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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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Improved joystick allows motion in 6 degrees of freedom, biased toward central position and orientation by 16 segments of cable serving as springs. Improvement in feel and control results from nonlinear compliance of cable-spring assembly. Nonlinear variations accommodate natural reactions of hand and brain. Operator functions as part of feedback control loop. More comfortable, increases ability to exert control and reduces fatigue.
During the past few years considerable insight was gained into the QUEST algorithm both as a maximum likelihood estimator and as a Kalman filter/smoother for systems devoid of dynamical noise. The new algorithms and software are described and analytical comparisons are made with the more conventional attitude Kalman filter. It is also described how they may be accommodated to noisy dynamical systems.
For the past 15 years, Computer Sciences Corporation (CSC) has participated in a process improvement program as a member of the Software Engineering Laboratory (SEL), which is sponsored by GSFC. The benefits CSC has derived from involvement in this program are analyzed. In the environment studied, it shows that improvements were indeed achieved, as evidenced by a decrease in error rates and costs over a period in which both the size and the complexity of the developed systems increased substantially. The principles and mechanics of the process improvement program, the lessons CSC has learned, and how CSC has capitalized on these lessons are also discussed.
Three lunar missions lasting three years are described that make up the exploratory mapping phase of the Space Exploration Initiative. The three phases are: (1) a polar-orbiting satellite to map surface chemistry and mineralogy; (2) an orbiter to map the lunar terrain and gravity field; and (3) on-site investigation by means of rovers and remote-sensing instruments. The lunar mapping scenario relies on robotics technologies and is expected to cost 100-150 million dollars per phase and to require no more than three years.
A joint NASA/USAF program to exploit and develop control-structures interactions (CSI) to enhance the control of flexible body response to provide improved performance for future spacecraft is reviewed. Attention is given the primary analytical design activity, led by NASA/Langley, to develop an integrated structure/control system design to replace current separately designed and subsequently integrated structure and control systems. Consideration is given to other related programs including ASTREX, the CSI Evolutionary Model, the Space Integrated Control Experiment, and the joint NASA/DOD Guest Investigator project.
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Fuzzy control techniques are analyzed to explain why the fuzzy control that is based on the expert's knowledge is often smoother and more stable than the control performed manually by the same experts. A precise mathematical explanation of this phenomenon is presented. Results obtained make it possible to predict the quality of the fuzzy control.
The videotape discusses the new composites that will be used to create lighter yet stronger aircraft wings.
This video shows the advanced cockpit making piloting more efficient and flying safer.
NASA has completed a preliminary mission and systems study of nuclear electric propulsion (NEP) systems for 'split-sprint' human exploration and related robotic cargo missions to Mars. This paper describes the study, the mission architecture selected, the NEP system and technology development needs, proposed development schedules, and estimated development costs. Since current administration policy makers have delayed funding for key technology development activities that could make Mars exploration missions a reality in the near future, NASA will have time to evaluate various alternate mission options, and it appears prudent to ensure that Mars mission plans focus on astronaut and mission safety, while reducing costs to acceptable levels. The split-sprint nuclear electric propulsion system offers trip times comparable to nuclear thermal propulsion (NTP) systems, while providing mission abort opportunities that are not possible with 'reference' mission architectures. Thus, NEP systems offer short transit times for the astronauts, reducing the exposure of the crew to intergalactic cosmic radiation. The high specific impulse of the NEP system, which leads to very low propellant requirements, results in significantly lower 'initial mass in low earth orbit' (IMLEO). Launch vehicle packaging studies show that the NEP system can be launched, assembled, and deployed, with about one less 240-metric-ton heavy lift launch vehicle (HLLV) per mission opportunity - a very Technology development cost of the nuclear reactor for an NEP system would be shared with the proposed nuclear surface power systems, since nuclear systems will be required to provide substantial electrical power on the surface of Mars. The NEP development project plan proposed includes evolutionary technology development for nuclear electric propulsion systems that expands upon SP-100 (Space Power - 100 kw(e)) technology that has been developed for lunar and Mars surface nuclear power, and small NEP systems for interplanetary probes. System upgrades are expected to evolve that will result in even shorter trip times, improved payload capabilities, and enhanced safety and reliability.
A Microrover Flight Experiment (MFEX) based on a basic Rocky 4 design and conducted in the framework of the NASA Mars Environmental Survey (MESUR) Pathfinder program is described. The MFEX rover design features six powered wheels attached by a set of 'bogie levers' to a single body. The rover is designed to perform technology, science, and mission experiments. Instruments on the rover mechanisms will determine wheel-soil interactions, detect hazards, and determine navigational errors. Science data will be gathered using an alpha-proton-X-ray spectrometer against one or more rocks, and possible soil. The pathfinder will also serve as an engineering test of a transport and landing system for the MESUR network mission and the rover will image the lander to assess its condition.
The topics discussed include the following: virtual reality, man machine systems, and human-computer interface.
The research into the advancement of software error compensation techniques is discussed in this video. Although these techniques were originally designed for coordinate measuring machines, they are now used for machine tools as well.
In stellar dynamical computer simulations, as well as other types of simulations using particles, time step size is often held constant in order to guarantee a high degree of energy conservation. In many applications, allowing the time step size to change in time can offer a great saving in computational cost, but variable-size time steps usually imply a substantial degradation in energy conservation. We present a meta-algorithm' for choosing time steps in such a way as to guarantee time symmetry in any integration scheme, thus allowing vastly improved energy conservation for orbital calculations with variable time steps. We apply the algorithm to the familiar leapfrog scheme, and generalize to higher order integration schemes, showing how the stability properties of the fixed-step leapfrog scheme can be extended to higher order, variable-step integrators such as the Hermite method. We illustrate the remarkable properties of these time-symmetric integrators for the case of a highly eccentric elliptical Kepler orbit and discuss applications to more complex problems.
The 3.0-micrometers water of hydration absorption feature observed in the IR photometry of many low-albedo and some medium-albedo asteroids strongly correlates with the 0.7-micrometers Fe(+2) to Fe(+3) oxidized iron absorption feature observed in narrowband spectrophotometry of these asteroids. Using this relationship, an empirical algorithm for predicting the presence of water of hydration in the surface material of a Solar System body using photometry obtained through the Eight-Color Asteroid Survey nu (0.550 micrometers), w (0.701 micrometers), and x (0.853 micrometers) filters was developed and applied to the ECAS photometry of asteroids and outer planet satellites. The percentage of objects in low-albedo, outer main-belt asteroid classes that test positively for water of hydration increases from P to B to C to G class and correlates linearly with the increasing mean albedos of those objects testing positively. The medium-albedo M-class asteroids do not test positively in large number using this algorithm. Aqueously altered asteroids dominate the Solar System population between heliocentric distances of 2.6 to 3.5 AU, bracketing the Solar System region where the aqueous alteration mechanism operated most strongly. One jovian satellite, J VI Himalia, and one saturnian satellite. Phoebe, tested positively for water of hydration, supporting the hypothesis that these may be captured C-class asteroids from a postaccretional dispersion. The proposed testing technique could be applied to an Earth-based survey of asteroids or a space-probe study of an asteroid's surface characteristic in order to identify a potential water source.
Gas-gap thermal switches associated with sorption compressors of some heat pumps and cryogenic systems designed for higher performance, according to proposal, by introducing controlled turbulent flows into gas gaps. Utilizes convection in turbulent flow to transfer heat at greater rate. Design takes advantage of flow of working fluid. Working fluid also serve as heat transfer medium in gas gap.
Four design modifications enable fabrication of improved ohmic contacts on InP-based semiconductor devices. First modification consists of insertion of layer of gold phosphide between n-doped InP and metal or other overlayer of contact material. Second, includes first modification plus use of particular metal overlayer to achieve very low contact resistivities. Third, also involves deposition of Au(2)P(3) interlayer; in addition, refractory metal (W or Ta) deposited to form contact overlayer. In fourth, contact layer of Auln alloy deposited directly on InP. Improved contacts exhibit low electrical resistances and fabricated without exposing devices to destructive predeposition or postdeposition treatments.
This paper addresses the advantages of utilizing a centrifuge test over the conventional static load test methods to structurally qualify aerospace structures. Three recent test cases are reviewed and used as examples to highlight these benefits. In addition, the overall capability of Goddard's High Capacity Centrifuge (HCC) is outlined along with some unique features that were designed specifically to reduce costs, test turn around time, and increase test item safety.