SEARCH · Search NASA
Results for “Tether”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Instructions for the use of the marquardt ibm 7040 computer program. controlled tethering in space
Computer program for orbiting three body system simulation in Fortran
Electrodynamics of long conducting tethers in the near-earth environment
An analytical approach was developed to evaluate the electrodynamic interactions affecting a thin, bare metallic wire moving in the ionosphere. The wire's diameter was smaller than the Debye length; therefore, the plasma sheath around the wire was taken into account in computing inducing drag force and torque. Computer programs were prepared for the numerical evaluation of mathematical functions that were required to compute the distribution of the potential along the wire and of the current in the wire. Numerical calculations based on this software are shown.
Aerospatiale is ready to develop a convertiplane with tethering rotors
Information on the recent study of the convertiplane is reported. The convertiplane was designed to replace the conventional helicopter. Its speed is much faster than that of the helicopter, it uses less fuel, and can carry up to five passengers. The discovery of the convertiplane was brought about because the helicopter is handicapped by its slow speed and can carry only a few passengers.
System noise analysis of the dumbbell tethered satellite for gravity-gradient measurements
An analysis of the dumbbell gravity gradiometer concept for measuring short wavelength variations in the earth's gravity gradient is presented. Variations in the gradient are recorded by measuring tension variations in a vertically stabilized satellite consisting of heavy masses connected by a long wire or rod. Tension noise arises from the excitation of various mechanical oscillations of the system. The principal noise sources that were identified are fluctuations in atmospheric drag heating and drag force resulting from density variations and winds. Approximate analytical expressions are presented for the tension noise as a function of the system design parameters for various possible configurations. Computer simulations using numerical integration were performed to study the tension noise for several sample cases. Three designs consistent with Shuttle launch capabilities are discussed.
Development and application of the Manned Maneuvering Unit, work restraint system, stowage container and return line tether
The Manned Maneuvering Unit (MMU), a self-contained zero-gravity backpack designed for astronaut extravehicular activity, is discussed with reference to the system requirements and characteristics, and potential near-term and future uses. Attention is given to the MMU man-machine interfaces, propulsion capability, attitude control, crew restraint hardware, donning, doffing, activation, and deactivation. Specific applications discussed include: spacecraft inspection and servicing, assembly of large space systems, payload deployment/retrieval, and crew rescue.
Tethered Communication Satellites
Report describes concept for placing several communication satellites in geostationary orbit without taking up more space than assigned to single satellite. Proposed scheme eases orbital crowding more economically than space platforms. Concept requires minimal redesign of existing satellites and accommodates many satellites in just one orbital slot. System much lighter in weight than geostationary platform and easier and more economical to transport.
Proceedings of a Workshop on Applications of Tethers in Space, Volume 2
The panel conclusions for each of the following panels (science applications; electrodynamic interactions; transportation applications; artificial gravity; constellations; and technology and test) are given.
Pultrusion Process for Fabrication of Tethers (preliminary Concepts)
Three composite materials were manufactured by the pultrusion process, coiled on 24 inch diameter spools for a period of two months, uncoiled and evaluated for memory recall. These materials were pultruded to lengths of approximately 150 feet and cross section profiles were maintained at 0.143 inch in thickness by 0.566 inch in width. Mechanical properties were studied and results compared. The reinforcement material volume percent of each was identical. Of the three systems, the Kevlar reinforced composite had the highest specific strength, the lowest flexural modulus, and the lowest memory recall. Further evaluations of materials and fabrication technology of pultrusion should be conducted to address some problem areas encountered in this preliminary concept. Areas for further study are suggested.
Quasi non-intrusive sampling and analysis of gases associated with the boundary layer on the tethered satellite and similar supersonic and hypersonic research vehicles
The effect that one candidate inlet, an assembly of capillary openings in a thin glass plate (a multichannel plate), might have on the overall sampling process is considered. The flow characteristics of the plate, under a variety of conditions of external pressure and mass flow, is evaluated. A review of capillary flow theory is presented with some development of the pertinent equations. The predicted mass flow will be compared to that determined perimentally to assess the effect that mass flow through one capillary might have upon a neighboring capillary. Mass spectrometric measurements of mixtures flowing through the multichannel plate (MCP) is also considered. In the first part of the experiments, the flow was in a direction normal to the surface of the plate. The experimental gases were Argon and mixtures of carbon dioxide in air. Ongoing experiments are discussed which are conducted with the flow parallel to the surface of the plate, a simulation of the kind of flow that a flight vehicle would experience.
Analytical investigation of the dynamics of tethered constellations in Earth orbit, phase 2
This Quarterly Report deals with the deployment maneuver of a single-axis, vertical constellation with three masses. A new, easy to handle, computer code that simulates the two-dimensional dynamics of the constellation has been implemented. This computer code is used for designing control laws for the deployment maneuver that minimizes the acceleration level of the low-g platform during the maneuver.
Dynamics of tethered constellations in Earth orbit
Topics covered include station keeping of single-axis and two-axis constellations; single-axis vertical constellations with low-g platform; single-axis vertical constellations with three masses; deployment strategy; and damping of vibrational modes.
Tethered satellite design
The capability of the satellite to perform a variety of space operations to be accomplished from the shuttle is reviewed considering use of the satellite with man-in-loop and closed loop modes and deployment (toward or away from Earth, up to 100 km), stationkeeping, retrieval and control of the satellite. Scientific payloads are to be used to perform experiments and scientific investigation for applications such as magnetometry, electrodynamics, atmospheric science, chemical release, communications, plasmaphysics, dynamic environment, and power and thrust generation. The TSS-S will be reused for at least 3 missions after reconfiguration and refurbishment by changing the peculiar mission items such as thermal control, fixed boom for experiments, aerodynamic tail for yaw attitude control, external skin, experiments, and any other feature. The TSS-S is to be composed of three modules in order to allow independent integration of a single module and to facilitate the refurbishment and reconfiguration between flights. The three modules are service, auxiliary propulsion, and payload modules.
Laboratory simulation of the electrodynamic interactions of a tethered satellite with an ionospheric plasma
An improved experimental set-up in the Orleans Plasma Chamber allowed investigations of the I-V characteristics of a conductive spherical body (10 cm diameter) in a plasma environment. Moreover, the influence of a transversal magnetic field at 0.6 and 1.2 G was investigated, for the first time, both on the sheath potential profile and current collection. Floating potential profiles were measured at 16 different radial distances from the test body up to 9 body radii in 8 different angular positions. The test body potential could be increased in the range from -200 V up to +100 V. Preliminary results are shown and discussed.
Theory of plasma contractors for electrodynamic tethered satellite systems
Recent data from ground and space experiments indicate that plasma releases from an object dramatically reduce the sheath impedance between the object and the ambient plasma surrounding it. Available data is in qualitative accord with the theory developed to quantify the flow of current in the sheath. Electron transport in the theory is based on a fluid model of a collisionless plasma with an effective collision frequency comparable to frequencies of plasma oscillations. The theory leads to low effective impedances varying inversely with the square root of the injected plasma density. To support such a low impedance mode of operation using an argon plasma source for example requires that only one argon ion be injected for each thirty electrons extracted from the ambient plasma. The required plasma flow rates are quite low; to extract one ampere of electron current requires a mass flow rate of about one gram of argon per day.
Tethers and asteroids for artificial gravity assist in the solar system
Explore the source record for details and available documents.
A three-mass tethered system for micro-g/variable-g applications
Explore the source record for details and available documents.