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Two high voltage, Series Connected Boost Regulators (SCBR) were developed to demonstrate the benefits of the SCBR topology for low Earth orbit communication satellites. The resulting breadboards had a power density of 1,200 W/kg and a measured efficiency of 95-99%. Several peak power tracking methods and algorithms were implemented to demonstrate the ability of the SCBR to peak power track a solar array. The peak power tracker derived maximum power at all times and reduced the number of sunlight battery discharges necessary. The breadboards also demonstrated several modularity techniques, which will allow a common SCBR module to be used in several applications. The breadboards were tested in an end-to-end high voltage test facility using high fidelity solar array simulators, an actual NiH2 battery, and simulated constant power loads. Design details and test results are presented.

Development of a high specific energy battery is one of the objectives of the lightweight nickel-hydrogen (Ni-H2) program at the NASA Glenn Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a lighter weight electrode for the nickel-hydrogen cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active material. Initial tests include activation and capacity measurements at five different discharge levels, C/2, 1.0C, 1.37C, 2.0C, and 2.74C. The electrodes are life cycle tested using a half-cell configuration at 40 and 80% depths-of-discharge (DOD) in a low-Earth-orbit regime. The electrodes that pass the initial tests are life cycle-tested in a boilerplate nickel-hydrogen cell before flightweight designs are built and tested.

This paper presents the results of research efforts performed to evaluate the performance of rechargeable battery management technologies at low temperatures. Three battery chemistries are considered in this work. These are the Nickel-Cadmium (NiCd), Nickel-Metal Hydride (NiMH) and Lithium-ion (Li-ion). Battery management evaluation kits from two battery manufacturers were acquired and tested. These are the DS2434k, DS2435k and DS2437k from Dallas Semiconductor and the MAX712, MAX846A and MAX2003A from MAXIM Integrated Products. The kits were characterized in a chamber whose temperature was changed and regulated using liquid nitrogen. The temperature of the chamber was varied from 20°C to −180°C. At each temperature, the battery voltage, current, state of charge, temperature and other auxiliary variables as monitored by each chip were recorded. Also, the performance of each kit after a complete cooling and heating cycle is recorded.

NASA Glenn Research Center and the Wallops Flight Facility jointly conducted a PEM fuel cell power system development effort for high altitude balloon applications. This was the first phase of NASA efforts to offer higher balloon payload power levels with extended duration mission capabilities for atmospheric science missions. At present, lead-acid batteries typically supply about 100 watts of power to the balloon payload for approximately 8 hours duration. The H2-O2 PEM fuel cell demonstration system developed for this effort can supply at least 200 watts for 48 hours duration. The system was designed and fabricated, then tested in ambient ground environments as well as in a thermal vacuum chamber to simulate operation at 75 kft. altitude. Initially, this program was planned to culminate with a demonstration flight test but no flight has been scheduled, thus far.

Refractive secondary concentrators are being considered for solar thermal applications because of their ability to achieve maximum efficiency through the use of total internal reflection for the concentration and distribution of solar energy. A prototype refractive secondary concentrator was built based on ray tracing analysis to demonstrate this collection and distribution concept. The design included a conical secondary concentrator and a faceted extractor. The objective of this effort was to functionally evaluate the performance of the refractive secondary concentrator/extractor prototype and to compare the results with modeling. Most of the light was found to exit the refractive secondary concentrator through the extractor. In addition, the degree of attenuation encountered by the light as it passed through the refractive secondary concentrator was of interest.

Many studies have been performed to quantify the formation and evolution of roughness on ice shapes created in Appendix C icing conditions, which exhibits supercooled liquid droplets ranging from 1-50 µm. For example Anderson and Shin (1997), Anderson et al. (1998), and Shin (1994) represent early studies of ice roughness during short-duration icing events measured in the Icing Research Tunnel at the NASA Glenn Research Center. In the historical literature, image analysis techniques were employed to characterize the roughness. Using multiple images of the roughness elements, these studies of roughness focused on extracting parametric representations of ice roughness elements. While the image analysis approach enabled many insights into icing physics, recent improvements in laser scanning approaches have revolutionized the process of ice accretion shape characterization.

NASA and the FAA conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding of high ice water content (HIWC) and develop onboard weather radar processing techniques to detect regions of HIWC ahead of an aircraft to enable tactical avoidance of the potentially hazardous conditions. Both HIWC RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory equipped with a Honeywell RDR-4000 weather radar and in-situ microphysical instruments to characterize the ice crystal clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results. The first campaign was conducted in August 2015 with a base of operations in Ft. Lauderdale, Florida.

NASA's Constellation program has selected the closed cycle hydrogen oxygen Polymer Electrolyte Membrane (PEM) regenerative Fuel Cell (RFC) as its baseline solar energy storage system for the lunar outpost and manned rover vehicles. Since the outpost and manned rovers are "human-rated", these energy storage systems will have to be of proven reliability exceeding 99 percent over the length of the mission. Because of the low (TRL=5) development state of the closed cycle hydrogen oxygen PEM RFC at present, and because there is no equivalent technology base in the commercial sector from which to draw or infer reliability information from, NASA will have to spend significant resources developing this technology from TRL 5 to TRL 9, and will have to embark upon an ambitious reliability development program to make this technology ready for a manned mission. Because NASA would be the first user of this new technology, NASA will likely have to bear all the costs associated with its development.