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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 343 records · Page 19

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NASA NTRS1992

The 1991-1992 project summaries

The Department of Mechanical Engineering at The University of Texas at Austin participated in seven cooperative design projects this year. Six of the projects were associated with the Johnson Space Center and include the design of a thermal control system for an inflatable lunar habitat module, a vibration isolation system for a space shuttle cycle ergometer, a radiator shading device for a lunar outpost, a reusable astronaut safety tether, a resistive exercise device for use on the space shuttle, and a fleet of autonomous regolith throwing devices for radiation shielding of lunar habitats. The seventh project is associated with the Jet Propulsion Lab and involves the design of a shock absorbing wheel for a small six-wheeled Martian rover vehicle.

Nichols, Steven P.↗

NASA NTRS1985

Report of the Electrodynamic Interactions Panel

A wide range of opportunities is provided by the electrodynamic tether to more fully understand the generation of waves in plasmas, the behavior of field aligned currents, the behavior of large body-space plasma interactions, and for process simulation, using the electrodynamic tether to study processes and phenomena relevant to solar system and astrophysics plasma physics. The electrodynamic tether offers a means of study and experimentation in space which will provide a rich yield in new scientific results and will enhance the understanding of space plasma physics. It also has promising technological applications (e.g., the generation of electrical power and thrust) which may be highly significant to future space operations.

Stone, N. H.↗

NASA NTRS2003

Tethers as Debris: Hydrocode Simulation of Impacts of Polymer Tether Fragments on Aluminum Plates

Tethers promise to find use in a variety of space applications. Despite being narrow objects, their great lengths result in them having large total areas. Consequently, tethers are very susceptible to being severed by orbital debris. Extensive work has been done designing tethers that resist severs by small debris objects, in order to lengthen their working lives. It is from this perspective that most recent work has considered the tether - debris question. The potential of intact tethers, or severed tether fragments, as debris, to pose a significant collision risk to other spacecraft has been less well studied. Understanding the consequences of such collisions is important in assessing the risks tethers pose to other spacecraft. This paper discusses the damage that polymer tethers may produce on aluminum plates, as revealed by hypervelocity impact simulations using the SPHC hydrodynamic code.

Evans, Steven W.↗

NASA NTRS2004

Review of the ProSEDS Electrodynamic Tether Mission Development

The Propulsive Small Expendable Deployer System (ProSEDS) space experiment was ready to fly as a secondary payload on a Delta-II expendable launch vehicle in late March 2003. Concerns raised in February 2003 by the International Space Station resulted in the delay of the launch of ProSEDS. Issues associated with the delayed launch date and a change in starting altitude resulted in the cancellation of the mission. ProSEDS was intended to deploy a tether (5 km bare wire plus 10 km non-conducting Dyneema) from a Delta I1 second stage to achieve adequate drag thrust that would lower the orbit of the system over days as opposed to months due to atmospheric drag. It was also designed to utilize the tether-generated current to provide limited spacecraft power. Considerable effort and testing went in to developing the ProSEDS system by a dedicated team. Through this effort, important technological issues were identified and addressed and this presentation will discuss some of the important technical issues and hurdles that had to be addressed to successfully prepare for flight. It is intended that this information will be of use for future tether mission and experiment designers.

Vaughn, Jason A.↗

NASA NTRS1988

Status of tethered satellite system (TSS) development

The Tethered Satellite System (TSS) is a cooperative space system and science development activity being carried out by the U.S. and Italy. The TSS will involve an instrument-laden satellite that can be deployed from the cargo bay of the Shuttle Orbiter using a long tether to altitudes both above and below that of the Orbiter. This paper discusses the predevelopment activities, development approach and management relationships, current hardware and software designs and interfaces, overall science experiment status and plans, and mission operation planning for the first TSS mission.

Laue, Jay H.↗

NASA NTRS2005

Participation in the Analysis of the Far-Infrared/Submillimeter Interferometer

We have contributed to the development of the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) by analyzing various aspects related to the tethers that connect the spacecraft of this space interferometer. We have focused our analysis on key topics as follows: (a) helping in the configuration selection; (b) computing the system eigenfrequencies as a function of baseline length; (c) developing techniques and conceptual design of devices for damping the tether oscillations; (d) carrying out numerical simulations of tethered formation to assess the effects of environmental perturbations upon the baseline length variation; (e) devising control laws for fast retargeting of the interferometer at moderate baseline lengths; (f) estimating the survivability to micrometeoroid impacts of a tether at L2; and (g) developing a conceptual design of a high-strength and survivable tether.

Lorenzini, Enrico C.↗

NASA NTRS1980

Remote sensing of oceanic phytoplankton - Present capabilities and future goals

A description is given of current work in the development of sensors, and their integration into increasingly powerful systems, for oceanic phytoplankton abundance estimation. Among the problems relevant to such work are phytoplankton ecology, the spatial and temporal domains, available sensor platforms, and sensor combinations. Among the platforms considered are satellites, aircraft, tethered balloons, helicopters, ships, and the Space Shuttle. Sensors discussed include microwave radiometers, laser fluorosensors, microwave scatterometers, multispectral scanners, Coastal Ocean Dynamics Radar (CODAR), and linear array detectors. Consideration is also given to the prospects for such future sensor systems as the National Oceanic Satellite System (NOSS) and the Airborne Integrated Mapping System (AIMS).

Esaias, W. E.↗

NASA NTRS1984

Shuttle 'Challenger' aerodynamic performance from flight data - Comparisons with predicted values and 'Columbia' experience

Longitudinal aerodynamic performance comparisons between flight extracted and predicted values are presented for the first eight NASA Space Shuttle entry missions. Challenger results are correlated with the ensemble five flight Columbia experience and indicate effects due to differing angle-of-attack and body flap deflection profiles. An Appendix is attached showing the results of each flight using both the LaRC LAIRS and NOAA atmospheres. Discussions are presented which review apparent density anomalies observed in the flight data, with particular emphasis on the suggested shears and turbulence encountered during STS-2 and STS-4. Atmospheres derived from Shuttle data are presented which show structure different than that remotely sensed and imply regions of unstable air masses as a plausible explanation. Though additional aerodynamic investigations are warranted, an added benefit of Shuttle flight data for atmospheric research is discussed, in particular, as applicable to future NASA space vehicles such as AOTVs and tethered satellites.

Findlay, J. T.↗

NASA NTRS1993

Estimating Conical Motion From Magnetometer Measurements

Method of digital processing of outputs of magnetometer mounted on scientific instrument or other assembly provides estimates of parameters of slow oscillatory motion of assembly at constant or nearly constant frequency, in which motion one axis of assembly describes elliptical cone about nominal fixed or nearly fixed axis. Conceived for use in estimating rotational-and-vibrational motion of small instrumented satellite and 20-km-long tether anchored at lower end to Space Shuttle. Applicable to almost any situation in which assembly moves conically about known axis while measuring known vector.

Polites, M. E.↗

NASA NTRS2002

Tethers as Debris: Hydrocode Simulation of Impacts of Tether Fragments on Planar Aerospace Materials

Tethers promise to find use in a variety of space applications. Despite being narrow objects, their great lengths result in them having large total areas, and so tethers are quite susceptible to being severed by orbital debris. Extensive work has been done designing tethers that resist severs by small debris objects, and hence have longer working lives. It is from this perspective that most recent work has considered the tether - debris question. The potential of intact tethers, or severed tether fragments, as debris to pose a significant collision risk to other spacecraft has been less well studied. Understanding the consequences of such encounters is important in assessing the risks to other spacecraft posed by tethers. In this paper I discuss the damage that two types of tethers may produce on planar aerospace materials, as revealed by hyper- velocity impact simulations using the SPHC hydrodynamic code. Tether types considered include a single nylon line and a complex design including metal wires. Target materials considered include the aluminum plates typically used in debris shielding, and solar panels.

Evans, Steven W.↗

NASA NTRS2003

Human-Robot Control Strategies for the NASA/DARPA Robonaut

The Robotic Systems Technology Branch at the NASA Johnson Space Center (JSC) is currently developing robot systems to reduce the Extra-Vehicular Activity (EVA) and planetary exploration burden on astronauts. One such system, Robonaut, is capable of interfacing with external Space Station systems that currently have only human interfaces. Robonaut is human scale, anthropomorphic, and designed to approach the dexterity of a space-suited astronaut. Robonaut can perform numerous human rated tasks, including actuating tether hooks, manipulating flexible materials, soldering wires, grasping handrails to move along space station mockups, and mating connectors. More recently, developments in autonomous control and perception for Robonaut have enabled dexterous, real-time man-machine interaction. Robonaut is now capable of acting as a practical autonomous assistant to the human, providing and accepting tools by reacting to body language. A versatile, vision-based algorithm for matching range silhouettes is used for monitoring human activity as well as estimating tool pose.

Diftler, M. A.↗

NASA NTRS2006

Electrodynamic Tether

A tether system for providing thrust to or power subsystems of an artificial satellite in a low earth orbit. The tether has three main sections, an insulated section connected to the satellite, a conducting section connected to the insulating section for drawing in and releasing electrons from the space plasma and a non-conducting section for providing a tension to the other sections of the tether. An oxygen resistant coating is applied to the bare wire of the conducting section as well as the insulated wires of the insulated section that prevents breakdown during tether operations in the space plasma. The insulated and bare wire sections also surround a high tensile flexible polymer core to prevent any debris from breaking the tether during use.

Johnson, Charles L.↗

NASA NTRS1984

Space Systems Technology Conference, Costa Mesa, CA, June 5-7, 1984, Technical Papers

Space station technology is considered along with a shuttle tethered satellite system development program, the development of advanced orbital maintenance/servicing techniques for EVA applications, human systems interfaces for space stations, materials and structures for space applications, progress in space nuclear reactor power systems technology development with the aid of the SP-100 Program, and the design of reliable power systems for communications satellites. Attention is given to problems and concepts of space station guidance and control, spacecraft data management hardware state-of-the-art, progressive autonomy, and automation in teleoperation from a man-machine interface viewpoint. A space exploration outlook is provided, and the space power systems of the early 21st century are discussed.

Source record↗

NASA NTRS1988

The tethered satellite electrodynamics experiment project

NASA and Italy's PSN have undertaken the Tethered Satellite Electrodynamics Experiment, in which two tethered bodies will be equipped with data-collecting scientific instruments, as the first stage of the development of the Tethered Satellite System that can be deployed by the Space Shuttle. The experiment will give attention to the electromagnetic interaction between the satellite/tether/orbiter system and the ambient space plasma, and should demonstrate the operation of both satellite- and Shuttle-borne electrodynamic instruments with a conductive tether.

Price, John M.↗

NASA NTRS1985

The excitation of plasma waves by a current source moving in a magnetized plasma - The MHD approximation

Alfven waves are important in natural-space phenomena, and studies of these waves have been conducted by performing active experiments in space plasma. One method to study these waves involves the use of an electrodynamic tether. The electrodynamic tether consists of a subsatellite with a conducting outer surface connected to the Space Shuttle by an insulator-clad, conducting wire about 20 kilometers in length. The emf generated by the motion of the tether across the geomagnetic field will act to drive a current through the tethered system. It is pointed out that this current in the tether acts as a source for exciting the shear-Alfven wave. In the present investigation it is shown that fringing effects play a dominant role in determining the radiation pattern for currently envisioned deployments of the tether. The current paper is the first of three papers concerned with the excitation of low-frequency waves arising from a current source moving through a cold, magnetized plasma.

Rasmussen, C. E.↗

NASA NTRS2000

Overview of Advanced Space Propulsion Activities in the Space Environmental Effects Team at MSFC

Exploration of our solar system, and beyond, requires spacecraft velocities beyond our current technological level. Technologies addressing this limitation are numerous. The Space Environmental Effects (SEE) Team at the Marshall Space Flight Center (MSFC) is focused on three discipline areas of advanced propulsion; Tethers, Beamed Energy, and Plasma. This presentation will give an overview of advanced propulsion related activities in the Space Environmental Effects Team at MSFC. Advancements in the application of tethers for spacecraft propulsion were made while developing the Propulsive Small Expendable Deployer System (ProSEDS). New tether materials were developed to meet the specifications of the ProSEDS mission and new techniques had to be developed to test and characterize these tethers. Plasma contactors were developed, tested and modified to meet new requirements. Follow-on activities in tether propulsion include the Air-SEDS activity. Beamed energy activities initiated with an experimental investigation to quantify the momentum transfer subsequent to high power, 5J, ablative laser interaction with materials. The next step with this experimental investigation is to quantify non-ablative photon momentum transfer. This step was started last year and will be used to characterize the efficiency of solar sail materials before and after exposure to Space Environmental Effects (SEE). Our focus with plasma, for propulsion, concentrates on optimizing energy deposition into a magnetically confined plasma and integration of measurement techniques for determining plasma parameters. Plasma confinement is accomplished with the Marshall Magnetic Mirror (M3) device. Initial energy coupling experiments will consist of injecting a 50 amp electron beam into a target plasma. Measurements of plasma temperature and density will be used to determine the effect of changes in magnetic field structure, beam current, and gas species. Experimental observations will be compared to predictions from computer modeling.

Edwards, David↗

NASA NTRS1985

Space Science and Applications

The exploitation of the present tethered system and the need for repeat missions; multiple payloads placed along the tether; the extension of the present altitude limit to below 130 km; the development of free-flying tether satellites for studying both the Earth's atmosphere and ionosphere and also for studying the plantes; and a subtether were discussed. Areas of research were identified: aeronomy studies, gravity and magnetic potential mission, advanced sensors for geodynamics, and mapping and remote sensing.

Hudson, R.↗

NASA NTRS2002

Tether Impact Rate Simulation and Prediction with Orbiting Satellites

Space elevators and other large space structures have been studied and proposed as worthwhile by futuristic space planners for at least a couple of decades. In June 1999 the Marshall Space Flight Center sponsored a Space Elevator workshop in Huntsville, Alabama, to bring together technical experts and advanced planners to discuss the current status and to define the magnitude of the technical and programmatic problems connected with the development of these massive space systems. One obvious problem that was identified, although not for the first time, were the collision probabilities between space elevators and orbital debris. Debate and uncertainty presently exist about the extent of the threat to these large structures, one in this study as large in size as a space elevator. We have tentatively concluded that orbital debris although a major concern not sufficient justification to curtail the study and development of futuristic new millennium concepts like the space elevators.

Harrison, Jim↗