Development of high performance gimbaled inertial sensors for aeronautical and space application.
High performance gimbaled inertial sensors for aeronautical and space applications
Andersen, J. P.↗
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An assessment of the status and trends in satellite communications 1986-2000: An information document prepared for the Communications Subcommittee of the Space Applications Advisory Committee
This is a response to a Space Applications Advisory Committee (SAAC) request for information about the status and trends in satellite communications, to be used to support efforts to conceive and recommend long range goals for NASA communications activities. Included in this document are assessments of: (1) the outlook for satellite communications, including current applications, potential future applications, and impact of the changing environment such as optical fiber networks, the Integrated Services Digital Network (ISDN) standard, and the rapidly growing market for Very Small Aperture Terminals (VSAT); (2) the restrictions imposed by our limited spectrum resource; and (3) technology needs indicated by future trends. Potential future systems discussed include: large powerful satellites for providing personal communications; VSAT compatible satellites with onboard switching and having voice capability; large satellites which offer a pervasive T1 network service (primarily for video-phone); and large geostationary communications facilities which support common use by several carriers. Also, discussion is included of NASA particular needs and possible future systems. Based on the mentioned system concepts, specific technology recommendations are provided for the time frames of now - 1993, 1994 - 2000, and 2000 - 2010.
Poley, W. A.↗
Microwave integrated circuits for space applications
Monolithic microwave integrated circuits (MMIC), which incorporate all the elements of a microwave circuit on a single semiconductor substrate, offer the potential for drastic reductions in circuit weight and volume and increased reliability, all of which make many new concepts in electronic circuitry for space applications feasible, including phased array antennas. NASA has undertaken an extensive program aimed at development of MMICs for space applications. The first such circuits targeted for development were an extension of work in hybrid (discrete component) technology in support of the Advanced Communication Technology Satellite (ACTS). It focused on power amplifiers, receivers, and switches at ACTS frequencies. More recent work, however, focused on frequencies appropriate for other NASA programs and emphasizes advanced materials in an effort to enhance efficiency, power handling capability, and frequency of operation or noise figure to meet the requirements of space systems.
Leonard, Regis F.↗
Improved Nuclear Reactor and Shield Mass Model for Space Applications
New technologies are being developed to explore the distant reaches of the solar system. Beyond Mars, solar energy is inadequate to power advanced scientific instruments. One technology that can meet the energy requirements is the space nuclear reactor. The nuclear reactor is used as a heat source for which a heat-to-electricity conversion system is needed. Examples of such conversion systems are the Brayton, Rankine, and Stirling cycles. Since launch cost is proportional to the amount of mass to lift, mass is always a concern in designing spacecraft. Estimations of system masses are an important part in determining the feasibility of a design. I worked under Michael Barrett in the Thermal Energy Conversion Branch of the Power & Electric Propulsion Division. An in-house Closed Cycle Engine Program (CCEP) is used for the design and performance analysis of closed-Brayton-cycle energy conversion systems for space applications. This program also calculates the system mass including the heat source. CCEP uses the subroutine RSMASS, which has been updated to RSMASS-D, to estimate the mass of the reactor. RSMASS was developed in 1986 at Sandia National Laboratories to quickly estimate the mass of multi-megawatt nuclear reactors for space applications. In response to an emphasis for lower power reactors, RSMASS-D was developed in 1997 and is based off of the SP-100 liquid metal cooled reactor. The subroutine calculates the mass of reactor components such as the safety systems, instrumentation and control, radiation shield, structure, reflector, and core. The major improvements in RSMASS-D are that it uses higher fidelity calculations, is easier to use, and automatically optimizes the systems mass. RSMASS-D is accurate within 15% of actual data while RSMASS is only accurate within 50%. My goal this summer was to learn FORTRAN 77 programming language and update the CCEP program with the RSMASS-D model.
Robb, Kevin↗
Adjustable Autonomy and Human-Agent Teamwork in Practice: An Interim Report on Space Applications
We give a preliminary perspective on the basic principles and pitfalls of adjustable autonomy and human-centered teamwork. We then summarize the interim results of our study on the problem of work practice modeling and human-agent collaboration in space applications, the development of a broad model of human-agent teamwork grounded in practice, and the integration of the Brahms, KAoS, and NOMADS agent frameworks. We hope our work will benefit those who plan and participate in work activities in a wide variety of space applications, as well as those who are interested in design and execution tools for teams of robots that can function as effective assistants to humans.
Bradshaw, Jeffrey M.↗
Structural Dynamic Testing Results for Air-Independent Proton Exchange Membrane (PEM) Fuel Cell Technologies for Space Applications
In 2016, the NASA Advanced Exploration Systems (AES) project office funded research at the NASA Glenn Research Center to evaluate the maturity of the Proton Exchange Membrane (PEM) fuel cell technology and its viability for supporting launch vehicle and space applications. This technology evaluation included vibration, reactant purity, and vacuum exposure sensitivity testing. The evaluation process did not include microgravity testing. This paper discusses the vibration sensitivity testing of two air-independent fuel cell stacks provided by different vendors to assess the ability of currently available fuel cell stack hardware to survive the projected random vibrational environment that would be encountered in an upper stage launch vehicle. Baseline performance testing was utilized to quantify stack performance and overboard leak rate at standard atmospheric conditions in order to provide a reference for post-test comparison. Both fuel cell stacks were tested at a random vibration qualification level of 10.4 grms for five minutes in each axis. Low-level sinusoidal sweeps were conducted before and after each random vibration level run to see if any significant change in resonances were detected. Following vibration facility testing, the baseline performance testing was repeated. Test results demonstrated no measurable change in fuel cell electrochemical or mechanical performance, indicating that the two evaluated PEM fuel cell stacks may be suitable for space applications pending microgravity testing.
Gilligan, Ryan P.↗
A Framework for Robust Multivariable Optimization of Integrated Circuits in Space Applications
Application Specific Integrated Circuit (ASIC) design for space applications involves multiple challenges of maximizing performance, minimizing power and ensuring reliable operation in extreme environments. This is a complex multidimensional optimization problem which must be solved early in the development cycle of a system due to the time required for testing and qualification severely limiting opportunities to modify and iterate. Manual design techniques which generally involve simulation at one or a small number of corners with a very limited set of simultaneously variable parameters in order to make the problem tractable are inefficient and not guaranteed to achieve the best possible results within the performance envelope defined by the process and environmental requirements. What is required is a means to automate design parameter variation, allow the designer to specify operational constraints and performance goals, and to analyze the results in a way which facilitates identifying the tradeoffs defining the performance envelope over the full set of process and environmental corner cases. The system developed by the Mixed Signal ASIC Group (MSAG) at the Goddard Space Flight Center is implemented as framework of software modules, templates and function libraries. It integrates CAD tools and a mathematical computing environment, and can be customized for new circuit designs with only a modest amount of effort as most common tasks are already encapsulated. Customization is required for simulation test benches to determine performance metrics and for cost function computation. Templates provide a starting point for both while toolbox functions minimize the code required. Once a test bench has been coded to optimize a particular circuit, it is also used to verify the final design. The combination of test bench and cost function can then serve as a template for similar circuits or be re-used to migrate the design to different processes by re-running it with the new process specific device models. The system has been used in the design of time to digital converters for laser ranging and time-of-flight mass spectrometry to optimize analog, mixed signal and digital circuits such as charge sensitive amplifiers, comparators, delay elements, radiation tolerant dual interlocked (DICE) flip-flops and two of three voter gates.
DuMonthier, Jeffrey↗
Space applications of diamagnetic suspensions
Conventional noncontact magnetic suspensions require power and sensor feedback to maintain stability of the levitated object. Magnetic suspensions using superconductors require neither power nor feedback for stability but must be maintained at low temperatures. This paper discusses a little known type of magnetic bearing that does not require power, sensor feedback, or cooling: diamagnetic suspension. While the bearing pressure for diamagnetic suspensions is typically limited to 1 g/sq cm, their simplicity, environmental tolerances, and wide range of material choices suggest that they may be useful for a number of space applications. This paper discusses the fundamentals of diamagnetic suspensions as well as their potential space applications.
Pelrine, Ronald E.↗
Hybrid regenerative fuel cell systems for space applications
This paper describes a hybrid regenerative fuel cell (RFC) system for space application, which is made up of an alkaline fuel cell (Space Shuttle fuel cell) and an acid electrolysis unit (solid polymer electrolyte). In the RFC, gas produced from the acid electrolysis unit and water produced by the alkaline fuel cell are repeatedly reacted in the other unit. The results of RFC's tests indicate that the system is feasible in terms of fluid/unit compatibility. In addition, the fuel cell thermal-control system proved capable of controlling fuel cell temperatures throughout long open-circuit periods. Diagrams of the RFC and its subsystems are included.
Saucier, David R.↗
Strawman payload data for science and applications space platforms
The need for a free flying science and applications space platform to host compatible long duration experiment groupings in Earth orbit is discussed. Experiment level information on strawman payload models is presented which serves to identify and quantify the requirements for the space platform system. A description data base on the strawman payload model is presented along with experiment level and group level summaries. Payloads identified in the strawman model include the disciplines of resources observations and environmental observations.
Source record↗
Use of mercuric iodide X-ray detectors with alpha backscattering spectrometers for space applications
The authors present X-ray fluorescence (XRF) spectra of different extraterrestrial samples taken with a mercuric iodide (HgI2) spectrometer inserted into an alpha backscattering instrument identical to that used in the Soviet Phobos mission. The results obtained with the HgI2 ambient temperature detector are compared with those obtained using an Si(Li) cryogenically cooled detector. Efforts to design an optimized instrument for space application are also described. The results presented indicate that the energy resolution and sensitivity of HgI2 detectors are adequate to meet the performance needs of a number of proposed space applications, particularly those in which cooled silicon X-ray detectors are impractical or even not usable, such as for the target science programs on geoscience opportunities for lunar surface, Mars surface, and other comet and planetary missions being planned by NASA and ESA.
Iwanczyk, J. S.↗
Liquid lubrication for space applications
Reviewed here is the state of the art of liquid lubrication for space applications. The areas discussed are types of liquid lubrication mechanisms, space environmental effects on lubrication, classification of lubricants, liquid lubricant additives, grease lubrication, mechanism materials, bearing anomalies and failures, lubricant supply techniques, and application types and lubricant needs for those applications.
Fusaro, Robert L.↗
Liquid lubrication for space applications
Reviewed here is the state of the art of liquid lubrication for space applications. The areas discussed are types of liquid lubrication mechanisms, space environmental effects on lubrication, classification of lubricants, liquid lubricant additives, grease lubrication, mechanism materials, bearing anomalies and failures, lubricant supply techniques, and application types and lubricant needs for those applications.
Fusaro, Robert L.↗
Graphics Technology in Space Applications (GTSA 1989)
This document represents the proceedings of the Graphics Technology in Space Applications, which was held at NASA Lyndon B. Johnson Space Center on April 12 to 14, 1989 in Houston, Texas. The papers included in these proceedings were published in general as received from the authors with minimum modifications and editing. Information contained in the individual papers is not to be construed as being officially endorsed by NASA.
Griffin, Sandy↗
Computer graphics testbed to simulate and test vision systems for space applications
A system was developed for displaying computer graphics images of space objects and the use of the system was demonstrated as a testbed for evaluating vision systems for space applications. In order to evaluate vision systems, it is desirable to be able to control all factors involved in creating the images used for processing by the vision system. Considerable time and expense is involved in building accurate physical models of space objects. Also, precise location of the model relative to the viewer and accurate location of the light source require additional effort. As part of this project, graphics models of space objects such as the Solarmax satellite are created that the user can control the light direction and the relative position of the object and the viewer. The work is also aimed at providing control of hue, shading, noise and shadows for use in demonstrating and testing imaging processing techniques. The simulated camera data can provide XYZ coordinates, pitch, yaw, and roll for the models. A physical model is also being used to provide comparison of camera images with the graphics images.
Cheatham, John B.↗
A survey of advanced battery systems for space applications
The results of a survey on advanced secondary battery systems for space applications are presented. The objectives were: to identify advanced battery systems capable of meeting the requirements of various types of space missions, with significant advantages over currently available batteries, to obtain an accurate estimate of the anticipated improvements of these advanced systems, and to obtain a consensus for the selection of systems most likely to yield the desired improvements. Few advanced systems are likely to exceed a specific energy of 150 Wh/kg and meet the additional requirements of safety and reliability within the next 15 years. The few that have this potential are: (1) regenerative fuel cells, both alkaline and solid polymer electrolyte (SPE) types for large power systems; (2) lithium-intercalatable cathodes, particularly the metal ozides intercalatable cathodes (MnO2 or CoO2), with applications limited to small spacecrafts requiring limited cycle life and low power levels; (3) lithium molten salt systems (e.g., LiAl-FeS2); and (4) Na/beta Alumina/Sulfur or metal chlorides cells. Likely technological advances that would enhance the performance of all the above systems are also identified, in particular: improved bifunctional oxygen electrodes; improved manufacturing technology for thin film lithium electrodes in combination with polymeric electrolytes; improved seals for the lithium molten salt cells; and improved ceramics for sodium/solid electrolyte cells.
Attia, Alan I.↗
Review of two-phase flow liquid metal MHD and turbine energy conversion concepts for space applications
Two-phase energy conversion systems could be liquid metal magnetohydrodynamic (LMMHD) with no moving parts or two-phase turbines. Both of them are inherently simple and reliable devices which can operate in a wide range of temperatures. Their thermal efficiency is significantly higher than for conventional cycles due to reheat of vapor by liquid phase during the energy converting expansion. Often they can be more easily coupled to heat sources. These features make two-phase systems particularly promising for space application. Insufficient research has been done in the past. So far achieved LMMHD generator and two-phase turbine efficiencies are in the 40 to 45 percent range. However if certain fluid dynamic and design problems are resolved these efficiencies could be brought into the range of 70 percent. This would make two-phase systems extremely competitive as compared to present or other proposed conversion system for space. Accordingly, well directed research effort on potential space applications of two-phase conversion systems would be a wise investment.
Fabris, Gracio↗
A broadband THz receiver for low background space applications
We have developed a sensitive bolometric receiver for low background space applications. In a 10 percent bandwidth at 1 THz, this receiver is approximately 100 times more sensitive than a quantum limited heterodyne receiver with a 1 GHz IF bandwidth. This receiver is designed to be used for the long wavelength band (200-700 microns) in the MIPS instrument on NASA's SIRTF satellite. The bolometers are cooled to 100 mK by an adiabatic demagnetization refrigerator. Roughly 60 g of cesium chrome alum salt is partially demagnetized to 100 mK, followed by a slow regulated downramp to compensate for the heat leak. The hold time of the ADR system is about 18 hours with a temperature stability of delta T(sub rms) approx. equals 10 micro-K. The composite bolometers have electrical responsivities of 10(exp 9)V/W and electrical NEP's of about 3x10(exp -17) W/square root of Hz. The bolometer signals are read out by JFET preamplifiers located on the helium plate and operated at 120 K. We have addressed a number of space qualification issues, such as the development of an analog magnet controller, construction of a cryogenic shake-table for bolometers and selection of the paramagnetic salt CCA which can survive a bakeout at 50 C. The receiver is scheduled to be flown in the spring of 1992 on a balloon telescope. This flight has a dual purpose. One is to provide realistic test of the capabilities of the new receiver. The other is to search for anisotropies in the cosmic microwave background on scales of a few degrees.
Hagmann, C.↗