSU set a record as the coldest recyclable thermal storage device (by over 40 °C) in space flight history and demonstrated the capability to significantly reduce the weight of cooling systems for future spaceborne infrared sensors.