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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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At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Telescoping space station modules

A design concept is described wherein telescoping space station modules would be utilized to nearly double the useful volume onboard a station. Methods for utilizing the concept to obtain enchanced protection from space debris and radiation are described. The amenability of the concept to variation in station configuration, assembly, and disassembly is discussed. A modification of the concept which could provide flexibility in the manner in which the Shuttle Orbiter is docked with the station and enhance collision avoidance during such maneuvers is described.

Witcofski, R. D.↗
NASA NTRS1985

Space research in the era of the space station

The major elements of the NASA manned space station are described, and science activities it could be used for are suggested. The core facilities include at least two major laboratory modules with supporting utilities, including habitation accommodations, docking facilities, power and heat rejection units, and external space and support for attached payloads. A vertically oriented structure, called the Power Tower, is being studied. Scientific accommodations inside the modules include major facility instrumentation for a variety of microgravity research projects, with initial emphasis upon materials research and life sciences. The second element is composed of free-flying satellites operating in orbits near the core station. The third element consists of satellites in polar orbits. One or more large, multi-instrument platforms are planned for Earth observation and solar-terrestrial processes research.

Banks, P. M.↗
NASA NTRS1986

Personnel occupied woven envelope robot

The use of nonmetallic or fabric structures for space application is considered. The following structures are suggested: (1) unpressurized space hangars; (2) extendable tunnels for soft docking; and (3) manned habitat for space stations, storage facilities, and work structures. The uses of the tunnel as a passageway: for personnel and equipment, eliminating extravehicular activity, for access to a control cabin on a space crane and between free flyers and the space station are outlined. The personnal occupied woven envelope robot (POWER) device is shown. The woven envelope (tunnel) acts as part of the boom of a crane. Potential applications of POWER are outlined. Several possible deflection mechanisms and design criteria are determined.

Wessling, F. C.↗
NASA NTRS1986

Dynamic characteristics of power-tower space stations with 15-foot truss bays

A power tower space station concept which generates power with photovoltaic arrays and where the truss structure has a bay size of 15 ft is described. Rigid body and flexible body dynamic characteristics are presented for a 75-kW Initial Operating Capability (IOC) and 150-kW and 300-kW growth stations. The transient response of the IOC and 300-kW growth stations to shuttle dock, orbit reboost, and mobile remote manipulator system translation loads are studied. Displacements, accelerations, and bending moments at various locations on the IOC and 300-kW growth stations are presented.

Dorsey, J. T.↗
NASA NTRS1986

Proven, long-life hydrogen/oxygen thrust chambers for space station propulsion

The development of the manned space station has necessitated the development of technology related to an onboard auxiliary propulsion system (APS) required to provide for various space station attitude control, orbit positioning, and docking maneuvers. A key component of this onboard APS is the thrust chamber design. To develop the required thrust chamber technology to support the Space Station Program, the NASA Lewis Research Center has sponsored development programs under contracts with Aerojet TechSystems Company and with Bell Aerospace Textron Division of Textron, Inc. During the NASA Lewis sponsored program with Aerojet TechSystems, a 25 lb sub f hydrogen/oxygen thruster has been developed and proven as a viable candidate to meet the needs of the Space Station Program. Likewise, during the development program with Bell Aerospace, a 50 lb sub f hydrogen/oxygen Thrust Chamber has been developed and has demonstrated reliable, long-life expectancy at anticipated space station operating conditions. Both these thrust chambers were based on design criteria developed in previous thruster programs and successfully verified in experimental test programs. Extensive thermal analyses and models were used to design the thrusters to achieve total impulse goals of 2 x 10 to the 6th power lb sub f-sec. Test data for each thruster will be compared to the analytical predictions for the performance and heat transfer characteristics. Also, the results of thrust chamber life verification tests will be presented.

Richter, G. P.↗
NASA NTRS1985

Non-linear guidance laws for automatic orbital rendezvous

In the automatic assembly of space stations or the automatic rendezvous and docking of a space-shuttle vehicle with a space station, it is of interest to determine suitable guidance laws for orbital rendezvous which are amenable to on-board implementation. In this paper, various forms of nonlinear guidance laws for automatic orbital rendezvous of two bodies represented by point masses in a central Newtonian gravitational field are derived. A basic requirement is that the approach be smooth and nonoscillatory. The global dynamic behavior of each of the resulting feedback systems is determined analytically and/or by computer simulation.

Wang, P. K. C.↗
NASA NTRS1985

Space station adaptabilty to tether applications

This paper examines the Space Station configuration, requirements, and operations, and considers its adaptability to accommodate each tether application. These include power and thrust generation, rendezvous and docking, science platforms, variable gravity, and satellite boost and deboost. It attempts to uncover incompatibilities, and suggests compromises which would be required to effectively utilize each specific application. The goal is to enhance the overall understanding of the adaptability of the Space Station to tether applications.

Penzo, P. A.↗
NASA NTRS1986

Space Station dynamic modeling, control and simulation

Dynamic disturbances of many orders of magnitude greater than those of conventional spacecraft will be routine for the Space Station. Accurate knowledge of inflight structural dynamics and disturbances will be lacking. System identification will reduce uncertainties. To deal with the remaining model errors and time-varying elements, adaptive control may be required. Dynamic models for two Space Station configurations are derived. A direct model reference adaptive control algorithm is synthesized and evaluated with respect to the station model parameter errors and plant dynamics truncations. Both the rigid body and the flexible modes are treated. Simulation results show that convergence of the adaptive algorithm can be achieved in 100 to about 300 seconds with reasonable performance even during Shuttle hard docking operations in which station mass and inertia are instantaneously changed by more than 100 percent.

Ih, C.-H. C.↗
NASA NTRS1986

The dynamics of a space station tethered refueling facility

The fluid stored in a tethered orbital refueling facility is settled at the bottom of the storage tanks by gravity-gradient forces. The fluid motions (slosh) induced by outside disturbances must be limited to ensure the tank outlet is not uncovered during a fluid transfer. The dynamics of a LO2/LH2 TORF attached to the space station have been analyzed to identify design parameters necessary to limit fluid motion. Using the worst case disturbance of a shuttle docking at the space station, the fluid motion was found to be a function of tether length and allowable facility swing angle. Acceptable fluid behavior occurs for tether lengths of at least 1000 ft. To ensure motions induced by separate disturbances do not add to unacceptable values, a slosh damping coefficient of 5 percent is recommended.

Abbott, P.↗
NASA NTRS1987

Ultrasonic Ranging System With Increased Resolution

Master-oscillator frequency increased. Ultrasonic range-measuring system with 0.1-in. resolution provides continuous digital display of four distance readings, each updated four times per second. Four rangefinder modules in system are modified versions of rangefinder used for automatic focusing in commercial series of cameras. Ultrasonic pulses emitted by system innocuous to both people and equipment. Provides economical solutions to such distance-measurement problems as posed by boats approaching docks, truck backing toward loading platform, runway-clearance readout for tail of airplane with high angle attack, or burglar alarm.

Meyer, William E.↗
NASA NTRS1987

Control and Simulation of Space-Station Vibrations

Adaptive control system reduces effects of model uncertainties. Report outlines method for finite-element dynamic analysis of space station. Purpose is to determine periods and modes of oscillation of structure and to analyze effect of proposed adaptive control system to damp out unwanted vibrations. With simplifications proposed, finite-element simulations performed during dynamic event, like docking of Space Shuttle, and used to control vibration-damping actuators.

Ih, Che-Hang Charles↗
NASA NTRS1985

Preliminary evaluation of the airborne imaging spectrometer for vegetation analysis in the Klamath National Forest of northeastern California

The experiences and results associated with a project entitled Preliminary Evaluation of the Airborne Imaging Spectrometer for Vegetation Analysis is documented. The primary goal of the project was to provide ground truth, manual interpretation, and computer processing of data from an experimental flight of the Airborne Infrared Spectrometer (AIS) to determine the extent to which high spectral resolution remote sensing could differentiate among plant species, and especially species of conifers, for a naturally vegetated test site. Through the course of the research, JPL acquired AIS imagery of the test areas in the Klamath National Forest, northeastern California, on two overflights of both the Dock Well and Grass Lake transects. Over the next year or so, three generations of data was also received: first overflight, second overflight, and reprocessed second overflight. Two field visits were made: one trip immediately following the first overflight to note snow conditions and temporally-related vegetation states at the time of the sensor overpass; and a second trip about six weeks later, following acquisition of prints of the images from the first AIS overpass.

Strahler, A. H.↗
NASA NTRS1986

Passive damping augmentation for flexible structures

The present work concentrates on the application and extension of absorber design and optimization techniques to a multimode, multi-DOF, large space structure, namely the NASA space station. The principal issue addressed is the optimal tuning of several absorbers for the transient response of a multi-DOF system, including the effects of modal coupling, existing structural damping, absorber placement, and adsorber mass. The space station is subject to many transient disturbances such as docking, orbit reboost, crew motion, and payload slewing. A notable steady-state excitation source is the Science Research Centrifuge, which rotates at a frequency in the bandwidth of the primary structural modes. Because of the relatively advanced state of development of steady-state absorber design techniques, only the transient cases are considered in this study.

Sesak, J. R.↗
NASA NTRS1986

Pseudo-prototyping of aerospace mechanical dynamic systems with a generalized computer program

The ADAMS computer program for automated analysis of mechanisms and machines is described. The program automatically formulates mathematical models for prototype or existing mechanisms with the minimum necessary physical and geometric data. The model can then be analyzed in various modes of analysis. The outputs (displacements, velocities, acceleration and forces) can be produced in tabular and graphical (plots, wire frame graphics) form. The application of this computer program to simulating satellite docking maneuvers is illustrated.

Sohoni, Vikram N.↗
NASA NTRS1987

Orbital fluid servicing and resupply operations

The capability to reservice spacecraft and satellites with expendable fluids will provide significant increases in the usability, operational efficiency and cost effectiveness of in-space systems. Initial resupply will be accomplished from the Orbiter cargo bay starting with monopropellant servicing which will eventually be extended to servicing of bipropellants and pressurants. Other fluids, such as freon, ammonia, methanol, superfluid helium, and liquid/gaseous nitrogen may also need to be resupplied once a space station becomes a reality. These fluids/gases are required for subsystem working fluid replacement and payload/experiment fluid replenishment. A logistics module operating on a 90 day schedule is planned for space station servicing. Resupplying hundreds of thousands of pounds of cryogenic propellants and reactants for users such as the Orbital Transfer Vehicle (OTV) also represents future logistics challenges. Implementation of on-orbit fluid transfer requires solving many problems including fluid management in the low-g environment, system docking and interface mating, configuration of user friendly avionics to monitor and control the entire servicing operation, and minimized maintenance and enhanced reliability. Candidate fluid transfer methods and possible gas transfer methods are discussed, and preliminary storable monopropellant and bipropellant tanker designs are summarized.

Eberhardt, R. N.↗
NASA NTRS1987

Precise computer controlled positioning of robot end effectors using force sensors

A major problem in space applications of robotics and docking of spacecraft is the development of technology for automated precise positioning of mating components with smooth motion and soft contact. To achieve the above objective, a design method was developed for optimally placing the closed-loop poles of a discretized robotic control system at exact prescribed locations inside the unit circle of the complex z-plane. The design method combines the merits of the pole placement and the linear quadratic design approaches. The proposed design procedure is based on the assignment of one real eigenvalue or two complex conjugate (or real) eigenvalues at each design step. The method involves solutions of simple algebraic equations and this is considered to be efficient for on-line or off-line computations. Also, two methods for the linearization of the nonlinear model of a robotic manipulator were presented. Since automatic control of multi-degree freedom robotic manipulators involves high nonlinear equations of systems, a pilot project was proposed involving the control of a one-dimensional system. This simple system can be readily implemented for testing the concepts and algorithms.

Shieh, Leang S.↗
NASA NTRS1987

Numerical modeling of on-orbit propellant motion resulting from an impulsive acceleration

In-space docking and separation maneuvers of spacecraft that have large fluid mass fractions may cause undesirable spacecraft motion in response to the impulsive-acceleration-induced fluid motion. An example of this potential low gravity fluid management problem arose during the development of the shuttle/Centaur vehicle. Experimentally verified numerical modeling techniques were developed to establish the propellant dynamics, and subsequent vehicle motion, associated with the separation of the Centaur vehicle from the shuttle orbiter cargo bay. Although the shuttle/Centaur development activity was suspended, the numerical modeling techniques are available to predict on-orbit liquid motion resulting from impulsive accelerations for other missions and spacecraft.

Aydelott, John C.↗
NASA NTRS1987

Preloadable vector sensitive latch

A preloadable vector-sensitive latch which automatically releases when the force vector from a latch memebr reaches a specified release angle is presented. In addition, it contains means to remove clearance between the latched members and to preload the latch to prevent separation at angles less than the specified release angle. The latch comprises a triangular main link, a free link connected between a first corner of the main link and a yoke member, a housing, and an actuator connected between the yoke member and the housing. A return spring bias means connects the main link to a portion of the housing. A second corner of the main link is slidably and pivotally connected to the housing via a slot in a web portion of the housing. The latch housing has a rigid docking ring alignable with a mating locking ring which is engageable by a locking roller journalled on the third corner of the triangular main link.

Acres, William R.↗