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At least 253 records · Page 14

The NASA space power technology program

NASA has a broad technology program in the field of space power. This paper describes that program, including the roles and responsibilities of the various NASA field centers and major contractors. In the power source area, the paper discusses the SP-100 Space Nuclear Power Project, which has been under way for about seven years and is making substantial progress toward development of components for a 100-kilowatt power system that can be scaled to other sizes. This system is a candidate power source for nuclear electric propulsion, as well as for a power plant for a lunar base. In the energy storage area, the paper describes NASA's battery- and fuel-cell development programs. NASA is actively working on NiCd, NiH2, and lithium batteries. A status update is also given on a U.S. Air Force-sponsored program to develop a large (150 ampere-hour) lithium-thionyl chloride battery for the Centaur upper-stage launch vehicle. Finally, the area of power management and distribution (PMAD) is addressed, including power system components such as solid-state switches and power integrated circuits. Automated load management and other computer-controlled functions offer considerable payoffs. The state of the art in space power is described, along with NASA's medium- and long-term goals in the area.

Stephenson, R. Rhoads↗

National Aeronautics and Space Administration (nasa)/american Society for Engineering Education (ASEE) Summer Faculty Fellowship Program, 1991, Volume 1

Presented here is a compilation of the final reports of the research projects done by the faculty members during the summer of 1991. Topics covered include optical correlation; lunar production and application of solar cells and synthesis of diamond film; software quality assurance; photographic image resolution; target detection using fractal geometry; evaluation of fungal metabolic compounds released to the air in a restricted environment; and planning and resource management in an intelligent automated power management system.

Hyman, William A.↗

User interface design principles for the SSM/PMAD automated power system

Martin Marietta has developed a user interface for the space station module power management and distribution (SSM/PMAD) automated power system testbed which provides human access to the functionality of the power system, as well as exemplifying current techniques in user interface design. The testbed user interface was designed to enable an engineer to operate the system easily without having significant knowledge of computer systems, as well as provide an environment in which the engineer can monitor and interact with the SSM/PMAD system hardware. The design of the interface supports a global view of the most important data from the various hardware and software components, as well as enabling the user to obtain additional or more detailed data when needed. The components and representations of the SSM/PMAD testbed user interface are examined. An engineer's interactions with the system are also described.

Jakstas, Laura M.↗

EMTP based stability analysis of space station electric power system in a test bed environment

The Space Station Freedom Electric Power System (EPS) will convert solar energy into electric energy and distribute the same using an 'all dc', Power Management and Distribution (PMAD) System. Power conditioning devices (dc to dc converters) are needed to interconnect parts of this system operating at different nominal voltage levels. Operation of such devices could generate under damped oscillations (instability) under certain conditions. Criteria for instability are examined and verified for a single device. Suggested extension of the criteria to a system operation is examined by using the EMTP model of the PMAD DC test bed. Wherever possible, data from the test bed is compared with the modeling results.

Dravid, Narayan V.↗

EMTP based stability analysis of Space Station Electric Power System in a test bed environment

The Space Station Freedom Electric Power System (EPS) will convert solar energy into electric energy and distribute the same using an 'all dc', Power Management and Distribution (PMAD) System. Power conditioning devices (dc to dc converters) are needed to interconnect parts of this system operating at different nominal voltage levels. Operation of such devices could generate under damped oscillations (instability) under certain conditions. Criteria for instability are examined and verified for a single device. Suggested extension of the criteria to a system operation is examined by using the EMTP model of the PMAD dc test bed. Wherever possible, data from the test bed is compared with the modeling results.

Dravid, Narayan V.↗

Impact of Radiation Hardness and Operating Temperatures of Silicon Carbide Electronics on Space Power System Mass

The effect of silicon carbide (SiC) electronics operating temperatures on Power Management and Distribution (PMAD), or Power Conditioning (PC), subsystem radiator size and mass requirements was evaluated for three power output levels (100 kW(e) , 1 MW(e), and 10 MW(e)) for near term technology ( i.e. 1500 K turbine inlet temperature) Closed Cycle Gas Turbine (CCGT) power systems with a High Temperature Gas Reactor (HTGR) heat source. The study was conducted for assumed PC radiator temperatures ranging from 370 to 845 K and for three scenarios of electrical energy to heat conversion levels which needed to be rejected to space by means of the PC radiator. In addition, during part of the study the radiation hardness of the PC electronics was varied at a fixed separation distance to estimate its effect on the mass of the instrument rated reactor shadow shield. With both the PC radiator and the conical shadow shield representing major components of the overall power system the influence of the above on total power system mass was also determined. As expected, results show that the greatest actual mass savings achieved by the use of SiC electronics occur with high capacity power systems. Moreover, raising the PC radiator temperature above 600 K yields only small additional system mass savings. The effect of increased radiation hardness on total system mass is to reduce system mass by virtue of lowering the shield mass.

Juhasz, Albert J.↗

A Unique Power System For The ISS Fluids And Combustion Facility

Unique power control technology has been incorporated into an electrical power control unit (EPCU) for the Fluids and Combustion Facility (FCF). The objective is to maximize science throughput by providing a flexible power system that is easily reconfigured by the science payload. Electrical power is at a premium on the International Space Station (ISS). The EPCU utilizes advanced power management techniques to maximize the power available to the FCF experiments. The EPCU architecture enables dynamic allocation of power from two ISS power channels for experiments. Because of the unique flexible remote power controller (FRPC) design, power channels can be paralleled while maintaining balanced load sharing between the channels. With an integrated and redundant architecture, the EPCU can tolerate multiple faults and still maintain FCF operation. It is important to take full advantage of the EPCU functionality. The EPCU acts as a buffer between the experimenter and the ISS power system with all its complex requirements. However, FCF science payload developers will still need to follow guidelines when designing the FCF payload power system. This is necessary to ensure power system stability, fault coordination, electromagnetic compatibility, and maximum use of available power for gathering scientific data.

Fox, David A.↗

Autonomous Telemetry Collection for Single-Processor Small Satellites

For the Space Technology 5 mission, which is being developed under NASA's New Millennium Program, a single spacecraft processor will be required to do on-board real-time computations and operations associated with attitude control, up-link and down-link communications, science data processing, solid-state recorder management, power switching and battery charge management, experiment data collection, health and status data collection, etc. Much of the health and status information is in analog form, and each of the analog signals must be routed to the input of an analog-to-digital converter, converted to digital form, and then stored in memory. If the micro-operations of the analog data collection process are implemented in software, the processor may use up a lot of time either waiting for the analog signal to settle, waiting for the analog-to-digital conversion to complete, or servicing a large number of high frequency interrupts. In order to off-load a very busy processor, the collection and digitization of all analog spacecraft health and status data will be done autonomously by a field-programmable gate array that can configure the analog signal chain, control the analog-to-digital converter, and store the converted data in memory.

Speer, Dave↗

Hydrogen Research for Spaceport and Space-Based Applications: Fuel Cell Projects

The activities presented are a broad based approach to advancing key hydrogen related technologies in areas such as fuel cells, hydrogen production, and distributed sensors for hydrogen-leak detection, laser instrumentation for hydrogen-leak detection, and cryogenic transport and storage. Presented are the results from research projects, education and outreach activities, system and trade studies. The work will aid in advancing the state-of-the-art for several critical technologies related to the implementation of a hydrogen infrastructure. Activities conducted are relevant to a number of propulsion and power systems for terrestrial, aeronautics and aerospace applications. Fuel cell research focused on proton exchange membranes (PEM), solid oxide fuel cells (SOFC). Specific technologies included aircraft fuel cell reformers, new and improved electrodes, electrolytes, interconnect, and seals, modeling of fuel cells including CFD coupled with impedance spectroscopy. Research was conducted on new materials and designs for fuel cells, along with using embedded sensors with power management electronics to improve the power density delivered by fuel cells. Fuel cell applications considered were in-space operations, aviation, and ground-based fuel cells such as; powering auxiliary power units (APUs) in aircraft; high power density, long duration power supplies for interplanetary missions (space science probes and planetary rovers); regenerative capabilities for high altitude aircraft; and power supplies for reusable launch vehicles.

Anderson, Tim↗

Nuclear Power Concepts for High-Power Electric Propulsion Missions to Mars

Under the Mars Transportation Assessment Study, NASA and DOE are performing analyses and generating concepts for crewed Nuclear Electric Propulsion (NEP) missions to Mars. This paper presents the results of trade studies and concept development for the nuclear electric power system, consisting of the fission reactor, radiation shielding, power conversion, heat rejection and power management & distribution (PMAD). The nuclear power team completed trade studies to evaluate different reactor and power conversion technologies and developed preliminary concepts for the crew shielding, waste heat radiators, and PMAD. The initial results suggest that a modified terrestrial microreactor combined with supercritical CO2 Brayton conversion could be used to perform the crew and cargo missions with satisfactory performance and modest risk.

Lee Mason↗

Power Electronics Module with Integrated Ceramic Heat Exchanger

NREL, in partnership with Synteris and Packet Digital, has developed a 3D-printable ceramic package for power electronic modules to improve their thermal management, power density, performance, and lifetime. Existing power modules contain flat ceramic substrates that serve as both the electrically insulating component and thermal conductor that transfer the large heat outputs of these devices. The team has developed an additive manufacturing process that replaces the traditional insulating metalized substrate, substrate attach, and baseplate/heat exchanger with an additively-manufactured ceramic packaging that acts as both an electrical insulator and heat exchanger for better thermal management. The design, manufacturability, and function of this power module will be discussed.

25 ENERGY STORAGE↗

Power Electronics Thermal Management

This project conducts research to develop new power electronics thermal management technologies to increase power density, enable high WBG temperature operation, and decrease cost. One of the main challenges to achieving high power densities is associated with packaging of high-temperature (250°C) WBG devices near lower-temperature-rated components (e.g., electrical boards and capacitors). Additionally, the high junction temperatures of the WBG devices will result in large temperature gradients through the power module layers that will present reliability challenges and require higher-temperature substrates and bonding materials.

47 OTHER INSTRUMENTATION↗

Power Electronics Thermal Management

This project conducts research to develop new power electronics thermal management technologies to increase power density, enable high WBG temperature operation, and decrease cost. One of the main challenges to achieving high power densities is associated with packaging of high-temperature (up to 250 degrees C) WBG devices near lower-temperature-rated components (e.g., electrical boards and capacitors). Additionally, the high junction temperatures of the WBG devices will result in large temperature gradients through the power module layers, which will present reliability challenges and require higher-temperature substrates and bonding materials.

ADVANCED PROPULSION SYSTEMS↗

An integrated approach to space station power system autonomous control

Space Station electrical power management must be accomplished autonomously in order to decrease both airborne and ground support costs. Attention is presently given to the augmentation of terrestrial utility algorithmic decision aids for power dispatching for space station use, using expert systems to direct power demand analyses and the integration of results into operational decisions. Functions to be thus managed encompass power scheduling, energy allocation, failure cause diagnoses, goal proposal and plan preparation, consequence evaluation, and execution plan selection. The operating states of the system are normal, preventive, emergency, and restorative.

Dolce, James L.↗

Human Mars Surface Mission Surface Power Impacts on Timeline and Traverse Capabilities

The National Aeronautics and Aerospace Administration’s (NASA) Mars Architecture Team (MAT) developed a concept for power management operations to support a thirty-day, minimal infrastructure Mars surface mission. The surface elements in this minimal surface mission concept include three landers as platforms for surface operations, a crewed Mars ascent vehicle (MAV), an unpressurized rover, and a pressurized rover where the crew will live for the duration of the thirty-day mission. In this analysis the power system is a ten kilowatt fission power system, which has been selected for its resiliency to dust storms, and will provide power for all aspects of the surface mission including thermal management of propellant and electronic systems, communications, and battery recharge of mobile surface assets. Developing a power management plan with the consideration of the various elements and mission phases helps define the traverse and exploration capabilities for the crew in the pressurized rover. Also, considerations need to be made for the different power requirements for each phase of the surface mission including arrival, offload, surface exploration, launch preparation, and departure. The described analysis aims to achieve a balance of maintaining power to critical systems while enabling desired traverse and exploration range in the pressurized rover. Additionally, a few enhancing technologies were explored that could expand the power capability if the additional capacity is necessary in the future. This study is used as a baseline to understand the constraints on all aspects of the surface mission for a minimal surface infrastructure human Mars campaign if a ten-kilowatt fission surface power system is available on the surface.

Michael B. Chappell↗

Human Mars Mission Surface Power Impacts on Timeline and Traverse Capabilities

The National Aeronautics and Aerospace Administration’s (NASA) Mars Architecture Team (MAT) developed a concept for power management operations to support a thirty-day, minimal infrastructure Mars surface mission. The surface elements in this minimal surface mission concept include three landers as platforms for surface operations, a crewed Mars ascent vehicle (MAV), an unpressurized rover, and a pressurized rover where the crew will live for the duration of the thirty-day mission. In this analysis the power system is a ten kilowatt fission power system, which has been selected for its resiliency to dust storms, and will provide power for all aspects of the surface mission including thermal management of propellant and electronic systems, communications, and battery recharge of mobile surface assets. Developing a power management plan with the consideration of the various elements and mission phases helps define the traverse and exploration capabilities for the crew in the pressurized rover. Also, considerations need to be made for the different power requirements for each phase of the surface mission including arrival, offload, surface exploration, launch preparation, and departure. The described analysis aims to achieve a balance of maintaining power to critical systems while enabling desired traverse and exploration range in the pressurized rover. Additionally, a few enhancing technologies were explored that could expand the power capability if the additional capacity is necessary in the future. This study is used as a baseline to understand the constraints on all aspects of the surface mission for a minimal surface infrastructure human Mars campaign if a ten-kilowatt fission surface power system is available on the surface.

Michael B Chappell↗

A solar power system for an early Mars expedition

As NASA looks at missions that will expand human presence in the solar system, the power requirements for such missions need to be defined, developed and analyzed. One mission under consideration consists of a 40 day manned Mars surface expedition to perform science experiments. The mission time was centered around an aerocentric longitude (Ls) of 90 deg to lessen the probability of an occurrence of a local or planetary dust storm. The mission site was arbitrarily located at the Martian equator. The power requirements were assumed to be 40 kWe for life support and experiment power during the Martian day and 20 kWe for life support during the Martian night. A solar energy system consisting of roll-out amorphous silicon arrays and a hydrogen-oxygen regenerative fuel cell energy storage system was chosen for the study. The power available from a roll-out array, when plotted against time, approaches a cosine-like curve and depends on both array area and the amount of solar irradiance impinging on its horizontal surface. The array is sized to provide at least 20 KWe when the sun is 12.5 deg above the horizon and ramp up to 140 kWe peak power at Martian noon. In this configuration, the array is capable of supplying 40 KWe continuously to the user for the majority of the Martian day while supplying the excess energy to the electrolyzer portion of the energy storage system. A roll-out, pumped loop radiator system is used to dissipate the waste heat produced by the fuel cell. The power management and distribution system inverts the power from the individual solar array sub-modules and the fuel cell stacks and connects them to a 440 VAC single phase 20 kHz main bus. The total power system is comprised of 80 individual solar array modules with an integral bus and three energy storage modules consisting of fuel cell and electrolyzer stacks, reactant storage tanks, and a roll-out radiator. Power system mass, stowed volume, and deployed area were determined. Day/night power splits of 40/10 kWe, 40/30 kWe, and 40/40 kWe were also considered to determine the impact of a range of nighttime power requirements on the baseline system.

Mckissock, Barbara I.↗

Technology challenges and trade-offs in application of multiple-beam antennas to NASA's Personal Access Satellite System

A review is presented of the trade-offs and technology challenges that exist in developing the multiple-beam satellite antennas for NASA's Personal Access Satellite System. Different types of multiple-beam antenna systems that can provide full coverage of the CONUS such as switched beam, fixed beam, or scanned beam systems are examined. Some techniques for interbeam power management for efficient utilization of satellite power and reliable operation are discussed.

Manshadi, F.↗