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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Thirty-nine papers on cosmic ray anisotropies, law energy auroral particles, helium and hydrogen airglow, ionospheric irregularities, thermospheric winds, interhemisphere ion transport, ion cyclotron heating, ion temperature morphology, ion chemistry, ion convection, and spacecraft interactions with the atmosphere and ionosphere are described.
A problem in the automatic assembly of space stations is the determination of guidance laws for the terminal rendezvous and docking of two structural components or modules. The problem involves the feedback control of both the relative attitude and translational motion of the modules. A suitable mathematical model based on rigid body dynamics was used. The basic requirements, physical constraints and difficulties associated with the control problem are discussed. An approach which bypasses some of the difficulties is proposed. A nonlinear guidance law satisfying the basic requirements is derived. The implementation requirements is discussed. The performance of the resulting feedback control system with rigid and flexible structural components is studied by computer simulation.
Hyperbolic systems of conversation laws are considered which are discretized in space by spectral collocation methods and advanced in time by finite difference schemes. At any time-level a domain deposition method based on an iteration by subdomain procedure was introduced yielding at each step a sequence of independent subproblems (one for each subdomain) that can be solved simultaneously. The method is set for a general nonlinear problem in several space variables. The convergence analysis, however, is carried out only for a linear one-dimensional system with continuous solutions. A precise form of the error reduction factor at each iteration is derived. Although the method is applied here to the case of spectral collocation approximation only, the idea is fairly general and can be used in a different context as well. For instance, its application to space discretization by finite differences is straight forward.
A generalized curvilinear coordinate Taylor weak statement implicit finite element algorithm is developed for the two-dimensional and axisymmetric compressible Navier-Stokes equations for ideal and reacting gases. For accurate hypersonic simulation, air is modeled as a mixture of five perfect gases, i.e., molecular and atomic oxygen and nitrogen as well as nitric oxide. The associated pressure is then determined via Newton solution of the classical chemical equilibrium equation system. The directional semidiscretization is achieved using an optimal metric data Galerkin finite element weak statement, on a developed 'companion conservation law system', permitting classical test and trial space definitions. Utilizing an implicit Runge-Kutta scheme, the terminal algorithm is then nonlinearly stable, and second-order accurate in space and time on arbitrary curvilinear coordinates. Subsequently, a matrix tensor product factorization procedure permits an efficient numerical linear algebra handling for large Courant numbers. For ideal- and real-gas hypersonic flows, the algorithm generates essentially nonoscillatory numerical solutions in the presence of strong detached shocks and boundary layer-inviscid flow interactions.
The ability to develop highly advanced simulators is a critical need that has the ability to significantly impact the aerospace industry. The aerospace industry is advancing at an ever increasing pace and flight simulators must match this development with ever increasing urgency. In order to address both current problems and potential advancements with flight simulator techniques, several aspects of current control law technology of the National Aeronautics and Space Administration (NASA) Langley Research Center's Cockpit Motion Facility (CMF) motion base simulator were examined. Preliminary investigation of linear models based upon hardware data were examined to ensure that the most accurate models are used. This research identified both system improvements in the bandwidth and more reliable linear models. Advancements in the compensator design were developed and verified through multiple techniques. The position error rate feedback, the acceleration feedback and the force feedback were all analyzed in the heave direction using the nonlinear model of the hardware. Improvements were made using the position error rate feedback technique. The acceleration feedback compensator also provided noteworthy improvement, while attempts at implementing a force feedback compensator proved unsuccessful.
Law Environmental, Inc. is a professional engineering and Earth sciences consulting firm. When a client, who operates an electricity generating plant required assistance in evaluating the effects of a heated water discharge on aquatic life, Law proposed a Visiting Investigator Program (VIP) to Stennis Space Center (SSC). The VIP is directed toward small companies who could use remote sensing profitably, but do not have the money to explore new technologies. SSC provided remote sensing data to Law enabling it to produce images of the thermal "plume," the water area affected by the discharge. After comparisons of plant and animal life with similar life in an unaffected control area, Law concluded that the discharge effect was not significant.
Basic Hypersonic Data and Equations (HYPERDATA) spreadsheet computer program provides data gained from three analyses of performance of space plane. Equations used to perform analyses derived from Newton's second law of physics, derivation included. First analysis is parametric study of some basic factors affecting ability of space plane to reach orbit. Second includes calculation of thickness of spherical fuel tank. Third produces ratio between volume of fuel and total mass for each of various aircraft. HYPERDATA intended for use on Macintosh(R) series computers running Microsoft Excel 3.0.
A flexible aircraft or space structure with active control is typically modeled by a large-order state space system of equations in order to accurately represent the rigid and flexible body modes, unsteady aerodynamic forces, actuator dynamics and gust spectra. The control law of this multi-input/multi-output (MIMO) system is expected to satisfy multiple design requirements on the dynamic loads, responses, actuator deflection and rate limitations, as well as maintain certain stability margins, yet should be simple enough to be implemented on an onboard digital microprocessor. A software package for performing an analog or digital control law synthesis for such a system, using optimal control theory and constrained optimization techniques is described.
In response to Public Law 98-371, dated July 18, 1984, the NASA Advanced Technology Advisory Committee has studied automation and robotics for use in the Space Station. The Executive Overview, Volume 1 presents the major findings of the study and recommends to NASA principles for advancing automation and robotics technologies for the benefit of the Space Station and of the U.S. economy in general. As a result of its study, the Advanced Technology Advisory Committee believes that a key element of technology for the Space Station is extensive use of advanced general-purpose automation and robotics. These systems could provide the United States with important new methods of generating and exploiting space knowledge in commercial enterprises and thereby help preserve U.S. leadership in space.
Wind profiles can be measured from space using current technology. These wind profiles are essential for answering many of the interdisciplinary scientific questions to be addressed by EOS, the Earth Observing System. This report provides guidance for the development of a spaceborne wind sounder, the Laser Atmospheric Wind Sounder (LAWS), discussing the current state of the technology and reviewing the scientific rationale for the instrument. Whether obtained globally from the EOS polar platform or in the tropics and subtropics from the Space Station, wind profiles from space will provide essential information for advancing the skill of numerical weather prediction, furthering knowledge of large-scale atmospheric circulation and climate dynamics, and improving understanding of the global biogeochemical and hydrologic cycles. The LAWS Instrument Panel recommends that it be given high priority for new instrument development because of the pressing scientific need and the availability of the necessary technology. LAWS is to measure wind profiles with an accuracy of a few meters per second and to sample at intervals of 100 km horizontally for layers km thick.
Scaling laws of penetration of particles traveling at meteoroid velocity, summarizing simulation techniques
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The laser atmospheric wind sounder (LAWS) is a facility instrument of the Earth Observing System (EOS) and is the culmination of over 20 years of effort in the field of laser Doppler wind sensing. LAWS will by the first instrument to fly in space with the capability of providing global-scale tropospheric wind profiles at high spatial resolutions. Global-scale wind profiles are necessary for: (1) more accurate diagnostics of large-scale circulation and climate dynamics; (2) improved numerical weather prediction; (3) improved understanding of mesoscale systems; (4) improved understanding of global biogeochemical and hydrologic cycles. The objective of phase 1 of the LAWS study was to evaluate competing concepts and develop a baseline configuration for the LAWS instrument. The first phase of the study consisted of identifying realistic concepts for LAWS and analyzing them in sufficient detail to be able to choose the most promising one for the LAWS application. System configurations were then developed for the chosen concept. The concept and subsequent configuration were to be compatible with two prospective platforms: the Japanese polar orbiting platform (JPOP) and the Space Station Freedom (as an attached payload). After an objective and comprehensive concept selection process, a heterodyne detection Doppler lidar using a CO2 laser transmitter operating at 9.1 microns over a 2.1 micron system with a solid state laser was chosen. The CO2 lidar concept was then analyzed in detail to arrive at a configuration for the instrument and its major subsystems. A configuration for LAWS was arrived at which meets the performance requirements, and this design is presented.
The motivations, features and expected benefits and applications of the NASA SMART program are summarized. SMART is intended to push the state of the art in automation and robotics, a goal that Public Law 98-371 mandated be an inherent part of the Space Station program. The effort would first require tests of sensors, manipulators, computers and other subsystems as seeds for the evolution of flight-qualified subsystems. Consideration is currently being given to robotics systems as add-ons to the RMS, MMU and OMV and a self-contained automation and robotics module which would be tended by astronaut visits. Probable experimentation and development paths that would be pursued with the equipment are discussed, along with the management structure and procedures for the program. The first hardware flight is projected for 1989.
The statistics of convective soil patterns are analyzed using statistical crystallography. An underlying hierarchy of order is found to span four orders of magnitude in characteristic pattern length. Strict mathematical requirements determine the two-dimensional (2D) topology, such that random partitioning of space yields a predictable statistical geometry for polygons. For all lengths, Aboav's and Lewis's laws are verified; this result is consistent both with the need to fill 2D space and most significantly with energy carried not by the patterns' interior, but by the boundaries. Together, this suggests a common mechanism of formation for both micro- and macro-freezing patterns.
The goal of theory is to understand how the fundamental laws of physics laws of physics and chemistry give rise to the features of the universe. It is recommended that NASA establish independent theoretical research programs in planetary sciences and in astrophysics similar to the solar-system plasma-physics theory program, which is characterized by stable, long-term support for theorists in university departments, NASA centers, and other organizations engaged in research in topics relevant to present and future space-derived data. It is recommended that NASA keep these programs under review to full benefit from the resulting research and to assure opportunities for inflow of new ideas and investigators. Also, provisions should be made by NASA for the computing needs of the theorists in the programs. Finally, it is recommended that NASA involve knowledgeable theorists in mission planning activities at all levels, from the formulation of long-term scientific strategies through the planning and operation of specific missions.
While Ocular Coherence Tomography (OCT) is not a first-line modality to evaluate anterior eye structures terrestrially, it is a resource already available on the International Space Station (ISS) that can be used in medical contingencies that involve the anterior eye. With remote guidance and subject matter expert (SME) support from the ground, a minimally trained crewmember can now use OCT to evaluate anterior eye pathologies on orbit. OCT utilizes low-coherence interferometry to produce detailed cross-sectional and 3D images of the eye in real time. Terrestrially, it has been used to evaluate macular pathologies and glaucoma. Since 2013, OCT has been used onboard the ISS as one part of a suite of hardware to evaluate the Visual Impairment/Intracranial Pressure risk faced by astronauts, specifically assessing changes in the retina and choroid during space flight. The Anterior Segment Module (ASM), an add-on lens, was also flown for research studies, providing an opportunity to evaluate the anterior eye in real time if clinically indicated. Anterior eye pathologies that could be evaluated using OCT were identified. These included corneal abrasions and ulcers, scleritis, and acute angle closure glaucoma. A remote guider script was written to provide ground specialists with step-by-step instructions to guide ISS crewmembers, who do not get trained on the ASM, to evaluate the anterior eye. The instructions were tested on novice subjects and/or operators, whose feedback was incorporated iteratively. The final remote guider script was reviewed by SME optometrists and NASA flight surgeons. The novel application of OCT technology to space flight allows for the acquisition of objective data to diagnose anterior eye pathologies when other modalities are not available. This demonstrates the versatility of OCT and highlights the advantages of using existing hardware and remote guidance skills to expand clinical capabilities in space flight.
A control method applicable to multiple-input multiple-output nonlinear time-invariant systems in which desired behavior can be expressed explicitly as a trajectory in system state space is developed. The precomputed state dependent control method is basically a synthesis technique in which a suboptimal control law is developed off-line, prior to system operation. This law is obtained by conducting searches at a finite number of points in state space, in the vicinity of some desired trajectory, to obtain a set of constant control vectors which tend to return the system to the desired trajectory. These vectors are used to evaluate the unknown coefficients in a control law having an assumed hyperellipsoidal form. The resulting coefficients constitute the heart of the controller and are used in the on-line computation of control vectors. Two examples of PSDC are given prior to the more detailed description of the NERVA control system development.