Electrodynamic tether system study: Extended study

NASA Technical Reports Server (NTRS)

1988-01-01

This document is the final report of a study performed by Ball Space Systems Division (BSSD) for the NASA Johnson Space Center under an extension to contract NAS9-17666. The tasks for the extended study were as follows: (1) Define an interface between the Electrodynamic Tether System (ETS) and the Space Station (SS); (2) Identify growth paths for the 100 kW ETS defined in the original study to a 200 kW level of performance; (3) Quantify orbit perturbations caused by cyclic day/night operations of a Plasma Motor/Generator (PMG) on the SS and explore methods of minimizing these effects; (4) Define the analyses, precursor technology, ground tests, and precursor demonstrations leading up to a demonstration mission for an electrodynamic tether system that would be capable of producing maneuvering thrust levels of 25 newtons; and (5) Propose a development schedule for the demonstration mission and preliminary cost estimates.

Tethers

NASA Technical Reports Server (NTRS)

Cutler, Andrew Hall; Carroll, Joseph A.

1992-01-01

A tether of sufficient strength, capable of being lengthened or shortened and having appropriate apparatuses for capturing and releasing bodies at its ends, may be useful in propulsion applications. For example, a tether could allow rendezvous between spacecraft in substantially different orbits without using propellant. A tether could also allow co-orbiting spacecraft to exchange momentum and separate. Thus, a reentering spacecraft (such as the Shuttle) could give its momentum to one remaining on orbit (such as the space station). Similarly, a tether facility could gain momentum from a high I(sub sp)/low thrust mechanism (which could be an electrodynamics tether) and transfer than momentum by means of a tether to payloads headed for many different orbits. Such a facility would, in effect, combine high I(sub sp) with high thrust, although only briefly. An electrodynamic tether could propel a satellite from its launch inclination to a higher or lower inclination. Tethers could also allow samples to be taken from bodies such as the Moon. Three types of tether operations are illustrated. The following topics are discussed: (1) tether characteristics; (2) tether propulsion methods--basics, via momentum transfer, and electrodynamic tether propulsion; and (3) their use in planetary exploration.

Artist's Concept of Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

1999-01-01

Pictured is an artist's concept of NASA's Propulsive Small Expendable Deployer System experiment (ProSEDS). ProSEDS will demonstrate the use of an electrodynamic tether, basically a long, thin wire, for propulsion. An electrodynamic tether uses the same principles as electric motors in toys, appliances and computer disk drives, and generators in automobiles and power plants. When electrical current is flowing through the tether, a magnetic field is produced that pushes against the magnetic field of the Earth. For ProSEDS, the current in the tether results by virtue of the voltage generated when the tether moves through the Earth's magnetic field at more than 17,000 mph. This approach can produce drag thrust generating useable power. Since electrodynamic tethers require no propellant, they could substantially reduce the weight of the spacecraft and provide a cost-effective method of reboosting spacecraft. The initial flight of ProSEDS is scheduled to fly aboard an Air Force Delta II rocket in summer of 2002. In orbit, ProSEDS will deploy from a Delta II second stage. It will be a 3.1-mile (5 kilometer) long, ultrathin base-wire tether cornected with a 6.2-mile (10 kilometer) long nonconducting tether. The ProSEDS experiment is managed by the Space Transportation Directorate at the Marshall Space Flight Center.

Pathfinder

NASA Image and Video Library

1999-03-25

Pictured is an artist's concept of NASA's Propulsive Small Expendable Deployer System experiment (ProSEDS). ProSEDS will demonstrate the use of an electrodynamic tether, basically a long, thin wire, for propulsion. An electrodynamic tether uses the same principles as electric motors in toys, appliances and computer disk drives, and generators in automobiles and power plants. When electrical current is flowing through the tether, a magnetic field is produced that pushes against the magnetic field of the Earth. For ProSEDS, the current in the tether results by virtue of the voltage generated when the tether moves through the Earth's magnetic field at more than 17,000 mph. This approach can produce drag thrust generating useable power. Since electrodynamic tethers require no propellant, they could substantially reduce the weight of the spacecraft and provide a cost-effective method of reboosting spacecraft. The initial flight of ProSEDS is scheduled to fly aboard an Air Force Delta II rocket in summer of 2002. In orbit, ProSEDS will deploy from a Delta II second stage. It will be a 3.1-mile (5 kilometer) long, ultrathin base-wire tether cornected with a 6.2-mile (10 kilometer) long nonconducting tether. The ProSEDS experiment is managed by the Space Transportation Directorate at the Marshall Space Flight Center.

Selected tether applications in space: Phase 2. Executive summary

NASA Technical Reports Server (NTRS)

Thorson, M. H.; Lippy, L. J.

1985-01-01

The application of tether technology has the potential to increase the overall performance efficiency and capability of the integrated space operations and transportation systems through the decade of the 90s. The primary concepts for which significant economic benefits were identified are dependent on the space station as a storage device for angular momentum and as an operating base for the tether system. Concepts examined include: (1) tether deorbit of shuttle from space station; (2) tethered orbit insertion of a spacecraft from shuttle; (3) tethered platform deployed from space station; (4) tether-effected rendezvous of an OMV with a returning OTV; (5) electrodynamic tether as an auxiliary power source for space station; and (6) tether assisted launch of an OTV mission from space station.

Selected tether applications in space: An analysis of five selected concepts

NASA Technical Reports Server (NTRS)

1984-01-01

Ground rules and assumptions; operations; orbit considerations/dynamics; tether system design and dynamics; functional requirements; hardware concepts; and safety factors are examined for five scenarios: tethered effected separation of an Earth bound shuttle from the space station; tether effected orbit boost of a spacecraft (AXAF) into its operational orbit from the shuttle; an operational science/technology platform tether deployed from space station; a tether mediated rendezvous involving an OMV tether deployed from space station to rendezvous with an aerobraked OTV returning to geosynchronous orbit from a payload delivery mission; and an electrodynamic tether used in a dual motor/generator mode to serve as the primary energy storage facility for space station.

International Space Station Electrodynamic Tether Reboost Study

NASA Technical Reports Server (NTRS)

Johnson, L.; Herrmann, M.

1998-01-01

The International Space Station (ISS) will require periodic reboost due to atmospheric aerodynamic drag. This is nominally achieved through the use of thruster firings by the attached Progress M spacecraft. Many Progress flights to the ISS are required annually. Electrodynamic tethers provide an attractive alternative in that they can provide periodic reboost or continuous drag cancellation using no consumables, propellant, nor conventional propulsion elements. The system could also serve as an emergency backup reboost system used only in the event resupply and reboost are delayed for some reason.

Space Test of Bare-Wire Anode Tethers

NASA Technical Reports Server (NTRS)

Johnson, L.; Fujii, H. A.; Sanmartin, J. R.

2007-01-01

An international team, lead by Tokyo Metropolitan University, is developing a mission concept for a suborbital test of orbital-motion-limited (OML) bare-wire anode current collection for application to electrodynamic tether propulsion. The tether is a tape with a 50-mm width, 0.05-mm thickness, and 1-km length. This will be the first space test of the OML theory. In addition, by being an engineering demonstration (of space tethers), the mission will demonstrate electric beam generation for "sounding" determination of the neutral density profile in the ionospheric "E-layer." If selected by the Institute of Space and Astronautical Science/Japanese Aerospace Exploration Agency (JAXA), the mission will launch in early 2009 using an $520 Sounding Rocket. During ascent, and above =100 km in attitude, the 1-km tape tether will be deployed at a rate of 8 m/s. Once deployed, the tape tether will serve as an anode, collecting ionospheric electrons. The electrons will be expelled into space by a hollow cathode device, thereby completing the circuit and allowing current to flow.This paper will describe the objectives of the proposed mission, the technologies to be employed, and the application of the results to future space missions using electrodynamic tethers for propulsion or power generation.

Tether Technology Interchange Meeting

NASA Technical Reports Server (NTRS)

Harrison, James K. (Compiler)

1998-01-01

This is a compilation of 25 papers presented at a tether technical interchange meeting in Huntsville, AL, on September 9-10, 1997. After each presentation, a technical discussion was held to clarify and expand the salient points. A wide range of subjects was covered including tether dynamics, electrodynamics, space power generation, plasma physics, ionospheric physics, towing tethers, tethered reentry schemes, and future tether missions.

Application of the NASCAP Spacecraft Simulation Tool to Investigate Electrodynamic Tether Current Collection in LEO

NASA Technical Reports Server (NTRS)

Adams, Mitzi; HabashKrause, Linda

2012-01-01

Recent interest in using electrodynamic tethers (EDTs) for orbital maneuvering in Low Earth Orbit (LEO) has prompted the development of the Marshall ElectroDynamic Tether Orbit Propagator (MEDTOP) model. The model is comprised of several modules which address various aspects of EDT propulsion, including calculation of state vectors using a standard orbit propagator (e.g., J2), an atmospheric drag model, realistic ionospheric and magnetic field models, space weather effects, and tether librations. The natural electromotive force (EMF) attained during a radially-aligned conductive tether results in electrons flowing down the tether and accumulating on the lower-altitude spacecraft. The energy that drives this EMF is sourced from the orbital energy of the system; thus, EDTs are often proposed as de-orbiting systems. However, when the current is reversed using satellite charged particle sources, then propulsion is possible. One of the most difficult challenges of the modeling effort is to ascertain the equivalent circuit between the spacecraft and the ionospheric plasma. The present study investigates the use of the NASA Charging Analyzer Program (NASCAP) to calculate currents to and from the tethered satellites and the ionospheric plasma. NASCAP is a sophisticated set of computational tools to model the surface charging of three-dimensional (3D) spacecraft surfaces in a time-varying space environment. The model's surface is tessellated into a collection of facets, and NASCAP calculates currents and potentials for each one. Additionally, NASCAP provides for the construction of one or more nested grids to calculate space potential and time-varying electric fields. This provides for the capability to track individual particles orbits, to model charged particle wakes, and to incorporate external charged particle sources. With this study, we have developed a model of calculating currents incident onto an electrodynamic tethered satellite system, and first results are shown here.

The radiation impedance of an electrodynamic tether with end connectors

NASA Technical Reports Server (NTRS)

Hastings, Daniel E.; Wang, J.

1987-01-01

Electrodynamic tethers are wires deployed across the earth's geomagnetic field through which a current is flowing. The radiation impedance of a tether with end connectors carrying an ac current is computed from classical antenna theory. This simulates the use of a tether on a space structure. It is shown that the current flow pattern at the tether connector is critical to determining the overall radiation impedance. If the tether makes direct electrical contact with the ionosphere then radiation impedances of the order of several thousand Ohms can be expected. If the only electrical contact is through the end connectors then the impedance is only a few Ohms for a dc current rising to several tens of Ohms for an ac current with frequencies in the whistler range.

Applications of Tethers in Space: Workshop Proceedings, Volume 1

NASA Technical Reports Server (NTRS)

Baracat, W. A. (Compiler)

1986-01-01

The complete documentation of the workshop including all addresses, panel reports, charts, and summaries are presented. This volume presents all the reports on the fundamentals of applications of tethers in space. These applications include electrodynamic interactions, transportation, gravity utilization, constellations, technology and test, and science applications.

Design Concept for a Reusable/Propellantless MXER Tether Space Transportation System

NASA Technical Reports Server (NTRS)

McCandless, B., II; Kustas, F. m.; Marshall, L. S.; Lytle, W. B.; Hansen, N. P.

2005-01-01

The Momentum Exchange/Electrodynamic Reboost (MXER) tether facility is a transformational concept that significantly reduces the fuel requirements (and associated costs) in transferring payloads above low earth orbit (LEO). Facility reboost is accomplished without propellant by driving current against a voltage created by a conducting tether's interaction with the Earth's magnetic field (electrodynamic reboost). This system can be used for transferring a variety of payloads (scientific, cargo, and human space vehicles) to multiple destinations including geosynchronous transfer orbit, the Moon or Mars. MXER technology advancement requires development in two key areas: survivable, high tensile strength non-conducting tethers and reliable, lightweight payload catch/release mechanisms. Fundamental requirements associated with the MXER non-conducting strength tether and catch mechanism designs will be presented. Key requirements for the tether design include high specific-strength (tensile strength/material density), material survivability to the space environment (atomic oxygen and ultraviolet radiation), and structural survivability to micrometeoroid/orbital debris (MM/OD) impacts. The driving mechanism key,gequirements include low mass-to-capture-volume ratio, positional and velocity error tolerance, and operational reliability. Preliminary tether and catch mechanism design criteria are presented, which have been used as guidelines to "screen" and down-select initial concepts. Candidate tether materials and protective coatings are summarized along with their performance in simulated space environments (e.g., oxygen plasma, thermal cycling). A candidate catch mechanism design concept is presented along with examples of demonstration hardware.

Theoretical investigation of the generation and injection of electromagnetic waves in space plasma by means of a long-orbiting tether

NASA Technical Reports Server (NTRS)

Dobrowolny, M.

1981-01-01

Analysis of the various mechanisms of electromagnetic wave generation by the shuttle-borne orbiting tether of the T.S.S. Facility shows that significant electrodynamic power levels are available even when overestimating the loss mechanisms expected to intervene. This electrodynamic power is in part dissipated by Joule losses in the tether, in part goes to accelerate electrons through the sheath surrounding the balloon (when in a downward deployment), and in part goes into e.m. wave generation. A preliminary estimate shows that a 100 km tether in orbit would produce ULF/ELF signals that are detectable on the ground with state-of-the-art magnetometric instrumentation.

Electrodynamic Propulsion System Tether Experiment (T-REX)

NASA Technical Reports Server (NTRS)

Johnson, L.; Fujii, H. A.; Sanmartin, J. R.

2010-01-01

A Japanese-led international team is developing a suborbital test of orbital-motion-limited (OML) bare wire anode current collection for application to electrodynamic tether (EDT) propulsion. The tether is a tape with a width of 25 mm, thickness of 0.05 mm, and is 300 m in length. This will be the first space test of OML theory. The mission will launch in the summer of 2010 using an S520 Sounding Rocket. During ascent, and above approximately 100 km in attitude, the tape tether will be deployed at a rate of approximately8 m/s. Once deployed, the tape tether will serve as an anode, collecting ionospheric electrons. The electrons will be expelled into space by a hollow cathode device, thereby completing the circuit and allowing current to flow. The total amount of current collected will be used to assess the validity of OML theory. This paper will describe the objectives of the proposed mission, the technologies to be employed, and the application of the results to future space missions using EDTs for propulsion or power generation

A two-dimensional theory of plasma contactor clouds used in the ionosphere with an electrodynamic tether

NASA Technical Reports Server (NTRS)

Hastings, D. E.; Gatsonis, N. A.; Rivas, D. A.

1988-01-01

Plasma contactors have been proposed as a means of making good electrical contact between biased surfaces such as found at the ends of an electrodynamic tether and the space environment. A plasma contactor is a plasma source which emits a plasma cloud which facilitates the electrical connection. The physics of this plasma cloud is investigated for contactors used as electron collectors and it is shown that contactor clouds in space will consist of a spherical core possibly containing a shock wave. Outside of the core the cloud will expand anisotropically across the magnetic field leading to a turbulent cigar shape structure along the field. This outer region is itself divided into two regions by the ion response to the electric field. A two-dimensional theory of the motion of the cloud across the magnetic field is developed. The current voltage characteristic of an Argon plasma contactor cloud is estimated for several ion currents in the range of 1-100 Amperes. It is shown that small ion current contactors are more efficient than large ion current contactors. This suggests that if a plasma contactor is used on an electrodynamic tether then a miltiple tether array will be more efficient than a single tether.

STS-75 Flight Day 1

NASA Technical Reports Server (NTRS)

1996-01-01

On this first day of the STS-75 mission, the flight crew, Cmdr. Andrew Allen, Pilot Scott Horowitz, Payload Cmdr. Franklin Chang-Diaz, Payload Specialist Umberto Guidoni (Italy), and Mission Specialists Jeffrey Hoffman, Maurizio Cheli (ESA) and Claude Nicollier (ESA), were shown performing pre-launch and launching activities. This international space mission's primary objective is the deployment of the Tethered Satellite System Reflight (TSS-1R) to a 12 mile length from the shuttle, a variety of experiments, and the satellite retrieval. These experiments include: Research on Orbital Plasma Electrodynamics (ROPE); TSS Deployer Core Equipment and Satellite Core Equipment (DCORE/SCORE); Research on Electrodynamic Tether Effects (RETE); Magnetic Field Experiments for TSS Missions (TEMAG); Shuttle Electrodynamic Tether Systems (SETS); Shuttle Potential and Return Electron Experiment (SPREE); Tether Optical Phenomena Experiment (TOP); and Observations at the Earth's Surface of Electromagnetic Emissions by TSS (OESSE). The mission's secondary objectives were those experiments found in the United States Microgravity Payload-3 (USMP-3), which include: Advanced Automated Directional Solidification Furnace (AADSF); Material pour l'Etude des Phenomenes Interessant la Solidification sur Terre et en Orbite (MEPHISTO); Space Acceleration Measurement System (SAMS); Orbital Acceleration Research Experiment (OARE); Critical Fluid Scattering Experiment (ZENO); and Isothermal Dendritic Growth Experiment (IDGE).

Unique Results and Lessons Learned From the TSS Missions

NASA Technical Reports Server (NTRS)

Stone, Nobie H.

2016-01-01

The Tethered Satellite System (TSS) Space Shuttle missions, TSS-1 in 1993 and TSS-1R in 1996, were the height of space tether technology development in the U.S. Altogether, the investment made by NASA and the Italian Space Agency (ASI) over the thirteen-year period of the TSS Program totaled approximately $400M-exclusive of the two Space Shuttle flights provided by NASA. Since those two pioneering missions, there have been several smaller tether flight experiments, but interest in this promising technology has waned within NASA as well as the DOD agencies. This is curious in view of the unique capabilities of space tether systems and the fact that they have been flight validated in earth orbit and shown to perform better than the preflight dynamic or electrodynamic theoretical predictions. While it is true that the TSS-1 and TSS-1R missions experienced technical difficulties, the causes of these early developmental problems are now known to have been engineering design flaws, material selection, and procedural issues that (1) are unrelated to the basic viability of space tether technology, and (2) can be readily corrected. The purpose of this paper is to review the dynamic and electrodynamic fundamentals of space tethers and the unique capabilities they afford (that are enabling to certain types of space missions); to elucidate the nature, cause, and solution of the early developmental problems; and to provide an update on progress made in development of the technology.

Electrodynamic tether system study

NASA Technical Reports Server (NTRS)

1987-01-01

The purpose of this program is to define an Electrodynamic Tether System (ETS) that could be erected from the space station and/or platforms to function as an energy storage device. A schematic representation of the ETS concept mounted on the space station is presented. In addition to the hardware design and configuration efforts, studies are also documented involving simulations of the Earth's magnetic fields and the effects this has on overall system efficiency calculations. Also discussed are some preliminary computer simulations of orbit perturbations caused by the cyclic/night operations of the ETS. System cost estimates, an outline for future development testing for the ETS system, and conclusions and recommendations are also provided.

Electrodynamic Bare Tether Systems as a Thruster for the Momentum-Exchange/Electrodynamic Reboost(MXER)Project

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Krivorutsky, E. N.; Gallagher, D. L.

2006-01-01

The concept of electrodynamic tether propulsion has a number of attractive features and has been widely discussed for different applications. Different system designs have been proposed and compared during the last 10 years. In spite of this, the choice of proper design for any particular mission is a unique problem. Such characteristics of tether performance as system acceleration, efficiency, etc., should be calculated and compared on the basis of the known capability of a tether to collect electrical current. We discuss the choice of parameters for circular and tape tethers with regard to the Momentum-Exchange/Electrodynamic Reboost (MXER) tether project.

Shuttle Orbiter tethered subsatellite for exploring and tapping space plasmas

NASA Technical Reports Server (NTRS)

Banks, P. M.; Williamson, P. R.; Oyama, K. I.

1981-01-01

Consideration is given to the possibilities for studies in space plasma physics offered by a subsatellite mechanically tethered above the Space Shuttle Orbiter by a long conducting wire. The proposed experiment, designated the Shuttle Electrodynamic Tether Systems (SETS) is based on the concept of collecting electrons at the subsatellite and ejecting them from the Orbiter, made possible by the emf generated by the motion of the tether across geomagnetic field lines. The power generated in this manner can be used both for practical purposes within the Orbiter and for the creation of large-amplitude plasma and electromagnetic waves within the surrounding plasma. For a conducting spherical subsatellite 30 m in diameter with a 10-km tether drawing 1 A, calculations show that emfs on the order of 1000-2000 V and energy dissipation of as much as 10,000 W can be obtained, accompanied by the generation of two regions of net electric charge in the ionosphere. Scientific studies considered for SETS include the measurement of MHD waves artificially generated in the ionosphere, the investigation of current-driven plasma instabilities, VLF wave generation and the simulation of electrodynamics associated with the motion of celestial bodies through plasma.

Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

1999-01-01

NASA's Propulsive Small Expendable Deployer System experiment (ProSEDS) will demonstrate the use of an electrodynamic tether, basically a long, thin wire, for propulsion. An electrodynamic tether uses the same principles as electric motors in toys, appliances and computer disk drives, and generators in automobiles and power plants. When electrical current is flowing through the tether, a magnetic field is produced that pushes against the magnetic field of the Earth. For ProSEDS, the current in the tether results by virtue of the voltage generated when the tether moves through the Earth's magnetic field at more than 17,000 mph. This approach can produce drag thrust generating useable power. Since electrodynamic tethers require no propellant, they could substantially reduce the weight of the spacecraft and provide a cost-effective method of reboosting spacecraft. The initial flight of ProSEDS is scheduled to fly aboard an Air Force Delta II rocket in the summer of 2002. In orbit, ProSEDS will deploy from a Delta II second stage. It will be a 3.1-mile (5 kilometer) long, ultrathin base-wire cornected with a 6.2-mile (10 kilometer) long nonconducting tether. This photograph shows Less Johnson, a scientist at MSFC inspecting the nonconducting part of a tether as it exits a deployer similar to the one to be used in the ProSEDS experiment. The ProSEDS experiment is managed by the Space Transportation Directorate at MSFC.

Pathfinder

NASA Image and Video Library

1999-03-01

NASA's Propulsive Small Expendable Deployer System experiment (ProSEDS) will demonstrate the use of an electrodynamic tether, basically a long, thin wire, for propulsion. An electrodynamic tether uses the same principles as electric motors in toys, appliances and computer disk drives, and generators in automobiles and power plants. When electrical current is flowing through the tether, a magnetic field is produced that pushes against the magnetic field of the Earth. For ProSEDS, the current in the tether results by virtue of the voltage generated when the tether moves through the Earth's magnetic field at more than 17,000 mph. This approach can produce drag thrust generating useable power. Since electrodynamic tethers require no propellant, they could substantially reduce the weight of the spacecraft and provide a cost-effective method of reboosting spacecraft. The initial flight of ProSEDS is scheduled to fly aboard an Air Force Delta II rocket in the summer of 2002. In orbit, ProSEDS will deploy from a Delta II second stage. It will be a 3.1-mile (5 kilometer) long, ultrathin base-wire cornected with a 6.2-mile (10 kilometer) long nonconducting tether. This photograph shows Less Johnson, a scientist at MSFC inspecting the nonconducting part of a tether as it exits a deployer similar to the one to be used in the ProSEDS experiment. The ProSEDS experiment is managed by the Space Transportation Directorate at MSFC.

Design Rules and Analysis of a Capture Mechanism for Rendezvous between a Space Tether and Payload

NASA Technical Reports Server (NTRS)

Sorensen, Kirk F.; Canfield, Stephen L.; Norris, Marshall A.

2006-01-01

Momentum-exchange/electrodynamic reboost (MXER) tether systems have been proposed to serve as an "upper stage in space". A MXER tether station would boost spacecraft from low Earth orbit to a high-energy orbit quickly, like a high-thrust rocket. Then, it would slowly rebuild its orbital momentum through electrodynamic thrust, minimizing the use of propellant. One of the primary challenges in developing a momentum-exchange/electrodynamic reboost tether system as identified by the 2003 MXER Technology Assessment Group is in the development of a mechanism that will enable the processes of capture, carry and release of a payload by the rotating tether as required by the MXER tether approach. This paper will present a concept that will achieve the desired goals of the capture system. This solution is presented as a multi-DOF (degree-of-freedom) capture mechanism with nearly passive operation that features matching of the capture space and expected window of capture error, efficient use of mass and nearly passive actuation during the capture process. This paper will describe the proposed capture mechanism concept and provide an evaluation of the concept through a dynamic model and experimental tests performed on a prototype article of the mechanism in a dynamically similar environment. This paper will also develop a set of rules to guide the design of such a capture mechanism based on analytical and experimental analyses. The primary contributions of this paper will be a description of the proposed capture mechanism concept, a collection of rules to guide its design, and empirical and model information that can be used to evaluate the capability of the concept

Tethered Satellite System (TSS-1R)-Post Flight (STS-75) Engineering Performance Report

NASA Technical Reports Server (NTRS)

Lavoie, Anthony R.

1996-01-01

The first mission of the Tethered Satellite deployer was flown onboard Atlantis in 1992 during the Space Transportation System (STS) flight STS-46. Due to a mechanical interference with the level wind mechanism the satellite was only Deployed to 256 m rather than the planned 20,000 m. Other problems were also experienced during the STS-46 flight and several modifications were made to the Deployer and Satellite. STS-75 was a reflight of the Tethered Satellite System 1 (TSS-1) designated as Tethered Satellite System 1 Reflight (TSS-1 R) onboard Columbia. As on STS-46, the TSS payload consisted of the Deployer, the Satellite, 3 cargo bay mounted experiments: Shuttle Electrodynamic Tether System (SETS), Shuttle Potential and Return Electron Experiment (SPREE), Deployer Core Equipment (DCORE) 4 Satellite mounted experiments: Research on Electrodynamics Tether Effects (RETE), Research on Orbital Plasma Electrodynamics (ROPE), Satellite Core Instruments (SCORE), Tether Magnetic Field Experiment (TEMAG) and an aft flight deck camera: Tether Optical Phenomena Experiment (TOP). Following successful pre-launch, launch and pre-deployment orbital operations, the Deployer deployed the Tethered Satellite to 19,695 m at which point the tether broke within the Satellite Deployment Boom (SDB). The planned length for On-Station I (OST1) was 20,700 m The Satellite flew away from the Orbiter with the tether attached. The satellite was "safed" and placed in a limited power mode via the RF link. The Satellite was contacted periodically during overflights of ground stations. Cargo bay science activities continued for the period of time allocated to TSS-1 R operations.

Electrodynamic Tether

NASA Technical Reports Server (NTRS)

Johnson, Charles L. (Inventor); Ballance, Judy L. (Inventor); Welzyn, Kenneth J. (Inventor); Vaughn, Jason A. (Inventor); Lorenzini, Enrico (Inventor); Schuler, Peter S. (Inventor)

2006-01-01

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.

An Overview of Electrodynamic Tether Performance in the Jovian System

NASA Technical Reports Server (NTRS)

Gallagher, Dennis; Johnson, Les; Bagenal, Fran; Moore, James

1998-01-01

The Jovian magnetosphere with its strong magnetic field and rapid planetary rotation present new opportunities and challenges for the use of electrodynamic tethers. An overview of the basic plasma physics properties of an electrodynamic tether moving through the Jovian magnetosphere is examined. Tether use for both propulsion and power generation are considered. Close to the planet, tether propulsive forces are found to be as high as 50 Newtons and power levels as high as 1 million Watts.

A Model for Dynamic Simulation and Analysis of Tether Momentum Exchange

NASA Technical Reports Server (NTRS)

Canfield, Stephen; Johnson, David; Sorensen, Kirk; Welzyn, Ken; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

Momentum-exchange/electrodynamic reboost (MXER) tether systems may enable high-energy missions to the Moon, Mars, and beyond by serving as an 'upper stage in space'. Existing rockets that use an MXER tether station could double their capability to launch communications satellites and help improve US competitiveness. A MXER tether station would boost spacecraft from low Earth orbit to a high-energy orbit quickly, like a high-thrust rocket. Then, using the same principles that make an electric motor work, it would slowly rebuild its orbital momentum by pushing against the Earth's magnetic field-without using any propellant. One of the significant challenges in developing a momentum-exchange/electrodynamic reboost tether systems is in the analysis and design of the capture mechanism and its effects on the overall dynamics of the system. This paper will present a model for a momentum-exchange tether system that can simulate and evaluate the performance and requirements of such a system.

Investigation of electrodynamic stabilization and control of long orbiting tethers. [space shuttle payloads

NASA Technical Reports Server (NTRS)

Arnold, D. A.; Dobrowolny, M.

1981-01-01

An algorithm for using electric currents to control pendular oscillations induced by various perturbing forces on the Skyhook wire is considered. Transverse and vertical forces on the tether; tether instability modes and causes during retrieval by space shuttle; simple and spherical pendulum motion and vector damping; and current generation and control are discussed. A computer program for numerical integration of the in-plane and out-of-plane displacements of the tether vs time was developed for heuristic study. Some techniques for controlling instabilities during payload retrieval and methods for employing the tether for launching satellites from the space shuttle are considered. Derivations and analyses of a general nature used in all of the areas studied are included.

Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

Curtis, Leslie; Johnson, Les; Brown, Norman S. (Technical Monitor)

2002-01-01

The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta 11 Expendable Launch Vehicle second stage. ProSEDS, which is planned on an Air Force GPS Satellite replacement mission in June 2002, will use the flight proven Small Expendable Deployer System (SEDS) to deploy a tether (5 km bare wire plus 10 km non-conducting Dyneema) from a Delta 11 second stage to achieve approx. 0.4N drag thrust. ProSEDS will utilize the tether-generated current to provide limited spacecraft power. The ProSEDS instrumentation includes Langmuir probes and Differential Ion Flux Probes, which will determine the characteristics of the ambient ionospheric plasma. Two Global Positioning System (GPS) receivers will be used (one on the Delta and one on the endmass) to help determine tether dynamics and to limit transmitter operations to occasions when the spacecraft is over selected ground stations. The flight experiment is a precursor to the more ambitious electrodynamic tether upper stage demonstration mission, which will be capable of orbit raising, lowering and inclination changes-all using electrodynamic thrust. An immediate application of ProSEDS technology is for the removal of spent satellites for orbital debris mitigation. In addition to the use of this technology to provide orbit transfer and debris mitigation it may also be an attractive option for future missions to Jupiter and any other planetary body with a magnetosphere.

Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

Ballance, Judy; Johnson, Les; Rogacki, John R. (Technical Monitor)

2000-01-01

The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta II Expendable Launch Vehicle (ELV) second stage. ProSEDS, which is planned to fly in 2001, will use the flight proven Small Expendable Deployer System (SEDS) to deploy a tether (5km bare wire plus 10 km spectra or dyneema) from a Delta II second stage to achieve approximately 0.4N drag thrust. ProSEDS will utilize the tether-generated current to provide limited spacecraft power. The ProSEDs instrumentation includes a Langmuir probe and Differential Ion Flux Probe, which will determine the characteristics of the ambient ionospheric plasma. Two Global Positioning System (GPS) receivers will be used (one on the Delta and one on the endmass) to help determine tether dynamics and to limit transmitter operations to occasions when the spacecraft is over selected ground stations, The flight experiment is a precursor to the more ambitious electrodynamic tether upper stage demonstration mission, which will be capable of orbit raising, lowering and inclination changes-all using electrodynamic thrust. An immediate application of ProSEDS technology is for the deorbit of spent satellites for orbital debris mitigation. In addition to the use of this technology to provide orbit transfer and debris mitigation it may also be an attractive option for future missions to Jupiter and any other planetary body with a magnetosphere.

In-Space Propulsion for Science and Exploration

NASA Technical Reports Server (NTRS)

Bishop-Behel, Karen; Johnson, Les

2004-01-01

This paper presents viewgraphs on the development of In-Space Propulsion Technologies for Science and Exploration. The topics include: 1) In-Space Propulsion Technology Program Overview; 2) In-Space Propulsion Technology Project Status; 3) Solar Electric Propulsion; 4) Next Generation Electric Propulsion; 5) Aerocapture Technology Alternatives; 6) Aerocapture; 7) Advanced Thermal Protection Systems Developed and Being Tested; 8) Solar Sails; 9) Advanced Chemical Propulsion; 10) Momentum Exchange Tethers; and 11) Momentum-exchange/electrodynamic reboost (MXER) Tether Basic Operation.

Comparison of technologies for deorbiting spacecraft from low-earth-orbit at end of mission

NASA Astrophysics Data System (ADS)

Sánchez-Arriaga, G.; Sanmartín, J. R.; Lorenzini, E. C.

2017-09-01

An analytical comparison of four technologies for deorbiting spacecraft from Low-Earth-Orbit at end of mission is presented. Basic formulas based on simple physical models of key figures of merit for each device are found. Active devices - rockets and electrical thrusters - and passive technologies - drag augmentation devices and electrodynamic tethers - are considered. A basic figure of merit is the deorbit device-to-spacecraft mass ratio, which is, in general, a function of environmental variables, technology development parameters and deorbit time. For typical state-of-the-art values, equal deorbit time, middle inclination and initial altitude of 850 km, the analysis indicates that tethers are about one and two orders of magnitude lighter than active technologies and drag augmentation devices, respectively; a tether needs a few percent mass-ratio for a deorbit time of a couple of weeks. For high inclination, the performance drop of the tether system is moderate: mass ratio and deorbit time increase by factors of 2 and 4, respectively. Besides collision risk with other spacecraft and system mass considerations, such as main driving factors for deorbit space technologies, the analysis addresses other important constraints, like deorbit time, system scalability, manoeuver capability, reliability, simplicity, attitude control requirement, and re-entry and multi-mission capability (deorbit and re-boost) issues. The requirements and constraints are used to make a critical assessment of the four technologies as functions of spacecraft mass and initial orbit (altitude and inclination). Emphasis is placed on electrodynamic tethers, including the latest advances attained in the FP7/Space project BETs. The superiority of tape tethers as compared to round and multi-line tethers in terms of deorbit mission performance is highlighted, as well as the importance of an optimal geometry selection, i.e. tape length, width, and thickness, as function of spacecraft mass and initial orbit. Tether system configuration, deployment and dynamical issues, including a simple passive way to mitigate the well-known dynamical instability of electrodynamic tethers, are also discussed.

Space Environmental Effects on Coated Tether Materials

NASA Technical Reports Server (NTRS)

Gittemeier, Keith A.; Hawk, Clark W.; Finckenor, Miria M.; Watts, Ed

2005-01-01

The University of Alabama in Huntsville s Propulsion Research Center has teamed with NASA's Marshall Space Flight Center (MSFC) to research the effects of atomic oxygen (AO) bombardment on coated tether materials. Tethers Unlimited Inc. has provided several candidate tether materials with various coatings for AO exposure in MSFC s Atomic Oxygen Beam Facility. Additional samples were exposed to ultraviolet (UV) radiation at MSFC. AO erodes most organic materials, and ultraviolet radiation embrittles polymers. This test series was performed to determine the effect of AO and UV on the mechanical integrity of tether materials that were treated with AO-protective coatings, such as polyhedral oligomeric silsesquioxane (POSS) or metallization. Both TUI's Multi-Application Survivable Tether (MAST) Experiment and Marshall Space Flight Center s Momentum Exchange Electrodynamic Reboost (MXER) programs will benefit from this research by helping to determine tether materials and coatings that give the longest life with the lowest mass penalty.

Tethers in space handbook

NASA Technical Reports Server (NTRS)

Reese, T. G.; Baracat, W. A.; Butner, C. L.

1986-01-01

The handbook provides a list and description of ongoing tether programs. This includes the joint U.S.-Italy demonstration project, and individual U.S. and Italian studies and demonstration programs. An overview of the current activity level and areas of emphasis in this emerging field is provided. The fundamental physical principles behind the proposed tether applications are addressed. Four basic concepts of gravity gradient, rotation, momentum exchange, and electrodynamics are discussed. Information extracted from literature, which supplements and enhances the tether applications is also presented. A bibliography is appended.

The PROPEL Electrodynamic Tether Demonstration Mission

NASA Technical Reports Server (NTRS)

Bilen, Sven G.; Johnson, C. Les; Wiegmann, Bruce M.; Alexander, Leslie; Gilchrist, Brian E.; Hoyt, Robert P.; Elder, Craig H.; Fuhrhop, Keith P.; Scadera, Michael

2012-01-01

The PROPEL ("Propulsion using Electrodynamics") mission will demonstrate the operation of an electrodynamic tether propulsion system in low Earth orbit and advance its technology readiness level for multiple applications. The PROPEL mission has two primary objectives: first, to demonstrate the capability of electrodynamic tether technology to provide robust and safe, near-propellantless propulsion for orbit-raising, de-orbit, plane change, and station keeping, as well as to perform orbital power harvesting and formation flight; and, second, to fully characterize and validate the performance of an integrated electrodynamic tether propulsion system, qualifying it for infusion into future multiple satellite platforms and missions with minimal modification. This paper provides an overview of the PROPEL system and design reference missions; mission goals and required measurements; and ongoing PROPEL mission design efforts.

Tuned mass damping system for a pendulum in gravity and microgravity fields

NASA Astrophysics Data System (ADS)

Atour, Farah

2016-07-01

An electrodynamic tether is a simple idea, but one with an amazing number of uses. Electrodynamic tether is a long conductor wire that is attached to the satellite, which can act as a generator or motor, from its motion through the earth's magnetic field. And it has the potential to make space travel significantly cheaper. The lack of electrodynamic tether's widespread in common applications can be attributed to the variable Lorentz forces occuring on the tethers, which will cause them to oscillate and may go out of control, de-orbit the satellite and fall to Earth. A tuned mass damper system, for short refered as tilger, is suggested as damper of oscillations of tethers. A system composed of a tuned mass damper and a simple pendulum simulating the tether was therefore constructed. 350 sets of experimental trials were done on the system, while it was installed inside a drop tower capsule resting on the ground, in order to pick four optimum setup experiments that will undergo a series of microgravity experiments at the Bremen Drop Tower in Bremen, Germany. The GJU Bachelor Research students found that the oscillations of the simple pendulum will not be affected by the tilger during the free fall experiment, except if a feedback mechanism is installed between the simple pendulum and the tilger. In this case, the tilger will dampen the simple pendulum oscillations during free fall.

Tethered Satellite System (TSS) core equipment

NASA Technical Reports Server (NTRS)

Bonifazi, C.

1986-01-01

To date, three Tethered Satellite System (TSS) missions of the Italian provided scientific satellite orbiting in the ionosphere connected to U.S. Space Shuttle is foreseen. The first mission will use an electrically conductive tether of 20 km deployed upward from the orbiter flying at 300 km altitude. This mission will allow investigation of the TSS electrodynamic interaction with the ionosphere due to the high voltage induced across the two terminators of the system during its motion throughout the geomagnetic field. The second mission will use a dielectric tether of 100 km deployed downward from the Orbiter flying at 230 km altitude. Tethered-vehicle access to altitude as low as 120 to 150 km from the Orbiter would permit direct long term observation of phenomena in the lower thermosphere and determination of other dynamical physical processes. The third mission would use the same configuration of the first electrodynamic mission with the complete Core Equipment. Study of power generation by tethered systems would be possible by operating the Core Equipment in the inverted current mode. This mode of operation would allow ion current collection upon the TSS satellite by controlling its potential with respect to the ambient ionospheric plasma. The main requirements of the Core Equipment configuration to date foreseen for the first TSS electrodynamic mission is described. Besides the Core Equipment purposes, its hardware and operational sub-modes of operation are described.

The TSS-1R Electrodynamic Tether Experiment: Scientific and Technological Results

NASA Technical Reports Server (NTRS)

Stone, Nobie H.; Raitt, John

1998-01-01

The bi-national, US-Italian, Tethered Satellite System (TSS) program was designed to provide a unique opportunity to explore certain space plasma- electrodynamic processes and the orbital mechanics of a gravity-gradient stabilized system of two satellites linked by a long conducting tether. The second flight, TSS-LR, was launched February 22, 1996 on STS-75 and satellite deployment began at MET 3/00:27. A unique data set was obtained over the next five hours, as the tether was deployed to a length of 19695 meters, which has allowed significant science to be accomplished. This presentation will focus on electrodynamic processes generated by the tether--in particular, the collection of electrical current from the ionospheric plasma. Of particular significance is an apparent transition of the physics of current collection when the potential of the collecting body becomes greater than the ram energy of the ionospheric atomic oxygen ions. Previous theoretical models of current collection were electrostatic--assuming that the orbital motion of the system, which is highly subsonic with respect to electron thermal motion, was un- important. This may still be acceptable for the case of relatively slow-moving sounding rockets. However, the TSS-LR results show that motion relative to the plasma must be accounted for in orbiting systems.

Plasma Interactions With a Negative Biased Electrodynamic Tether

NASA Technical Reports Server (NTRS)

Vaughn, Jason A.; Curtis, Leslie; Welzyn, Ken J.

2004-01-01

The ProSEDS conductive tether design incorporates two distinct types of tethers from a plasma interaction viewpoint. The 200 m closest to the Delta II spacecraft is insulated from the plasma, and the remaining 4800 m is semi-bare. This latter portion is considered semi-bare because a conductive coating, which is designed to collect electrons from the plasma, was applied to the wires to regulate the overall tether temperature. Because the tether has both insulating and conductive tether sections, a transition point exists between the two that forms a triple point with the space plasma. Also, insulated tethers can arc to the space plasma if the insulation is weakened or breached by pinholes caused by either improper handling or small meteoroid and orbital debris strikes. Because electrodynamic tethers are typically long, they have a high probability of these impacts. The particles, which strike the tether, may not have sufficient size to severe the tether, but they can easily penetrate the tether insulation producing a plasma discharge to the ambient plasma. Samples of both the ProSEDS tether transition region and the insulated tether section with various size of pinholes were placed into the MSFC plasma chamber and biased to typical ProSEDS open circuit tether potentials (-500 V to -1600 V). The results of the testing showed that the transition region of the tether (i.e. the triple point) arced to the ambient plasma at -900 V, and the tethers damaged by a pinhole or simulated debris strike arced to the plasma between -700 V and -900 V. Specific design steps were taken to eliminate the triple point issue in the ProSEDS tether design and make it ready for flight. To reduce the pinhole arcing risk, ProSEDS mission operations were changed to eliminate the high negative potential on the insulated tether. The results of the testing campaign and the design changes implemented to ensure a successful flight are described.

Proceedings of a Workshop on Applications of Tethers in Space, Volume 2

NASA Technical Reports Server (NTRS)

1983-01-01

The panel conclusions for each of the following panels (science applications; electrodynamic interactions; transportation applications; artificial gravity; constellations; and technology and test) are given.

Electrodynamics panel presentation

NASA Technical Reports Server (NTRS)

Mccoy, J.

1986-01-01

The Plasma Motor Generator (PMG) concept is explained in detail. The PMG tether systems being used to calculate the estimated performance data is described. The voltage drops and current contact geometries involved in the operation of an electrodynamic tether are displayed illustrating the comparative behavior of hollow cathodes, electron guns, and passive collectors for current coupling into the ionosphere. The basic PMG design involving the massive tether cable with little or no satellite mass at the far end(s) are also described. The Jupiter mission and its use of electrodynamic tethers are given. The need for demonstration experiments is stressed.

Analytical investigation of the dynamics of tethered constellations in Earth orbit, phase 2

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.; Gullahorn, Gordon E.; Cosmo, Mario L.; Estes, Robert D.; Grossi, Mario D.

1994-01-01

This final report covers nine years of research on future tether applications and on the actual flights of the Small Expendable Deployment System (SEDS). Topics covered include: (1) a description of numerical codes used to simulate the orbital and attitude dynamics of tethered systems during station keeping and deployment maneuvers; (2) a comparison of various tethered system simulators; (3) dynamics analysis, conceptual design, potential applications and propagation of disturbances and isolation from noise of a variable gravity/microgravity laboratory tethered to the Space Station; (4) stability of a tethered space centrifuge; (5) various proposed two-dimensional tethered structures for low Earth orbit for use as planar array antennas; (6) tethered high gain antennas; (7) numerical calculation of the electromagnetic wave field on the Earth's surface on an electrodynamically tethered satellite; (8) reentry of tethered capsules; (9) deployment dynamics of SEDS-1; (10) analysis of SEDS-1 flight data; and (11) dynamics and control of SEDS-2.

Atomic Oxygen Effects on Coated Tether Materials

NASA Technical Reports Server (NTRS)

Gittemeier, Keith A.; Hawk, Clark W.; Finckenor, Miria M.; Watts, Ed

2005-01-01

The University of Alabama in Huntsville s Propulsion Research Center has teamed with NASA's Marshall Space Flight Center (MSFC) to research the effects of atomic oxygen (AO) bombardment on coated tether materials. Tethers Unlimited Inc. has provided several candidate tether materials with various coatings for (AO) exposure in MSFC's Atomic Oxygen Beam Facility. Additional samples were exposed to ultraviolet (UV) radiation at MSFC. AO erodes most organic materials, and ultraviolet radiation embrittles polymers. This test series was performed to determine the effect of AO and UV on the mechanical integrity of tether materials that were treated with AO-protective coatings, such as Photosil or metallization. Both TUI's Multi-Application Survivable Tether (MAST) Experiment and Marshall Space Flight Center's Momentum Exchange Electrodynamic Reboost (MXER) programs will benefit from this research by helping to determine tether materials and coatings that give the longest life with the lowest mass penalty.

Emerging Propulsion Technologies

NASA Technical Reports Server (NTRS)

Keys, Andrew S.

2006-01-01

The Emerging Propulsion Technologies (EPT) investment area is the newest area within the In-Space Propulsion Technology (ISPT) Project and strives to bridge technologies in the lower Technology Readiness Level (TRL) range (2 to 3) to the mid TRL range (4 to 6). A prioritization process, the Integrated In-Space Transportation Planning (IISTP), was developed and applied in FY01 to establish initial program priorities. The EPT investment area emerged for technologies that scored well in the IISTP but had a low technical maturity level. One particular technology, the Momentum-eXchange Electrodynamic-Reboost (MXER) tether, scored extraordinarily high and had broad applicability in the IISTP. However, its technical maturity was too low for ranking alongside technologies like the ion engine or aerocapture. Thus MXER tethers assumed top priority at EPT startup in FY03 with an aggressive schedule and adequate budget. It was originally envisioned that future technologies would enter the ISP portfolio through EPT, and EPT developed an EPT/ISP Entrance Process for future candidate ISP technologies. EPT has funded the following secondary, candidate ISP technologies at a low level: ultra-lightweight solar sails, general space/near-earth tether development, electrodynamic tether development, advanced electric propulsion, and in-space mechanism development. However, the scope of the ISPT program has focused over time to more closely match SMD needs and technology advancement successes. As a result, the funding for MXER and other EPT technologies is not currently available. Consequently, the MXER tether tasks and other EPT tasks were expected to phased out by November 2006. Presentation slides are presented which provide activity overviews for the aerocapture technology and emerging propulsion technology projects.

Development of the Flight Tether for ProSEDS

NASA Technical Reports Server (NTRS)

Curtis, Leslie; Vaughn, Jason; Welzyn, Ken; Carroll, Joe; Brown, Norman S. (Technical Monitor)

2002-01-01

The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta 11 Expendable Launch Vehicle second stage. ProSEDS will use the flight-proven Small Expendable Deployer System to deploy a newly designed and developed tether which will provide tether generated drag thrust of approx. 0.4 N. The development and production of very long tethers with specific properties for performance and survivability will be required to enable future tether missions. The ProSEDS tether design and the development process may provide some lessons learned for these future missions. The ProSEDS system requirements drove the design of the tether to have three different sections of tether each serving a specialized purpose. The tether is a total of 15 kilometers long: 10 kilometers of a non-conductive Dyneema lead tether; 5 km of CCOR conductive coated wire; and 220 meters of insulated wire with a protective Kevlar overbraid. Production and joining of long tether lengths involved many development efforts. Extensive testing of tether materials including ground deployment of the full-length ProSEDS tether was conducted to validate the tether design and performance before flight.

The PROPEL Electrodynamic Tether Mission and Connecting to the Ionosphere

NASA Technical Reports Server (NTRS)

Gilchrist, Brian; Bilen, Sven; Hoyt, Rob; Stone,Nobie; Vaughn, Jason; Fuhrhop, Keith; Krause, Linda; Khazanov, George; Johnson, Les

2012-01-01

The exponential increase of launch system size.and cost.with delta-V makes missions that require large total impulse cost prohibitive. Led by NASA's Marshall Space Flight Center, a team from government, industry, and academia has developed a flight demonstration mission concept of an integrated electrodynamic (ED) tethered satellite system called PROPEL: "Propulsion using Electrodynamics". The PROPEL Mission is focused on demonstrating a versatile configuration of an ED tether to overcome the limitations of the rocket equation, enable new classes of missions currently unaffordable or infeasible, and significantly advance the Technology Readiness Level (TRL) to an operational level. We are also focused on establishing a far deeper understanding of critical processes and technologies to be able to scale and improve tether systems in the future. Here, we provide an overview of the proposed PROPEL mission. One of the critical processes for efficient ED tether operation is the ability to inject current to and collect current from the ionosphere. Because the PROPEL mission is planned to have both boost and deboost capability using a single tether, the tether current must be capable of flowing in both directions and at levels well over 1 A. Given the greater mobility of electrons over that of ions, this generally requires that both ends of the ED tether system can both collect and emit electrons. For example, hollow cathode plasma contactors (HCPCs) generally are viewed as state-of-the-art and high TRL devices; however, for ED tether applications important questions remain of how efficiently they can operate as both electron collectors and emitters. Other technologies will be highlighted that are being investigated as possible alternatives to the HCPC such as Solex that generates a plasma cloud from a solid material (Teflon) and electron emission (only) technologies such as cold-cathode electron field emission or photo-electron beam generation (PEBG) techniques.

Pathfinder

NASA Image and Video Library

2004-04-15

This picture is an artist's concept of an orbiting vehicle using the Electrodynamic Tethers Propulsion System. Relatively short electrodynamic tethers can use solar power to push against a planetary magnetic field to achieve propulsion without the expenditure of propellant.

Grid-Sphere Electrodes for Contact with Ionospheric Plasma

NASA Technical Reports Server (NTRS)

Stone, Nobie H.; Poe, Garrett D.

2010-01-01

Grid-sphere electrodes have been proposed for use on the positively biased end of electrodynamic space tethers. A grid-sphere electrode is fabricated by embedding a wire mesh in a thin film from which a spherical balloon is formed. The grid-sphere electrode would be deployed from compact stowage by inflating the balloon in space. The thin-film material used to inflate the balloon is formulated to vaporize when exposed to the space environment. This would leave the bare metallic spherical grid electrode attached to the tether, which would present a small cross-sectional area (essentially, the geometric wire shadow area only) to incident neutral atoms and molecules. Most of the neutral particles, which produce dynamic drag when they impact a surface, would pass unimpeded through the open grid spaces. However, partly as a result of buildup of a space charge inside the grid-sphere, and partially, the result of magnetic field effects, the electrode would act almost like a solid surface with respect to the flux of electrons. The net result would be that grid-sphere electrodes would introduce minimal aerodynamic drag, yet have effective electrical-contact surface areas large enough to collect multiampere currents from the ionospheric plasma that are needed for operation of electrodynamic tethers. The vaporizable-balloon concept could also be applied to the deployment of large radio antennas in outer space.

Emerging Propulsion Technologies

NASA Astrophysics Data System (ADS)

Bonometti, J. A.

2004-11-01

The Emerging Propulsion Technologies (EPT) technology area is a branch of the In-Space Program that serves as a bridge to bring high-risk/high-payoff technologies to a higher level of maturity. Emerging technologies are innovative and, if successfully developed, could result in revolutionary science capabilities for NASA science missions. EPT is also charged with the responsibility of assessing the technology readiness level (TRL) of technologies under consideration for inclusion in the ISP portfolio. One such technology is the Momentum-eXchange/Electrodynamic Reboost (MXER) tether concept, which is the current, primary investment of EPT. The MXER tether is a long, rotating cable placed in an elliptical Earth orbit, whose rapid rotation allows its tip to catch a payload in a low Earth orbit and throw that payload to a high-energy orbit. Electrodynamic tether propulsion is used to restore the orbital energy transferred by the MXER tether to the payload and reboost the tether's orbit. This technique uses solar power to drive electrical current collected from the Earth's ionosphere through the tether, resulting in a magnetic interaction with the terrestrial field. Since the Earth itself serves as the reaction mass, the thrust force is generated without propellant and allows the MXER facility to be repeatedly reused without re-supply. Essentially, the MXER facility is a 'propellantless' upper stage that could assist nearly every mission going beyond low Earth orbit. Payloads to interplanetary destinations could especially benefit from the boost provided by the MXER facility, resulting in launch vehicle cost reductions, increased payload fractions and more frequent mission opportunities. Synergistic tether technologies resulting from MXER development could include science sampling in the upper atmosphere, remote probes or attached formation flying, artificial gravity experiments with low Coriolis forces, and other science needs that use long, ultra-light strength or conducting cables in space. Tether development additionally embraces the science investigation of ionospheric physics, micrometeorite and space particulates in LEO and precise earth environment knowledge of gravity fields, solar flux, .thermal environments and magnetic fields.

Electrodynamic Tether Propulsion and Power Generation at Jupiter

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Johnson, L.; Moore, J.; Bagenal, F.

1998-01-01

The results of a study performed to evaluate the feasibility and merits of using an electrodynamic tether for propulsion and power generation for a spacecraft in the Jovian system are presented. The environment of the Jovian system has properties which are particularly favorable for utilization of an electrodynamic tether. Specifically, the planet has a strong magnetic field and the mass of the planet dictates high orbital velocities which, when combined with the planet's rapid rotation rate, can produce very large relative velocities between the magnetic field and the spacecraft. In a circular orbit close to the planet, tether propulsive forces are found to be as high as 50 N and power levels as high as 1 MW.

Space Shuttle Projects

NASA Image and Video Library

1996-02-23

An STS-75 onboard photo of the Tethered Satellite System-1 Reflight (TSS-1R) atop its extended boom. The TSS-1R was a reflight of TSS-1, which was flown on the Space Shuttle in July/August, 1992. Building on the knowledge gained on the TSS-1 about tether dynamics, the TSS will circle the Earth at an altitude of 296 kilometers (184 miles), placing the tether system well within the rarefield, electrically charged layer of the atmosphere known as the ionosphere. The satellite was plarned to be deployed 20.7 kilometers (12.9 miles) above the Shuttle. The conducting tether, generating high voltage and electrical currents as it moves through the ionosphere cutting magnetic field lines, would allow scientists to examine the electrodynamics of a conducting tether system. In addition, the TSS would increase our understanding of physical processes in the near-Earth space environment, such as plasma waves and currents. The tether on the TSS broke as the Satellite was nearing the full extent of its 12.5 mile deployment from the Shuttle. The TSS was a cooperative development effort by the Italian Space Agency (ASI) and NASA, and was managed by scientists at the Marshall Space Flight Center.

Free Re-boost Electrodynamic Tether on the International Space Station

NASA Technical Reports Server (NTRS)

Bonometti, Joseph A.; Sorenson, Kirk F.; Jansen, Ralph H.; Dankanich, John W.; Frame, Kyle L.

2005-01-01

The International Space Station (ISS) currently experiences significant orbital drag that requires constant make up propulsion or the Station will quickly reenter the Earth's Atmosphere. The reboost propulsion is presently achieved through the firing of hydrazine rockets at the cost of considerable propellant mass. The problem will inevitably grow much worse as station components continue to be assembled, particularly when the full solar panel arrays are deployed. This paper discusses many long established themes on electrodynamic propulsion in the context of Exploration relevance, shows how to couple unique ISS electrical power system characteristics and suggests a way to tremendously impact ISS's sustainability. Besides allowing launch mass and volume presently reserved for reboost propellant to be reallocated for science experiments and other critically needed supplies, there are a series of technology hardware demonstrations steps that can be accomplished on ISS, which are helpful to NASA s Exploration mission. The suggested ElectroDynamic (ED) tether and flywheel approach is distinctive in its use of free energy currently unusable, yet presently available from the existing solar array panels on ISS. The ideas presented are intended to maximize the utility of Station and radically increase orbital safety.

Fortissimo: A Japanese Space Test Of Bare Wire Anode Tethers

NASA Technical Reports Server (NTRS)

Johnson, Les; Fujii, H. A.; Sanmartin, J. R.

2008-01-01

A Japanese led international team is developing a suborbital test of orbital-motion-limited (OML) bare wire anode current collection for application to electrodynamic tether (EDT) propulsion. The tether is a tape with a width of 25 mm, thickness of 0.05 mm, and is 300 m in length. This will be the first space test of OML theory. The mission will launch in the summer of 2009 using an S520 Sounding Rocket. During ascent, and above approx. 100 km in attitude, the tape tether will be deployed at a rate of approx. 8 m/s. Once deployed, the tape tether will serve as an anode, collecting ionospheric electrons. The electrons will be expelled into space by a hollow cathode device, thereby completing the circuit and allowing current to flow. The total amount of current collected will be used to assess the validity of OML theory. This paper will describe the objectives of the proposed mission, the technologies to be employed, and the application of the results to future space missions using EDTs for propulsion or power generation.

Lyapunov Orbits in the Jupiter System Using Electrodynamic Tethers

NASA Technical Reports Server (NTRS)

Bokelmann, Kevin; Russell, Ryan P.; Lantoine, Gregory

2013-01-01

Various researchers have proposed the use of electrodynamic tethers for power generation and capture from interplanetary transfers. The effect of tether forces on periodic orbits in Jupiter-satellite systems are investigated. A perturbation force is added to the restricted three-body problem model and a series of simplifications allows development of a conservative system that retains the Jacobi integral. Expressions are developed to find modified locations of equilibrium positions. Modified families of Lyapunov orbits are generated as functions of tether size and Jacobi integral. Zero velocity curves and stability analyses are used to evaluate the dynamical properties of tether-modified orbits.

Magnetobraking: Use of tether electrodynamic drag for Earth return from Mars

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

1994-01-01

It has often been proposed that a vehicle returning from Mars will use aerobraking in the Earth's atmosphere to dissipate hyperbolic excess velocity to capture into Earth orbit. Here a different system for dissipating excess velocity without expenditure of reaction mass, magnetobraking, is proposed. Magnetobraking uses the force on an electrodynamic tether in the Earth's magnetic field to produce thrust. An electrodynamic tether is deployed from the spacecraft as it approaches the Earth. The Earth's magnetic field produces a force on electrical current in the tether. If the tether is oriented perpendicularly to the Earth's magnetic field and to the direction of motion of the spacecraft, force produced by the Earth's magnetic field can be used to either brake or accelerate the spacecraft without expenditure of reaction mass. The peak acceleration on the Mars return is 0.007 m/sq sec, and the amount of braking possible is dependent on the density and current-carrying capacity of the tether, but is independent of length. A superconducting tether is required. The required critical current is shown to be within the range of superconducting technology now available in the laboratory.

UAH/NASA Workshop on The Uses of a Tethered Satellite System

NASA Technical Reports Server (NTRS)

Wu, S. T. (Editor)

1978-01-01

Potential applications of the system are categorized into four areas: geological applications, atmospheric applications, electrodynamics and plasma studies, and technology applications. The multiple-use tethered system with feedback control, will be capable of supporting a payload or satellite suspended from the Shuttle cargo bay, at distances up to 100 kilometers from the Shuttle. Experiments proposed include: geomagnetic mapping, lower atmospheric measurements, ionospheric interactions with large space structures, solar wind transport, and magnetohydrodynamic measurements.

Currents between tethered electrodes in a magnetized laboratory plasma

NASA Technical Reports Server (NTRS)

Stenzel, R. L.; Urrutia, J. M.

1989-01-01

Laboratory experiments on important plasma physics issues of electrodynamic tethers were performed. These included current propagation, formation of wave wings, limits of current collection, nonlinear effects and instabilities, charging phenomena, and characteristics of transmission lines in plasmas. The experiments were conducted in a large afterglow plasma. The current system was established with a small electron-emitting hot cathode tethered to an electron-collecting anode, both movable across the magnetic field and energized by potential difference up to V approx.=100 T(sub e). The total current density in space and time was obtained from complete measurements of the perturbed magnetic field. The fast spacecraft motion was reproduced in the laboratory by moving the tethered electrodes in small increments, applying delayed current pulses, and reconstructing the net field by a linear superposition of locally emitted wavelets. With this technique, the small-amplitude dc current pattern is shown to form whistler wings at each electrode instead of the generally accepted Alfven wings. For the beam electrode, the whistler wing separates from the field-aligned beam which carries no net current. Large amplitude return currents to a stationary anode generate current-driven microinstabilities, parallel electric fields, ion depletions, current disruptions and time-varying electrode charging. At appropriately high potentials and neutral densities, excess neutrals are ionized near the anode. The anode sheath emits high-frequency electron transit-time oscillations at the sheath-plasma resonance. The beam generates Langmuir turbulence, ion sound turbulence, electron heating, space charge fields, and Hall currents. An insulated, perfectly conducting transmission line embedded in the plasma becomes lossy due to excitation of whistler waves and magnetic field diffusion effects. The implications of the laboratory observations on electrodynamic tethers in space are discussed.

Implementation Options for the PROPEL Electrodynamic Tether Demonstration Mission

NASA Technical Reports Server (NTRS)

Bilen, Sven G.; Johnson, C. Les; Gilchrist, Brian E.; Hoyt, Robert P.; Elder, Craig H.; Fuhrhop, Keith P.; Scadera, Michael; Stone, Nobie

2014-01-01

The PROPEL ("Propulsion using Electrodynamics") flight demonstration mission concept will demonstrate the use of an electrodynamic tether (EDT) for generating thrust, which will allow the propulsion system to overcome the limitations of the rocket equation. The mission concept has been developed by a team of government, industry, and academia partners led by NASA Marshall Space Flight Center (MSFC). PROPEL is being designed for versatility of the EDT system with multiple end users in mind and to be flexible with respect to platform. Previously, we reported on a comprehensive mission design for PROPEL with a mission duration of six months or longer with multiple mission goals including demonstration of significant boost, deboost, inclination change, and drag make-up activities. To explore a range of possible configurations, primarily driven by cost considerations, other mission concept designs have been pursued. In partnership with the NASA's Office of Chief Technologist (OCT) Game Changing Program, NASA MSFC Leadership, and the MSFC Advanced Concepts Office, a mission concept design was developed for a near-term EDT propulsion flight validation mission. The Electrodynamic Tether Propulsion Study (ETPS) defined an EDT propulsion system capable of very large delta-V for use on future missions developed by NASA, DoD, and commercial customers. To demonstrate the feasibility of an ETPS, the study focused on a space demonstration mission concept design with configuration of a pair of tethered satellite busses, one of which is the Japanese H-II Transfer Vehicle (HTV). The HTV would fly its standard ISS resupply mission. When resupply mission is complete, the ISS reconfigures and releases the HTV to perform the EDT experiment at safe orbital altitudes below the ISS. Though the focus of this particular mission concept design addresses a scenario involving the HTV or a similar vehicle, the propulsion system's capability is relevant to a number of applications, as noted above. The ETPS builds on prior work on long-life, failure-resistant, conducting tethers and includes an instrument suite with demonstrated heritage capable of performing necessary diagnostics to measure performance against predictions for a given system size (to be determined) and boost rate. Mission designs in other configurations and launch vehicle options are being developed such that the system can be demonstration should a flight opportunity be identified. We will report on past and ongoing implementation options for PROPEL.

Graduate Student Researchers Program (GSRP)

NASA Technical Reports Server (NTRS)

Westerhoff, John

2004-01-01

An advanced concept in in-space transportation currently being studied is the Momentum-Exchange/Electrodynamic Reboost Tether System (MXER). The MXER system is a permanently orbiting platform designed to boost payloads from low earth orbit (LEO). Unlike conventional rockets that use propellants, MXER acts as a large momentum wheel, imparting a Av to a payload at the expense of its own orbital energy. After throwing a payload, the system reboosts itself using an electrodynamic tether to push against Earth s magnetic field and brings itself back up to an operational orbit to prepare for the next payload. The ability to reboost itself allows for continued reuse of the system without the expenditure of propellants. Considering the cost of lifting propellant from the ground to LEO to do the same Av boost at $10000 per pound, the system cuts the launch cost of the payload dramatically, and subsequently, the MXER system pays for itself after a small number of missions. As such, this technology is a valuable addition to NASA s mission for in-space transportation.

Practicality of Using a Tether for Electrodynamic Reboost of the International Space Station

NASA Technical Reports Server (NTRS)

Blumer, J. H.; Donahue, Benjamin B.; Bangham, Michal E.; Roth, A. (Technical Monitor)

2001-01-01

ElectroDynamic (ED) Tethers can generate continuous low thrust in a low Earth orbit. An induced current running through the length of the tether reacts with the geomagnetic field to produce thrust. The amount of thrust scales with tether lens!th and current. The International Space Station (ISS) requires periodic reboost to maintain an approximately circular orbit t above the Earth. The baseline reboost method is a traditional bi-propellant rocket thruster and tankage system which must to be refueled via Soyuz / Progress or other launch vehicle. The estimated propellant costs associated with keeping ISS in the designated orbit over a 10-year life have been extremely high. The ED Tether would draw energy from the renewable ISS Solar Array electrical power system. Propulsion requirements for ISS vary depending on solar wind and other conditions. It is projected that a ED Tether could provide the majority of the required reboost thrust for ISS for a nominal solar year. For above nominal solar wind years the ISS would have to use the rocket reboost system, but at a greatly reduced level. Thus resulting in substantial cost savings, via the reduction in the number of Earth-to-orbit launch vehicle flights to the ISS that must bring reboost propellant. However, the purposes of this paper is to further Previous research on an ISS ED Tether and examine the operational and technical issues working against using a ED Tether on ISS. Issues such as Shuttle rendezvous and flight path concerns raise serious safety concerns and restrictions on tether use. Tether issues such as tether librations and off angle thrust raise concerns about impacts to microgravity payloads and the long-term effect on ISS orbital path and inclination. Operational issues such as peak power available to an ED Tether and allowable duty cycle may impose severe restrictions on tether design and ultimately limit the practicality of an ED Tether on ISS. Thus while at first glance the cost numbers appear to be strongly in favor of an ED Tether the limitations imposed by safety, operations and technical concerns may severely undermine the economic model. Possible Solutions to these problems have been investigated and proposed, however some items like off angle thrust are still being actively investigated for an adequate solution.

The investigation of tethered satellite system dynamics

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1985-01-01

The tether control law to retrieve the satellite was modified in order to have a smooth retrieval trajectory of the satellite that minimizes the thruster activation. The satellite thrusters were added to the rotational dynamics computer code and a preliminary control logic was implemented to simulate them during the retrieval maneuver. The high resolution computer code for modelling the three dimensional dynamics of untensioned tether, SLACK3, was made fully operative and a set of computer simulations of possible tether breakages was run. The distribution of the electric field around an electrodynamic tether in vacuo severed at some length from the shuttle was computed with a three dimensional electrodynamic computer code.

Application of the Trio-Tri-Star Carpal Wrist for use in a Solar Array Tracking Mechanism for the Momentum-eXchange/Electrodynamic Reboost (MXER) Tether Concept

NASA Technical Reports Server (NTRS)

Robertson, Jeffrey

2006-01-01

This paper describes the application of the Trio-Tri-Star Carpal Wrist to the Momentum Exchange Electro-Dynamic Re-boost (MXER) tether, an advanced space transportation concept being developed by the In-Space Propulsion Technology Office at NASA s Marshall Space Flight Center in Huntsville, Alabama. Dr. Joseph Bonometti and Mr. Kirk Sorensen are the principal engineers. In the paper, a brief overview of the MXER concept is given, with an emphasis on the design problem that this wrist is designed to address. The Trio-Tri-Star Carpal Wrist, a three degree of freedom parallel manipulator, invented by Dr. Stephen J. Canfield of Tennessee Tech University, is described with an overview of wrist geometry, kinematics, and stress analysis. A working model of the wrist was assembled at MSFC using Dr. Canfield s prototype to demonstrate its operation. Finally, a design description and supporting analysis of a MXER flight concept wrist is given, with recommendations for future development work.

Technology Area Roadmap for In-Space Propulsion Technologies

NASA Technical Reports Server (NTRS)

Johnson, Les; Meyer, Michael; Palaszewski, Bryan; Coote, David; Goebel, Dan; White, Harold

2012-01-01

The exponential increase of launch system size.and cost.with delta-V makes missions that require large total impulse cost prohibitive. Led by NASA fs Marshall Space Flight Center, a team from government, industry, and academia has developed a flight demonstration mission concept of an integrated electrodynamic (ED) tethered satellite system called PROPEL: \\Propulsion using Electrodynamics.. The PROPEL Mission is focused on demonstrating a versatile configuration of an ED tether to overcome the limitations of the rocket equation, enable new classes of missions currently unaffordable or infeasible, and significantly advance the Technology Readiness Level (TRL) to an operational level. We are also focused on establishing a far deeper understanding of critical processes and technologies to be able to scale and improve tether systems in the future. Here, we provide an overview of the proposed PROPEL mission. One of the critical processes for efficient ED tether operation is the ability to inject current to and collect current from the ionosphere. Because the PROPEL mission is planned to have both boost and deboost capability using a single tether, the tether current must be capable of flowing in both directions and at levels well over 1 A. Given the greater mobility of electrons over that of ions, this generally requires that both ends of the ED tether system can both collect and emit electrons. For example, hollow cathode plasma contactors (HCPCs) generally are viewed as state-of-the-art and high TRL devices; however, for ED tether applications important questions remain of how efficiently they can operate as both electron collectors and emitters. Other technologies will be highlighted that are being investigated as possible alternatives to the HCPC such as Solex that generates a plasma cloud from a solid material (Teflon) and electron emission (only) technologies such as cold-cathode electron field emission or photo-electron beam generation (PEBG) techniques

Why Not Space Tethers?

NASA Technical Reports Server (NTRS)

Stone, Noble H.

2007-01-01

The Tethered Satellite System Space Shuttle missions, TSS-1 in 1993 and TSS-1R in 1996, were the height of space tether technology development. Since NASA's investment of some $200M and two Shuttle missions in those two pioneering missions, there have been several smaller tether flight experiments, but interest in this promising technology has waned within NASA as well as the DOD agencies. This is curious in view of the unique capabilities of space tether systems and the fact that they have been flight validated and shown to perform as, or better than, expected in earth orbit. While it is true that the TSS-1, TSS-1R and SEDS-2 missions experienced technical difficulties, the causes of these early developmental problems are now known to be design or materials flaws that are (1) unrelated to the basic viability of space tether technology, and (2) they are readily corrected. The purpose of this paper is to review the dynamic and electrodynamic fundamentals of space tethers and the unique capabilities they afford (that are enabling to certain types of space missions); to elucidate the nature, cause, and solution of the early developmental problems; and to provide an update on progress made in development of the technology. Finally, it is shown that (1) all problems experienced during early development of the technology now have solutions; and (2) the technology has been matured by advances made in strength and robustness of tether materials, high voltage engineering in the space environment, tether health and status monitoring, and the elimination of the broken tether hazard. In view of this, it is inexplicable why this flight-validated technology has not been utilized in the past decade, considering the powerful and unique capabilities that space tethers can afford that are, not only required to carryout, otherwise, unobtainable missions, but can also greatly reduce the cost of certain on-going space operations.

Investigation of electrodynamic stabilization and control of long orbiting tethers

NASA Technical Reports Server (NTRS)

Colombo, G.; Arnold, D.

1984-01-01

The state-of-the-art in tether modelling among participants in the Tethered Satellite System (TSS) Program, the slack tether and its behavior, and certain advanced applications of the tether to problems in orbital mechanics are identified. The features and applications of the TSS software set are reviewed. Modelling the slack tether analytically with as many as 50 mass points and the application of this new model to a study of the behavior of a broken tether near the Shuttle are described. A reel control algorithm developed by SAO and examples of its use are described, including an example which also demonstrates the use of the tether in transferring a heavy payload from a low-orbiting Shuttle to a high circular orbit. Capture of a low-orbiting payload by a Space Station in high circular orbit is described. Energy transfer within a dumbbell-type spacecraft by cyclical reeling operations or gravitational effects on the natural elasticity of the connecting tether, it is shown, can circularize the orbit of the spacecraft.

Spacecraft Solar Sails Containing Electrodynamic Tethers

NASA Technical Reports Server (NTRS)

Johnson, Les; Matloff, Greg

2005-01-01

A report discusses a proposal to use large, lightweight solar sails embedded with electrodynamic tethers (essentially, networks of wires) to (1) propel robotic spacecraft to distant planets, then (2) exploit the planetary magnetic fields to capture the spacecraft into orbits around the planets. The purpose of the proposal is, of course, to make it possible to undertake long interplanetary missions without incurring the large cost and weight penalties of conventional rocket-type propulsion systems. Through transfer of momentum from reflected solar photons, a sail would generate thrust outward from the Sun. Upon arrival in the vicinity of a planet, the electrodynamic tethers would be put to use: Motion of the spacecraft across the planetary magnetic field would induce electric currents in the tether wires, giving rise to an electromagnetic drag force that would be exploited to brake the spacecraft for capture into orbit. The sail with embedded tethers would be made to spin to provide stability during capture. Depending upon the requirements of a particular application, it could be necessary to extend the tether to a diameter greater than that of the sail.

On equilibrium positions and stabilization of electrodynamic tether system in the orbital frame

NASA Astrophysics Data System (ADS)

Tikhonov, A. A.; Shcherbakova, L. F.

2018-05-01

An electrodynamic tether system (EDTS) in a near-Earth circular orbit is considered. EDTS contains conductive tether with lumped masses attached to it at the ends. Possible equilibrium positions of the stretched tether under the influence of gravity gradient, Ampere and Lorentz forces in orbital frame are investigated. It is shown that in addition to the vertical equilibrium position, the "inclined" equilibrium positions of the tensioned tether are also possible. Conditions are obtained for the EDTS parameters, under which there is only one vertical position of the tether equilibrium. On the basis of nonlinear differential equations of motion, using the Lyapunov functions method, sufficient conditions for the stability of the vertical position of the tether equi-librium are obtained. It is shown that stabilization of the tether in this position is possible in the presence of damping in the EDTS system. The results of numerical simulation are presented.

ProSEDS Telemetry System Utilization of GPS Position Data for Transmitter Cycling

NASA Technical Reports Server (NTRS)

Kennedy, Paul; Sims, Herb

2000-01-01

NASA Marshall Space Flight Center will launch the Propulsive Small Expendable Deployer System (ProSEDS) space experiment in late 2000. ProSEDS will demonstrate the use of an electrodynamic tether propulsion system and will utilize a conducting wire tether to generate limited spacecraft power. This paper will provide an overview of the ProSEDS mission and will discuss the design, development and test of the spacecraft telemetry system which utilizes a custom designed GPS subsystem to determine spacecraft position relative to ground station location and to control transmitter on/off cycling based on spacecraft state vector and ground station visibility.

The investigation of tethered satellite system dynamics

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1985-01-01

Progress in tethered satellite system dynamics research is reported. A retrieval rate control law with no angular feedback to investigate the system's dynamic response was studied. The initial conditions for the computer code which simulates the satellite's rotational dynamics were extended to a generic orbit. The model of the satellite thrusters was modified to simulate a pulsed thrust, by making the SKYHOOK integrator suitable for dealing with delta functions without loosing computational efficiency. Tether breaks were simulated with the high resolution computer code SLACK3. Shuttle's maneuvers were tested. The electric potential around a severed conductive tether with insulator, in the case of a tether breakage at 20 km from the Shuttle, was computed. The electrodynamic hazards due to the breakage of the TSS electrodynamic tether in a plasma are evaluated.

Dynamics Simulation Model for Space Tethers

NASA Technical Reports Server (NTRS)

Levin, E. M.; Pearson, J.; Oldson, J. C.

2006-01-01

This document describes the development of an accurate model for the dynamics of the Momentum Exchange Electrodynamic Reboost (MXER) system. The MXER is a rotating tether about 100-km long in elliptical Earth orbit designed to catch payloads in low Earth orbit and throw them to geosynchronous orbit or to Earth escape. To ensure successful rendezvous between the MXER tip catcher and a payload, a high-fidelity model of the system dynamics is required. The model developed here quantifies the major environmental perturbations, and can predict the MXER tip position to within meters over one orbit.

Current-voltage characteristics of a cathodic plasma contactor with discharge chamber for application in electrodynamic tether propulsion

NASA Astrophysics Data System (ADS)

Xie, Kan; Martinez, Rafael A.; Williams, John D.

2014-04-01

This paper focuses on the net electron-emission current as a function of bias voltage of a plasma source that is being used as the cathodic element in a bare electrodynamic tether system. An analysis is made that enables an understanding of the basic issues determining the current-voltage (C-V) behaviour. This is important for the efficiency of the electrodynamic tether and for low impedance performance without relying on the properties of space plasma for varying orbital altitudes, inclinations, day-night cycles or the position of the plasma contactor relative to the wake of the spacecraft. The cathodic plasma contactor considered has a cylindrical discharge chamber (10 cm in diameter and ˜11 cm in length) and is driven by a hollow cathode. Experiments and a 1D spherical model are both used to study the contactor's C-V curves. The experiments demonstrate how the cathodic contactor would emit electrons into space for anode voltages in the range of 25-40 V, discharge currents in the range of 1-2.5 A, and low xenon gas flows of 2-4 sccm. Plasma properties are measured and compared with (3 A) and without net electron emission. A study of the dependence of relevant parameters found that the C-V behaviour strongly depends on electron temperature, initial ion energy and ion emission current at the contactor exit. However, it depended only weakly on ambient plasma density. The error in the developed model compared with the experimental C-V curves is within 5% at low electron-emission currents (0-2 A). The external ionization processes and high ion production rate caused by the discharge chamber, which dominate the C-V behaviour at electron-emission currents over 2 A, are further highlighted and discussed.

A corrected tether-mission to Jupiter

NASA Astrophysics Data System (ADS)

Sanchez-Arriaga, G.; Charro, M.

2012-09-01

A spacecraft slowly descending in equatorial orbit through the inner magnetosphere of Jupiter over a period of months would provide a wealth of knowledge through space and time resolved observations. An electrodynamic (ED) bare-foil tether has been proposed as allowing a spacecraft to attain a circular orbit below Jovian radiation belts and Halo ring (so as to then carry out scientific observations) using Lorentz drag on the current induced in the tether for orbit insertion, followed by a series of perijove passes to progressively lower the apojove. Accumulated radiation dose was reasonable when using a 50 km long tether. It was recently shown, however, that electron collection by the tether would then be in a relativistic regime. This yields a penetration depth in aluminum exceeding foil thickness. Reducing the length to 10 km is here proposed, followed by a reconsideration of the scientific mission objectives.

Command Generation and Control of Momentum Exchange Electrodynamic Reboost Tethered Satellite

NASA Technical Reports Server (NTRS)

Robertson, Michael J.

2005-01-01

The research completed for this NASA Graduate Student Research Program Fellowship sought to enhance the current state-of-the-art dynamic models and control laws for Momentum Exchange Electrodynamic Reboost satellite systems by utilizing command generation, specifically Input Shaping. The precise control of tethered spacecraft with flexible appendages is extremely difficult. The complexity is magnified many times when the satellite must interact with other satellites as in a momentum exchange via a tether. The Momentum Exchange Electronic Reboost Tether (MXER) concept encapsulates all of these challenging tasks [l]. Input Shaping is a command generation technique that allows flexible spacecraft to move without inducing residual vibration [2], limit transient deflection [3] and utilize fuel-efficient actuation [4]. Input shaping is implemented by convolving a sequence of impulses, known as the input shaper, with a desired system command to produce a shaped input that is then used to drive the system. This process is demonstrated in Figure 1. The shaped command is then use to drive the system without residual vibration while meeting many other performance specifications. The completed work developed tether control algorithms for retrieval. A simple model of the tether response has been developed and command shaping was implemented to minimize unwanted dynamics. A model of a flexible electrodynamic tether has been developed to investigate the tether s response during reboost. Command shaping techniques have been developed to eliminate the tether oscillations and reduce the tether s deflection to pre-specified levels during reboost. Additionally, a model for the spin-up of a tethered system was developed. This model was used in determining the parameters for optimization the resulting angular velocity.

Space Shuttle Projects

NASA Image and Video Library

1992-08-24

This STS-46 onboard photo is of the Tethered Satellite System-1 (TSS-1) being deployed from its boom as it is perched above the cargo bay of the Earth-orbiting Space Shuttle Atlantis. Circling the Earth at an altitude of 296 kilometers (184 miles), the TSS-1 will be well within the tenuous, electrically charged layer of the atmosphere known as the ionosphere. There, a satellite attached to the orbiter by a thin conducting cord, or tether, will be reeled from the Shuttle payload bay. On this mission the satellite was plarned to be deployed 20 kilometers (12.5 miles) above the Shuttle. The conducting tether will generate high voltage and electrical currents as it moves through the atmosphere allowing scientists to examine the electrodynamics of a conducting tether system. These studies will not only increase our understanding of physical processes in the near-Earth space environment, but will also help provide an explanation for events witnessed elsewhere in the solar system. The crew of the STS-46 mission were unable to reel the satellite as planned. After several unsuccessful attempts, they were only able to extend the satellite 9.8 kilometers (6.1 miles). The TSS was a cooperative development effort by the Italian Space Agency (ASI), and NASA.

Ionospheric Multi-Point Measurements Using Tethered Satellite Sensors

NASA Technical Reports Server (NTRS)

Gilchrist, B. E.; Heelis, R. A.; Raitt, W. J.

1998-01-01

Many scientific questions concerning the distribution of electromagnetic fields and plasma structures in the ionosphere require measurements over relatively small temporal and spatial scales with as little ambiguity as possible. It is also often necessary to differentiate several geophysical parameters between horizontal and vertical gradients unambiguously. The availability of multiple tethered satellites or sensors, so-called "pearls-on-a-string," may make the necessary measurements practical. In this report we provide two examples of scientific questions which could benefit from such measurements (1) high-latitude magnetospheric-ionospheric coupling; and, (2) plasma structure impact on large and small-scale electrodynamics. Space tether state-of-the-art and special technical considerations addressing mission lifetime, sensor pointing, and multi-stream telemetry are reviewed.

T-Rex: A Japanese Space Tether Experiment

NASA Technical Reports Server (NTRS)

Johnson, Les

2009-01-01

Electrodynamic tether (EDT) thrusters work by virtue of the force a magnetic field exerts on a wire carrying an electrical current. The force, which acts on any charged particle moving through a magnetic field (including the electrons moving in a current-carrying wire), were concisely expressed by Lorentz in 1895 in an equation that now bears his name. The force acts in a direction perpendicular to both the direction of current flow and the magnetic field vector. Electric motors make use of this force: a wire loop in a magnetic field is made to rotate by the torque the Lorentz Force exerts on it due to an alternating current in the loop times so as to keep the torque acting in the same sense. The motion of the loop is transmitted to a shaft, thus providing work. Although the working principle of EDT thrusters is not new, its application to space transportation may be significant. In essence, an EDT thruster is just a clever way of getting an electrical current to flow in a long orbiting wire (the tether) so that the Earth s magnetic field will accelerate the wire and, consequently the payload attached to the wire. The direction of current flow in the tether, either toward or away from the Earth along the local vertical, determines whether the magnetic force will raise or lower the orbit. The bias voltage of a vertically deployed metal tether, which results just from its orbital motion (assumed eastward) through Earth s magnetic field, is positive with respect to the ambient plasma at the top and negative at the bottom. This polarization is due to the action of the Lorentz force on the electrons in the tether. Thus, the natural current flow is the result of negative electrons being attracted to the upper end and then returned to the plasma at the lower end. The magnetic force in this case has a component opposite to the direction of motion, and thus leads to a lowering of the orbit and eventually to re-entry. In this generator mode of operation the Lorentz Force serves both to drive the current and then to act on the current to decelerate the system. One of the most important features of tether thrusters is that they use renewable energy sources to drive the electrical current flow in either the orbit-raising or orbit-lowering modes. Sources inherent to Earth orbit are used. To raise the orbit, sunlight can be converted to the electrical energy required to drive the tether current. To lower the orbit, the orbital energy itself (supplied by the Earth-to-orbit launcher when it raises the system into orbit) is the energy source of the tether current via the action of the Lorentz Force. Electrodynamic tethers can be directly applied to a wide spectrum of uses in space. As a propulsion system, they include satellite de-orbit, transfer of a satellite from one orbit to another, altitude maintenance for large spacecraft such as the International Space Station, and since it works wherever there is a magnetic field and an ionosphere planetary exploration missions. An electrodynamic tether upper stage could be used as an Orbit Transfer Vehicle (OTV) to move payloads within low earth orbit. The OTV would rendezvous with the payload and launch vehicle, grapple the payload and maneuver it to a new orbital altitude or inclination without the use of boost propellant. The tug could then lower its orbit to rendezvous with the next payload and repeat the process. Conceivably, such a system could perform several orbital maneuvering assignments without resupply, making it relatively inexpensive to operate.

Space Shuttle Projects

NASA Image and Video Library

1992-08-08

Sharing this scene with a half-moon is the Tethered Satellite System (TSS), in a photo captured onboard the STS-46. Circling Earth at an altitude of 296 kilometers (184 miles), the TSS-1 will be well within the tenuous, electrically charged layer of the atmosphere known as the ionosphere. There, a satellite attached to the orbiter by a thin conducting cord, or tether, will be reeled from the Shuttle payload bay. On this mission the satellite was plarned to be deployed 20 kilometers (12.5 miles) above the Shuttle. The conducting tether will generate high voltage and electrical currents as it moves through the atmosphere allowing scientists to examine the electrodynamics of a conducting tether system. These studies will not only increase our understanding of physical processes in the near-Earth space environment, but will also help provide an explanation for events witnessed elsewhere in the solar system. The crew of the STS-46 mission were unable to reel the satellite as planned. After several unsuccessful attempts, they were only able to extend the satellite 9.8 kilometers (6.1 miles). The TSS was a cooperative development effort by the Italian Space Agency (ASI), and NASA.

Applications of the Electrodynamic Tether to Interstellar Travel

NASA Technical Reports Server (NTRS)

Matloff, Gregory L.; Johnson, Les

2005-01-01

After considering relevant properties of the local interstellar medium and defining a sample interstellar mission, this paper considers possible interstellar applications of the electrodynamic tether, or EDT. These include use of the EDT to provide on-board power and affect trajectory modifications and direct application of the EDT to starship acceleration. It is demonstrated that comparatively modest EDTs can provide substantial quantities of on-board power, if combined with a large-area electron-collection device such as the Cassenti toroidal-field ramscoop. More substantial tethers can be used to accomplish large-radius thrustless turns. Direct application of the EDT to starship acceleration is apparently infeasible.

Tethered constellations

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1986-01-01

The studies that have been carried out on Tethered Constellations are briefly addressed. A definition of a tethered constellation is any number of masses/platforms greater that two connected by tethers in a stable configuration. Configurations and stability constraints are reviewed. Conclusions reached are: (1) The 1-D, horizontal, passively stabilized constellations have been ruled out; (2) Fishbone constellations have been also ruled out; (3) Alternative stable 2-D configurations have been devised such as the quadrangular configuration stabilized by electrodynamic forces (ESC), the quadrangular configuration stabilized by differential air drag (DSC), and the pseudo elliptical configuration stabilized by electrodynamic forces (PEC). Typical dimensions for these constellations are 10 km (horizontal) by 20 km (vertical) with balloon diameters around 100 m in the case of a DSC and a power consumption around 7 KW for an ESC or PEC.

The Science and Applications Tethered Platform (SATP) project

NASA Technical Reports Server (NTRS)

Merlina, P.

1986-01-01

The capabilities of tether systems in orbit are going to be demonstrated by the first planned flights of the Tethered Satellite System (TSS). These test flights will investigate the properties of tether systems as low altitude atmospheric research facilities and as electric power generators. Studies are being conducted with the purpose of testing a variety of concepts and approaches. A comparative analysis of results will allow the choosing of the most promising ideas for further development. The broad range of applications presently under study include applications in electrodynamics, transportation, microgravity in addition to basic research. The SATP project definition study is now about midway through its first phase. The analyses conducted have led to an appraisal of users interest in the project and to a deeper understanding of the problems associated with large, long-lived tether systems in space. In addition, two specialized platform designs, devoted to microgravity and precise pointing applications, are being studied because of their potential usefulness and the promise of technical feasibility.

The use of tethers for payload orbital transfer. Continuation of investigation of electrodynamic stabilization and control of long orbiting tethers, volume 2

NASA Technical Reports Server (NTRS)

Colombo, G.; Martinez-Sanchez, M.; Arnold, D.

1982-01-01

The SKYHOOK program was used to do simulations of two cases of the use of the tether for payload orbital transfer. The transport of a payload along the tether from a heavy lower platform to an upper launching platform is considered. A numerical example of the Shuttle launching a payload using an orbital tether facility is described.

Electrodynamic tethers for energy conversion

NASA Technical Reports Server (NTRS)

Nobles, W.

1986-01-01

Conductive tethers have been proposed as a new method for converting orbital mechanical energy into electrical power for use on-board a satellite (generator mode) or conversely (motor mode) as a method of providing electric propulsion using electrical energy from the satellite. The operating characteristics of such systems are functionally dependent on orbit altitude and inclination. Effects of these relationships are examined to determine acceptable regions of application. To identify system design considerations, a specific set of system performance goals and requirements are selected. The case selected is for a 25 kW auxiliary power system for use on Space Station. Appropriate system design considerations are developed, and the resulting system is described.

Spaceflight mechanics 1992; Proceedings of the 2nd AAS/AIAA Meeting, Colorado Springs, CO, Feb. 24-26, 1992. Pts. 1 & 2

NASA Astrophysics Data System (ADS)

Diehl, Roger E.; Schinnerer, Ralph G.; Williamson, Walton E.; Boden, Daryl G.

The present conference discusses topics in orbit determination, tethered satellite systems, celestial mechanics, guidance optimization, flexible body dynamics and control, attitude dynamics and control, Mars mission analyses, earth-orbiting mission analysis/debris, space probe mission analyses, and orbital computation numerical analyses. Attention is given to electrodynamic forces for control of tethered satellite systems, orbiting debris threats to asteroid flyby missions, launch velocity requirements for interceptors of short range ballistic missiles, transfers between libration-point orbits in the elliptic restricted problem, minimum fuel spacecraft reorientation, orbital guidance for hitting a fixed point at maximum speed, efficient computation of satellite visibility periods, orbit decay and reentry prediction for space debris, and the determination of satellite close approaches.

Spaceflight mechanics 1992; Proceedings of the 2nd AAS/AIAA Meeting, Colorado Springs, CO, Feb. 24-26, 1992. Pts. 1 & 2

NASA Technical Reports Server (NTRS)

Diehl, Roger E. (Editor); Schinnerer, Ralph G. (Editor); Williamson, Walton E. (Editor); Boden, Daryl G. (Editor)

1992-01-01

The present conference discusses topics in orbit determination, tethered satellite systems, celestial mechanics, guidance optimization, flexible body dynamics and control, attitude dynamics and control, Mars mission analyses, earth-orbiting mission analysis/debris, space probe mission analyses, and orbital computation numerical analyses. Attention is given to electrodynamic forces for control of tethered satellite systems, orbiting debris threats to asteroid flyby missions, launch velocity requirements for interceptors of short range ballistic missiles, transfers between libration-point orbits in the elliptic restricted problem, minimum fuel spacecraft reorientation, orbital guidance for hitting a fixed point at maximum speed, efficient computation of satellite visibility periods, orbit decay and reentry prediction for space debris, and the determination of satellite close approaches.

Corrigendum to "Dynamics of a flexible tethered satellite system utilising various materials for coplanar and non-coplanar models" [Adv. Space Res. 56 (2015) 648-663

NASA Astrophysics Data System (ADS)

Hong, Aaron Aw Teik; Varatharajoo, Renuganth

2015-12-01

The authors would like to thank Dr. N.A. Ismail for some of the discussions found in her thesis as these discussions have facilitated to achieve some of the results published in this article. Therefore, Ismail, N.A., "The Dynamics of a Flexible Motorised Momentum Exchange Tether (MMET)", PhD. thesis, University of Glasgow, UK, pp. 26-41, 2012 is cited accordingly herein. The thesis was missed out from the reference list in the original version of this article due to an oversight with no other intention. Similarly the thesis by Stevens, R.E., "Optimal Control of Electrodynamic Tether Satellites", PhD. thesis, Air Force Institute of Technology, USA, pp. 87-96, 2008 is referred for a further readership completeness.

Space Shuttle Project

NASA Image and Video Library

1992-08-24

A crewmember aboard the Space Shuttle Orbiter Atlantis (STS-46) used a 70mm handheld camera to capture this medium closeup view of early operations with the Tethered Satellite System (TSS). TSS-1 is being deployed from its boom as it is perched above the cargo bay of the Earth-orbiting Shuttle circling the Earth at an altitude of 296 kilometers (184 miles), the TSS-1 will be well within the tenuous, electrically charged layer of the atmosphere known as the ionosphere. There, a satellite attached to the orbiter by a thin conducting cord, or tether, will be reeled from the Shuttle payload bay. On this mission the satellite was plarned to be deployed 20 kilometers (12.5 miles) above the Shuttle. The conducting tether will generate high voltage and electrical currents as it moves through the atmosphere allowing scientists to examine the electrodynamics of a conducting tether system. These studies will not only increase our understanding of physical processes in the near-Earth space environment, but will also help provide an explanation for events witnessed elsewhere in the solar system. The crew of the STS-46 mission were unable to reel the satellite as planned. After several unsuccessful attempts, they were only able to extend the satellite 9.8 kilometers (6.1 miles). The TSS was a cooperative development effort by the Italian Space Agency (ASI), and NASA.

System engineering study of electrodynamic tether as a spaceborne generator and radiator of electromagnetic waves in the ULF/ELF frequency band

NASA Technical Reports Server (NTRS)

Estes, Robert D.

1987-01-01

An electrodynamic tether deployed from a satellite in low-Earth orbit can perform, if properly instrumented, as a partially self-powered generator of electromagnetic waves in the ULF/ELF band, potentially at power levels high enough to be of practical use. Two basic problems are examined. The first is that of the level of wave power that the system can be expected to generate in the ULF/ELF radiation band. The second major question is whether an electrodynamic tethered satellite system for transmitting waves can be made partially self-powering so that power requirements for drag compensation can be met within economical constraints of mass, cost, and complexity. The theoretical developments and the system applications study are presented. The basic design criteria, the drag-compensation method, the effects on the propagation paths from orbit to Earth surface of high-altitude nuclear debris patches, and the estimate of masses and sizes are covered. An outline of recommended analytical work, to be performed as a follow-on to the present study, is contained.

The investigation of tethered satellite system dynamics

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1984-01-01

Tethered satellite system (TSS) dynamics were studied. The dynamic response of the TSS during the entire stationkeeping phase for the first electrodynamic mission was investigated. An out of plane swing amplitude and the tether's bowing were observed. The dynamics of the slack tether was studied and computer code, SLACK2, was improved both in capabilities and computational speed. Speed hazard related to tether breakage or plasma contactor failure was examined. Preliminary values of the potential difference after the failure and of the drop of the electric field along the tether axis have been computed. The update of the satellite rotational dynamics model is initiated.

Plasma contactor design for electrodynamic tether applications

NASA Technical Reports Server (NTRS)

Wilbur, Paul J.; Laupa, Thomas G.

1988-01-01

The plasma contacting process is described and experiments are discussed that suggest the key role that cold ions play in establishing a low impedance plasma bridge that can conduct current in either direction between a contactor electrode and a dilute plasma. A ring cusp contactor is shown to provide from 1000-mA of electron emission to 500-mA of electron collection as its bias relative to a simulated space plasma is varied through an 80-v range.

Active Debris Removal Using Modified Launch Vehicle Upper Stages

NASA Astrophysics Data System (ADS)

Nasseri, S. Ali; Emanuelli, Matteo; Raval, Siddharth; Turconi, Andrea

2013-09-01

During the past few years, several research programs have assessed the current state and future evolution of space debris in the Low Earth Orbit region. These studies indicate that space debris density could reach a critical level such that there will be a continuous increase in the number of debris objects, primarily driven by debris-debris collision activity known as the Kessler effect. These studies also highlight the urgency for active debris removal.An Active Debris Removal System (ADRS) is capable of approaching the debris object through a close-range rendezvous, stabilizing its attitude, establishing physical contact, and finally de-orbiting the debris object. The de-orbiting phase could be powered by propulsion systems such as chemical rockets or electrodynamic tether (EDT) systems.The aim of this project is to model and evaluate a debris removal mission in which an adapted rocket upper stage, equipped with an electrodynamic tether (EDT) system, is employed for de-orbiting a debris object. This ADRS package is installed initially as part of a launch vehicle on a normal satellite deployment mission, and a far-approach manoeuvre will be required to align the ADRS' orbit with that of the target debris. We begin by selecting a suitable target debris and launch vehicle, and then proceed with modelling the entire debris removal mission from launch to de-orbiting of the target debris object using Analytical Graphic Inc.'s Systems Tool Kit (STK).

Orbital Propagation of Momentum Exchange Tether Systems

NASA Technical Reports Server (NTRS)

Westerhoff, John

2002-01-01

An advanced concept in in-space transportation currently being studied is the Momentum-Exchange/Electrodynamic Reboost Tether System (MXER). The system acts as a large momentum wheel, imparting a Av to a payload in low earth orbit (LEO) at the expense of its own orbital energy. After throwing a payload, the system reboosts itself using an electrodynamic tether to push against Earth's magnetic field and brings itself back up to an operational orbit to prepare for the next payload. The ability to reboost itself allows for continued reuse of the system without the expenditure of propellants. Considering the cost of lifting propellant from the ,ground to LEO to do the same Av boost at $10000 per pound, the system cuts the launch cost of the payload dramatically, and subsequently, the MXER system pays for itself after a small number of missions.1 One of the technical hurdles to be overcome with the MXER concept is the rendezvous maneuver. The rendezvous window for the capture of the payload is on the order of a few seconds, as opposed to traditional docking maneuvers, which can take as long ets necessary to complete a precise docking. The payload, therefore, must be able to match its orbit to meet up with the capture device on the end of the tether at a specific time and location in the future. In order to be able to determine that location, the MXER system must be numerically propagated forward in time to predict where the capture device will be at that instant. It should be kept in mind that the propagation computation must be done faster than real-time. This study focuses on the efforts to find and/or build the tools necessary to numerically propagate the motion of the MXER system as accurately as possible.

Theoretical investigation of EM wave generation and radiation in the ULF, ELF, and VLF bands by the electrodynamic orbiting tether

NASA Technical Reports Server (NTRS)

Estes, Robert D.; Grossi, Mario D.

1989-01-01

The problem of electromagnetic wave generation by an electrodynamic tethered satellite system is important both for the ordinary operation of such systems and for their possible application as orbiting transmitters. The tether's ionospheric circuit closure problem is closely linked with the propagation of charge-carrying electromagnetic wave packets away from the tethered system. Work is reported which represents a step towards a solution to the problem that takes into account the effects of boundaries and of vertical variations in plasma density, collision frequencies, and ion species. The theory of Alfen wave packet generation by an electrodynamic tethered system in an infinite plasma medium is reviewed, and brief summary of previous work on the problem is given. The consequences of the presence of the boundaries and the vertical nonuniformity are then examined. One of the most significant new features to emerge when ion-neutral collisions are taken into account is the coupling of the Alfven waves to the fast magnetosonic wave. This latter wave is important, as it may be confined by vertical variations in the Alfven speed to a sort of leaky ionospheric wave guide, the resonances of which could be of great importance to the signal received on the Earth's surface. The infinite medium solution for this case where the (uniform) geomagnetic field makes an arbitrary angle with the vertical is taken as the incident wave-packet. Even without a full solution, a number of conclusions can be drawn, the most important of which may be that the electromagnetic field associated with the operation of a steady-current tethered system will probably be too weak to detect on the Earth's surface, even for large tethered currents. This is due to the total reflection of the incident wave at the atmospheric boundary and the inability of a steady-current tethered system to excite the ionospheric wave-guide. An outline of the approach to the numerical problem is given. The use of numerical integrations and boundary conditions consistent with a conducting Earth is proposed to obtain the solution for the horizontal electromagnetic field components at the boundary of the ionosphere with the atmospheric cavity.

Optimal Electrodynamic Tether Phasing Maneuvers

NASA Technical Reports Server (NTRS)

Bitzer, Matthew S.; Hall, Christopher D.

2007-01-01

We study the minimum-time orbit phasing maneuver problem for a constant-current electrodynamic tether (EDT). The EDT is assumed to be a point mass and the electromagnetic forces acting on the tether are always perpendicular to the local magnetic field. After deriving and non-dimensionalizing the equations of motion, the only input parameters become current and the phase angle. Solution examples, including initial Lagrange costates, time of flight, thrust plots, and thrust angle profiles, are given for a wide range of current magnitudes and phase angles. The two-dimensional cases presented use a non-tilted magnetic dipole model, and the solutions are compared to existing literature. We are able to compare similar trajectories for a constant thrust phasing maneuver and we find that the time of flight is longer for the constant thrust case with similar initial thrust values and phase angles. Full three-dimensional solutions, which use a titled magnetic dipole model, are also analyzed for orbits with small inclinations.

Orbital Winch for High-Strength, Space-Survivable Tethers

NASA Technical Reports Server (NTRS)

Hoyt, Robert; Barnes, Ian; Slostad, Jeffrey; Frank, Scott

2010-01-01

An Orbital Winch mechanism enables high-load, multi-line tethers to be deployed and retracted without rotating the spool on which the tether is wound. To minimize damage to the tether and the wound package during retraction or deployment under load, it can incorporate a Tension Management Module that reduces the infeed tension by a factor of 15 through the use of a powered capstan with guide rollers. This design eliminates the need for rotating high-voltage electrical connections in tether systems that use propellantless electro-dynamic propulsion. It can also eliminate the need for rotating optical connections in applications where the tether contains optical fibers. This winch design was developed to deploy a 15-km-long, 15-kg high-strength Hoytether structure incorporating conductive wires as part of the MXER-1 demonstration mission concept. Two slewing rings that orbit around the tether spool, combined with translation of one of the slewing rings back and forth along the spool axis to traverse the wind point, enables the winch to wind the tether. Variations of the traverse motion of the slewing ring can accomplish level winds and conical pirn winds. By removing the non-traversing slewing ring, and adding an actuated guide arm, the winch can manage rapid, low-drag deployment of a tether off the end of a pirn-wound spool, followed by controlled retraction and rewinding, in a manner very similar to a spin-casting reel. The winch requires at least two motor driver controller units to coordinate the action of two stepper motors to accomplish tether deployment or retraction.

Tethered satellite system

NASA Technical Reports Server (NTRS)

Sisson, J.

1986-01-01

A reusable system is to be developed to enable a variety of scientific investigations to be accomplished from the shuttle, considering the use of a tethered system with manual or automated control, deployment of a satellite toward or away from the Earth, up to 100 km, and conducting or nonconducting tether. Experiments and scientific investigations are to be performed using the tether system for applications such as magnetometry, electrodynamics, atmospheric science, and chemical release. A program is being implemented as a cooperative U.S./Italian activity. The proposed systems, investigations, and the program are charted and briefly discussed.

Laboratory simulation of the interaction between a tethered satellite system and the ionosphere

NASA Astrophysics Data System (ADS)

Vannaroni, G.; Giovi, R.; de Venuto, F.

1992-10-01

The authors report on the measurements performed in the IFSI/CNR plasma chamber at Frascati related to the laboratory investigation of the interaction between a plasma source and an ambient plasma of ionospheric type. Such an interaction is of relevant interest for the possibility of using electrodynamic tethered satellite systems, orbiting at ionospheric altitude, for generating electric power or propulsion in space. The interaction region was analyzed at various conditions of ambient magnetic field (/0-0.5/ G) and at different polarization levels of the plasma source (/0-40/ V). The plasma measurements were carried out with a diagnostic system using an array of Langmuir probes movable in the chamber so that a map of the plasma parameters could be obtained at the different experimental conditions.

Investigation of plasma contactors for use with orbiting wires

NASA Technical Reports Server (NTRS)

Estes, Robert D.; Grossi, Mario D.; Hohlfeld, Robert

1987-01-01

The proposed Shuttle-based short tether experiments with hollow cathodes have the potential for providing important data that will not be obtained in long tether experiments. A critical property for hollow cathode effectiveness as a plasma contactor is the cross magnetic field conductivity of the emitted plasma. The different effects of hollow cathode cloud overlap in the cases of motion-driven and battery-driven operation are emphasized. The calculations presented on the size and shape of the hollow cathode cloud improve the qualitative picture of hollow cathodes in low Earth orbit and provide estimates of time constants for establishing the fully-expanded cloud. The magnetic boundary value problem calculations indicate the way in which the magnetic field will effect the shape of the cloud by resisting expansion in the direction perpendicular to the field. The large-scale interactions of the system were also considered. It was concluded that recent plasma chamber experiments by Stenzel and Urrutia do not model an electrodynamic tether well enough to apply the results to tethered system behavior. Orbiting short tether experiments on hollow cathodes will provide critical information on hollow cathode performance and the underlying physics that cannot be obtained any other way. Experiments should be conducted as soon as funding and a suitable space vehicle are available.

Study of tethered satellite active attitude control

NASA Technical Reports Server (NTRS)

Colombo, G.

1982-01-01

Existing software was adapted for the study of tethered subsatellite rotational dynamics, an analytic solution for a stable configuration of a tethered subsatellite was developed, the analytic and numerical integrator (computer) solutions for this "test case' was compared in a two mass tether model program (DUMBEL), the existing multiple mass tether model (SKYHOOK) was modified to include subsatellite rotational dynamics, the analytic "test case,' was verified, and the use of the SKYHOOK rotational dynamics capability with a computer run showing the effect of a single off axis thruster on the behavior of the subsatellite was demonstrated. Subroutines for specific attitude control systems are developed and applied to the study of the behavior of the tethered subsatellite under realistic on orbit conditions. The effect of all tether "inputs,' including pendular oscillations, air drag, and electrodynamic interactions, on the dynamic behavior of the tether are included.

Orbital transfer and release of tethered payloads. Continuation of investigation of electrodynamic stabilization and control of long orbiting tethers Martinez-Sanchez, Manuel

NASA Technical Reports Server (NTRS)

Colombo, G.; Grossi, M. D.; Arnold, D.

1983-01-01

The effect of reeling operations on the orbital altitude of the tether system and the development of control laws to minimize tether rebound upon payload release were studied. The use of the tether for LEO/GEO payload orbital transfer was also investigated. It was concluded that (1) reeling operations can contribute a significant amount of energy to the orbit of the system and should be considered in orbit calculations and predictions, (2) deployment of payloads, even very large payloads, using tethers is a practical and fully stable operation, (3) tether augmented LEO/GEO transfer operations yield useful payload gains under the practical constraint of fixed size OTV's, and (4) orbit to orbit satellite retrieval is limited by useful revisit times to orbital inclinations of less than forty-five degrees.

The Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.

2002-01-01

This Annual Report covers the following main topics: 1) Updated Reference Mission. The reference ProSEDS (Propulsive Small Expendable Deployer System) mission is evaluated for an updated launch date in the Summer of 2002 and for the new 80-s current operating cycle. Simulations are run for nominal solar activity condition at the time of launch and for extreme conditions of dynamic forcing. Simulations include the dynamics of the system, the electrodynamics of the bare tether, the neutral atmosphere and the thermal response of the tether. 2) Evaluation of power delivered by the tether system. The power delivered by the tethered system during the battery charging mode is computed under the assumption of minimum solar activity for the new launch date. 3) Updated Deployment Control Profiles and Simulations. A number of new deployment profiles were derived based on the latest results of the deployment ground tests. The flight profile is then derived based on the friction characteristics obtained from the deployment tests of the F-1 tether. 4) Analysis/estimation of deployment flight data. A process was developed to estimate the deployment trajectory of the endmass with respect to the Delta and the final libration amplitude from the data of the deployer turn counters. This software was tested successfully during the ProSEDS mission simulation at MSFC (Marshall Space Flight Center) EDAC (Environments Data Analysis Center).

In-Space Transportation with Tethers

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.

1999-01-01

Any analysis of electrodynamic tethers for Space Station applications will soon arrive at the conclusion that currents on the order of 10 A are required. For power generation, we have to foresee needs of several kilowatts even for an emergency backup system. For reboost, we need thrust forces on the order of a Newton, due to the large aerodynamic drag of the Station. In addition, we are restricted by the need to keep perturbations to the Station environment to a minimum. Very long tethers are ruled out by this condition, as they would move the system's center of gravity too much and pose additional operational problems when the Station is docking with other spacecraft. It is easy to show that "standard" tether systems, such as TSS-1, which rely on a large spherical surface to collect electron current from the ionosphere, are unsuitable for ISS applications. A study conducted by MSFC into the possible use of the TSS - 1/R system on the Space Station came to the conclusion that it did not make sense. A quick calculation, using the 10 A benchmark, shows why. TSS-LR collected I A, while the satellite was biased to 1.5 kV. This was twice what had been predicted. Even so, the current collected by the satellite was observed to increase only as the square root of the bias voltage. Thus, to achieve 10 A with the TSS-1 system under the same (daytime) conditions would require a bias voltage of 150 kV, or a tether length of over 850 km! Going to a larger surface would help some, but there is a strong law of diminishing returns for that route. Even if very large spheres were to be allowed (say of 8 m radius), which might achieve useful power levels during optimal conditions of daytime plasma densities with a tether 10 km long, they would suffer from the other Achilles heel of passive spherical collectors: a strong drop in the current (and power goes as the square of the current), as the low plasma densities are encountered during the third of the orbit which is in the Earth's shadow.

REUSABLE PROPULSION ARCHITECTURE FOR SUSTAINABLE LOW-COST ACCESS TO SPACE

NASA Technical Reports Server (NTRS)

Bonometti, J. A.; Dankanich, J. W.; Frame, K. L.

2005-01-01

The primary obstacle to any space-based mission is, and has always been, the cost of access to space. Even with impressive efforts toward reusability, no system has come close to lowering the cost a significant amount. It is postulated here, that architectural innovation is necessary to make reusability feasible, not incremental subsystem changes. This paper shows two architectural approaches of reusability that merit further study investments. Both #inherently# have performance increases and cost advantages to make affordable access to space a near term reality. A rocket launched from a subsonic aircraft (specifically the Crossbow methodology) and a momentum exchange tether, reboosted by electrodynamics, offer possibilities of substantial reductions in the total transportation architecture mass - making access-to-space cost-effective. They also offer intangible benefits that reduce risk or offer large growth potential. The cost analysis indicates that approximately a 50% savings is obtained using today#s aerospace materials and practices.

System engineering study of electrodynamic tether as a spaceborne generator and radiator of electromagnetic waves in the ULF/ELF frequency band

NASA Technical Reports Server (NTRS)

Estes, R. D.; Grossi, M. D.; Lorenzini, E. C.

1986-01-01

The transmission and generation by orbiting tethered satellite systems of information carrying electromagnetic waves in the ULF/ELF frequency band to the Earth at suitably high signal intensities was examined and the system maintaining these intensities in their orbits for long periods of time without excessive onboard power requirements was investigated. The injection quantity power into electromagnetic waves as a function of system parameters such as tether length and orbital height was estimated. The basic equations needed to evaluate alternataing current tethered systems for external energy requirements are presented. The energy equations to tethered systems with various lengths, tether resistances, and radiation resistances, operating at different current values are applied. Radiation resistance as a function of tether length and orbital height is discussed. It is found that ULF/ELF continuously radiating systems could be maintained in orbit with moderate power requirements. The effect of tether length on the power going into electromagnetic waves and whether a single or dual tether system is preferable for the self-driven mode is discussed. It is concluded that the single tether system is preferable over the dual system.

Electrodynamic Tethers. 1: Power Generator in LEO. 2: Thrust for Propulsion and Power Storage

NASA Technical Reports Server (NTRS)

Mccoy, J. E.

1984-01-01

An electrodynamic tether consists of a long insulated wire in space whose orbital motion cuts across lines of magnetic flux to produce an induce voltage that in typical low orbits averages about 200 v/km. Such a system should be capable of generating substantial electrical power, at the expense of IXB drag acting on its orbital energy. If a reverse current is driven against the induced voltage, the system should act as a motor producing IXB thrust. A reference system was designed, capable of generating 20 KW of power into an electrical load located anywhere along the wire at the expense of 2.6N (20,000 J/sec) drag on the wire. In an ideal system, the conversion between mechanical and electrical energy would reach 100% efficiency. In the actual system part of the 20 KW is lost to internal resistance of the wire, plasma and ionosphere, while the drag force is increased by residual air drag. The 20 KW PMG system as designed is estimated to provide 18.7 KW net power to the load at total drag loss of 20.4 KJ/sec, or an overall efficiency of 92%. Similar systems using heavier wire appear capable of producing power levels in excess of 1 Megawatt at voltages of 2-4 KV, with conversion efficiency between mechanical and electrical power better than 95%. The hollow cathode based system should be readily reversible from generator to motor operation by driving a reverse current using onboard power.

Active Space Debris Removal using European Modified Launch Vehicle Upper Stages Equipped with Electrodynamic Tethers

NASA Astrophysics Data System (ADS)

Nasseri, Ali S.; Emanuelli, Matteo; Raval, Siddharth; Turconi, Andrea; Becker, Cristoph

2013-08-01

During the past few years, several research programs have assessed the current state and future evolution of the Low Earth Orbit region. These studies indicate that space debris density could reach a critical level such that there will be a continuous increase in the number of debris objects, primarily driven by debris-debris collision activity known as the Kessler effect. This cascade effect can be even more significant when intact objects as dismissed rocket bodies are involved in the collision. The majority of the studies until now have highlighted the urgency for active debris removal in the next years. An Active Debris Removal System (ADRS) is a system capable of approaching the debris object through a close-range rendezvous, establishing physical connection, stabilizing its attitude and finally de-orbiting the debris object using a type of propulsion system in a controlled manoeuvre. In its previous work, this group showed that a modified Fregat (Soyuz FG's 4th stage) or Breeze-M upper stage (Proton-M) launched from Plesetsk (Russian Federation) and equipped with an electro-dynamic tether (EDT) system can be used, after an opportune inclination's change, to de-orbit a Kosmos-3M second stage rocket body while also delivering an acceptable payload to orbit. In this paper, we continue our work on the aforementioned concept, presented at the 2012 Beijing Space Sustainability Conference, by comparing its performance to ADR missions using only chemical propulsion from the upper stage for the far approach and the de-orbiting phase. We will also update the EDT model used in our previous work and highlight some of the methods for creating physical contact with the object. Moreover, we will assess this concept also with European launch vehicles (Vega and Soyuz 2-1A) to remove space debris from space. In addition, the paper will cover some economic aspects, like the cost for the launches' operator in term of payload mass' loss at the launch. The entire debris removal mission from launch to de-orbiting of the target debris object will be analysed using Analytical Graphic Inc.'s Systems Tool Kit (STK).

Space Debris Removal Using Multi-Mission Modular Spacecraft

NASA Astrophysics Data System (ADS)

Savioli, L.; Francesconi, A.; Maggi, F.; Olivieri, L.; Lorenzini, E.; Pardini, C.

2013-08-01

The study and development of ADR missions in LEO have become an issue of topical interest to the attention of the space community since the future space flight activities could be threatened by collisional cascade events. This paper presents the analysis of an ADR mission scenario where modular remover kits are employed to de-orbit some selected debris in SSO, while a distinct space tug performs the orbital transfers and rendezvous manoeuvres, and installs the remover kits on the client debris. Electro-dynamic tether and electric propulsion are considered as de-orbiting alternatives, while chemical propulsion is employed for the space tug. The total remover mass and de-orbiting time are identified as key parameters to compare the performances of the two de-orbiting options, while an optimization of the ΔV required to move between five selected objects is performed for a preliminary design at system level of the space tug. Final controlled re-entry is also considered and performed by means of a hybrid engine.

Optimal Orbit Maneuvers with Electrodynamic Tethers

DTIC Science & Technology

2006-06-01

orbital elements , which completely describe a unique orbit ; equinoctial elements are not employed but left for future iterations of the formulation...periods in the maneuver. Follow on work, uch as the transformation of this state vector from classical orbital elements to the quinoctial set of...

Working group report on advanced high-voltage high-power and energy-storage space systems

NASA Technical Reports Server (NTRS)

Cohen, H. A.; Cooke, D. L.; Evans, R. W.; Hastings, D.; Jongeward, G.; Laframboise, J. G.; Mahaffey, D.; Mcintyre, B.; Pfizer, K. A.; Purvis, C.

1986-01-01

Space systems in the future will probably include high-voltage, high-power energy-storage and -production systems. Two such technologies are high-voltage ac and dc systems and high-power electrodynamic tethers. The working group identified several plasma interaction phenomena that will occur in the operation of these power systems. The working group felt that building an understanding of these critical interaction issues meant that several gaps in our knowledge had to be filled, and that certain aspects of dc power systems have become fairly well understood. Examples of these current collection are in quiescent plasmas and snap over effects. However, high-voltage dc and almost all ac phenomena are, at best, inadequately understood. In addition, there is major uncertainty in the knowledge of coupling between plasmas and large scale current flows in space plasmas. These gaps in the knowledge are addressed.

Tethered Space Satellite-1 (TSS-1): Technical Roundabouts

NASA Technical Reports Server (NTRS)

O'Connor, Brian; Stevens, Jennifer

2016-01-01

In the early 1990's US and Italian scientists collaborated to study the electrodynamics of dragging a satellite on a tether through the electrically charged portion of Earth's atmosphere called the ionosphere. An electrical current induced in the long wire could be used for power and thrust generation for a satellite. Other tether uses include momentum exchange, artificial gravity, deployment of sensors or antennas, and gravity-gradient stabilization for satellites. Before the Tethered Space Satellite (TSS-1), no long tether had ever been flown, so many questions existed on how it would actually behave. The TSS consisted of a satellite with science experiments attached to a 12.5 mile long, very thin (0.10 inch diameter) copper wire assembly wound around a spool in the deployer reel mechanism. With the Space Shuttle at an altitude of 160 nautical miles above earth, the satellite was to be deployed by raising it from the Shuttle bay on a boom facing away from Earth. Once cleared of the bay, the deployer mechanism was to slowly feed out the 12-plus miles of tether. Scientific data would be collected throughout the operation, after which the satellite would be reeled back in. Pre-flight testing system level tests involved setting up a tether receiver to catch the 12.5 mile tether onto another reel as it was being unwound by the deployer reel mechanism. Testing only the reel mechanism is straightforward. This test becomes more complicated when the TSS is mounted on the flight pallet at Kennedy Space Center (KSC). The system level tests must be passed before the pallet can be installed into the Space Shuttle cargo bay. A few months before flight, the TSS payload had been integrated onto the Spacelab pallet and system level tests, including unreeling and reeling the tether, had been successfully completed. Some of this testing equipment was then shipped back to the contractor Martin Marietta. Systems-level load analyses, which cannot be run until all information about each payload is finalized, was run in parallel with the physical integration of the hardware into the Shuttle payload bay. The coupled loads analysis, as it is called, incorporates any updates to the model due to system level tests, and any changes that were found during integration. The coupled loads analysis revealed that a single bolt attaching the deployer reel mechanism to the support structure had a "negative margin" - which is an indication that it might fail during operation. Hardware certification rules do not allow for hardware to fly with negative margins, so this issue had to be resolved before the flight. Since there is conservatism in engineering analysis, there is an option to "waive" the margin requirement, and fly the experiment as is. On the other hand, a structural failure of one payload could have serious or catastrophic consequences to other payloads and possibly the mission. Minor design changes or fixes might be feasible within the payload bay prior to launch. Any major design changes that required the spooling test to validate the hardware, or for the pallet to be removed, would cause TSS not to be ready for the Shuttle launch.

Advanced Electrodynamic Tether Systems: Modeling of Scattering and Unsteady Effects

DTIC Science & Technology

2008-06-06

SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: a. REPORT b. ABSTRACT c. THIS PAGE 17. LIMITATION OF ABSTRACT 18 . NUMBER OF PAGES 19a. NAME OF...Tether Simulation............................................................................................................... 18 4.3 Simulation of...panels) – the same for actual oxygen ions 18 r 10-1 100 101 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 4 r 0 1 2 3 4 5 6 7 8 9 100 0.2 0.4 0.6 0.8 1 EX

Investigation of EM Emissions by the Electrodynamic Tether, Inclusive of an Observational Program (EMET)

NASA Technical Reports Server (NTRS)

Estes, Robert D.

1998-01-01

Our TSS-1/R investigation, which we shall refer to as EMET in this report, was an integral part of the effort by the TSS-1/R Investigators' Working Group (IWG) to come to an understanding of the complex interaction between the tethered satellite system and the ionosphere. All of the space-borne experiments were designed to collect data relevant to the local interaction. Only the ground- based experiments, EMET and its Italian counterpart Observations on the Earth's Surface of Electromagnetic Emissions (OESEE), held out any hope of characterizing the long range effects of the interaction. This was to be done by detecting electromagnetic waves generated by the system in the ionosphere, assuming the signal reached the Earth's surface with sufficient amplitude. As the type of plasma waves excited to carry charge away from the charge-exchange regions of the system at each end of the tether is one of the theoretical points about which there is greatest disagreement, a definitive identification of tether-generated waves could mark significant progress in the so-called current closure problem of electrodynamic tethers. Dr. Mario Grossi of the Smithsonian Astrophysical Observatory (SAO) initiated the investigation, and his experience in the field of ULF-ELF waves and their detection was invaluable throughout its course. Rice University had the responsibility of setting up the EMET ULF-VLF ground stations under a subcontract from SAO. Principal Investigator (PI) for the Rice effort was Prof. William E. Gordon, who was primary observer at the Arecibo Observatory during TSS-LR. Dr. Steve Noble handled major day-to-day operations, training, and planning for the ground-based measurements. Dr. James McCoy of NASA JSC, a member of the Mona/Arecibo team, was pilot for the numerous flights ferrying personnel and equipment between Puerto Rico and Mona Island. Final responsibility for the measurements rested with SAO, and the activities of field personnel and SAO investigators were closely co-ordinated during the mission. Dr. Enrico Lorenzini of SAO served as the eyes, ears, and brain of EMET in the Science Operations Area and PI table during the mission, whenever the PI was absent during the round-the-clock mission operations. The Rice University final report to SAO, which is included as an Appendix, contains details of the remote sites, means of communication, sensors, etc., as well as the affiliations of personnel involved in the data-gathering effort.

Electrodynamic Tether Operations and Control

NASA Technical Reports Server (NTRS)

Glaese, John R.

2001-01-01

This Final Report is organized by tasks from the statement of work (SOW). A brief statement of each task with its task description followed by a discussion of the work performed is presented. The period of performance for this contract phase was from July 21, 2000 to March 19, 2001.

CubeSat Measurement and Demonstration of Coulomb Drag Effect for Deorbiting

NASA Astrophysics Data System (ADS)

2013-08-01

Deorbiting satellites by passive or active electrodynamic tether Lorentz force effect is well known. Probably less well known is that a charged conducting tether also interacts with the streaming ionospheric plasma by electrostatic Coulomb drag. Especially for the case of small satellites deorbited by thin tethers, the Coulomb drag effect can be larger than the Lorentz force effect. When a tether is optimised for Coulomb drag, the goal is only to keep it charged. The fact that the charged tether gathers current is then a side effect which can be minimised by using negative voltage and by making the tether very thin. Using negative voltage in most cases implies that one can use the satellite's conducting surface as the other electrode so that no electron or ion emitter is needed on the spacecraft for closing the circuit. Thinness of the tether is a large benefit not only from the mass saving and power consumption minimisation points of view, but also because a sufficiently thin tether (made e.g. four 25-50 micrometre thin aluminium wires) poses nearly no threat to other space assets in the even of an unwanted collision. ESTCube-1 is an Estonian 1U CubeSat which is scheduled for Vega launch in May 2013 to 680 km polar orbit. The payload of ESTCube-1 is a 10 m long Heytether made of 25-50 aluminium wires which can be charged to plus orminus 500 V by onboard voltage sources and electron gun. The mission of ESTCube-1 is to demonstrate deployment of very thin multiline (and thus micrometeoroid tolerant) tether and to measure the Coulomb drag effect on the charged tether by ionospheric plasma ram flow. The Coulomb drag has not been measured before and besides useful for deorbiting the effect can also be used to propel interplanetary spacecraft by the fast moving solar wind plasma stream. The measurement of the micronewton scale force is carried out by turning the voltage on and off in a synchronous way with the satellite's rotation and by measuring the cumulative change in the rotation rate over many spin periods. In the presentation we will give the latest update of the ESTCube-1 project as well as its follow-up Aalto-1 satellite mission.

Avionics Simulation, Development and Software Engineering

NASA Technical Reports Server (NTRS)

Francis, Ronald C.; Settle, Gray; Tobbe, Patrick A.; Kissel, Ralph; Glaese, John; Blanche, Jim; Wallace, L. D.

2001-01-01

This monthly report summarizes the work performed under contract NAS8-00114 for Marshall Space Flight Center in the following tasks: 1) Purchase Order No. H-32831D, Task Order 001A, GPB Program Software Oversight; 2) Purchase Order No. H-32832D, Task Order 002, ISS EXPRESS Racks Software Support; 3) Purchase Order No. H-32833D, Task Order 003, SSRMS Math Model Integration; 4) Purchase Order No. H-32834D, Task Order 004, GPB Program Hardware Oversight; 5) Purchase Order No. H-32835D, Task Order 005, Electrodynamic Tether Operations and Control Analysis; 6) Purchase Order No. H-32837D, Task Order 007, SRB Command Receiver/Decoder; and 7) Purchase Order No. H-32838D, Task Order 008, AVGS/DART SW and Simulation Support

An Approach to Optimal Control of Electrodynamic Tethers in a Stochastically Varying Drag Environment

DTIC Science & Technology

2011-05-06

and used to help address some of the complications and drawbacks of chemical propulsion systems. One such technology is electric propulsion, which...in and out of the orbital plane around its equilibrium point. The motion is similar to a swinging pendulum . These librations are due to the

Tethered Space Satellite-1 (TSS-1): Wound About a Bolt

NASA Technical Reports Server (NTRS)

O'Connor, Brian; Stevens, Jennifer

2016-01-01

In the early 1990's US and Italian scientists collaborated to study the electrodynamics on a long tether between two satellites as it moved through the electrically charged portion of Earth's atmosphere called the ionosphere. Potential uses for the electrical current induced in the long wire include power and thrust generation for a satellite, momentum exchange, artificial gravity, deployment of sensors or antennas, and gravity-gradient stabilization. The Tethered Space Satellite (TSS) was a first-of-its-kind experiment with long tethers in space. It consisted of a satellite with science experiments attached to a 12.5 mile long, very thin (0.10 inch diameter) copper wire assembly wound around a spool in the deployer reel mechanism. The whole mechanism sits on a pallet that is installed into the Shuttle bay. At an altitude of 160 nautical miles above earth, the satellite would be deplodeployed from the Shuttle bay by raising it on a boom facing away from Earth. Once cleared of the bay, the deployer mechanism would slowly feed out the 12-plus miles of tether. Scientific data would be collected throughout the operation, after which the satellite would be reeled back in. A receiver spool to catch the 12.5 mile tether as it was being unwound by the deployer reel mechanism was set up to do the system-level test of deployer real mechanism prior to installing the loaded pallet into the Shuttle bay. The system level tests were required before the pallet could be installed into the Space Shuttle cargo bay. A few months before flight, the system level tests, including unreeling and reeling the tether, were completed at Kennedy Space Center (KSC) and the TSS payload was installed onto the Spacelab pallet. Some of this testing equipment was then shipped back to the contractor, Martin Marietta. Integration with the Shuttle began. Systems-level load analyses, which cannot be run until all information about each payload is finalized, was run in parallel with the physical integration of the hardware into the Shuttle payload bay. An analysis, called Coupled loads analysis, incorporates any updates to the model due to system level tests of all the different payloads, and any changes that were found during integration. Engineering analysis examines the worst case scenarios for the loads the hardware will see. The two times during the mission where the dynamic loads are the worst were 1) the first 10-second portion of Shuttle lift off, and 2) a 2-second time during landing when the landing gears hit the ground. The coupled loads analysis using the final verification loads showed that a single bolt attaching the deployer reel mechanism to the support structure had a "negative margin" - which is an indication that it might fail - during touch down. Hardware certification rules do not allow for hardware to fly with negative margins. A structural failure of one payload could have serious or catastrophic consequences to other payloads, or may significantly damage the Orbiter. The issue had to be resolved before the flight.

Development of a Rotating Magnetized Plasma Device

NASA Astrophysics Data System (ADS)

Cooke, David; Patton, James; Reid, Remington; Stiles, Ashley; Morrison, Patrik; Koch, Andrei

2017-10-01

Momentum coupling in plasma is a mechanism that is central to a wide range of interesting and important phenomena, magnetosphere-ionosphere coupling, solar eruptions, the interaction of an electro-dynamic tether system in the Earth's ionosphere, and the Critical Ionization Velocity (CIV) mechanism are a few examples. One result of the Space Shuttle Tethered Satellite experiment, TSS-1R, was that the current-voltage response of the experiment in all orbit conditions fell into a narrow range of curves when parameterized as a plasma probe [Thompson, GRL,1998]. Another striking result was the lack of dependence on the Alfvén velocity or other electro-magnetic parameters. This result has led us to revisit the understanding of the speed with which an electric field propagates along the magnetic field using EM-PIC simulation and experiments in our new magnetized plasma chamber. Our initial experiment is a rotating plasma using a solenoidal magnetic field and a radial electric field, with pulsed differential rotation of the plasma column to study the strength of coupling and propagation speed. Characteristics of our `first light' rotating plasma will be presented. Supported by Air Force Office Scientific Research 16RVCOR264.

In-Space Transportation with Tethers

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico; Estes, Robert D.; Cosmo, Mario L.

1998-01-01

The annual report covers the research conducted on the following topics related to the use of spaceborne tethers for in-space transportation: ProSEDS tether modeling (current collection analyses, influence of a varying tether temperature); proSEDS mission analysis and system dynamics (tether thermal model, thermo-electro-dynamics integrated simulations); proSEDS-tether development and testing (tether requirements, deployment test plan, tether properties testing, deployment tests); and tethers for reboosting the space-based laser (mission analysis, tether system preliminary design, evaluation of attitude constraints).

Power and charge dissipation from an electrodynamic tether

NASA Technical Reports Server (NTRS)

Hite, Gerald E.

1987-01-01

The Plasma Motor-Generator project utilizes the influence of the geomagnetic field on a conductive tether attached to a LEO spacecraft to provide a reversible conversion of orbital energy into electrical energy. The behavior of the current into the ionospheric plasma under the influence of the geomagnetic field is of significant experimental and theoretical interest. Theoretical calculations are reviewed which start from Maxwell's equations and treat the ionospheric plasma as a linear dielectric medium. These calculations show a charge emitting tether moving in a magnetic field will generate electromagnetic waves in the plasma which carry the charge in the direction of the magnetic field. The ratio of the tether's speed to the ion cyclotron frequency which is about 25 m for a LEO is a characteristic length for the phenomena. Whereas for the dimensions of the contact plasma much larger than this value the waves are the conventional Alfven waves, when the dimensions are comparable or smaller, diffraction effects occur similar to those associated with Fresnel diffraction in optics. The power required to excite these waves for a given tether current is used to estimate the impedance associated with this mode of charge dissipation.

Space Tethers: Design Criteria

NASA Technical Reports Server (NTRS)

Tomlin, D. D.; Faile, G. C.; Hayashida, K. B.; Frost, C. L.; Wagner, C. Y.; Mitchell, M. L.; Vaughn, J. A.; Galuska, M. J.

1997-01-01

This document is prepared to provide a systematic process for the selection of tethers for space applications. Criteria arc provided for determining the strength requirement for tether missions and for mission success from tether severing due to micrometeoroids and orbital debris particle impacts. Background information of materials for use in space tethers is provided, including electricity-conducting tethers. Dynamic considerations for tether selection is also provided. Safety, quality, and reliability considerations are provided for a tether project.

Dynamics and offset control of tethered space-tug system

NASA Astrophysics Data System (ADS)

Zhang, Jingrui; Yang, Keying; Qi, Rui

2018-01-01

Tethered space-tug system is regarded as one of the most promising active debris removal technologies to effectively decrease the steep increasing population of space debris. In order to suppress the spin of space debris, single-tethered space-tug system is employed by regulating the tether. Unfortunately, this system is underactuated as tether length is the only input, and there are two control objectives: the spinning debris and the vibration of tether. Thus, it may suffer great oscillations and result in failure in space debris removal. This paper presents the study of attitude stabilization of the single-tethered space-tug system using not only tether length but also the offset of tether attachment point to suppress the spin of debris, so as to accomplish the space debris removal mission. Firstly, a precise 3D mathematical model in which the debris and tug are both treated as rigid bodies is developed to study the dynamical evolution of the tethered space-tug system. The relative motion equation of the system is described using Lagrange method. Secondly, the dynamic characteristic of the system is analyzed and an offset control law is designed to stabilize the spin of debris by exploiting the variation of tether offset and the regulation of tether length. Besides, an estimation formula is proposed to evaluate the capability of tether for suppressing spinning debris. Finally, the effectiveness of attitude stabilization by the utilization of the proposed scheme is demonstrated via numerical case studies.

Electron Field Emission Properties of Textured Platinum Surfaces

NASA Technical Reports Server (NTRS)

Sovey, James S.

2002-01-01

During ground tests of electric microthrusters and space tests of electrodynamic tethers the electron emitters must successfully operate at environmental pressures possibly as high as 1x10(exp -4) Pa. High partial pressures of oxygen, nitrogen, and water vapor are expected in such environments. A textured platinum surface was used in this work for field emission cathode assessments because platinum does not form oxide films at low temperatures. Although a reproducible cathode conditioning process did not evolve from this work, some short term tests for periods of 1 to 4 hours showed no degradation of emission current at an electric field of 8 V/mm and background pressures of about 1x10(exp -6) Pa. Increases of background pressure by air flow to about 3x10(exp -4) Pa yield a hostile environment for the textured platinum field emission cathode.

Magnetour: Surfing planetary systems on electromagnetic and multi-body gravity fields

NASA Astrophysics Data System (ADS)

Lantoine, Gregory; Russell, Ryan P.; Anderson, Rodney L.; Garrett, Henry B.

2017-09-01

A comprehensive tour of the complex outer planet systems is a central goal in space science. However, orbiting multiple moons of the same planet would be extremely prohibitive using traditional propulsion and power technologies. In this paper, a new mission concept, named Magnetour, is presented to facilitate the exploration of outer planet systems and address both power and propulsion challenges. This approach would enable a single spacecraft to orbit and travel between multiple moons of an outer planet, without significant propellant or onboard power source. To achieve this free-lunch 'Grand Tour', Magnetour exploits the unexplored combination of magnetic and multi-body gravitational fields of planetary systems, with a unique focus on using a bare electrodynamic tether for power and propulsion. Preliminary results indicate that the Magnetour concept is sound and is potentially highly promising at Jupiter.

The role of tethers on space station

NASA Technical Reports Server (NTRS)

Vontiesenhausen, G. (Editor)

1985-01-01

The results of research and development that addressed the usefulness of tether applications in space, particularly for space station are described. A well organized and structured effort of considerable magnitude involving NASA, industry and academia have defined the engineering and technological requirements of space tethers and their broad range of economic and operational benefits. The work directed by seven NASA Field Centers is consolidated and structured to cover the general and specific roles of tethers in space as they apply to NASA's planned space station. This is followed by a description of tether systems and operations. A summary of NASA's plans for tether applications in space for years to come is given.

Space experiments on basic technologies for a space elevator using microsatellites

NASA Astrophysics Data System (ADS)

Yamagiwa, Yoshiki; Nohmi, Masahiro; Aoki, Yoshio; Momonoi, Yu; Nanba, Hirotaka; Aiga, Masanori; Kumao, Takeru; Watahiki, Masahito

2017-09-01

We attempt to verify two basic technologies required for a space elevator using microsatellites; the tether (cable) deployment technology and the climber operation along the tether in space. Tether deployment is performed by a CubeSat called STARS-C (Space Tethered Autonomous Robotic Satellite - Cube) which will be released from the Japanese experimental module Kibo on ISS early in 2017. STARS-C consists of a mother satellite (MS) and daughter satellite (DS) connected by a 100-m tether. Its mission is focused on the tether deployment for studying the tether dynamics during the deployment with the goal of improving the smoothness of such deployment in future tether missions including space elevator. The MS and DS have common subsystems, including power, communication, and command and data handling systems. They also have a tether unit with spool and reel mechanisms as a mission system. In addition, we have been designing the next-step microsatellite called STARS-E (Space Tethered Autonomous Robotic Satellite - Elevator) under a Grant-in-Aid for Scientific Research. STARS-E is a 500-mm size satellite intended to verify the climber operation in space. It consists of a MS and DS jointed by a 2-km tether, and a climber that moves along the tether. STARS-C was launched on December 9 in 2016 and will be performed its mission early in 2017. STARS-E is in the BBM phase, and some designs are currently being fixed.

NASA In-Space Propulsion Technology Program: Overview and Update

NASA Technical Reports Server (NTRS)

Johnson, Les; Alexander, Leslie; Baggett, Randy M.; Bonometti, Joseph A.; Herrmann, Melody; James, Bonnie F.; Montgomery, Sandy E.

2004-01-01

NASA's In-Space Propulsion Technology Program is investing in technologies that have the potential to revolutionize the robotic exploration of deep space. For robotic exploration and science missions, increased efficiencies of future propulsion systems are critical to reduce overall life-cycle costs and, in some cases, enable missions previously considered impossible. Continued reliance on conventional chemical propulsion alone will not enable the robust exploration of deep space - the maximum theoretical efficiencies have almost been reached and they are insufficient to meet needs for many ambitious science missions currently being considered. The In-Space Propulsion Technology Program's technology portfolio includes many advanced propulsion systems. From the next-generation ion propulsion system operating in the 5- to 10-kW range to aerocapture and solar sails, substantial advances in - spacecraft propulsion performance are anticipated. Some of the most promising technologies for achieving these goals use the environment of space itself for energy and propulsion and are generically called 'propellantless' because they do not require onboard fuel to achieve thrust. Propellantless propulsion technologies include scientific innovations such as solar sails, electrodynamic and momentum transfer.tethers, aeroassist and aerocapture. This paper will provide an overview of both propellantless and propellant-based advanced propulsion technologies, as well as NASA's plans for advancing them as part of the In-Space Propulsion Technology Program.

NASA's In-Space Propulsion Technology Program: Overview and Status

NASA Technical Reports Server (NTRS)

Johnson, Les; Alexander, Leslie; Baggett, Randy; Bonometti, Joe; Herrmann, Melody; James, Bonnie; Montgomery, Sandy

2004-01-01

NASA's In-Space Propulsion Technology Program is investing in technologies that have the potential to revolutionize the robotic exploration of deep space. For robotic exploration and science missions, increased efficiencies of future propulsion systems are critical to reduce overall life-cycle costs and, in some cases, enable missions previously considered impossible. Continued reliance on conventional chemical propulsion alone will not enable the robust exploration of deep space - the maximum theoretical efficiencies have almost been reached and they are insufficient to meet needs for many ambitious science missions currently being considered. The In-Space Propulsion Technology Program s technology portfolio includes many advanced propulsion systems. From the next generation ion propulsion system operating in the 5 - 10 kW range, to advanced cryogenic propulsion, substantial advances in spacecraft propulsion performance are anticipated. Some of the most promising technologies for achieving these goals use the environment of space itself for energy and propulsion and are generically called, 'propellantless' because they do not require onboard fuel to achieve thrust. Propellantless propulsion technologies include scientific innovations such as solar sails, electrodynamic and momentum transfer tethers, aeroassist, and aerocapture. This paper will provide an overview of both propellantless and propellant-based advanced propulsion technologies, and NASA s plans for advancing them as part of the $60M per year In-Space Propulsion Technology Program.

NASA's In-Space Propulsion Technology Program: Overview and Update

NASA Technical Reports Server (NTRS)

Johnson, Les; Alexander, Leslie; Baggett, Randy M.; Bonometti, Joseph A.; Herrmann, Melody; James, Bonnie F.; Montgomery, Sandy E.

2004-01-01

NASA's In-Space Propulsion Technology Program is investing in technologies that have the potential to revolutionize the robotic exploration of deep space. For robotic exploration and science missions, increased efficiencies of future propulsion systems are critical to reduce overall life-cycle costs and, in some cases, enable missions previously considered impossible. Continued reliance on conventional chemical propulsion alone will not enable the robust exploration of deep space - the maximum theoretical efficiencies have almost been reached and they are insufficient to meet needs for many ambitious science missions currently being considered. The In-Space Propulsion Technology Program s technology portfolio includes many advanced propulsion systems. From the next-generation ion propulsion system operating in the 5- to 10-kW range to aerocapture and solar sails, substantial advances in spacecraft propulsion performance are anticipated. Some of the most promising technologies for achieving these goals ase the environment of space itself for energy and propulsion and are generically called 'propellantless' because they do not require onboard fuel to achieve thrust. Propellantless propulsion technologies include scientific innovations such as solar sails, electrodynamic and momentum transfer tethers, aeroassist, and aerocapture. This paper will provide an overview of both propellantless and propellant-based advanced propulsion technologies, as well as NASA s plans for advancing them as part of the In-Space Propulsion Technology Program.

Tethers in space: Birth and growth of a new avenue to space utilization

NASA Technical Reports Server (NTRS)

Vontiesenhausen, G.

1984-01-01

The evolution of the ideas of tether applications in space are traced from its origin in the last century past a dormant period of sixty-five years to the mid-seventies. At that time as a consequence of major revival efforts, NASA entered into serious investigations of the theoretical and practical feasibility of a large number of tethered concepts in space. These efforts culminated in the establishment of the Tethered Satellite System Project now at NASA in the advanced development phase. Extensive planning efforts are described, first, through a Tether Applications in Space Workshop which generated additional concepts and provided overall assessments and recommendations to NASA, and then through a NASA inter-center Tether Applications in Space Task Group which generated a four year program plan in the areas of further studies, technology, work and science and applications of tethers in space. An outlook into the future of tether applications that approaches some of the goals of the early visionaries is offered.

A dynamic analysis of the radiation excitation from the activation of a current collecting system in space

NASA Technical Reports Server (NTRS)

Wang, J.; Hastings, D. E.

1991-01-01

Current collecting systems moving in the ionosphere will induce electromagnetic wave radiation. The commonly used static analysis is incapable of studying the situation when such systems undergo transient processes. A dynamic analysis has been developed, and the radiation excitation processes are studied. This dynamic analysis is applied to study the temporal wave radiation from the activation of current collecting systems in space. The global scale electrodynamic interactions between a space-station-like structure and the ionospheric plasma are studied. The temporal evolution and spatial propagation of the electric wave field after the activation are described. The wave excitations by tethered systems are also studied. The dependencies of the temporal Alfven wave and lower hybrid wave radiation on the activation time and the space system structure are discussed. It is shown that the characteristics of wave radiation are determined by the matching of two sets of characteristic frequencies, and a rapid change in the current collection can give rise to substantial transient radiation interference. The limitations of the static and linear analysis are examined, and the condition under which the static assumption is valid is obtained.

Dynamic modeling and Super-Twisting Sliding Mode Control for Tethered Space Robot

NASA Astrophysics Data System (ADS)

Zhao, Yakun; Huang, Panfeng; Zhang, Fan

2018-02-01

Recent years, tethered space capturing systems have been considered as one of the most promising solutions for active space debris removal due to the increasing threat of space debris to spacecraft and astronauts. In this paper, one of the tethered space capturing systems, Tethered Space Robot (TSR), is investigated. TSR includes a space platform, a space tether, and a gripper as the terminal device. Based on the assumptions that the platform and the gripper are point masses and the tether is rigid, inextensible and remaining straight, the dynamic model of TSR is presented, in which the disturbances from space environment is considered. According to the previous study, the in-plane and out-of-plane angles of the tether oscillate periodically although the tether is released to the desired length. A super-twisting adaptive sliding mode control scheme is designed for TSR to eliminate the vibration of the tether to assure a successful capture in station-keeping phase. Both uncontrolled and controlled situations are simulated. The simulation results show that the proposed controller is effective. Additionally, after comparing with normal sliding mode control algorithm, it is verified that the proposed control scheme can avoid the chattering of normal sliding mode control and is robust for unknown boundary perturbations.

The effect of plasma density and emitter geometry on space charge limits for field emitter array electron charge emission into a space plasma

NASA Astrophysics Data System (ADS)

Morris, Dave; Gilchrist, Brian; Gallimore, Alec

2001-02-01

Field Emitter Array Cathodes (FEACs) are a new technology being developed for several potential spacecraft electron emission and charge control applications. Instead of a single hot (i.e., high powered) emitter, or a gas dependant plasma contactor, FEAC systems consist of many (hundreds or thousands) of small (micron level) cathode/gate pairs printed on a semiconductor wafer that effect cold field emission at relatively low voltages. Each individual cathode emits only micro-amp level currents, but a functional array is capable of amp/cm2 current densities. It is hoped that thus FEAC offers the possibility of a relatively low-power, simple to integrate, and inexpensive technique for the high level of current emissions that are required for an electrodynamic tether (EDT) propulsion mission. Space charge limits are a significant concern for the EDT application. Vacuum chamber tests and PIC simulations are being performed at the University of Michigan Plasmadynamics and Electric Propulsion Laboratory and Space Physics Research Laboratory to determine the effect of plasma density and emitter geometry on space charge limitations. The results of this work and conclusions to date of how to best mitigate space charge limits will be presented. .

Research on Orbital Plasma Electrodynamics (ROPE)

NASA Technical Reports Server (NTRS)

Intriligator, Devrie S.

1998-01-01

This final report summarizes some of the important scientific contributions to the Research on Orbital Plasma Electrodynamics (ROPE) investigation, to the Tethered Satellite System (TSS) mission, and to NASA that resulted from the work carried out under this contract at Carmel Research Center. These include Dr. Intriligator's participation in the PIT for the TSS-1R simulations and flight, her participation in ROPE team meetings and IWG meetings, her scientific analyses, and her writing and submitting technical papers to scientific journals. The scientific analyses concentrated on the characterization of energetic ions and their possible relation to pickup ion effects, correlation of particle and other effects (e.g., magnetic field, satellite surface), and collaboration with theorists including with ROPE co-investigators. In addition, scientific analyses were carried out of the effects due to satellite gas releases.

Middle atmospheric electrodynamics

NASA Technical Reports Server (NTRS)

Kelley, M. C.

1983-01-01

A review is presented of the advances made during the last few years with respect to the study of the electrodynamics in the earth's middle atmosphere. In a report of the experimental work conducted, attention is given to large middle atmospheric electric fields, the downward coupling of high altitude processes into the middle atmosphere, and upward coupling of tropospheric processes into the middle atmosphere. It is pointed out that new developments in tethered balloons and superpressure balloons should greatly increase the measurement duration of earth-ionospheric potential measurements and of stratospheric electric field measurements in the next few years. Theoretical work considered provides an excellent starting point for study of upward coupling of transient and dc electric fields. Hays and Roble (1979) were the first to construct a model which included orographic features as well as the classical thunderstorm generator.

Investigation of Endurance Performance of Carbon Nanotube Cathodes

NASA Astrophysics Data System (ADS)

Saito, Nanako; Yamagiwa, Yoshiki; Ohkawa, Yasushi; Nishida, Shin-Ichiro; Kitamura, Shoji

The Aerospace Research and Development Directorate of the Japan Aerospace Exploration Agency (JAXA) is considering a demonstration of electrodynamic tether (EDT) systems in low Earth orbit (LEO). Carbon nanotubes (CNTs) have some advantages as electron sources compared to conventional Spindt type emitters, and so are expected to be useful in EDT systems. Experiments to investigate the durability of CNT cathodes in a space environment had been conducted in a diode mode, but it was found that electron extraction tests, in which the cathode with a gate electrode is used, are necessary to evaluate the endurance of CNTs more accurately. In this paper, we conducted long duration operating tests of a cathode with a gate. It was found that there was almost no change in cathode performance at current densities below 100 A/m2 even after the cathode was operated for over 500 hours in the high vacuum environment.

Theory of plasma contractors for electrodynamic tethered satellite systems

NASA Technical Reports Server (NTRS)

Parks, D. E.; Katz, I.

1986-01-01

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.

Analysis of the effect of attachment point bias during large space debris removal using a tethered space tug

NASA Astrophysics Data System (ADS)

Chu, Zhongyi; Di, Jingnan; Cui, Jing

2017-10-01

Space debris occupies a valuable orbital resource and is an inevitable and urgent problem, especially for large space debris because of its high risk and the possible crippling effects of a collision. Space debris has attracted much attention in recent years. A tethered system used in an active debris removal scenario is a promising method to de-orbit large debris in a safe manner. In a tethered system, the flexibility of the tether used in debris removal can possibly induce tangling, which is dangerous and should be avoided. In particular, attachment point bias due to capture error can significantly affect the motion of debris relative to the tether and increase the tangling risk. Hence, in this paper, the effect of attachment point bias on the tethered system is studied based on a dynamic model established based on a Newtonian approach. Next, a safety metric of avoiding a tangle when a tether is tensioned with attachment point bias is designed to analyse the tangling risk of the tethered system. Finally, several numerical cases are established and simulated to validate the effects of attachment point bias on a space tethered system.

Learning characteristics of a space-time neural network as a tether skiprope observer

NASA Technical Reports Server (NTRS)

Lea, Robert N.; Villarreal, James A.; Jani, Yashvant; Copeland, Charles

1993-01-01

The Software Technology Laboratory at the Johnson Space Center is testing a Space Time Neural Network (STNN) for observing tether oscillations present during retrieval of a tethered satellite. Proper identification of tether oscillations, known as 'skiprope' motion, is vital to safe retrieval of the tethered satellite. Our studies indicate that STNN has certain learning characteristics that must be understood properly to utilize this type of neural network for the tethered satellite problem. We present our findings on the learning characteristics including a learning rate versus momentum performance table.

NASA's In-Space Propulsion Technology Program: A Step Toward Interstellar Exploration

NASA Technical Reports Server (NTRS)

Johnson, Les; James, Bonnie; Baggett, Randy; Montgomery, Sandy

2005-01-01

NASA's In-Space Propulsion Technology Program is investing in technologies that have the potential to revolutionize the robotic exploration of deep space. For robotic exploration and science missions, increased efficiencies of future propulsion systems are critical to reduce overall life-cycle costs and, in some cases, enable missions previously considered impossible. Continued reliance on conventional chemical propulsion alone will not enable the robust exploration of deep space. The maximum theoretical efficiencies have almost been reached and are insufficient to meet needs for many ambitious science missions currently being considered. By developing the capability to support mid-term robotic mission needs, the program is laying the technological foundation for travel to nearby interstellar space. The In-Space Propulsion Technology Program s technology portfolio includes many advanced propulsion systems. From the next-generation ion propulsion systems operating in the 5-10 kW range, to solar sail propulsion, substantial advances in spacecraft propulsion performance are anticipated. Some of the most promising technologies for achieving these goals use the environment of space itself for energy and propulsion and are generically called "propellantless" because they do not require onboard fuel to achieve thrust. Propellantless propulsion technologies include scientific innovations, such as solar sails, electrodynamic and momentum transfer tethers, and aerocapture. This paper will provide an overview of those propellantless and propellant-based advanced propulsion technologies that will most significantly advance our exploration of deep space.

Tether dynamics and control results for tethered satellite system's initial flight

NASA Astrophysics Data System (ADS)

Chapel, Jim D.; Flanders, Howard

The recent Tethered Satellite System-1 (TSS-1) mission has provided a wealth of data concerning the dynamics of tethered systems in space and has demonstrated the effectiveness of operational techniques designed to control these dynamics. In this paper, we review control techniques developed for managing tether dynamics, and discuss the results of using these techniques for the Tethered Satellite System's maiden flight on STS-46. In particular, the flight results of controlling libration dynamics, string dynamics, and slack tether are presented. These results show that tether dynamics can be safely managed. The overall stability of the system was found to be surprisingly good even at relatively short tether lengths. In fact, the system operated in passive mode at a tether length of 256 meters for over 9 hours. Only monitoring of the system was required during this time. Although flight anomalies prevented the planned deployment to 20 km, the extended operations at shorter tether lengths have proven the viability of using tethers in space. These results should prove invaluable in preparing for future missions with tethered objects in space.

Tether dynamics and control results for tethered satellite system's initial flight

NASA Technical Reports Server (NTRS)

Chapel, Jim D.; Flanders, Howard

1993-01-01

The recent Tethered Satellite System-1 (TSS-1) mission has provided a wealth of data concerning the dynamics of tethered systems in space and has demonstrated the effectiveness of operational techniques designed to control these dynamics. In this paper, we review control techniques developed for managing tether dynamics, and discuss the results of using these techniques for the Tethered Satellite System's maiden flight on STS-46. In particular, the flight results of controlling libration dynamics, string dynamics, and slack tether are presented. These results show that tether dynamics can be safely managed. The overall stability of the system was found to be surprisingly good even at relatively short tether lengths. In fact, the system operated in passive mode at a tether length of 256 meters for over 9 hours. Only monitoring of the system was required during this time. Although flight anomalies prevented the planned deployment to 20 km, the extended operations at shorter tether lengths have proven the viability of using tethers in space. These results should prove invaluable in preparing for future missions with tethered objects in space.

Design of a reusable kinetic energy absorber for an astronaut safety tether to be used during extravehicular activities on the Space Station

NASA Technical Reports Server (NTRS)

Borthwick, Dawn E.; Cronch, Daniel F.; Nixon, Glen R.

1991-01-01

The goal of this project is to design a reusable safety device for a waist tether which will absorb the kinetic energy of an astronaut drifting away from the Space Station. The safety device must limit the tension of the tether line in order to prevent damage to the astronaut's space suit or to the structure of the spacecraft. The tether currently used on shuttle missions must be replaced after the safety feature has been developed. A reusable tether for the Space Station would eliminate the need for replacement tethers, conserving space and mass. This report presents background information, scope and limitations, methods of research and development, alternative designs, a final design solution and its evaluation, and recommendations for further work.

The Deflection Plate Analyzer: A Technique for Space Plasma Measurements Under Highly Disturbed Conditions

NASA Technical Reports Server (NTRS)

Wright, Kenneth H., Jr.; Dutton, Ken; Martinez, Nelson; Smith, Dennis; Stone, Nobie H.

2004-01-01

A technique has been developed to measure the characteristics of space plasmas under highly disturbed conditions; e.g., non-Maxwellian plasmas with strong drifting populations and plasmas contaminated by spacecraft outgassing. The present method is an extension of the capabilities of the Differential Ion Flux Probe (DIFP) to include a mass measurement that does not include either high voltage or contamination sensitive devices such as channeltron electron multipliers or microchannel plates. This reduces the complexity and expense of instrument fabrication, testing, and integration of flight hardware as compared to classical mass analyzers. The new instrument design is called the Deflection Plate Analyzer (DPA) and can deconvolve multiple ion streams and analyze each stream for ion flux intensity (density), velocity (including direction of motion), mass, and temperature (or energy distribution). The basic functionality of the DPA is discussed. The performance characteristics of a flight instrument as built for an electrodynamic tether mission, the Propulsive Small Expendable Deployer System (ProSEDS), and the instrument s role in measuring key experimental conditions are also discussed.

The Deflection Plate Analyzer: A Technique for Space Plasma Measurements Under Highly Disturbed Conditions

NASA Technical Reports Server (NTRS)

Wright, Kenneth H., Jr.; Dutton, Ken; Martinez, Nelson; Smith, Dennis; Stone, Nobie H.

2003-01-01

A technique has been developed to measure the characteristics of space plasmas under highly disturbed conditions; e.g., non-Maxwellian plasmas with strong drifting populations and plasmas contaminated by spacecraft outgassing. The present method is an extension of the capabilities of the Differential Ion Flux Probe (DIFP) to include a mass measurement that does not include either high voltage or contamination sensitive devices such as channeltron electron multipliers or microchannel plates. This reduces the complexity and expense of instrument fabrication, testing, and integration of flight hardware as compared to classical mass analyzers. The new instrument design is called the Deflection Plate Analyzer (DPA) and can deconvolve multiple ion streams and analyze each stream for ion flux intensity (density), velocity (including direction of motion), mass, and temperature (or energy distribution). The basic functionality of the DPA is discussed. The performance characteristics of a flight instrument as built for an electrodynamic tether mission, the Propulsive Small Expendable Deployer System (ProSEDS), and the instrument s role in measuring key experimental conditions are also discussed.

Flight mechanics applications for tethers in space: Cooperative Italian-US programs

NASA Technical Reports Server (NTRS)

Bevilacqua, Franco; Merlina, Pietro; Anderson, John L.

1990-01-01

Since the 1974 proposal by Giuseppe Colombo to fly a tethered subsatellite from the Shuttle Orbiter, the creative thinking of many scientists and engineers from Italy and U.S. has generated a broad range of potential tether applications in space. Many of these applications have promise for enabling innovative research and operational activities relating to flight mechanics in earth orbit and at suborbital altitudes. From a flight mechanics standpoint the most interesting of the currently proposed flight demonstrations are: the second Tethered Satellite System experiment which offers both the potential for aerothermodynamics and hypersonics research and for atmospheric science research; the Tethered Initiated Space Recovery System which would enable orbital deboost and recovery of a re-entry vehicle and waste removal from a space station; and the Tether Elevator/Crawler System which would provide a variable microgravity environment and space station center of mass management. The outer atmospheric and orbital flight mechanics characteristics of these proposed tether flight demonstrations are described. The second Tethered Satellite System mission will deploy the tethered satellite earthward and will bring it as low as 130 km from ground and thus into the transition region between the atmosphere (non-ionized) and the partially ionized ionosphere. The atmospheric flight mechanics of the tethered satellite is discussed and simulation results are presented. The Tether Initiated Space Recovery System experiment will demonstrate the ability of a simple tether system to deboost and recover a reentry vehicle. The main feature of this demonstration is the utilization of a Small Expendable Deployment System (SEDS) and the low-tension deployment assumed to separate the reentry vehicle from the Shuttle. This low-tension deployment maneuver is discussed and its criticalities are outlined. The Tether Elevator/Crawler System is a new space element able to move in a controlled way between the ends of a deployed tethered system. A Shuttle test of an Elevator model is planned to demonstrate the unique capability of this element as a microgravity facility and to test the transfer motion control. The basic dynamical features of the Elevator system are presented and a preliminary assessment of the Elevator-induced tether vibrations is discussed.

Proceedings of a Workshop on Applications of Tethers in Space, Executive Summary

NASA Technical Reports Server (NTRS)

1983-01-01

The objectives were to identify potential applications for tethers in space; develop a first order assessment of the feasibility and benefits of tether applications; recommend future actions necessary to enable tether applications, including required technology advancements; and stimulate industry and government planners to consider the unique properties of tethers in designs for future missions.

Optimal Control of Electrodynamic Tethers

DTIC Science & Technology

2008-06-01

the out-of- plane component of the magnetic field which produces the required in- track thrust is reduced (see Eq. as th sp lo e a (4... the same orbital plane using an EDT. For the sake of testing the algorithm against a known solution we seek the maximum altitude an EDT can reach...be incl planes co gnetic equatorial plane ent of latit and m mi ains constant as the EDT ity the Eart e tilted with respect to the

The first mission of the Tethered Satellite System

NASA Technical Reports Server (NTRS)

Powers, C. Blake (Editor); Shea, Charlotte; Mcmahan, Tracy

1992-01-01

The era of space-age tethered operations moves toward reality with the launch of Tethered Satellite System-1 (TSS-1). The primary objective of this mission is to demonstrate the technology of long tethered systems in space and to demonstrate, through scientific investigations, that such systems are useful for research.

Space tether dynamics: an introduction

NASA Astrophysics Data System (ADS)

Denny, Mark

2018-05-01

The dynamics of orbiting tethers (space elevators and skyhooks) is developed from an unusual direction: Lagrangian rather than Newtonian mechanics. These basic results are derived among others: space elevator required length with and without counterweight, location and magnitude of maximum tether tension, skyhook orbital parameters and tether tension. These conceptual devices are being increasingly discussed as technologically feasible; here they make an interesting pedagogical application of Lagrangian mechanics suitable for undergraduate physics students.

Tethers in Space

NASA Astrophysics Data System (ADS)

Johnson, Les; Bilén, Sven G.; Gilchrist, Brian E.; Krause, Linda Habash

2017-09-01

This Special Section of Acta Astronautica contains several peer-reviewed papers selected from among those presented at the Fifth International Conference on Tethers in Space (TiS2016). After a hiatus of 21 years since the last Conference on Tethers in Space, TiS2016 brought together experts, practitioners, and other interested in space tethers and related fields. TiS2016 was held May 24-26, 2016 at The University of Michigan in Ann Arbor, Michigan, U.S.A. Leveraging the hard work of a great many volunteers, the conference co-chairs Prof. Brian Gilchrist and Prof. Sven Bilén welcomed an international contingent with authors from the U.S., Canada, Japan, Spain, China, Finland, Estonia, and Italy. The community provided updates on what has transpired since their last gathering by providing lessons learned; describing new technologies and subsystems; and proposing new tether missions and applications. Papers overviewed de-orbit systems, power generation, orbital maneuvering, momentum capture, debris removal, space tugs, space elevators, collision avoidance, and tether dynamics, among others.

Study of selected tether applications in space, phase 3, volume 2

NASA Technical Reports Server (NTRS)

1986-01-01

The results of a Phase 3 study of two Selected Tether Applications in Space (STAIS); deorbit of a Shuttle and launch of an Orbital Transfer Vehicle (OTV), both from the space station using a tether were examined. The study objectives were to: perform a preliminary engineering design, define operational scenarios, develop a common cost model, perform cost benefits analyses, and develop a Work Breakdown Structure (WBS). Key features of the performance analysis were to identify the net increases in effective Shuttle cargo capability if tethers are used to assist in the deorbit of Shuttles and the launching of the OTVs from the space station and to define deployer system designs required to accomplish these tasks. Deployer concepts were designed and discussed. Operational scenarios, including timelines, for both tethered and nontethered Shuttle and OTV operations at the space station were evaluated. A summary discussion of the Selected Tether Applications Cost Model (STACOM) and the results of the cost benefits analysis are presented. Several critical technologies needed to implement tether assisted deployment of payloads are also discussed. Conclusions and recommendations are presented.

Selected tether applications in space: Phase 2

NASA Technical Reports Server (NTRS)

Thorsen, M. H.; Lippy, L. J.

1985-01-01

System characteristics and design requirements are assessed for tether deployment. Criteria are established for comparing alternate concepts for: (1) deployment of 220 klb space shuttle from the space station; (2) tether assisted launch of a 20,000 lb payload to geosynchronous orbit; (3) placement of the 20,000 lb AXAF into 320 nmi orbit via orbiter; (4) retrieval of 20,000 lb AXAF from 205 nmi circular orbit for maintenance and reboost to 320 nmi; and (5) tethered OMV rendezvous and retrieval of OTV returning from a geosynchronous mission. Tether deployment systems and technical issues are discussed.

Precision tethered satellite attitude control. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Kline-Schoder, Robert J.

1990-01-01

Tethered spacecraft possess unique dynamic characteristics which make them advantageous for certain classes of experiments. One use for which tethers are particularly well suited is to provide an isolated platform for spaceborne observatories. The advantages of tethering a pointing platform 1 or 2 km from a space shuttle or space station are that, compared to placing the observatory on the parent spacecraft, vibrational disturbances are attenuated and contamination is eliminated. In practice, all satellites have some requirement on the attitude control of the spacecraft, and tethered satellites are no exception. It has previously been shown that conventional means of performing attitude control for tethered satellites are insufficient for any mission with pointing requirements more stringent than about 1 deg. This is due mainly to the relatively large force applied by the tether to the spacecraft. A particularly effective method of implementing attitude control for tethered satellites is to use this tether tension force to generate control torques by moving the tether attach point relative to the subsatellite center of mass. A demonstration of this attitude control technique on an astrophysical pointing platform has been proposed for a space shuttle flight test project and is referred to as the Kinetic Isolation Tether Experiment (KITE).

Learning characteristics of a space-time neural network as a tether skiprope observer

NASA Technical Reports Server (NTRS)

Lea, Robert N.; Villarreal, James A.; Jani, Yashvant; Copeland, Charles

1992-01-01

The Software Technology Laboratory at JSC is testing a Space Time Neural Network (STNN) for observing tether oscillations present during retrieval of a tethered satellite. Proper identification of tether oscillations, known as 'skiprope' motion, is vital to safe retrieval of the tethered satellite. Our studies indicate that STNN has certain learning characteristics that must be understood properly to utilize this type of neural network for the tethered satellite problem. We present our findings on the learning characteristics including a learning rate versus momentum performance table.

Space Station tethered elevator system

NASA Technical Reports Server (NTRS)

Haddock, Michael H.; Anderson, Loren A.; Hosterman, K.; Decresie, E.; Miranda, P.; Hamilton, R.

1989-01-01

The optimized conceptual engineering design of a space station tethered elevator is presented. The tethered elevator is an unmanned, mobile structure which operates on a ten-kilometer tether spanning the distance between Space Station Freedom and a platform. Its capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The report discusses the potential uses, parameters, and evolution of the spacecraft design. Emphasis is placed on the elevator's structural configuration and three major subsystem designs. First, the design of elevator robotics used to aid in elevator operations and tethered experimentation is presented. Second, the design of drive mechanisms used to propel the vehicle is discussed. Third, the design of an onboard self-sufficient power generation and transmission system is addressed.

Cosmic dust collection with a sub-satellite tethered to a space station

NASA Technical Reports Server (NTRS)

Corso, G. J.

1986-01-01

The number concentration and density of 1 micron and submicron sized grains in interplanetary space, as well as their relation to the larger zodical dust particles, and the importance of the Beta meteoroid phenomenon are currently being questioned. The best approach to collecting large numbers of intact micron and submicron sized cosmic dust particles in real time while avoiding terrestrial and man made contamination would be to employ a tethered subsatellite from a space station down into the Earth's atmosphere. Such a subsatellite tied to the space shuttle by a 100 km long tether is being developed. It is also possible that a permanent space station would allow the use of a tether even longer that 100 km. It should be noted that the same tethered collectors could also be employed to study the composition and flux of man made Earth orbiting debris in any direction within 100 km or so of the space station.

Cosmic dust collection with a sub satellite tethered to a Space Station

NASA Technical Reports Server (NTRS)

Corso, George J.

1987-01-01

The number concentration and density of 1 micron and submicron sized grains in interplanetary space, as well as their relation to the larger zodical dust particles, and the importance of the beta meteoroid phenomenon are currently being questioned. The best approach to collecting large numbers of intact micron and submicron sized cosmic dust particles in real time while avoiding terrestrial and man made contamination would be to employ a tethered subsatellite from a space station down into the earth's atmosphere. Such a subsatellite tied to the space shuttle by a 100 km long tether is being developed. It is also possible that a permanent space station would allow the use of a tether even longer than 100 km. It should be noted that the same tethered collectors could also be employed to study the composition and flux of man made earth orbiting debris in any direction within 100 km or so of the space station.

Theory and Modeling in Support of Tether

NASA Technical Reports Server (NTRS)

Chang, C. L.; Bergeron, G.; Drobot, A. D.; Papadopoulos, K.; Riyopoulos, S.; Szuszczewicz, E.

1999-01-01

This final report summarizes the work performed by SAIC's Applied Physics Operation on the modeling and support of Tethered Satellite System missions (TSS-1 and TSS-1R). The SAIC team, known to be Theory and Modeling in Support of Tether (TMST) investigation, was one of the original twelve teams selected in July, 1985 for the first TSS mission. The accomplishments described in this report cover the period December 19, 1985 to September 31, 1999 and are the result of a continuous effort aimed at supporting the TSS missions in the following major areas. During the contract period, the SAIC's TMST investigation acted to: Participate in the planning and the execution on both of the TSS missions; Provide scientific understanding on the issues involved in the electrodynamic tether system operation prior to the TSS missions; Predict ionospheric conditions encountered during the re-flight mission (TSS-lR) based on realtime global ionosounde data; Perform post mission analyses to enhance our understanding on the TSS results. Specifically, we have 1) constructed and improved current collection models and enhanced our understanding on the current-voltage data; 2) investigated the effects of neutral gas in the current collection processes; 3) conducted laboratory experiments to study the discharge phenomena during and after tether-break; and 4) perform numerical simulations to understand data collected by plasma instruments SPES onboard the TSS satellite; Design and produce multi-media CD that highlights TSS mission achievements and convey the knowledge of the tether technology to the general public. Along with discussions of this work, a list of publications and presentations derived from the TMST investigation spanning the reporting period is compiled.

Assessment of active methods for removal of LEO debris

NASA Astrophysics Data System (ADS)

Hakima, Houman; Emami, M. Reza

2018-03-01

This paper investigates the applicability of five active methods for removal of large low Earth orbit debris. The removal methods, namely net, laser, electrodynamic tether, ion beam shepherd, and robotic arm, are selected based on a set of high-level space mission constraints. Mission level criteria are then utilized to assess the performance of each redirection method in light of the results obtained from a Monte Carlo simulation. The simulation provides an insight into the removal time, performance robustness, and propellant mass criteria for the targeted debris range. The remaining attributes are quantified based on the models provided in the literature, which take into account several important parameters pertaining to each removal method. The means of assigning attributes to each assessment criterion is discussed in detail. A systematic comparison is performed using two different assessment schemes: Analytical Hierarchy Process and utility-based approach. A third assessment technique, namely the potential-loss analysis, is utilized to highlight the effect of risks in each removal methods.

Fractal electrodynamics via non-integer dimensional space approach

NASA Astrophysics Data System (ADS)

Tarasov, Vasily E.

2015-09-01

Using the recently suggested vector calculus for non-integer dimensional space, we consider electrodynamics problems in isotropic case. This calculus allows us to describe fractal media in the framework of continuum models with non-integer dimensional space. We consider electric and magnetic fields of fractal media with charges and currents in the framework of continuum models with non-integer dimensional spaces. An application of the fractal Gauss's law, the fractal Ampere's circuital law, the fractal Poisson equation for electric potential, and equation for fractal stream of charges are suggested. Lorentz invariance and speed of light in fractal electrodynamics are discussed. An expression for effective refractive index of non-integer dimensional space is suggested.

Phase 3 study of selected tether applications in space, mid-term review

NASA Technical Reports Server (NTRS)

1986-01-01

Topics addressed include: guidelines for the Space Transportation System (STS) payload deployer design; mini-orbital maneuvering vehicle (MOMV) design: shuttle tether deployer systems (STEDS); cost modeling; tethered platform analysis; fuel savings analysis; and STEDS control simulation.

Tethers in space handbook, second edition

NASA Technical Reports Server (NTRS)

Penzo, Paul A. (Editor); Ammann, Paul W. (Editor)

1989-01-01

The Tethers in Space Handbook, Second Edition represents an update to the initial volume issued in September 1986. As originally intended, this handbook is designed to serve as a reference manual for policy makers, program managers, educators, engineers, and scientists alike. It contains information for the uninitiated, providing insight into the fundamental behavior of tethers in space. For those familiar with space tethers, it includes a summary of past and ongoing studies and programs, a complete bibliography of tether publications, and names, addresses, and phone numbers of workers in the field. Perhaps its most valuable asset is the brief description of nearly 50 tether applications which have been proposed and analyzed over the past 10 years. The great variety of these applications, from energy generation to boosting satellites to gravity wave detection is an indication that tethers will play a significant part in the future of space development. This edition of the handbook preserves the major characteristics of the original; however, some significant rearrangements and additions have been made. The first section on Tether Programs has been brought up to date, and now includes a description of TSS-2, the aerodynamic NASA/Italian Space Agency (ASI) mission. Tether Applications follows, and this section has been substantially rearranged. First, the index and cross-reference for the applications have been simplified. Also, the categories have changed slightly, with Technology and Test changed to Aerodynamics, and the Constellations category removed. In reality, tether constellations may be applicable to many of the other categories, since it is simply a different way of using tethers. Finally, to separate out those applications which are obviously in the future, a Concepts category has been added. A new section included here on Conference Summaries recognizes the fact that the tether community is growing internationally, and that meetings provide a means of rapid communication and interaction. Finally, the Bibliography section has been considerably updated to include all known references. These are listed by author and by subject and include the papers to be presented at the Third International Conference in May 1989.

Failsafe multistrand tether structures for space propulsion

NASA Astrophysics Data System (ADS)

Forward, Robert L.

1992-07-01

The development of a circularly symmetric singly crosslinked multistrand space tether, named Hoytether, is reported. The Hoytether consists of a number of primary strands running the full length of the structure, with nearest neighbor primary strands crosslinked at intervals by secondary strands that are put under load only if a section of primary strand is cut by space debris. It has been demonstrated that a multistrand tether of the singly crosslinked Hoytether design can provide a long-lived failsafe multistrand replacement for a single-strand tether while imposing a minimal mass ratio penalty.

The dynamic phenomena of a tethered satellite: NASA's first Tethered Satellite Mission, TSS-1

NASA Technical Reports Server (NTRS)

Ryan, R. S.; Mowery, D. K.; Tomlin, D. D.

1993-01-01

The tethered satellite system (TSS) was envisioned as a means of extending a satellite from its base (space shuttle, space station, space platform) into a lower or higher altitude in order to more efficiently acquire data and perform science experiments. This is accomplished by attaching the satellite to a tether, deploying it, then reeling it in. When its mission is completed, the satellite can be returned to its base for reuse. If the tether contains a conductor, it can also be used as a means to generate and flow current to and from the satellite to the base. When current is flowed, the tether interacts with the Earth's magnetic field, deflecting the tether. When the current flows in one direction, the system becomes a propulsive system that can be used to boost the orbiting system. In the other direction, it is a power generating system. Pulsing the current sets up a dynamic oscillation in the tether, which can upset the satellite attitude and preclude docking. A basic problem occurs around 400-m tether length, during satellite retrieval when the satellite's pendulous (rotational) mode gets in resonance with the first lateral tether string mode. The problem's magnitude is determined by the amount of skiprope present coming into this resonance condition. This paper deals with the tethered satellite, its dynamic phenomena, and how the resulting problems were solved for the first tethered satellite mission (TSS-1). Proposals for improvements for future tethered satellite missions are included. Results from the first tethered satellite flight are summarized.

Space Tethers Design Criteria

NASA Technical Reports Server (NTRS)

Tomlin, Donald D.; Faile, Gwyn C.; Hayashida, Kazuo B.; Frost, Cynthia L.; Wagner, Carole Y.; Mitchell, Michael L.; Vaughn, Jason A.; Galuska, Michael J.

1998-01-01

The small expendable deployable system and tether satellite system programs did not have a uniform written criteria for tethers. The JSC safety panel asked what criteria was used to design the tethers. Since none existed, a criteria was written based on past experience for future tether programs.

Tether System for Exchanging Payloads Between the International Space Station and the Lunar Surface

NASA Technical Reports Server (NTRS)

Hoyt, Robert P.

1998-01-01

Systems composed of several rotating and/or hanging tethers may provide a means of exchanging supplies between low Earth orbit facilities and lunar bases without requiring the use of propellant. This work develops methods for designing a tether system capable of repeatedly exchanging payloads between a LEO facility such as the International Space Station or a Space Business Park and a base on the lunar surface. In this system, a hanging tether extended upwards from the LEO facility, places a payload into a slightly elliptical orbit, where it is caught by a rotating tether in a higher elliptical orbit. This rotating tether then tosses the payload to the moon. At the moon, a long rotating "Lunavator" tether catches the payload and deposits it on the surface of the moon. By transporting an equal mass of lunar materials such as oxygen back down to the LEO facility through the tether transport system, the momentum and energy of the system is conserved, allowing frequent traffic between LEO and the lunar surface with minimal propellant requirements.

Controlled tether extends satellite's orbital range

NASA Astrophysics Data System (ADS)

Wigotsky, V.

1984-06-01

A low orbit satellite tethered to the Space Shuttle Orbiter's cargo bay would be able to conduct upper atmosphere experiments without fear of orbit deterioration. NASA has in light of this initiated a Tethered Satellite System program aimed at the 1987 deployment of a 1,100-lb, 5 ft-diameter satellite to a distance of 6-12 miles from the Space Shuttle on a Kevlar tether. The distance of the fully developed system will be 62 miles, representing an altitude of 80 miles above the earth. Tether diameters under consideration are in the 0.065-0.1 inch range. The satellite control system will consist of a reel drive, a deployment boom, and a boom-mounted tether control, in order to vary tether tension during gravity gradient changes.

Overview on NASA's Advanced Electric Propulsion Concepts Activities

NASA Technical Reports Server (NTRS)

Frisbee, Robert H.

1999-01-01

Advanced electric propulsion research activities are currently underway that seek to addresses feasibility issues of a wide range of advanced concepts, and may result in the development of technologies that will enable exciting new missions within our solar system and beyond. Each research activity is described in terms of the present focus and potential future applications. Topics include micro-electric thrusters, electrodynamic tethers, high power plasma thrusters and related applications in materials processing, variable specific impulse plasma thrusters, pulsed inductive thrusters, computational techniques for thruster modeling, and advanced electric propulsion missions and systems studies.

Tether applications for space station

NASA Technical Reports Server (NTRS)

Nobles, W.

1986-01-01

A wide variety of space station applications for tethers were reviewed. Many will affect the operation of the station itself while others are in the category of research or scientific platforms. One of the most expensive aspects of operating the space station will be the continuing shuttle traffic to transport logistic supplies and payloads to the space station. If a means can be found to use tethers to improve the efficiency of that transportation operation, it will increase the operating efficiency of the system and reduce the overall cost of the space station. The concept studied consists of using a tether to lower the shuttle from the space station. This results in a transfer of angular momentum and energy from the orbiter to the space station. The consequences of this transfer is studied and how beneficial use can be made of it.

PREFACE: The 4th Symposium on the Mechanics of Slender Structures (MoSS2013)

NASA Astrophysics Data System (ADS)

Cao, Dengqing; Kaczmarczyk, Stefan

2013-07-01

This volume of Journal of Physics: Conference Series contains papers presented at the 4th Symposium on the Mechanics of Slender Structures (MoSS2013) run under the auspices of the Institute of Physics Applied Mechanics Group and hosted by Harbin Institute of Technology (China) from 7-9 January 2013. The conference has been organized in collaboration with the Technical Committee on Vibration and Sound of the American Society of Mechanical Engineers and follows a one day seminar on Ropes, Cables, Belts and Chains: Theory and Applications and the MoSS2006 symposium held at the University of Northampton (UK) in 2004 and 2006, respectively, the MoSS2008 symposium held at the University of Maryland Baltimore County (USA) in 2008 and the MoSS2010 symposium hosted by Mondragon University and held in San Sebastian (Spain) in 2010. The remit of the Symposium on the Mechanics of Slender Structures series involves a broad range of scientific areas. Applications of slender structures include terrestrial, marine and space systems. Moving elastic elements such as ropes, cables, belts and tethers are pivotal components of many engineering systems. Their lengths often vary when the system is in operation. The applications include vertical transportation installations and, more recently, space tether propulsion systems. Traction drive elevator installations employ ropes and belts of variable length as a means of suspension, and also for the compensation of tensile forces over the traction sheave. In cranes and mine hoists, cables and ropes are subject to length variation in order to carry payloads. Tethers experiencing extension and retraction are important components of offshore and marine installations, as well as being proposed for a variety of different space vehicle propulsion systems based on different applications of momentum exchange and electrodynamic interactions with planetary magnetic fields. Furthermore, cables and slender rods are used extensively in civil engineering; in cable-supported bridges, guyed masts and long-span roofs of buildings and stadia. Suspended cables are also applied as electricity transmission lines. Chains are used in various power transmission systems that include such mechanical systems as chain drives and chain saws. Moving conveyor belts are essential components in various material handling installations. Other structures such as pipelines, plates, beams, mechanical linkages and DNA structures also fall into this category. The behaviour of these elements plays a significant role in the performance of the host structure and a holistic approach is needed in the analysis and design of the entire system. This meeting brings together experts from various fields: structural mechanics, thermo-mechanics, dynamics, electrodynamics, vibration and control, structural health monitoring, artificial intelligence, materials science and applied mathematics to discuss the current state of research as well as rising trends and direction for future research in the area of mechanics of slender structures. The event is aimed at improving the understanding of structural and thermo-mechanical properties and behaviour of slender structures. The papers presented at the conference cover analytical, numerical and experimental research in various applications of slender structures. The Organizing Committee gratefully acknowledges support received from the co-sponsoring institutions and would like to thank the authors for their hard work and high quality contributions. Dengqing Cao Harbin Institute of Technology Stefan Kaczmarczyk The University of Northampton

Space Station tethered refueling facility operations

NASA Technical Reports Server (NTRS)

Kiefel, E. R.; Rudolph, L. K.; Fester, D. A.

1986-01-01

The space-based orbital transfer vehicle will require a large cryogenic fuel storage facility at the Space Station. An alternative to fuel storage onboard the Space Station, is on a tethered orbital refueling facility (TORF) which is separated from the Space Station by a sufficient distance to induce a gravity gradient to settle the propellants. Facility operations are a major concern associated with a tethered LO2/LH2 storage depot. A study was carried out to analyze these operations so as to identify the preferred TORF deployment direction (up or down) and whether the TORF should be permanently or intermittently deployed. The analyses considered safety, contamination, rendezvous, servicing, transportation rate, communication, and viewing. An upwardly, intermittently deployed facility is the preferred configuration for a tethered cryogenic fuel storage.

The tether inspection and repair experiment (TIRE)

NASA Technical Reports Server (NTRS)

Wood, George M.; Loria, Alberto; Harrison, James K.

1988-01-01

The successful development and deployment of reusable tethers for space applications will require methods for detecting, locating, and repairing damage to the tether. This requirement becomes especially important whenever the safety of the STS or the Space Station may be diminished or when critical supplies or systems would be lost in the event of a tether failure. A joint NASA/PSN study endeavor has recently been initiated to evaluate and address the problems to be solved for such an undertaking. The objectives of the Tether Inspection and Repair Experiment (TIRE) are to develop instrumentation and repair technology for specific classes of tethers defined as standards, and to demonstrate the technologies in ground-based and in-flight testing on the STS.

Applications of tethers in space: A review of workshop recommendations

NASA Technical Reports Server (NTRS)

Vontiesenhausen, G. (Editor)

1986-01-01

Well-organized and structured efforts of considerable magnitude involving NASA, industry, and academia have explored and defined the engineering and technological requirements of the use of tethers in space and have discovered their broad range of operational and economic benefits. The results of these efforts have produced a family of extremely promising candidate applications. The extensive efforts now in progress are gaining momentum and a series of flight demonstrations are being planned and can be expected to take place in a few years. This report provides an analysis and a review of NASA's second major workshop on Applications of Tethers in Space held in October 15 to 17, 1985, in Venice, Italy. It provides a summary of an up-to-date assessment and recommendations by the NASA Tether Applications in Space Program Planning Group, consisting of representatives of seven NASA Centers and responsible for tether applications program planning implementation as recommended by the workshop panels.

Space Tethers Programmatic Infusion Opportunities

NASA Technical Reports Server (NTRS)

Bonometti, J. A.; Frame, K. L.

2005-01-01

Programmatic opportunities abound for space Cables, Stringers and Tethers, justified by the tremendous performance advantages that these technologies offer and the rather wide gaps that must be filled by the NASA Exploration program, if the "sustainability goal" is to be met. A definition and characterization of the three categories are presented along with examples. A logical review of exploration requirements shows how each class can be infused throughout the program, from small experimental efforts to large system deployments. The economics of tethers in transportation is considered along with the impact of stringers for structural members. There is an array of synergistic methodologies that interlace their fabrication, implementation and operations. Cables, stringers and tethers can enhance a wide range of other space systems and technologies, including power storage, formation flying, instrumentation, docking mechanisms and long-life space components. The existing tether (i.e., MXER) program's accomplishments are considered consistent with NASA's new vision and can readily conform to requirements-driven technology development.

Tethered satellite control mechanism

NASA Technical Reports Server (NTRS)

Kyrias, G. M.

1983-01-01

The tethered satellite control mechanisms consist of four major subsystems. The reel drive mechanism stores the tether. It is motor driven and includes a level wind to uniformly feed the tether to the reel. The lower boom mechanism serves two primary functions: (1) it measures tether length and velocity as the tether runs through the mechanism, and (2) it reads the tether tension at the reel. It also provides change the direction for the tether from the reel to the upper boom mechanism. The deployment boom positions the upper boom mechanism with satellite out of the cargo bay. The deployment function places the 500-kg satellite 20 m away from the Space Shuttle (producing a small natural gravity gradient force), impacts an initial velocity to the satellite for deployment, and allows for satellite docking at a safe distance from the body of the Space Shuttle. The upper boom mechanism (UBM) services three functions: (1) it provides tether control to the satellite as the satellite swings in and out of plane; (2) it reads tether tension in the low range during the early deployment and final retrieval parts of the mission; and (3) it produces additional tether tension at the reel when tether tension to the satellite is in the low range.

Tethered gravity laboratories study

NASA Technical Reports Server (NTRS)

Lucchetti, F.

1990-01-01

The scope of the study is to investigate ways of controlling the microgravity environment of the International Space Station by means of a tethered system. Four main study tasks were performed. First, researchers analyzed the utilization of the tether systems to improve the lowest possible steady gravity level on the Space Station and the tether capability to actively control the center of gravity position in order to compensate for activities that would upset the mass distribution of the Station. The purpose of the second task was to evaluate the whole of the experiments performable in a variable gravity environment and the related beneficial residual accelerations, both for pure and applied research in the fields of fluid, materials, and life science, so as to assess the relevance of a variable g-level laboratory. The third task involves the Tethered Variable Gravity Laboratory. The use of the facility that would crawl along a deployed tether and expose experiments to varying intensities of reduced gravity is discussed. Last, a study performed on the Attitude Tether Stabilizer concept is discussed. The stabilization effect of ballast masses tethered to the Space Station was investigated as a means of assisting the attitude control system of the Station.

Investigating the Response and Expansion of Plasma Plumes in a Mesosonic Plasma Using the Situational Awareness Sensor Suite for the ISS (SASSI)

NASA Technical Reports Server (NTRS)

Gilchrist, Brian E.; Hoegy, W. R.; Krause, L. Habash; Minow, J. I.; Coffey, V. N.

2014-01-01

To study the complex interactions between the space environment surrounding the International Space Station (ISS) and the ISS space vehicle, we are exploring a specialized suite of plasma sensors, manipulated by the Space Station Remote Manipulator System (SSRMS) to probe the near-ISS mesosonic plasma ionosphere moving past the ISS. It is proposed that SASSI consists of the NASA Marshall Space Flight Center's (MSFC's) Thermal Ion Capped Hemispherical Spectrometer (TICHS), Thermal Electron Capped Hemispherical Spectrometer (TECHS), Charge Analyzer Responsive to Local Oscillations (CARLO), the Collimated PhotoElectron Gun (CPEG), and the University of Michigan Advanced Langmuir Probe (ALP). There are multiple expected applications for SASSI. Here, we will discuss the study of fundamental plasma physics questions associated with how an emitted plasma plume (such as from the ISS Plasma Contactor Unit (PCU)) responds and expands in a mesosonic magnetoplasma as well as emit and collect current. The ISS PCU Xe plasma plume drifts through the ionosphere and across the Earth's magnetic field, resulting in complex dynamics. This is of practical and theoretical interest pertaining to contamination concerns (e.g. energetic ion scattering) and the ability to collect and emit current between the spacecraft and the ambient plasma ionosphere. This impacts, for example, predictions of electrodynamic tether current performance using plasma contactors as well as decisions about placing high-energy electric propulsion thrusters on ISS. We will discuss the required measurements and connection to proposed instruments for this study.

Configuration maintaining control of three-body ring tethered system based on thrust compensation

NASA Astrophysics Data System (ADS)

Huang, Panfeng; Liu, Binbin; Zhang, Fan

2016-06-01

Space multi-tethered systems have shown broad prospects in remote observation missions. This paper mainly focuses on the dynamics and configuration maintaining control of space spinning three-body ring tethered system for such mission. Firstly, we establish the spinning dynamic model of the three-body ring tethered system considering the elasticity of the tether using Newton-Euler method, and then validate the suitability of this model by numerical simulation. Subsequently, LP (Likins-Pringle) initial equilibrium conditions for the tethered system are derived based on rigid body's equilibrium theory. Simulation results show that tether slack, snapping and interaction between the tethers exist in the three-body ring system, and its' configuration can not be maintained without control. Finally, a control strategy based on thrust compensation, namely thrust to simulate tether compression under LP initial equilibrium conditions is designed to solve the configuration maintaining control problem. Control effects are verified by numerical simulation compared with uncontrolled situation. Simulation results show that the configuration of the three-body ring tethered system could maintain under this active control strategy.

Tether Elevator Crawler Systems (TECS)

NASA Technical Reports Server (NTRS)

Swenson, Frank R.

1987-01-01

One of the needs of the experimenters on the space station is access to steady and controlled-variation microgravity environments. A method of providing these environments is to place the experiment on a tether attached to the space station. This provides a high degree of isolation from structural oscillations and vibrations. Crawlers can move these experiments along the tethers to preferred locations, much like an elevator. This report describes the motion control laws developed for these crawlers and the testing of laboratory models of these tether elevator crawlers.

Near Space Environments: Tethering Systems

NASA Technical Reports Server (NTRS)

Lucht, Nolan R.

2013-01-01

Near Space Environments, the Rocket University (Rocket U) program dealing with high altitude balloons carrying payloads into the upper earth atmosphere is the field of my project. The tethering from balloon to payload is the specific system I am responsible for. The tethering system includes, the lines that tie the payload to the balloon, as well as, lines that connect payloads together, if they are needed, as well as how to sever the tether to release payloads from the balloon. My objective is to design a tethering system that will carry a payload to any desired altitude and then sever by command at any given point during flight.

Tethers in Space Handbook

NASA Technical Reports Server (NTRS)

Cosmo, M. L. (Editor); Lorenzini, E. C. (Editor)

1997-01-01

A new edition of the Tethers in Space Handbook was needed after the last edition published in 1989. Tether-related activities have been quite busy in the 90's. We have had the flights of TSSI and TSSI-R, SEDS-1 and -2, PMG, TIPS and OEDIPUS. In less than three years there have been one international Conference on Tethers in Space, held in Washington DC, and three workshops, held at ESA/Estec in the Netherlands, at ISAS in Japan and at the University of Michigan, Ann Harbor. The community has grown and we finally have real flight data to compare our models with. The life of spaceborne tethers has not been always easy and we got our dose of setbacks, but we feel pretty optimistic for the future. We are just stepping out of the pioneering stage to start to use tethers for space science and technological applications. As we are writing this handbook TiPs, a NRL tether project is flying above our heads. There is no emphasis in affirming that as of today spacebome tethers are a reality and their potential is far from being fully appreciated. Consequently, a large amount of new information had to be incorporated into this new edition. The general structure of the handbook has been left mostly unchanged. The past editors have set a style which we have not felt needed change. The section on the flights has been enriched with information on the scientific results. The categories of the applications have not been modified, and in some cases we have mentioned the existence of related flight data. We felt that the section contributed by Joe Carroll, called Tether Data, should be maintained as it was, being a "classic" and still very accurate and not at all obsolete. We have introduced a new chapter entitled Space Science and Tethers since flight experience has shown that tethers can complement other space-based investigations. The bibliography has been updated. Due to the great production in the last few years %e had to restrict our search to works published in refereed journal. The production, however, is much more extensive. In addition, we have included the summary of the papers presented at the last International Conference which was a forum for first-hand information on all the flights.

Tethered Satellite System Contingency Investigation Board

NASA Technical Reports Server (NTRS)

1992-01-01

The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether control mechanism and to prepare a detailed plan for hardware inspection, test, and analysis including any appropriate hardware disassembly.

Tethered Satellite System Contingency Investigation Board

NASA Astrophysics Data System (ADS)

1992-11-01

The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether control mechanism and to prepare a detailed plan for hardware inspection, test, and analysis including any appropriate hardware disassembly.

ISSA/TSS power preliminary design

NASA Technical Reports Server (NTRS)

Main, John A.

1996-01-01

A projected power shortfall during the initial utilization flights of the International Space Station Alpha (ISSA) has prompted an inquiry into the use of the Tethered Satellite System (TSS) to provide station power. The preliminary design of the combined ISSA/TSS system is currently underway in the Preliminary Design Office at the Marshall Space Flight Center. This document focuses on the justification for using a tether system on space station, the physical principles behind such a system, and how it might be operated to best utilize its capabilities. The basic components of a simple DC generator are a magnet of some type and a conductive wire. Moving the wire through the magnetic field causes forces to be applied to the electric charges in the conductor, and thus current is induced to flow. This simple concept is the idea behind generating power with space-borne tether systems. The function of the magnet is performed by the earth's magnetic field, and orbiting a conductive tether about the earth effectively moves the tether through the field.

Space Debris Environment Remediation Concepts

NASA Technical Reports Server (NTRS)

Johnson, Nicholas L.; Klinkrad, Heiner

2009-01-01

Long-term projections of the space debris environment indicate that even drastic measures, such as an immediate, complete halt of launch and release activities, will not result in a stable environment of man-made space objects. Collision events between already existing space hardware will within a few decades start to dominate the debris population, and result in a net increase of the space debris population, also in size regimes which may cause further catastrophic collisions. Such a collisional cascading will ultimately lead to a run-away situation ("Kessler syndrome"), with no further possibility of human intervention. The International Academy of Astronautics (IAA) has been investigating the status and the stability of the space debris environment in several studies by first looking into space traffic management possibilities and then investigating means of mitigating the creation of space debris. In an ongoing activity, an IAA study group looks at ways of active space debris environment remediation. In contrast to the former mitigation study, the current activity concentrates on the active removal of small and large objects, such as defunct spacecraft, orbital stages, and mission-related objects, which serve as a latent mass reservoir that fuels initial catastrophic collisions and later collisional cascading. The paper will outline different mass removal concepts, e.g. based on directed energy, tethers (momentum exchange or electrodynamic), aerodynamic drag augmentation, solar sails, auxiliary propulsion units, retarding surfaces, or on-orbit capture. Apart from physical principles of the proposed concepts, their applicability to different orbital regimes, and their effectiveness concerning mass removal efficiency will be analyzed. The IAA activity on space debris environment remediation is a truly international project which involves more than 23 contributing authors from 9 different nations.

Langmuir Probe Spacecraft Potential End Item Specification Document

NASA Technical Reports Server (NTRS)

Gilchrist, Brian; Curtis, Leslie (Technical Monitor)

2001-01-01

This document describes the Langmuir Probe Spacecraft Potential (LPSP) investigation of the plasma environment in the vicinity of the ProSEDS Delta II spacecraft. This investigation will employ a group of three (3) Langmuir Probe Assemblies, LPAs, mounted on the Delta II second stage to measure the electron density and temperature (n(sub e) and T(sub e)), the ion density (n(sub i)), and the spacecraft potential (V(sub s)) relative to the surrounding ionospheric plasma. This document is also intended to define the technical requirements and flight-vehicle installation interfaces for the design, development, assembly, testing, qualification, and operation of the LPSP subsystem for the Propulsive Small Expendable Deployer System (ProSEDS) and its associated Ground Support Equipment (GSE). This document also defines the interfaces between the LPSP instrument and the ProSEDS Delta II spacecraft, as well as the design, fabrication, operation, and other requirements established to meet the mission objectives. The LPSP is the primary measurement instrument designed to characterize the background plasma environment and is a supporting instrument for measuring spacecraft potential of the Delta II vehicle used for the ProSEDS mission. Specifically, the LPSP will use the three LPAs equally spaced around the Delta II body to make measurements of the ambient ionospheric plasma during passive operations to aid in validating existing models of electrodynamic-tether propulsion. These same probes will also be used to measure Delta II spacecraft potential when active operations occur. When the electron emitting plasma contractor is on, dense neutral plasma is emitted. Effective operation of the plasma contactor (PC) will mean a low potential difference between the Delta II second stage and the surrounding plasma and represents one of the voltage parameters needed to fully characterize the electrodynamic-tether closed circuit. Given that the LP already needs to be well away from any near-field disturbances around the Delta II, it is possible to use the same probe with a simple reconfiguration of the electronics to measure potential with respect to the ambient plasma. The LP measurement techniques are outlined in the following text and discussed in detail in the Appendix. The scientific goals of the investigation, the physical and electrical characteristics of the instrument, and the on-orbit measurement requirements are also discussed in this document.

Acceleration levels on board the Space Station and a tethered elevator for micro and variable-gravity applications

NASA Technical Reports Server (NTRS)

Lorenzini, E. C.; Cosmo, M.; Vetrella, S.; Moccia, A.

1988-01-01

This paper investigates the dynamics and acceleration levels of a new tethered system for micro and variable-gravity applications. The system consists of two platforms tethered on opposite sides to the Space Station. A fourth platform, the elevator, is placed in between the Space Station and the upper platform. Variable-g levels on board the elevator are obtained by moving this facility along the upper tether, while micro-g experiments are carried out on board the Space Station. By controlling the length of the lower tether the position of the system CM can be maintained on board the Space Station despite variations of the station's distribution of mass. The paper illustrates the mathematical model, the environmental perturbations and the control techniques which have been adopted for the simulation and control of the system dynamics. Two sets of results from two different simulation runs are shown. The first set shows the system dynamics and the acceleration spectra on board the Space Station and the elevator during station-keeping. The second set of results demonstrates the capability of the elevator to attain a preselected g-level.

Tethered orbital refueling study

NASA Technical Reports Server (NTRS)

Fester, Dale A.; Rudolph, L. Kevin; Kiefel, Erlinda R.; Abbott, Peter W.; Grossrode, Pat

1986-01-01

One of the major applications of the space station will be to act as a refueling depot for cryogenic-fueled space-based orbital transfer vehicles (OTV), Earth-storable fueled orbit maneuvering vehicles, and refurbishable satellite spacecraft using hydrazine. One alternative for fuel storage at the space station is a tethered orbital refueling facility (TORF), separated from the space station by a sufficient distance to induce a gravity gradient force that settles the stored fuels. The technical feasibility was examined with the primary focus on the refueling of LO2/LH2 orbital transfer vehicles. Also examined was the tethered facility on the space station. It was compared to a zero-gravity facility. A tethered refueling facility should be considered as a viable alternative to a zero-gravity facility if the zero-gravity fluid transfer technology, such as the propellant management device and no vent fill, proves to be difficult to develop with the required performance.

Formations of Tethered Spacecraft as Stable Platforms for Far IR and Sub-mm Astronomy

NASA Technical Reports Server (NTRS)

Quadrelli, Marco B.; Hadaegh, Fred Y.; Shao, Michael; Lorenzini, Enrico C.

2004-01-01

In this paper we describe current research in tethered formations for interferometry, and a roadmap to demonstrating the required key technologies via on-ground and in-orbit testing. We propose an integrated kilometer-size tethered spacecraft formation flying concept which enables Far IR and Sub-mm astronomy observations from space. A rather general model is used to predict the dynamics, control, and estimation performance of formations of spacecraft connected by tethers in LEO and deep space. These models include the orbital and tethered formation dynamics, environmental models, and models of the formation estimator/controller/commander. Both centralized and decentralized control/sensing/estimation schemes are possible, and dynamic ranges of interest for sensing/control are described. Key component/subsystem technologies are described which need both ground-based and in-orbit demonstration prior to their utilization in precision space interferometry missions using tethered formations. Defining an orbiting formation as an ensemble of orbiting spacecraft performing a cooperative task, recent work has demonstrated the validity of the tethering the spacecraft to provide both the required formation rigidity and satisfy the formation reconfiguration needs such as interferometer baseline control. In our concept, several vehicles are connected and move along the tether, so that to reposition them the connecting tether links must vary in length. This feature enables variable and precise baseline control while the system spins around the boresight. The control architecture features an interferometer configuration composed of one central combiner spacecraft and two aligned collector spacecraft. The combiner spacecraft acts as the formation leader and is also where the centralized sensing and estimation functions reside. Some of the issues analyzed with the model are: dynamic modes of deformation of the distributed structure, architecture of the formation sensor, and sources of dynamical perturbation that need to be mitigated for precision operation in space. Examples from numerical simulation of an envisioned scenario in heliocentric orbit demonstrate the potential of the concept for space interferometry.

Space Station tethered waste disposal

NASA Technical Reports Server (NTRS)

Rupp, Charles C.

1988-01-01

The Shuttle Transportation System (STS) launches more payload to the Space Station than can be returned creating an accumulation of waste. Several methods of deorbiting the waste are compared including an OMV, solid rocket motors, and a tether system. The use of tethers is shown to offer the unique potential of having a net savings in STS launch requirement. Tether technology is being developed which can satisfy the deorbit requirements but additional effort is required in waste processing, packaging, and container design. The first step in developing this capability is already underway in the Small Expendable Deployer System program. A developmental flight test of a tether initiated recovery system is seen as the second step in the evolution of this capability.

Tethered gravity laboratories study

NASA Technical Reports Server (NTRS)

Lucchetti, F.

1989-01-01

The use is studied of tether systems to improve the lowest possible steady gravity level on the Space Station. Particular emphasis is placed by the microgravity community on the achievement of high quality microgravity conditions. The tether capability is explored for active control of the center of gravity and the analysis of possible tethered configurations.

Space time neural networks for tether operations in space

NASA Technical Reports Server (NTRS)

Lea, Robert N.; Villarreal, James A.; Jani, Yashvant; Copeland, Charles

1993-01-01

A space shuttle flight scheduled for 1992 will attempt to prove the feasibility of operating tethered payloads in earth orbit. due to the interaction between the Earth's magnetic field and current pulsing through the tether, the tethered system may exhibit a circular transverse oscillation referred to as the 'skiprope' phenomenon. Effective damping of skiprope motion depends on rapid and accurate detection of skiprope magnitude and phase. Because of non-linear dynamic coupling, the satellite attitude behavior has characteristic oscillations during the skiprope motion. Since the satellite attitude motion has many other perturbations, the relationship between the skiprope parameters and attitude time history is very involved and non-linear. We propose a Space-Time Neural Network implementation for filtering satellite rate gyro data to rapidly detect and predict skiprope magnitude and phase. Training and testing of the skiprope detection system will be performed using a validated Orbital Operations Simulator and Space-Time Neural Network software developed in the Software Technology Branch at NASA's Lyndon B. Johnson Space Center.

Understanding the Longitudinal Variability of Equatorial Electrodynamics using integrated Ground- and Space-based Observations

NASA Astrophysics Data System (ADS)

Yizengaw, E.; Moldwin, M.; Zesta, E.

2015-12-01

The currently funded African Meridian B-Field Education and Research (AMBER) magnetometer array comprises more than thirteen magnetometers stationed globally in the vicinity of geomagnetic equator. One of the main objectives of AMBER network is to understand the longitudinal variability of equatorial electrodynamics as function of local time, magnetic activity, and season. While providing complete meridian observation in the region and filling the largest land-based gap in global magnetometer coverage, the AMBER array addresses two fundamental areas of space physics: first, the processes governing electrodynamics of the equatorial ionosphere as a function of latitude (or L-shell), local time, longitude, magnetic activity, and season, and second, ULF pulsation strength at low/mid-latitude regions and its connection with equatorial electrojet and density fluctuation. The global AMBER network can also be used to augment observations from space-based instruments, such us the triplet SWARM mission and the upcoming ICON missions. Thus, in coordination with space-based and other ground-based observations, the AMBER magnetometer network provides a great opportunity to understand the electrodynamics that governs equatorial ionosphere motions. In this paper we present the longitudinal variability of the equatorial electrodynamics using the combination of instruments onboard SWARM and C/NOFS satellites and ground-based AMBER network. Both ground- and pace-based observations show stronger dayside and evening sector equatorial electrodynamics in the American and Asian sectors compared to the African sector. On the other hand, the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This raises the question if the evening sector equatorial electrodynamics (vertical drift), which is believed to be the main cause for the enhancement of Rayleigh-Taylor (RT) instability growth rate, is stronger in the American sector and weaker in the African sector - why are the occurrence and amplitude of equatorial irregularities stronger in the African sector?

On safe configurations of a natural-artificial space tether system

NASA Astrophysics Data System (ADS)

Rodnikov, A. V.

2018-05-01

We study the dynamics of a particle moving under gravitation of precessing dynamically symmetric rigid body if the particle motion is restricted by two unilateral (flexible) constraints realized by two weightless unstretchable tethers with ends fixed at body poles, formed as the intersection of the body surface with the axis of its dynamical symmetry. The system under consideration is a simple model of an original natural-artificial space construction consisting of an asteroid and a space station tethered to each other via two cables. We note that the problem is integrable for the system safe configurations, i.e. for motions along the constraints common boundary (both tethers are tensed) if the body gravitational potential is invariant with respect to rotation about the axis of dynamical symmetry. We study these motions depicting phase portraits for possible values of system parameters. We also deduce conditions for the particle coming off the boundary of constraint(s) (if the tether(s) are slackened) and analyze these conditions, eliminating corresponding areas from phase portraits. We also formulate some statements, concerning the particle safety.

Preliminary assessment of power-generating tethers in space and of propulsion for their orbit maintenance

NASA Technical Reports Server (NTRS)

English, R. E.; Finnegan, P. M.

1985-01-01

The concept of generating power in space by means of a conducting tether deployed from a spacecraft was studied. Using hydrogen and oxygen as the rocket propellant to overcome the drag of such a power-generating tether would yield more benefit than if used in a fuel cell. The mass consumption would be 25 percent less than the reactant consumption of fuel cells. Residual hydrogen and oxygen in the external tank and in the orbiter could be used very effectively for this purpose. Many other materials (such as waste from life support) could be used as the propellant. Electrical propulsion using tether generated power can compensate for the drag of a power-generating tether, half the power going to the useful load and the rest for electric propulsion. In addition, the spacecraft's orbital energy is a large energy reservoir that permits load leveling and a ratio of peak to average power equal to 2. Critical technologies to be explored before a power-generating tether can be used in space are delineated.

Convergence of quantum electrodynamics in a curved modification of Minkowski space.

PubMed Central

Segal, I E; Zhou, Z

1994-01-01

The interaction and total hamiltonians for quantum electrodynamics, in the interaction representation, are entirely regular self-adjoint operators in Hilbert space, in the universal covering manifold M of the conformal compactification of Minkowski space Mo. (M is conformally equivalent to the Einstein universe E, in which Mo may be canonically imbedded.) In a fixed Lorentz frame this may be expressed as convergence in a spherical space with suitable periodic boundary conditions in time. The traditional relativistic theory is the formal limit of the present variant as the space curvature vanishes. PMID:11607455

Propellantless Propulsion Technologies for In-Space Transportation

NASA Technical Reports Server (NTRS)

Johnson, Les; Cook, Stephen (Technical Monitor)

2001-01-01

In order to implement the ambitious science and exploration missions planned over the next several decades, improvements in in-space transportation and propulsion technologies must be achieved. For robotic exploration and science missions, increased efficiencies of future propulsion systems are critical to reduce overall life-cycle costs. Future missions will require 2 to 3 times more total change in velocity over their mission lives than the NASA Solar Electric Technology Application Readiness (NSTAR) demonstration on the Deep Space 1 mission. Rendezvous and return missions will require similar investments in in-space propulsion systems. New opportunities to explore beyond the outer planets and to the stars will require unparalleled technology advancement and innovation. The Advanced Space Transportation Program (ASTP) is investing in technologies to achieve a factor of 10 reduction in the cost of Earth orbital transportation and a factor of 2 or 3 reduction in propulsion system mass and travel time for planetary missions within the next 15 years. Since more than 70% of projected launches over the next 10 years will require propulsion systems capable of attaining destinations beyond Low Earth Orbit, investment in in-space technologies will benefit a large percentage of future missions. Some of the most promising technologies for achieving these goals use the environment of space itself for energy and propulsion and are generically called, "propellantless" because they do not require on-board fuel to achieve thrust. An overview of the state-of-the-art in propellantless propulsion technologies such as solar and plasma sails, electrodynamic and momentum transfer tethers, and aeroassist and aerocapture will be described. Results of recent earth-based technology demonstrations and space tests will also be discussed.

Shuttle/tethered satellite system conceptual design study

NASA Technical Reports Server (NTRS)

1976-01-01

A closed-loop control system was added to the tether reel which improves control over the tethered satellite. In addition to increasing the stability of the tethered satellite along local vertical, this control system is used for deployment and retrieval of tethered satellites. This conceptual design study describes a tether system for suspending a science payload at an altitude of 120 km from space shuttle orbiter flying at an altitude of 200 km. In addition to the hardware conceptual designs, various aspects concerning Orbiter accommodations are discussed.

Flowing Plasma Interaction with an Electric Sail Tether Element

NASA Technical Reports Server (NTRS)

Schneider, Todd; Vaughn, Jason; Wright, Kenneth; Anderson, Allen; Stone, Nobie

2017-01-01

Harnessing the power of the solar wind, an Electric Sail, or E-sail, is a relatively new concept that promises to deliver high speed propellant-less propulsion. The electric sail is an invention made in 2006 at the Kumpula Space Centre in Finland by Pekka Janhunen [Janhunen and Sandroos, 2007]. At its core, an electric sail utilizes multiple positively biased tethers which exchange momentum with solar wind protons via the repelling electric field established around each tether, in other words, by reflecting the solar wind protons. Recognizing the solar wind is a plasma, the effective repelling area of each tether is increased significantly by the formation a plasma sheath around each tether. Fig. 1 shows schematically a spacecraft employing an electric sail. The positive voltage bias (greater than10kV) applied to each tether naturally results in electron collection. Therefore, the electric sail concept necessarily includes an electron source (electron gun) to return collected electrons to space and maintain the positive bias of the tether system.

Dynamic analysis of the tether transportation system using absolute nodal coordinate formulation

NASA Astrophysics Data System (ADS)

Sun, Xin; Xu, Ming; Zhong, Rui

2017-10-01

Long space tethers are becoming a rising concern as an alternate way for transportation in space. It benefits from fuel economizing. This paper focuses on the dynamics of the tether transportation system, which consists of two end satellites connected by a flexible tether, and a movable vehicle driven by the actuator carried by itself. The Absolute Nodal Coordinate Formulation is applied to the establishment of the equation of motion, so that the influence caused by the distributed mass and elasticity of the tether is introduced. Moreover, an approximated method for accelerating the calculation of the generalized gravitational forces on the tether is proposed by substituting the volume integral every step into summation of finite terms. Afterwards, dynamic evolutions of such a system in different configurations are illustrated using numerical simulations. The deflection of the tether and the trajectory of the crawler during the transportation is investigated. Finally, the effect on the orbit of the system due to the crawler is revealed.

Electrodynamic Dust Shields on the International Space Station: Exposure to the Space Environment

NASA Technical Reports Server (NTRS)

Calle, C. I.; Hogue, M. D.; Johansen, M. R.; Yim, H.; Delaune, P. B.; Clements, J. S.

2012-01-01

Electrodynamic Dust Shields (EDS) have been in development at NASA as a dust mitigation method for lunar and Martian missions. An active dust mitigation strategy. such as that provided by the EDS, that can remove dust from surfaces, is of crucial importance to the planetary exploration program. We report on the development of a night experiment to fully ex pose four EDS panels to the space environment. This flight experiment is part of the Materials International Space Station experiment X(MISSE-X). an external platform on the International Space Station that will expose materials to the space environment.

The space station tethered elevator system

NASA Technical Reports Server (NTRS)

Anderson, Loren A.

1989-01-01

The optimized conceptual engineering design of a space station tethered elevator is presented. The elevator is an unmanned mobile structure which operates on a ten kilometer tether spanning the distance between the Space Station and a tethered platform. Elevator capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The potential uses, parameters, and evolution of the spacecraft design are discussed. Engineering development of the tethered elevator is the result of work conducted in the following areas: structural configurations; robotics, drive mechanisms; and power generation and transmission systems. The structural configuration of the elevator is presented. The structure supports, houses, and protects all systems on board the elevator. The implementation of robotics on board the elevator is discussed. Elevator robotics allow for the deployment, retrieval, and manipulation of tethered objects. Robotic manipulators also aid in hooking the elevator on a tether. Critical to the operation of the tethered elevator is the design of its drive mechanisms, which are discussed. Two drivers, located internal to the elevator, propel the vehicle along a tether. These modular components consist of endless toothed belts, shunt-wound motors, regenerative power braking, and computer controlled linear actuators. The designs of self-sufficient power generation and transmission systems are reviewed. Thorough research indicates all components of the elevator will operate under power provided by fuel cells. The fuel cell systems will power the vehicle at seven kilowatts continuously and twelve kilowatts maximally. A set of secondary fuel cells provides redundancy in the unlikely event of a primary system failure. Power storage exists in the form of Nickel-Hydrogen batteries capable of powering the elevator under maximum loads.

A Space Station tethered orbital refueling facility

NASA Technical Reports Server (NTRS)

Fester, D. A.; Rudolph, L. K.; Kiefel, E. R.

1985-01-01

A planned function of the Space Station is to refurbish and refuel an advanced space-based LO2/LH2 orbit transfer vehicle. An alternative to propellant storage at the station is to use a remote facility tied to the station with a long tether. Preliminary design of such a facility is described with emphasis on fluid transfer and storage requirements. Using tether lengths of at least 300 ft, gravity gradient forces will dominate surface tension in such a system. Although gravity driven transfer is difficult because of line pressure drops, fluid settling over the tank outlet greatly alleviates acquisition concerns and will facilitate vented tank fills. The major concern with a tethered orbital refueling facility is its considerable operational complexity including transport of the OTV to and from the facility.

Hybrid fuzzy sliding mode control for motorised space tether spin-up when coupled with axial and torsional oscillation

NASA Astrophysics Data System (ADS)

Chen, Yi; Cartmell, Matthew

2010-03-01

A specialised hybrid controller is applied to the control of a motorised space tether spin-up space coupled with an axial and a torsional oscillation phenomenon. A seven-degree-of-freedom (7-DOF) dynamic model of a motorised momentum exchange tether is used as the basis for interplanetary payload exchange in the context of control. The tether comprises a symmetrical double payload configuration, with an outrigger counter inertia and massive central facility. It is shown that including axial and torsional elasticity permits an enhanced level of performance prediction accuracy and a useful departure from the usual rigid body representations, particularly for accurate payload positioning at strategic points. A simulation with given initial condition data has been devised in a connecting programme between control code written in MATLAB and dynamics simulation code constructed within MATHEMATICA. It is shown that there is an enhanced level of spin-up control for the 7-DOF motorised momentum exchange tether system using the specialised hybrid controller.

Application Number 3: Using Tethers for Attitude Control

NASA Technical Reports Server (NTRS)

Muller, R. M.

1985-01-01

Past application of the gravity gradient concept to satellite attitude control produced attitude stabilities of from 1 to 10 degrees. The satellite members were rigigly interconnected and any motion in one part of the satellite would cause motion in all members. This experience has restricted gravity gradient stabilization to applications that need attitude stability no better than 1 degree. A gravity gradient technique that combines the flexible tether with an active control that will allow control stability much better than 1 degree is proposed. This could give gravity gradient stabilization much broader application. In fact, for a large structure like a space station, it may become the preferred method. Two possible ways of demonstrating the techniques using the Tethered Satellite System (TSS) tether to control the attitude of the shuttle are proposed. Then a possible space station tether configuration is shown that could be used to control the initial station. It is then shown how the technique can be extended to the control of space stations of virtually any size.

Precession and circularization of elliptical space-tether motion

NASA Technical Reports Server (NTRS)

Chapel, Jim D.; Grosserode, Patrick

1993-01-01

In this paper, we present a simplified analytic model for predicting motion of long space tethers. The perturbation model developed here addresses skip rope motion, where each end of the tether is held in place and the middle of the tether swings with a motion similar to that of a child's skip rope. If the motion of the tether midpoint is elliptical rather than circular, precession of the ellipse complicates the procedures required to damp this motion. The simplified analytic model developed in this paper parametrically predicts the precession of elliptical skip rope motion. Furthermore, the model shows that elliptic skip rope motion will circularize when damping is present in the longitudinal direction. Compared with high-fidelity simulation results, this simplified model provides excellent predictions of these phenomena.

Stability control of a flexible maneuverable tethered space net robot

NASA Astrophysics Data System (ADS)

Zhang, Fan; Huang, Panfeng

2018-04-01

As a promising solution for active space debris capture and removal, a maneuverable Tethered Space Net Robot (TSNR) is proposed as an improved Space Tethered Net (TSN). In addition to the advantages inherit to the TSN, the TSNR's maneuverability expands the capture's potential. However, oscillations caused by the TSNR's flexibility and elasticity of make higher requests of the control scheme. Based on the dynamics model, a modified adaptive super-twisting sliding mode control scheme is proposed in this paper for TSNR stability control. The proposed continuous control force can effectively suppress oscillations. Theoretical verification and numerical simulations demonstrate that the desired trajectory can be tracked steadily and efficiently by employing the proposed control scheme.

The dynamics of a space station tethered refueling facility

NASA Technical Reports Server (NTRS)

Abbott, P.; Rudolph, L. K.; Fester, D. A.

1986-01-01

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.

Electric sail space flight dynamics and controls

NASA Astrophysics Data System (ADS)

Montalvo, Carlos; Wiegmann, Bruce

2018-07-01

This paper seeks to investigate the space flight dynamics of a rotating barbell Electric Sail (E-Sail). This E-Sail contains two 6U CubeSats connected to 8 km tethers joined at a central hub. The central hub is designed to be an insulator so that each tether can have differing voltages. An electron gun positively charges each tether which interacts with the solar wind to produce acceleration. If the voltage on each tether is different, the trajectory of the system can be altered. Flapping modes and tension spikes are found during many of these maneuvers and care must be taken to mitigate the magnitude of these oscillations. Using sinusoidal voltage inputs, it is possible to control the trajectory of this two-body E-Sail and propel the system to Near-Earth-Objects or even deep space.

DROMO Propagator Revisited

NASA Astrophysics Data System (ADS)

Urrutxua, H.; Sanjurjo-Rivo, M.; Peláez, J.

2013-12-01

In year 2000 a house-made orbital propagator was developed by the SDGUPM (former Grupo de Dinámica de Tethers) based in a set of redundant variables including Euler parameters. This propagator was called DROMO. and it was mainly used in numerical simulations of electrodynamic tethers. It was presented for the first time in the international meeting V Jornadas de Trabajo en Mecánica Celeste, held in Albarracín, Spain, in 2002 (see reference 1). The special perturbation method associated with DROMO can be consulted in the paper.2 In year 1975, Andre Deprit in reference 3 proposes a propagation scheme very similar to the one in which DROMO is based, by using the ideal frame concept of Hansen. The different approaches used in references 3 and 2 gave rise to a small controversy. In this paper we carried out a different deduction of the DROMO propagator, underlining its close relation with the Hansen ideal frame concept, and also the similarities and the differences with the theory carried out by Deprit in 3. Simultaneously we introduce some improvements in the formulation that leads to a more synthetic propagator.

Theory of plasma contactors in ground-based experiments and low Earth orbit

NASA Technical Reports Server (NTRS)

Gerver, M. J.; Hastings, Daniel E.; Oberhardt, M. R.

1990-01-01

Previous theoretical work on plasma contactors as current collectors has fallen into two categories: collisionless double layer theory (describing space charge limited contactor clouds) and collisional quasineutral theory. Ground based experiments at low current are well explained by double layer theory, but this theory does not scale well to power generation by electrodynamic tethers in space, since very high anode potentials are needed to draw a substantial ambient electron current across the magnetic field in the absence of collisions (or effective collisions due to turbulence). Isotropic quasineutral models of contactor clouds, extending over a region where the effective collision frequency upsilon sub e exceeds the electron cyclotron frequency omega sub ce, have low anode potentials, but would collect very little ambient electron current, much less than the emitted ion current. A new model is presented, for an anisotropic contactor cloud oriented along the magnetic field, with upsilon sub e less than omega sub ce. The electron motion along the magnetic field is nearly collisionless, forming double layers in that direction, while across the magnetic field the electrons diffuse collisionally and the potential profile is determined by quasineutrality. Using a simplified expression for upsilon sub e due to ion acoustic turbulence, an analytic solution has been found for this model, which should be applicable to current collection in space. The anode potential is low and the collected ambient electron current can be several times the emitted ion current.

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

NASA Technical Reports Server (NTRS)

Evans, Steven W.

2003-01-01

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.

Experiments and simulation of a net closing mechanism for tether-net capture of space debris

NASA Astrophysics Data System (ADS)

Sharf, Inna; Thomsen, Benjamin; Botta, Eleonora M.; Misra, Arun K.

2017-10-01

This research addresses the design and testing of a debris containment system for use in a tether-net approach to space debris removal. The tether-net active debris removal involves the ejection of a net from a spacecraft by applying impulses to masses on the net, subsequent expansion of the net, the envelopment and capture of the debris target, and the de-orbiting of the debris via a tether to the chaser spacecraft. To ensure a debris removal mission's success, it is important that the debris be successfully captured and then, secured within the net. To this end, we present a concept for a net closing mechanism, which we believe will permit consistently successful debris capture via a simple and unobtrusive design. This net closing system functions by extending the main tether connecting the chaser spacecraft and the net vertex to the perimeter and around the perimeter of the net, allowing the tether to actuate closure of the net in a manner similar to a cinch cord. A particular embodiment of the design in a laboratory test-bed is described: the test-bed itself is comprised of a scaled-down tether-net, a supporting frame and a mock-up debris. Experiments conducted with the facility demonstrate the practicality of the net closing system. A model of the net closure concept has been integrated into the previously developed dynamics simulator of the chaser/tether-net/debris system. Simulations under tether tensioning conditions demonstrate the effectiveness of the closure concept for debris containment, in the gravity-free environment of space, for a realistic debris target. The on-ground experimental test-bed is also used to showcase its utility for validating the dynamics simulation of the net deployment, and a full-scale automated setup would make possible a range of validation studies of other aspects of a tether-net debris capture mission.

Tethered Satellite System (TSS)-1R survey photography

NASA Image and Video Library

1996-03-18

STS075-325-014 (25 Feb. 1996) --- The frayed end of the tether portion of the Tethered Satellite System (TSS) is seen at the end of the supportive boom. On February 25, 1996, the crew deployed the TSS, which later broke free. The seven member crew was launched aboard the Space Shuttle Columbia on February 22, 1996, and landed on March 9, 1996. Crewmembers were Andrew M. Allen, mission commander; Scott J. Horowitz, pilot; Franklin R. Chang-Diaz, payload commander; and Maurizio Cheli, European Space Agency (ESA); Jeffrey A. Hoffman and Claude Nicollier (ESA), all mission specialists; along with payload specialist Umberto Guidoni of the Italian Space Agency (ASI).

Approaching control for tethered space robot based on disturbance observer using super twisting law

NASA Astrophysics Data System (ADS)

Hu, Yongxin; Huang, Panfeng; Meng, Zhongjie; Wang, Dongke; Lu, Yingbo

2018-05-01

Approaching control is a key mission for the tethered space robot to perform the task of removing space debris. But the uncertainties of the TSR such as the change of model parameter have an important effect on the approaching mission. Considering the space tether and the attitude of the gripper, the dynamic model of the TSR is derived using Lagrange method. Then a disturbance observer is designed to estimate the uncertainty based on STW control method. Using the disturbance observer, a controller is designed, and the performance is compared with the dynamic inverse controller which turns out that the proposed controller performs better. Numerical simulation validates the feasibility of the proposed controller on the position and attitude tracking of the TSR.

Low Earth Orbit Environmental Effects on Space Tether Materials

NASA Technical Reports Server (NTRS)

Finckernor, Miria M.; Gitlemeier, Keith A.; Hawk, Clark W.; Watts, Ed

2005-01-01

Atomic oxygen (AO) and ultraviolet (UV) radiation erode and embrittle most polymeric materials. This research was designed to test several different materials and coatings under consideration for their application to space tethers, for resistance to these effects. The samples were vacuum dehydrated, weighed and then exposed to various levels of AO or UV radiation at the NASA Marshall Space Flight Center. They were then re-weighed to determine mass loss due to atomic oxygen erosion, inspected for damage and tensile tested to determine strength loss. The experiments determined that the Photosil coating process, while affording some protection, damaged the tether materials worse than the AO exposure. TOR-LM also failed to fully protect the materials, especially from UV radiation. The POSS and nickel coatings did provide some protection to the tethers, which survived the entire test regime. M5 was tested, uncoated, and survived AO exposure, though its brittleness prevented any tensile testing.

On low-energy effective action in three-dimensional = 2 and = 4 supersymmetric electrodynamics

NASA Astrophysics Data System (ADS)

Buchbinder, I. L.; Merzlikin, B. S.; Samsonov, I. B.

2013-11-01

We discuss general structure of low-energy effective actions in = 2 and = 4 three-dimensional supersymmetric electrodynamics (SQED) in gauge superfield sector. There are specific terms in the effective action having no four-dimensional analogs. Some of these terms are responsible for the moduli space metric in the Coulomb branch of the theory. We find two-loop quantum corrections to the moduli space metric in the = 2 SQED and show that in the = 4 SQED the moduli space does not receive two-loop quantum corrections.

Electromagnetic compatibility test report for the tethered satellite data acquisition and control assembly

NASA Astrophysics Data System (ADS)

Hoskins, Douglas; Snead, Robert

1988-05-01

This report details the results of an electromagnetic compatibility test on the SCI Systems Data Acquisition and Control Assembly (DACA). This assembly is an electronic processor which controls the central communication link from the Tethered Satellite System (TSS) to the Space Transportation System Orbiter Space Shuttle.

Tethered orbital propellant depot

NASA Technical Reports Server (NTRS)

Fester, D. A.; Rudolph, L. K.; Kiefel, E. R.

1985-01-01

A planned function of the Space Station is to refurbish and refuel an advanced space-based LO2/LH2 orbit transfer vehicle. An alternative to propellant storage at the station is to use a remote facility tied to the station with a log tether. Preliminary design of such a facility is described with emphasis on fluid transfer and storage requirements. Using tether lengths of at least 300 ft, gravity gradient forces will dominate surface tension in such a system. Although gravity given transfer is difficult because of line pressure drops, fluid settling over the tank outlet greatly alleviates acquisition concerns and will facilitate vented tank fills. The major concern with a tethered orbital refueling facility is its considerable operational complexity including transport of the OTV to and from the facility.

Phase 3 study of selected tether applications in space. Volume 2: Study results

NASA Technical Reports Server (NTRS)

1986-01-01

Engineering designs were developed relative to a tethered launch assist from the Shuttle for payloads up to 10,000 kg mass and the tethering of a 15,000 kg science platform from the space station. These designs are used for a cost benefit analysis which assesses the feasibility of using such systems as a practical alternative to what would otherwise be accomplished by conventional means. The term conventional as related to both these applications is intended to apply to the use of some form(s) of chemical propulsion system.

Laboratory simulation of the electrodynamic interactions of a tethered satellite with an ionospheric plasma

NASA Technical Reports Server (NTRS)

Bonifazi, C.; Lebreton, J. P.; Vannaroni, G.; Cosmovici, C.; Debrie, R.; Hamelin, M.; Pomathiod, L.; Arends, H.

1986-01-01

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.

View of the TSS-1R after the tether broke

NASA Image and Video Library

1996-04-03

STS075-360-021 (22 Feb.- 9 March 1996) --- The loose tether forms a faint diagonal line in this scene recorded on a later fly-by. On Feb. 25, 1996, the crew deployed the Tethered Satellite System (TSS), which later broke free. The seven member crew was launched aboard the space shuttle Columbia on Feb. 22, 1996, and landed on March 9, 1996. Crew members were Andrew M. Allen, mission commander; Scott J. Horowitz, pilot; Franklin R. Chang-Diaz, payload commander; and Maurizio Cheli, European Space Agency (ESA); Jeffrey A. Hoffman and Claude Nicollier, ESA, all mission specialists; along with payload specialist Umberto Guidoni of the Italian Space Agency (ASI).

Kagawa Satellite “STARS” in Shikoku

NASA Astrophysics Data System (ADS)

Nohmi, Masahiro; Yamamoto, Takeshi; Andatsu, Akira; Takagi, Yohei; Nishikawa, Yusuke; Kaneko, Takashi; Kunitom, Daisuke

The Space Tethered Autonomous Robotic Satellite (STARS) is being developed in Kagawa University, and it will be launched by the H-IIA rocket by Japan Aerospace Exploration Agency (JAXA) in summer 2008. STARS is the first satellite developed in Shikoku, and its specific characteristics are: (i) mother and daughter satellites, which have basic satellite system respectively, and those are launched at the same time; (ii) large space system more than 5m by extending tether; (iii) robotic system, the daughter satellite controls its arm link and the mother satellite controls tether extension. Development of STARS in Kagawa University demonstrates space technology in local community, which has been considered to be a national project. Also, it promotes popularization, enlightenment, and understanding of space technology in local area of the Kagawa prefecture and around it.

Middle atmospheric electric fields over thunderstorms

NASA Technical Reports Server (NTRS)

Holzworth, Robert H.

1992-01-01

This grant has supported a variety of investigations all having to do with the external electrodynamics of thunderstorms. The grant was a continuation of work begun while the PI was at the Aerospace Corporation (under NASA Grant NAS6-3109) and the general line of investigation continues today under NASA Grants NAG5-685 and NAG6-111. This report will briefly identify the subject areas of the research and associated results. The period actually covered by the grant NAG5-604 included the following analysis and flights: (1) analysis of five successful balloon flights in 1980 and 1981 (under the predecessor NASA grant) in the stratosphere over thunderstorms; (2) development and flight of the Hy-wire tethered balloon system for direct measurement of the atmospheric potential to 250 kV (this involved multiple tethered balloon flight periods from 1981 through 1986 from several locations including Wallops Island, VA, Poker Flat and Ft. Greely, AK and Holloman AFB, NM.); (3) balloon flights in the stratosphere over thunderstorms to measure vector electric fields and associated parameters in 1986 (2 flights), 1987 (4 flights), and 1988 (2 flights); and (4) rocket-borne optical lightning flash detectors on two rocket flights (1987 and 1988) (the same detector design that was used for the balloon flights listed under #3). In summary this grant supported 8 stratospheric zero-pressure balloon flights, tethered aerostat flights every year between 1982-1985, instruments on 2 rockets, and analysis of data from 6 stratospheric flights in 1980/81.

Tethering sockets and wrenches

NASA Technical Reports Server (NTRS)

Johnson, E. P.

1990-01-01

The tethering of sockets and wrenches was accomplished to improve the safety of working over motor segments. To accomplish the tethering of the sockets to the ratchets, a special design was implemented in which a groove was machined into each socket. Each socket was then fitted with a snap ring that can spin around the machined groove. The snap ring is tethered to the handle of the ratchet. All open end wrenches are also tethered to the ratchet or to the operator, depending upon the type. Tests were run to ensure that the modified tools meet torque requirements. The design was subsequently approved by Space Safety.

Snags hit tethered satellite mission

NASA Technical Reports Server (NTRS)

Schuiling, Roelof

1993-01-01

The processing and course of the STS-46 Space Shuttle Atlantis mission are described. Problems experienced by the astronaut team in deploying the Tethered Satellite System during the mission are recounted.

SPHERES tethered formation flight testbed: advancements in enabling NASA's SPECS mission

NASA Astrophysics Data System (ADS)

Chung, Soon-Jo; Adams, Danielle; Saenz-Otero, Alvar; Kong, Edmund; Miller, David W.; Leisawitz, David; Lorenzini, Enrico; Sell, Steve

2006-06-01

This paper reports on efforts to control a tethered formation flight spacecraft array for NASA's SPECS mission using the SPHERES test-bed developed by the MIT Space Systems Laboratory. Specifically, advances in methodology and experimental results realized since the 2005 SPIE paper are emphasized. These include a new test-bed setup with a reaction wheel assembly, a novel relative attitude measurement system using force torque sensors, and modeling of non-ideal tethers to account for tether vibration modes. The nonlinear equations of motion of multi-vehicle tethered spacecraft with elastic flexible tethers are derived from Lagrange's equations. The controllability analysis indicates that both array resizing and spin-up are fully controllable by the reaction wheels and the tether motor, thereby saving thruster fuel consumption. Based upon this analysis, linear and nonlinear controllers have been successfully implemented on the tethered SPHERES testbed, and tested at the NASA MSFC's flat floor facility using two and three SPHERES configurations.

STS-75 crew insignia

NASA Image and Video Library

1997-10-01

STS075-S-001 (September 1995) --- The STS-75 crew patch depicts the space shuttle Columbia and the Tethered Satellite connected by a 21-kilometer electronically conducting tether. The orbiter/satellite system is passing through Earth?s magnetic field which, like an electronic generator, will produce thousands of volts of electricity. Columbia is carrying the United States Microgravity pallet to conduct microgravity research in material science and thermodynamics. The tether is crossing Earth?s terminator signifying the dawn of a new era for space tether applications and in mankind?s knowledge of Earth?s ionosphere, material science, and thermodynamics. The patch was designed for the STS-75 crew members by Mike Sanni. The NASA insignia design for space shuttle flights is reserved for use by the astronauts and for other official use as the NASA Administrator may authorize. Public availability has been approved only in the forms of illustrations by the various news media. When and if there is any change in this policy, which is not anticipated, the change will be publicly announced. Photo credit: NASA

Tethered nuclear power for the Space Station

NASA Technical Reports Server (NTRS)

Bents, D. J.

1985-01-01

A nuclear space power system the SP-100 is being developed for future missions where large amounts of electrical power will be required. Although it is primarily intended for unmanned spacecraft, it can be adapted to a manned space platform by tethering it above the station through an electrical transmission line which isolates the reactor far away from the inhabited platform and conveys its power back to where it is needed. The transmission line, used in conjunction with an instrument rate shield, attenuates reactor radiation in the vicinity of the space station to less than one-one hundredth of the natural background which is already there. This combination of shielding and distance attenuation is less than one-tenth the mass of boom-mounted or onboard man-rated shields that are required when the reactor is mounted nearby. This paper describes how connection is made to the platform (configuration, operational requirements) and introduces a new element the coaxial transmission tube which enables efficient transmission of electrical power through long tethers in space. Design methodology for transmission tubes and tube arrays is discussed. An example conceptual design is presented that shows SP-100 at three power levels 100 kWe, 300 kWe, and 1000 kWe connected to space station via a 2 km HVDC transmission line/tether. Power system performance, mass, and radiation hazard are estimated with impacts on space station architecture and operation.

Tethered nuclear power for the space station

NASA Technical Reports Server (NTRS)

Bents, D. J.

1985-01-01

A nuclear space power system the SP-100 is being developed for future missions where large amounts of electrical power will be required. Although it is primarily intended for unmanned spacecraft, it can be adapted to a manned space platform by tethering it above the station through an electrical transmission line which isolates the reactor far away from the inhabited platform and conveys its power back to where it is needed. The transmission line, used in conjunction with an instrument rate shield, attenuates reactor radiation in the vicinity of the space station to less than one-one hundredth of the natural background which is already there. This combination of shielding and distance attenuation is less than one-tenth the mass of boom-mounted or onboard man-rated shields that are required when the reactor is mounted nearby. This paper describes how connection is made to the platform (configuration, operational requirements) and introduces a new element the coaxial transmission tube which enables efficient transmission of electrical power through long tethers in space. Design methodology for transmission tubes and tube arrays is discussed. An example conceptual design is presented that shows SP-100 at three power levels 100 kWe, 300 kWe, and 1000 kWe connected to space station via a 2 km HVDC transmission line/tether. Power system performance, mass, and radiation hazard are estimated with impacts on space station architecture and operation.

On the dynamical stability of the space 'monorail'

NASA Astrophysics Data System (ADS)

Bergamaschi, S.; Manni, D.

The dynamical stability of 'monorail' tethered-satellite/elevator configurations being studied for the Space Station is investigated analytically, treating the end platforms and elevator as point masses, neglecting tether elasticity, and taking the Coriolis force and the complex gravitational field into account in analyzing the orbital-plane motion of the system. A mathematical model is constructed; the equations of motion are derived; and results obtained by numerical integration for platform masses 100,000 and 10,000 kg, elevator mass 5000 kg, and a 10-km-long 6-mm-diameter 4070-kg-mass tether are presented in graphs and briefly characterized.

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

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.

2005-01-01

We have contributed to the development of the Submillimiter 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) developing control laws for reconfiguring the baseline length; (f) devising control laws for fast retargeting of the interferometer at moderate baseline lengths; (g) estimating the survivability to micrometeoroid impacts of a tether at L2; and (h) developing a conceptual design of a high- strength and survivable tether. The work was conducted for NASA Goddard Space Flight Center under Grant NNG04GQ21G with William Danchi as technical monitor.

Tether Optical Phenomena (TOP) experiment

NASA Image and Video Library

1996-03-14

STS075-310-002 (22 Feb.-9 March 1996) --- Astronaut Maurizio Cheli, STS-75 mission specialist, works with the Tether Optical Phenomenon System (TOPS) on the flight deck of the Earth-orbiting Space Shuttle Columbia. Cheli, representing the European Space Agency (ESA), joined four other astronauts and an international payload specialists for 16 days of scientific research in Earth-orbit.

Scientific return of a lunar elevator

NASA Astrophysics Data System (ADS)

Eubanks, T. M.; Radley, C. F.

2016-11-01

The concept of a space elevator dates back to Tsilokovsky, but they are not commonly considered in near-term plans for space exploration, perhaps because a terrestrial elevator would not be possible without considerable improvements in tether material. A Lunar Space Elevator (LSE), however, can be built with current technology using commercially available tether polymers. This paper considers missions leading to infrastructure capable of shortening the time, lowering the cost and enhancing the capabilities of robotic and human explorers. These missions use planetary scale tethers, strings many thousands of kilometers long stabilized either by rotation or by gravitational gradients. These systems promise major reduction in transport costs versus chemical rockets, in a rapid timeframe, for a modest investment. Science will thus benefit as well as commercial activities.

Partial Gravity Biological Tether Experiment on the Deep Space Gateway

NASA Astrophysics Data System (ADS)

Wallace, S.; Graham, L.

2018-02-01

A tether-based partial gravity bacterial biological experiment represents a viable biological experiment to investigate the fundamental internal cellular processes between altered levels of gravity and cellular adaption.

High precision and high yield fabrication of dense nanoparticle arrays onto DNA origami at statistically independent binding sites

NASA Astrophysics Data System (ADS)

Takabayashi, Sadao; Klein, William P.; Onodera, Craig; Rapp, Blake; Flores-Estrada, Juan; Lindau, Elias; Snowball, Lejmarc; Sam, Joseph T.; Padilla, Jennifer E.; Lee, Jeunghoon; Knowlton, William B.; Graugnard, Elton; Yurke, Bernard; Kuang, Wan; Hughes, William L.

2014-10-01

High precision, high yield, and high density self-assembly of nanoparticles into arrays is essential for nanophotonics. Spatial deviations as small as a few nanometers can alter the properties of near-field coupled optical nanostructures. Several studies have reported assemblies of few nanoparticle structures with controlled spacing using DNA nanostructures with variable yield. Here, we report multi-tether design strategies and attachment yields for homo- and hetero-nanoparticle arrays templated by DNA origami nanotubes. Nanoparticle attachment yield via DNA hybridization is comparable with streptavidin-biotin binding. Independent of the number of binding sites, >97% site-occupation was achieved with four tethers and 99.2% site-occupation is theoretically possible with five tethers. The interparticle distance was within 2 nm of all design specifications and the nanoparticle spatial deviations decreased with interparticle spacing. Modified geometric, binomial, and trinomial distributions indicate that site-bridging, steric hindrance, and electrostatic repulsion were not dominant barriers to self-assembly and both tethers and binding sites were statistically independent at high particle densities.High precision, high yield, and high density self-assembly of nanoparticles into arrays is essential for nanophotonics. Spatial deviations as small as a few nanometers can alter the properties of near-field coupled optical nanostructures. Several studies have reported assemblies of few nanoparticle structures with controlled spacing using DNA nanostructures with variable yield. Here, we report multi-tether design strategies and attachment yields for homo- and hetero-nanoparticle arrays templated by DNA origami nanotubes. Nanoparticle attachment yield via DNA hybridization is comparable with streptavidin-biotin binding. Independent of the number of binding sites, >97% site-occupation was achieved with four tethers and 99.2% site-occupation is theoretically possible with five tethers. The interparticle distance was within 2 nm of all design specifications and the nanoparticle spatial deviations decreased with interparticle spacing. Modified geometric, binomial, and trinomial distributions indicate that site-bridging, steric hindrance, and electrostatic repulsion were not dominant barriers to self-assembly and both tethers and binding sites were statistically independent at high particle densities. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03069a

Simulation of a tethered microgravity robot pair and validation on a planar air bearing

NASA Astrophysics Data System (ADS)

Mantellato, R.; Lorenzini, E. C.; Sternberg, D.; Roascio, D.; Saenz-Otero, A.; Zachrau, H. J.

2017-09-01

A software model has been developed to simulate the on-orbit dynamics of a dual-mass tethered system where one or both of the tethered spacecraft are able to produce propulsive thrust. The software simulates translations and rotations of both spacecraft, with the visco-elastic tether being simulated as a lumped-mass model. Thanks to this last feature, tether longitudinal and lateral modes of vibration and tether tension can be accurately assessed. Also, the way the spacecraft motion responds to sudden tether tension spikes can be studied in detail. The code enables the simulation of different scenarios, including space tug missions for deorbit maneuvers in a debris mitigation context and general-purpose tethered formation flight missions. This study aims to validate the software through a representative test campaign performed with the MIT Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) planar air bearing system. Results obtained with the numerical simulator are compared with data from direct measurements in different testing setups. The studied cases take into account different initial conditions of the spacecraft velocities and relative attitudes, and thrust forces. Data analysis is presented comparing the results of the simulations with direct measurements of acceleration and Azimuth rate of the two bodies in the planar air bearing test facility using a Nylon tether. Plans for conducting a microgravity test campaign using the SPHERES satellites aboard the International Space Station are also being scheduled in the near future in order to further validate the simulation using data from the relevant operational environment of extended microgravity with full six degree of freedom (per body) motion.

Drop Tower tests in preparation of a Tethered Electromagnetic Docking space demonstration

NASA Astrophysics Data System (ADS)

Olivieri, Lorenzo; Francesconi, Alessandro; Antonello, Andrea; Bettiol, Laura; Branz, Francesco; Duzzi, Matteo; Mantellato, Riccardo; Sansone, Francesco; Savioli, Livia

2016-07-01

A group of students of the University of Padova is recently developing some technologies to implement a Tethered Electromagnetic Docking (TED) experiment, a novel system for close rendezvous and mating manoeuvres between two spacecraft, consisting in a small tethered probe ejected by the chaser and magnetically guided by a receiving electromagnet mounted on the target. Because of the generated magnetic field, automatic self-alignment and mating are possible; then, as the tether is rewinded, the chaser is able to dock with the target. This concept allows to simplify standard docking procedures, thanks to the reduction of proximity navigation and guidance requirements, as well as consequent fuel reduction. Other interesting applications are expected, from active debris removal to space tugging; in particular, the utilization of the tethered connection for detumbling operations is considered. The realization of a space demonstrator requires a preliminary verification of the critical technologies employed in TED, in particular the magnetic guidance and the probe deploy and retrieve; in the framework of ESA "Drop your Thesis!" 2014 and 2016 campaigns the experiments FELDs (Flexible Electromagnetic Leash Docking system) and STAR (System for Tether Automatic Retrieval) have been focused on the test of such critical elements in the relevant microgravity environment of ZARM Drop Tower in Bremen. In particular, FELDs consisted in a simplified model of TED with a magnetic target interface, a passive tethered probe and its launch system: the experiment allowed to assess the passive self-alignment of the probe with respect to the target and to study the effect of friction between the tether and the release system. Similarly, STAR is investigating the tether actively controlled deployment and retrieval, with the experiment campaign planned on November 2016. In addition, another microgravity experiment is in preparation for the investigation of active magnetic navigation: PACMAN (Position and Attitude Control with MAgnetic Navigation) will consist in a CubeSat-sized spacecraft mock-up using on-board actively-controlled electromagnetic coils for guidance This paper describes the TED concept and presents the evaluation its performances with respect to standard docking procedure. The roadmap in TED development is then introduced, focusing on the importance of microgravity tests in the assessment of its critical technologies and discussing the influence of the collected data on the design drivers of the proposed space demonstrator.

Review of deployment technology for tethered satellite systems

NASA Astrophysics Data System (ADS)

Yu, B. S.; Wen, H.; Jin, D. P.

2018-03-01

Tethered satellite systems (TSSs) have attracted significant attention due to their potential and valuable applications for scientific research. With the development of various launched on-orbit missions, the deployment of tethers is considered a crucial technology for operation of a TSS. Both past orbiting experiments and numerical results have shown that oscillations of the deployed tether due to the Coriolis force and environmental perturbations are inevitable and that the impact between the space tether and end-body at the end of the deployment process leads to complicated nonlinear phenomena. Hence, a set of suitable control methods plays a fundamental role in tether deployment. This review article summarizes previous work on aspects of the dynamics, control, and ground-based experiments of tether deployment. The relevant basic principles, analytical expressions, simulation cases, and experimental results are presented as well.

Tethered Satellites as an Enabling Platform for Operational Space Weather Monitoring Systems

NASA Technical Reports Server (NTRS)

Gilchrist, Brian E.; Krause, Linda Habash; Gallagher, Dennis Lee; Bilen, Sven Gunnar; Fuhrhop, Keith; Hoegy, Walt R.; Inderesan, Rohini; Johnson, Charles; Owens, Jerry Keith; Powers, Joseph;

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

NASA Technical Reports Server (NTRS)

Edwards, David; Carruth, Ralph; Vaughn, Jason; Schneider, Todd; Kamenetzky, Rachel; Gray, Perry

2000-01-01

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.

The use of tethered satellites for the collection of cosmic dust and the sampling of man made orbital debris far from the space station

NASA Technical Reports Server (NTRS)

Corso, G. J.

1986-01-01

The use of a tethered subsatellite employed downward into the earth's upper atmosphere to an altitude of about 110 km above the earth would eliminate the orbital contamination problem while at the same time affording a measure of atmospheric braking to reduce the velocities of many particles to where they may be captured intact or nearly so with properly designed collectors. The same technique could also be used to monitor the flux of all types of man-made orbital debris out to a distance of more than a hundred kilometers in any direction from the space station. In this way the build up of any debris belt orbiting earth could be determined. The actual collecting elements used for both purposes could be of several different materials and designs so as to optimize the collection of different types of particles with different densities. Stacks of foils, films, plastics, and foams, as well as simple capture cells would be mounted in clusters around the outside of a tethered satellite and protected by iris covers until the tethered had been fully deployed. If the orientation history of the satellite were known the direction of the incoming material could be infered. A chief advantage in deploying such tethered collectors from the Space Station instead of from the shuttle is the ability to maintain deployment of the tether for days instead of hours resulting in much greater yields of intact particles and impact debris.

17. NBS TOOL ROOM. MISCELLANEOUS TOOLS USED DURING EXTRA VEHICULAR ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. NBS TOOL ROOM. MISCELLANEOUS TOOLS USED DURING EXTRA VEHICULAR ACTIVITY (EVA) MISSIONS AND NBS TRAINING. FROM LEFT TO RIGHT THE TOOLS ARE: SHUTTLE TRANSPORTATION SYSTEM (STS) PORTABLE FOOT RESTRAINT (PFR), ESSEX WRENCH, SOCKET WRENCH, SAFETY TETHER REEL (LEFT REAR), MINI WORKSTATION (CENTER REAR), TETHERS (FRONT CENTER), HUBBLE SPACE TELESCOPE (HST) POWER TOOL (FRONT RIGHT), HUBBLE SPACE TELESCOPE & PORTABLE FOOT RESTRAINT (REAR RIGHT). - Marshall Space Flight Center, Neutral Buoyancy Simulator Facility, Rideout Road, Huntsville, Madison County, AL

Attitude Control Tradeoff Study Between the Use of a Flexible Beam and a Tether Configuration for the Connection of Two Bodies in Orbit

NASA Technical Reports Server (NTRS)

Graff, S. H.

1985-01-01

Sometimes it is necessary to mount a payload remotely from the main body of a spacecraft or space station. The reasons for this vary from vibration isolation to avoidance of measurement contamination. For example the SP-100 project, which grew out of the increased interest in nuclear power in space for space stations and for deep space explorations, requires separation of the nuclear reactor from the user because of vibration, heat and radiation. The different attitude control problems for beam and tether configurations are discussed. The beam configuration uses a conservative design approach. The vibration, beam flexibility and deployment concerns are analyzed. The tether configuration offers some very attractive design features, but not without several thorny problems. These problems are analyzed. One configuration will be recommended for the main thrust of the SP-100 design effort based on attitude control considerations.

New Propulsion Technologies For Exploration of the Solar System and Beyond

NASA Technical Reports Server (NTRS)

Johnson, Les; Cook, Stephen (Technical Monitor)

2001-01-01

In order to implement the ambitious science and exploration missions planned over the next several decades, improvements in in-space transportation and propulsion technologies must be achieved. For robotic exploration and science missions, increased efficiencies of future propulsion systems are critical to reduce overall life-cycle costs. Future missions will require 2 to 3 times more total change in velocity over their mission lives than the NASA Solar Electric Technology Application Readiness (NSTAR) demonstration on the Deep Space 1 mission. Rendezvous and return missions will require similar investments in in-space propulsion systems. New opportunities to explore beyond the outer planets and to the stars will require unparalleled technology advancement and innovation. The Advanced Space Transportation Program (ASTP) is investing in technologies to achieve a factor of 10 reduction in the cost of Earth orbital transportation and a factor of 2 reduction in propulsion system mass and travel time for planetary missions within the next 15 years. Since more than 70% of projected launches over the next 10 years will require propulsion systems capable of attaining destinations beyond Low Earth Orbit, investment in in-space technologies will benefit a large percentage of future missions. The ASTP technology portfolio includes many advanced propulsion systems. From the next generation ion propulsion system operating in the 5 - 10 kW range, to fission-powered multi-kilowatt systems, substantial advances in spacecraft propulsion performance are anticipated. Some of the most promising technologies for achieving these goals use the environment of space itself for energy and propulsion and are generically called, "propellantless" because they do not require on-board fuel to achieve thrust. An overview of the state-of-the-art in propellantless propulsion technologies such as solar and plasma sails, electrodynamic and momentum transfer tethers, and aeroassist and aerocapture will also be described. Results of recent earth-based technology demonstrations and space tests for many of these new propulsion technologies will be discussed.

Tethered Satellites as Enabling Platforms for an Operational Space Weather Monitoring System

NASA Technical Reports Server (NTRS)

Krause, L. Habash; Gilchrist, B. E.; Bilen, S.; Owens, J.; Voronka, N.; Furhop, K.

2013-01-01

Space weather nowcasting and forecasting models require assimilation of near-real time (NRT) space environment data to improve the precision and accuracy of operational products. Typically, these models begin with a climatological model to provide "most probable distributions" of environmental parameters as a function of time and space. The process of NRT data assimilation gently pulls the climate model closer toward the observed state (e.g. via Kalman smoothing) for nowcasting, and forecasting is achieved through a set of iterative physics-based forward-prediction calculations. The issue of required space weather observatories to meet the spatial and temporal requirements of these models is a complex one, and we do not address that with this poster. Instead, we present some examples of how tethered satellites can be used to address the shortfalls in our ability to measure critical environmental parameters necessary to drive these space weather models. Examples include very long baseline electric field measurements, magnetized ionospheric conductivity measurements, and the ability to separate temporal from spatial irregularities in environmental parameters. Tethered satellite functional requirements will be presented for each space weather parameter considered in this study.

Tethers as Debris: Simulating Impacts of Tether Fragments on Shuttle Tiles

NASA Technical Reports Server (NTRS)

Evans, Steven W.

2004-01-01

The SPHC hydrodynamic code was used to simulate impacts of Kevlar and aluminum projectiles on a model of the LI-900 type insulating tiles used on Space Shuffle Orbiters The intent was to examine likely damage that such tiles might experience if impacted by orbital debris consisting of tether fragments. Projectile speeds ranged from 300 meters per second to 10 kilometers per second. Damage is characterized by penetration depth, tile surface-hole diameter, tile body-cavity diameter, coating fracture diameter, tether and cavity wall material phases, and deformation of the aluminum backwall.

The development of optimal control laws for orbiting tethered platform systems

NASA Technical Reports Server (NTRS)

Bainum, P. M.; Woodard, S.; Juang, J.-N.

1986-01-01

A mathematical model of the open and closed loop in-orbit plane dynamics of a space platform-tethered-subsatellite system is developed. The system consists of a rigid platform from which an (assumed massless) tether is deploying (retrieving) a subsatellite from an attachment point which is, in general, offset from the platform's mass center. A Lagrangian formulation yields equations describing platform pitch, subsatellite tether-line swing, and varying tether length motions. These equations are linearized about the nominal station keeping motion. Control can be provided by both modulation of the tether tension level and by a momentum type platform-mounted device; system controllability depends on the presence of both control inputs. Stability criteria are developed in terms of the control law gains, the platform inertia ratio, and tether offset parameter. Control law gains are obtained based on linear quadratic regulator techniques. Typical transient responses of both the state and required control effort are presented.

Summary presentation of the technology and test panel

NASA Technical Reports Server (NTRS)

Siemers, P.

1985-01-01

Tether related technology issues were investigated along with potential applications. Several of the applications do not derive necessarily from nor are they related to a technology issue. Tether designs must concern itself with length requirements (whether the tether is to be flexible or stiff) and what the environmental impact is on the particular material that is proposed for the tether. As far as tether manufacturing techniques, a lot of technology related work is required to develop cost effective manfacturing capabilities for the future tether. There are techniques that are used on the ground now. However, after some of the proposed applications are determined to be feasible, it may be that the best way to manufacture the tether is to pretend the satellite is a spider and allow it to spin its own web in space. The technology required to developed tapered tethers was considered. Definition of the taper, where the center of that taper should be, and the taper's relation to the end masses are all of concern.

Electrodynamic Dust Shield for Lunar/ISS Experiment Project

NASA Technical Reports Server (NTRS)

Zeitlin, Nancy; Calle, Carlos; Hogue, Michael; Johansen, Michael; Mackey, Paul

2015-01-01

The Electrostatics and Surface Physics Laboratory at Kennedy Space Center is developing a dust mitigation experiment and testing it on the lunar surface and on the International Space Station (ISS). The Electrodynamic Dust Shield (EDS) clears dust off surfaces and prevents accumulation by using a pattern of electrodes to generate a non-uniform electric field over the surface being protected. The EDS experiment will repel dust off materials such as painted Kapton and glass to demonstrate applications for thermal radiators, camera lenses, solar panels, and other hardware and equipment.

Dynamics of tether-assisted reentry vehicle systems

NASA Astrophysics Data System (ADS)

Zhu, Renzhang; Misra, A. K.; Lin, Huabao

The dynamics of tether-assisted reentry of a capsule is considered in this paper. A major advantage in tethered-assisted reentry is the ability to replace a retro-rocket by a tether. In this reentry procedure, a capsule is deployed down to a design altitude near the local vertical, and at an appropriate time the capsule is disconnected from the tether and enters into a reentry trajectory. In addition to static release, swing release is also considered in this paper. Three deployment schemes appropriate for swing release are considered. A two-stage accelerated-exponential/decelerated-exponential deployment appears to be the best of the three. In comparison with static release, for the same duration of return, this swing release can lead to about 22 percent reduction in tether length at the cost of an increase in tension in the tether by only 8 to 12 percent, and thus, it could decrease the tether mass launched into space. The paper analyzes the detailed dynamics of the tethered system before release as well as the reentry dynamics of the capsule after release along with the heat generated during reentry.

Electrodynamic Dust Shield for Space Applications

NASA Technical Reports Server (NTRS)

Mackey, Paul J.; Johansen, Michael R.; Olsen, Robert C.; Raines, Matthew G.; Phillips, James R., III; Cox, Rachel E.; Hogue, Michael D.; Pollard, Jacob R. S.; Calle, Carlos I.

2016-01-01

Dust mitigation technology has been highlighted by NASA and the International Space Exploration Coordination Group (ISECG) as a Global Exploration Roadmap (GER) critical technology need in order to reduce life cycle cost and risk, and increase the probability of mission success. The Electrostatics and Surface Physics Lab in Swamp Works at the Kennedy Space Center has developed an Electrodynamic Dust Shield (EDS) to remove dust from multiple surfaces, including glass shields and thermal radiators. Further development is underway to improve the operation and reliability of the EDS as well as to perform material and component testing outside of the International Space Station (ISS) on the Materials on International Space Station Experiment (MISSE). This experiment is designed to verify that the EDS can withstand the harsh environment of space and will look to closely replicate the solar environment experienced on the Moon.

Proceedings of a Workshop on Applications of Tethers in Space: Executive Summary

NASA Technical Reports Server (NTRS)

Baracat, W. A. (Compiler)

1986-01-01

The workshop was attended by persons from government, industry, and academic institutions to discuss the rapidly evolving area of tether applications in space. Many new applications were presented at the workshop, and existing applications were revised, refined, and prioritized as to which applications should be implemented and when. The workshop concluded with summaries developed individually and jointly by each of the applications panels.

Bruce Wiegman with a tether for the Electostatic Propulsion System.

NASA Image and Video Library

2015-09-30

BRUCE WIEGMANN, AN ENGINEER AT NASA'S MARSHALL SPACE FLIGHT CENTER IN HUNTSVILLE, ALABAMA, EXAMINES A HAIR-THIN TETHER THAT WILL BE PART OF AN ELECTROSTATIC PROPULSION SYSTEM THAT COULD SEND SPACECRAFT ON INTERSTELLAR MISSIONS.

Tether Deployer And Brake

NASA Technical Reports Server (NTRS)

Carroll, Joseph A.; Alexander, Charles M.

1993-01-01

Design concept promises speed, control, and reliability. Scheme for deploying tether provides for fast, free, and snagless payout and fast, dependable braking. Developed for small, expendable tethers in outer space, scheme also useful in laying transoceanic cables, deploying guidance wires to torpedoes and missiles, paying out rescue lines from ship to ship via rockets, deploying antenna wires, releasing communication and power cables to sonobuoys and expendable bathythermographs, and in reeling out lines from fishing rods.

Kotov holds Retractable Equipment Tethers in the SM during Expedition 22

NASA Image and Video Library

2010-01-06

ISS022-E-019986 (6 Jan. 2010) --- Russian cosmonaut Oleg Kotov, Expedition 22 flight engineer, holds a stowage box containing extravehicular activity (EVA) retractable equipment tethers in the Zvezda Service Module of the International Space Station.

On the design and feasibility of a pneumatically supported actively guided space tower

NASA Astrophysics Data System (ADS)

Seth, Raj Kumar

2010-07-01

Space tethers have been investigated widely as a means to provide easy access to space. However, the design and construction of such a device presents significant unsolved technological challenges. An alternative approach is proposed to the construction of a space elevator that utilises a free-standing core structure to provide access to near space regions and to reduce the cost of space launch. The theoretical and experimental investigation of the bending of inflatable cylindrical cantilevered beams made of modem fabric materials provides the basis for the design of an inflatable space tower. Experimental model structures were deployed and tested in order to determine design guidelines for the core structure. The feasibility of the construction of a thin walled inflatable space tower of 20 km vertical extent comprised of pneumatically inflated sections that are actively controlled and stabilised to balance external disturbances and support the structure is discussed. The response of the structure under wind loads is analyzed and taken into account for determining design guidelines. Such an approach avoids problems associated with a space tether including material strength constraints, the need for in-space construction, the fabrication of a cable at least 50,000 km in length, and the ageing and meteorite damage effects associated with a thin tether or cable in Low Earth Orbit. A suborbital tower of 20 km height would provide an ideal mounting point where a geostationary orbital space tether could be attached without experiencing atmospheric turbulence and weathering in the lower atmosphere. The tower can be utilized as a platform for various scientific and space missions or as an elevator to carry payloads and tourists. In addition, space towers can significantly be utilized to generate electrical power by harvesting high altitude renewable energy sources. Keywords: Space Elevator, Inflatable Space Tower, Inflatable Structure, Inflatable Beam, Inflatable Multiple-beam Structure, Cantilevered Beam, Pneumatic Structures.

TSS-1R Failure Mode Evaluation

NASA Technical Reports Server (NTRS)

Vaughn, Jason A.; McCollum, Matthew B.; Kamenetzky, Rachel R.

1997-01-01

Soon after the break of the tether during the Tethered Satellite System (TSS-1R) mission in February, 1996, a Tiger Team was assembled at the George C. Marshall Space Flight Center to determine the tether failure mode. One possible failure scenario was the Kevlar' strength member of the tether failed because of degradation due to electrical discharge or electrical arcing. During the next several weeks, extensive electrical discharge testing in low vacuum and plasma environments was conducted in an attempt to reproduce the electrical activity recorded by on-board science instruments during the mission. The results of these tests are presented in this paper.

Covariant electrodynamics in linear media: Optical metric

NASA Astrophysics Data System (ADS)

Thompson, Robert T.

2018-03-01

While the postulate of covariance of Maxwell's equations for all inertial observers led Einstein to special relativity, it was the further demand of general covariance—form invariance under general coordinate transformations, including between accelerating frames—that led to general relativity. Several lines of inquiry over the past two decades, notably the development of metamaterial-based transformation optics, has spurred a greater interest in the role of geometry and space-time covariance for electrodynamics in ponderable media. I develop a generally covariant, coordinate-free framework for electrodynamics in general dielectric media residing in curved background space-times. In particular, I derive a relation for the spatial medium parameters measured by an arbitrary timelike observer. In terms of those medium parameters I derive an explicit expression for the pseudo-Finslerian optical metric of birefringent media and show how it reduces to a pseudo-Riemannian optical metric for nonbirefringent media. This formulation provides a basis for a unified approach to ray and congruence tracing through media in curved space-times that may smoothly vary among positively refracting, negatively refracting, and vacuum.

SPHERES tethered formation flight testbed: application to NASA's SPECS mission

NASA Astrophysics Data System (ADS)

Chung, Soon-Jo; Kong, Edmund M.; Miller, David W.

2005-08-01

This paper elaborates on theory and experiment of the formation flight control for the future space-borne tethered interferometers. The nonlinear equations of multi-vehicle tethered spacecraft system are derived by Lagrange equations and decoupling method. The preliminary analysis predicts unstable dynamics depending on the direction of the tether motor. The controllability analysis indicates that both array resizing and spin-up are fully controllable only by the reaction wheels and the tether motor, thereby eliminating the need for thrusters. Linear and nonlinear decentralized control techniques have been implemented into the tethered SPHERES testbed, and tested at the NASA MSFC's flat floor facility using two and three SPHERES configurations. The nonlinear control using feedback linearization technique performed successfully in both two SPHERES in-line configuration and three triangular configuration while varying the tether length. The relative metrology system, using the ultra sound metrology system and the inertial sensors as well as the decentralized nonlinear estimator, is developed to provide necessary state information.

Space Environmental Testing of the Electrodynamic Dust Shield Technology

NASA Technical Reports Server (NTRS)

Calle, Carlos I.; Mackey, P. J.; Hogue, M. D.; Johansen, M .R.; Yim, H.; Delaune, P. B.; Clements, J. S.

2013-01-01

NASA's exploration missions to Mars and the moon may be jeopardized by dust that will adhere to surfaces of (a) Optical systems, viewports and solar panels, (b) Thermal radiators, (c) Instrumentation, and (d) Spacesuits. We have developed an active dust mitigation technology, the Electrodynamic Dust Shield, a multilayer coating that can remove dust and also prevents its accumulation Extensive testing in simulated laboratory environments and on a reduced gravity flight shows that high dust removal performance can be achieved Long duration exposure to the space environment as part of the MISSE-X payload will validate the technology for lunar missions.

The Hitchhiker's Guide to the Outer Solar System

NASA Technical Reports Server (NTRS)

Ono, Masahiro; Quadrelli, Marco; Lantoine, Gregory; Backes, Paul; Lopez Ortega, Alejandro; Grip, Havard; Yen, Chen-Wan; Jewitt, David

2015-01-01

We propose a novel deep space propulsion method called the Comet Hitchhiker. The concept is to perform momentum exchange with small bodies (i.e., asteroid and comet) using an extendable/retrievable tether and a harpoon. Unlike previously proposed tethered fly-by, the use of extendable tether enables to change the relative speed with a target. Hence Hitchhiker would be a prospective means of providing orbit insertion deltaV, particularly for rendezvous missions to small bodies in the outer Solar System such as Kuiper belt objects and Centaurs, which are not easily manageable with chemical propulsion or solar electric propulsion. Furthermore, by applying regenerative brake during a hitchhike maneuver, a Hitchhiker can harvest energy. The stored energy can be used to make a departure from the target by quickly retrieving the tether, which we call a inverse hitchhike maneuver. By repeating hitchhike and inverse Hitchhike maneuvers, a Hitchhiker could perform a mission to rendezvous with multiple targets efficiently, which we call a multi-hitchhike mission. We derive the basic equation of Hitchhiker, namely the Space Hitchhike Equation, which relates the specific strength and mass fraction of tether to achievable ?V. We then perform detailed feasibility analysis through finite element simulations of tether as well as hypervelocity impact simulations of the harpoon using the Adaptive Mesh Refinement Objected-oriented C++ (AMROC) algorithm. The analysis results suggest that a hitchhike maneuver with deltaV = approximately 1.5km/s is feasible with flight proven materials such as Kevlar/Zylon tether and tungsten harpoon. A carbon nanotube tether, combined with diamond harpoon, would enable approximately 10 km/s hitchhike maneuver. Finally, we present two particular mission scenarios for Hitchhiker: Pluto rendezvous and a multi-hitchhike mission to the Themis family asteroids in the main belt.

The development of optimal control laws for orbiting tethered platform systems

NASA Technical Reports Server (NTRS)

Bainum, P. M.

1986-01-01

A mathematical model of the open and closed loop in orbit plane dynamics of a space platform-tethered-subsatellite system is developed. The system consists of a rigid platform from which an (assumed massless) tether is deploying (retrieving) a subsatellite from an attachment point which is, in general, offset from the platform's mass center. A Langrangian formulation yields equations describing platform pitch, subsatellite tetherline swing, and varying tether length motions. These equations are linearized about the nominal station keeping motion. Control can be provided by both modulation of the tether tension level and by a momentum type platform-mounted device; system controllability depends on the presence of both control inputs. Stability criteria are developed in terms of the control law gains, the platform inertia ratio, and tether offset parameter. Control law gains are obtained based on linear quadratic regulator techniques. Typical transient responses of both the state and required control effort are presented.

Feasibility Study of Space Based Solar Power to Tethered Aerostat Systems

NASA Technical Reports Server (NTRS)

Blank, Stephen J.; Leete, Stephen J.; Jaffe, Paul

2013-01-01

The feasibility of two-stage Space-Based Solar Power to Tethered Aerostat to Earth (SSP-TA) system architectures that offer significant advantages over conventional single stage space-to-earth architectures is being studied. There have been many proposals for the transmission of solar power collected in space to the surface of the earth so that solar energy could provide a major part of the electric power requirements on earth. There are, however, serious difficulties in implementing the single stage space-based solar power systems that have been previously studied. These difficulties arise due to: i) the cost of transporting the components needed for the extremely large microwave transmit beaming aperture into space orbit, ii) the even larger collection apertures required on earth, iii) the potential radiation hazard to personnel and equipment on earth, and iv) a lack of flexibility in location of the collection station on the earth. Two candidate system architectures are described here to overcome these difficulties. In both cases a two-stage space to tethered aerostat to earth transmission system (SSP-TA) is proposed. The use of high altitude tethered aerostats (or powered airships) avoids the effects of attenuation of EM energy propagating through the earth s lower atmosphere. This allows the use of beaming frequencies to be chosen from the range of high millimeter (THz) to near-infra-red (NIR) to the visible. This has the potential for: i) greatly reduced transportation costs to space, ii) much smaller receiver collection apertures and ground stations, iii) elimination of the potential radiation hazard to personnel and equipment on earth, and iv) ease in transportation and flexibility in location of the collection station on the earth. A preliminary comparison of system performance and efficiencies is presented.

Chaotic Motions in the Dynamics of Space Tethered Systems. 1. Analysis of the Problem

NASA Astrophysics Data System (ADS)

Pirozhenko, A. V.

The determined-chaos phenomenon in the dynamics of space tethered systems is analyzed. A model problem, the essence of stochastic regimes of motion in the oscillation of masses in the internal degrees of freedom is formulated. A number of calculus approaches to the phenomenon is considered and the supposition is made that it is impossible to define the essence of the phenomenon by the mathematical methods traditional for mechanics.

Bounded parametric control of plane motions of space tethered system

NASA Astrophysics Data System (ADS)

Bezglasnyi, S. P.; Mukhametzyanova, A. A.

2018-05-01

This paper is focused on the problem of control of plane motions of a space tethered system (STS). The STS is modeled as a heavy rod with two point masses. Point masses are fixed on the rod. A third point mass can move along the rod. The control is realized as a continuous change of the distance from the centre of mass of the tethered system to the movable mass. New limited control laws processes of excitation and damping are built. Diametric reorientation and gravitational stabilization to the local vertical of an STS were obtained. The problem is solved by the method of Lyapunov's functions of the classical theory of stability. The theoretical results are confirmed by numerical calculations.

75 FR 47316 - Centennial Challenges 2010 Strong Tether Challenge

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-05

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Centennial Challenges 2010 Strong Tether Challenge... teams that wish to compete may register. Centennial Challenges is a program of prize competitions to..., please visit: http://www.spaceward.org/elevator2010-ts . For general information on the NASA Centennial...

Applicability of 100kWe-class of space reactor power systems to NASA manned space station missions

NASA Technical Reports Server (NTRS)

Silverman, S. W.; Willenberg, H. J.; Robertson, C.

1985-01-01

An assessment is made of a manned space station operating with sufficiently high power demands to require a multihundred kilowatt range electrical power system. The nuclear reactor is a competitor for supplying this power level. Load levels were selected at 150kWe and 300kWe. Interactions among the reactor electrical power system, the manned space station, the space transportation system, and the mission were evaluated. The reactor shield and the conversion equipment were assumed to be in different positions with respect to the station; on board, tethered, and on a free flyer platform. Mission analyses showed that the free flyer concept resulted in unacceptable costs and technical problems. The tethered reactor providing power to an electrolyzer for regenerative fuel cells on the space station, results in a minimum weight shield and can be designed to release the reactor power section so that it moves to a high altitude orbit where the decay period is at least 300 years. Placing the reactor on the station, on a structural boom is an attractive design, but heavier than the long tethered reactor design because of the shield weight for manned activity near the reactor.

Space weather forecasting with a Multimodel Ensemble Prediction System (MEPS)

NASA Astrophysics Data System (ADS)

Schunk, R. W.; Scherliess, L.; Eccles, V.; Gardner, L. C.; Sojka, J. J.; Zhu, L.; Pi, X.; Mannucci, A. J.; Butala, M.; Wilson, B. D.; Komjathy, A.; Wang, C.; Rosen, G.

2016-07-01

The goal of the Multimodel Ensemble Prediction System (MEPS) program is to improve space weather specification and forecasting with ensemble modeling. Space weather can have detrimental effects on a variety of civilian and military systems and operations, and many of the applications pertain to the ionosphere and upper atmosphere. Space weather can affect over-the-horizon radars, HF communications, surveying and navigation systems, surveillance, spacecraft charging, power grids, pipelines, and the Federal Aviation Administration (FAA's) Wide Area Augmentation System (WAAS). Because of its importance, numerous space weather forecasting approaches are being pursued, including those involving empirical, physics-based, and data assimilation models. Clearly, if there are sufficient data, the data assimilation modeling approach is expected to be the most reliable, but different data assimilation models can produce different results. Therefore, like the meteorology community, we created a Multimodel Ensemble Prediction System (MEPS) for the Ionosphere-Thermosphere-Electrodynamics (ITE) system that is based on different data assimilation models. The MEPS ensemble is composed of seven physics-based data assimilation models for the ionosphere, ionosphere-plasmasphere, thermosphere, high-latitude ionosphere-electrodynamics, and middle to low latitude ionosphere-electrodynamics. Hence, multiple data assimilation models can be used to describe each region. A selected storm event that was reconstructed with four different data assimilation models covering the middle and low latitude ionosphere is presented and discussed. In addition, the effect of different data types on the reconstructions is shown.

MIC: Magnetically Deployable Structures for Power, Propulsion, Processing, Habitats and Energy Storage at Manned Lunar Bases

NASA Astrophysics Data System (ADS)

Powell, James; Maise, George; Paniagua, John; Rather, John

2007-01-01

MIC (Magnetically Inflated Cables) is a new approach for robotically erecting very large, strong, rigid, and ultra-lightweight structures in space. MIC structures use a network of high current (SC) cables with attached high tensile strength Kevlar or Spectra tethers. MIC is launched as a compact package of coiled SC cables and tethers on a conventional launch vehicle. Once in space the SC cables are electrically energized. The resultant strong outwards magnetic forces expand them and the restraining tethers into a large structure, which can be 100's of meters in size. MIC structures can be configured for many different applications, including solar electric generation, solar thermal propulsion, energy storage, large space telescopes, magnetic shielding for astronauts, etc. The MIC technology components, including high temperature superconductors (HTS), thermal insulation, high strength tethers, and cryogenic refrigerators all exist commercially. Refrigeration requirements are very modest, on the order of 100 watts thermal per kilometer of MIC cable, with an input electric power to the refrigeration system of ~5 kW(e) per km. baseline MIC designs are described for a manned lunar base, including: 1) a 1 MW(e) solar electric system, 2) a high Isp (~900 seconds) solar thermal tug to transport 30 ton payloads between the Earth and the Moon, 3) a 2000 Megajoule electric energy storage system for peaking and emergency power, and 4) a large (~1 km) space telescope.

Tether Dynamics Simulation

NASA Technical Reports Server (NTRS)

1987-01-01

The proceedings of the conference are presented. The objective was to provide a forum for the discussion of the structure and status of existing computer programs which are used to simulate the dynamics of a variety of tether applications in space. A major topic was different simulation models and the process of validating them. Guidance on future work in these areas was obtained from a panel discussion; the panel was composed of resource and technical managers and dynamic analysts in the tether field. The conclusions of this panel are also presented.

Topologically massive magnetic monopoles

NASA Astrophysics Data System (ADS)

Aliev, A. N.; Nutku, Y.; Saygili, K.

2000-10-01

We show that in the Maxwell-Chern-Simons theory of topologically massive electrodynamics the Dirac string of a monopole becomes a cone in anti-de Sitter space with the opening angle of the cone determined by the topological mass, which in turn is related to the square root of the cosmological constant. This proves to be an example of a physical system, a priori completely unrelated to gravity, which nevertheless requires curved spacetime for its very existence. We extend this result to topologically massive gravity coupled to topologically massive electrodynamics within the framework of the theory of Deser, Jackiw and Templeton. The two-component spinor formalism, which is a Newman-Penrose type approach for three dimensions, is extended to include both the electrodynamical and gravitational topologically massive field equations. Using this formalism exact solutions of the coupled Deser-Jackiw-Templeton and Maxwell-Chern-Simons field equations for a topologically massive monopole are presented. These are homogeneous spaces with conical deficit. Pure Einstein gravity coupled to the Maxwell-Chern-Simons field does not admit such a monopole solution.

Variable gravity research facility

NASA Technical Reports Server (NTRS)

Allan, Sean; Ancheta, Stan; Beine, Donna; Cink, Brian; Eagon, Mark; Eckstein, Brett; Luhman, Dan; Mccowan, Daniel; Nations, James; Nordtvedt, Todd

1988-01-01

Spin and despin requirements; sequence of activities required to assemble the Variable Gravity Research Facility (VGRF); power systems technology; life support; thermal control systems; emergencies; communication systems; space station applications; experimental activities; computer modeling and simulation of tether vibration; cost analysis; configuration of the crew compartments; and tether lengths and rotation speeds are discussed.

Jupiter, Tether, and Lenz's Law

NASA Technical Reports Server (NTRS)

Lee, Russell

1999-01-01

Jupiter has a large, complex, and intense magnetic field that is thought to arise from electrical currents in the rapidly spinning metallic hydrogen interior. The strong magnetic field can induce currents when the conductive tether is directed toward or away from Jupiter. The currents can be stored and used for both propulsion and power generation. Therefore, our spacecraft might be able to visit several Jovian moons or maintain in the orbit around Jupiter. In our future space traveling, we also can use this technical skill to travel to other planets without any fuel. First-year physics textbooks describe Lenz's Law in which current is induced in a conductor moving through a stationary magnetic field. A demonstration of induced current in a stationary conductor and moving magnetic field is described, which may have space-tether application.

Tethered satellite system control using electromagnetic forces and reaction wheels

NASA Astrophysics Data System (ADS)

Alandi Hallaj, Mohammad Amin; Assadian, Nima

2015-12-01

In this paper a novel non-rotating space tethered configuration is introduced which its relative positions controlled using electromagnetic forces. The attitude dynamics is controlled by three reaction wheels in the body axes. The nonlinear coupled orbital dynamics of a dumbbell tethered satellite formation flight are derived through a constrained Lagrangian approach. These equations are presented in the leader satellite orbital frame. The tether is assumed to be mass-less and straight, and the J2 perturbation is included to the analysis. The forces and the moments of the electromagnetic coils are modeled based on the far-filed model of the magnetic dipoles. A guidance scheme for generating the desired positions as a function of time in Cartesian form is presented. The satellite tethered formation with variable length is controlled utilizing a linear controller. This approach is applied to a specified scenario and it is shown that the nonlinear guidance method and the linear controller can control the nonlinear system of the tethered formation and the results are compared with optimal control approach.

Developing Capture Mechanisms and High-Fidelity Dynamic Models for the MXER Tether System

NASA Technical Reports Server (NTRS)

Canfield, Steven L.

2007-01-01

A team consisting of collaborators from Tennessee Technological University (TTU), Marshall Space Flight Center, BD Systems, and the University of Delaware (herein called the TTU team) conducted specific research and development activities in MXER tether systems during the base period of May 15, 2004 through September 30, 2006 under contract number NNM04AB13C. The team addressed two primary topics related to the MXER tether system: 1) Development of validated high-fidelity dynamic models of an elastic rotating tether and 2) development of feasible mechanisms to enable reliable rendezvous and capture. This contractor report will describe in detail the activities that were performed during the base period of this cycle-2 MXER tether activity and will summarize the results of this funded activity. The primary deliverables of this project were the quad trap, a robust capture mechanism proposed, developed, tested, and demonstrated with a high degree of feasibility and the detailed development of a validated high-fidelity elastic tether dynamic model provided through multiple formulations.

Energy considerations in the partial space elevator

NASA Astrophysics Data System (ADS)

Woo, Pamela; Misra, Arun K.

2014-06-01

The space elevator has been proposed as an alternate method for space transportation. A partial elevator is composed of a tether of several hundreds of kilometres, held vertically in tension between two end masses, with its centre of orbit placed at the geosynchronous orbit. A spacecraft can dock at the lower end, and then use the climber on the elevator to ascend to higher altitudes. In this paper, energy calculations are performed, to determine whether a partial elevator can provide sufficient savings in operational costs, compared to the traditional rocket-powered launch. The energy required to launch a spacecraft from a Low Earth Orbit (LEO) to the geostationary orbit (GEO) is calculated for two trajectories. In the first trajectory, the spacecraft travels from LEO to GEO via a Hohmann transfer. In the second trajectory, the spacecraft travels from LEO to the lower end of the partial space elevator with a Hohmann transfer, and then uses the elevator to climb to GEO. The total energy required is compared between the two trajectories. The effects of tether length, spacecraft-to-climber mass ratio, altitude of LEO, and tether material are investigated.

KSC-2013-4281

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander has been attached to a tether and is being prepared for a tether test on a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The tether test includes lifting the lander 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

Large structures and tethers working group

NASA Technical Reports Server (NTRS)

Murphy, G.; Garrett, H.; Samir, U.; Barnett, A.; Raitt, J.; Sullivan, J.; Katz, I.

1986-01-01

The Large Structures and Tethers Working Group sought to clarify the meaning of large structures and tethers as they related to space systems. Large was assumed to mean that the characteristic length of the structure was greater than one of such relevant plasma characteristics as ion gyroradius or debey length. Typically, anything greater than or equal to the Shuttle dimensions was considered large. It was agreed that most large space systems that the tether could be better categorized as extended length, area, or volume structures. The key environmental interactions were then identified in terms of these three categories. In the following Working Group summary, these categories and the related interactions are defined in detail. The emphasis is on how increases in each of the three spatial dimensions uniquely determine the interactions with the near-Earth space environment. Interactions with the environments around the other planets and the solar wind were assumed to be similar or capable of being extrapolated from the near-Earth results. It should be remembered in the following that the effects on large systems do not just affect specific technologies but will quite likely impact whole missions. Finally, the possible effects of large systems on the plasma environment, although only briefly discussed, were felt to be of potentially great concern.

Hollow cathodes as electron emitting plasma contactors Theory and computer modeling

NASA Technical Reports Server (NTRS)

Davis, V. A.; Katz, I.; Mandell, M. J.; Parks, D. E.

1987-01-01

Several researchers have suggested using hollow cathodes as plasma contactors for electrodynamic tethers, particularly to prevent the Shuttle Orbiter from charging to large negative potentials. Previous studies have shown that fluid models with anomalous scattering can describe the electron transport in hollow cathode generated plasmas. An improved theory of the hollow cathode plasmas is developed and computational results using the theory are compared with laboratory experiments. Numerical predictions for a hollow cathode plasma source of the type considered for use on the Shuttle are presented, as are three-dimensional NASCAP/LEO calculations of the emitted ion trajectories and the resulting potentials in the vicinity of the Orbiter. The computer calculations show that the hollow cathode plasma source makes vastly superior contact with the ionospheric plasma compared with either an electron gun or passive ion collection by the Orbiter.

Attitude control analysis of tethered de-orbiting

NASA Astrophysics Data System (ADS)

Peters, T. V.; Briz Valero, José Francisco; Escorial Olmos, Diego; Lappas, V.; Jakowski, P.; Gray, I.; Tsourdos, A.; Schaub, H.; Biesbroek, R.

2018-05-01

The increase of satellites and rocket upper stages in low earth orbit (LEO) has also increased substantially the danger of collisions in space. Studies have shown that the problem will continue to grow unless a number of debris are removed every year. A typical active debris removal (ADR) mission scenario includes launching an active spacecraft (chaser) which will rendezvous with the inactive target (debris), capture the debris and eventually deorbit both satellites. Many concepts for the capture of the debris while keeping a connection via a tether, between the target and chaser have been investigated, including harpoons, nets, grapples and robotic arms. The paper provides an analysis on the attitude control behaviour for a tethered de-orbiting mission based on the ESA e.Deorbit reference mission, where Envisat is the debris target to be captured by a chaser using a net which is connected to the chaser with a tether. The paper provides novel insight on the feasibility of tethered de-orbiting for the various mission phases such as stabilization after capture, de-orbit burn (plus stabilization), stabilization during atmospheric pass, highlighting the importance of various critical mission parameters such as the tether material. It is shown that the selection of the appropriate tether material while using simple controllers can reduce the effort needed for tethered deorbiting and can safely control the attitude of the debris/chaser connected with a tether, without the danger of a collision.

77 FR 50956 - Exclusion of Tethered Launches From Licensing Requirements

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-23

..., but do not apply to amateur rocket activities or to space activities carried out by the United States... hitting the ground. Some of these tethered launches met the FAA's amateur rocket activity criteria,\\1\\ and thus were excluded from chapter III requirements. Those that did not meet the amateur rocket criteria...

Selected Tether Applications Cost Model

NASA Technical Reports Server (NTRS)

Keeley, Michael G.

1988-01-01

Diverse cost-estimating techniques and data combined into single program. Selected Tether Applications Cost Model (STACOM 1.0) is interactive accounting software tool providing means for combining several independent cost-estimating programs into fully-integrated mathematical model capable of assessing costs, analyzing benefits, providing file-handling utilities, and putting out information in text and graphical forms to screen, printer, or plotter. Program based on Lotus 1-2-3, version 2.0. Developed to provide clear, concise traceability and visibility into methodology and rationale for estimating costs and benefits of operations of Space Station tether deployer system.

The motion and control of a complex three-body space tethered system

NASA Astrophysics Data System (ADS)

Shi, Gefei; Zhu, Zhanxia; Chen, Shiyu; Yuan, Jianping; Tang, Biwei

2017-11-01

This paper is mainly devoted to investigating the dynamics and stability control of a three body-tethered satellite system which contains a main satellite and two subsatellites connected by two straight, massless and inextensible tethers. Firstly, a detailed mathematical model is established in the central gravitational field. Then, the dynamic characteristics of the established system are investigated and analyzed. Based on the dynamic analysis, a novel sliding mode prediction model (SMPM) control strategy is proposed to suppress the motion of the built tethered system. The numerical results show that the proposed underactuated control law is highly effective in suppressing the attitude/libration motion of the underactuated three-body tethered system. Furthermore, cases of different target angles are also examined and analyzed. The simulation results reveal that even if the final equilibrium states differ from different selections of the target angles, the whole system can still be maintained in acceptable areas.

Conserved charges for black holes in Einstein-Gauss-Bonnet gravity coupled to nonlinear electrodynamics in AdS space

NASA Astrophysics Data System (ADS)

Mišković, Olivera; Olea, Rodrigo

2011-01-01

Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.

Conserved charges for black holes in Einstein-Gauss-Bonnet gravity coupled to nonlinear electrodynamics in AdS space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miskovic, Olivera; Olea, Rodrigo; Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso

2011-01-15

Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, itmore » extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.« less

The Tethered Balloon Current Generator - A space shuttle-tethered subsatellite for plasma studies and power generation

NASA Technical Reports Server (NTRS)

Williamson, P. R.; Banks, P. M.

1976-01-01

The objectives of the Tethered Balloon Current Generator experiment are to: (1) generate relatively large regions of thermalized, field-aligned currents, (2) produce controlled-amplitude Alfven waves, (3) study current-driven electrostatic plasma instabilities, and (4) generate substantial amounts of power or propulsion through the MHD interaction. A large balloon (a diameter of about 30 m) will be deployed with a conducting surface above the space shuttle at a distance of about 10 km. For a generally eastward directed orbit at an altitude near 400 km, the balloon, connected to the shuttle by a conducting wire, will be positive with respect to the shuttle, enabling it to collect electrons. At the same time, the shuttle will collect positive ions and, upon command, emit an electron beam to vary current flow in the system.

Vacuum nonlinear electrodynamic polarization effects in hard emission of pulsars and magnetars

NASA Astrophysics Data System (ADS)

Denisov, V. I.; Sokolov, V. A.; Svertilov, S. I.

2017-09-01

The nonlinear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on the electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum (nonlinear electrodynamics is obtained. It has been shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and the rest of pulse can have arbitrary polarization. The observational possibilities of vacuum birefringence are discussed. In this paper we give the estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum nonlinear electrodynamics birefringence.

Vacuum nonlinear electrodynamic polarization effects in hard emission of pulsars and magnetars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denisov, V.I.; Sokolov, V.A.; Svertilov, S.I., E-mail: vid.msu@yandex.ru, E-mail: sokolov.sev@inbox.ru, E-mail: sis@coronas.ru

The nonlinear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on the electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum (nonlinear electrodynamics is obtained. It has been shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and themore » rest of pulse can have arbitrary polarization. The observational possibilities of vacuum birefringence are discussed. In this paper we give the estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum nonlinear electrodynamics birefringence.« less

Five degrees of freedom linear state-space representation of electrodynamic thrust bearings

NASA Astrophysics Data System (ADS)

Van Verdeghem, J.; Kluyskens, V.; Dehez, B.

2017-09-01

Electrodynamic bearings can provide stable and contactless levitation of rotors while operating at room temperatures. Depending solely on passive phenomena, specific models have to be developed to study the forces they exert and the resulting rotordynamics. In recent years, models allowing us to describe the axial dynamics of a large range of electrodynamic thrust bearings have been derived. However, these bearings being devised to be integrated into fully magnetic suspensions, the existing models still suffer from restrictions. Indeed, assuming the spin speed as varying slowly, a rigid rotor is characterised by five independent degrees of freedom whereas early models only considered the axial degree. This paper presents a model free of the previous limitations. It consists in a linear state-space representation describing the rotor's complete dynamics by considering the impact of the rotor axial, radial and angular displacements as well as the gyroscopic effects. This set of ten equations depends on twenty parameters whose identification can be easily performed through static finite element simulations or quasi-static experimental measurements. The model stresses the intrinsic decoupling between the axial dynamics and the other degrees of freedom as well as the existence of electrodynamic angular torques restoring the rotor to its nominal position. Finally, a stability analysis performed on the model highlights the presence of two conical whirling modes related to the angular dynamics, namely the nutation and precession motions. The former, whose intrinsic stability depends on the ratio between polar and transverse moments of inertia, can be easily stabilised through external damping whereas the latter, which is stable up to an instability threshold linked to the angular electrodynamic cross-coupling stiffness, is less impacted by that damping.

Visualization of Space-Time Ambiguities to be Explored by NASA GEC Mission with a Critique of Synthesized Measurements for Different GEC Mission Scenarios

NASA Technical Reports Server (NTRS)

Sojka, Jan J.

2003-01-01

The Grant supported research addressing the question of how the NASA Solar Terrestrial Probes (STP) Mission called Geospace electrodynamics Connections (GEC) will resolve space-time structures as well as collect sufficient information to solve the coupled thermosphere-ionosphere- magnetosphere dynamics and electrodynamics. The approach adopted was to develop a high resolution in both space and time model of the ionosphere-thermosphere (I-T) over altitudes relevant to GEC, especially the deep-dipping phase. This I-T model was driven by a high- resolution model of magnetospheric-ionospheric (M-I) coupling electrodynamics. Such a model contains all the key parameters to be measured by GEC instrumentation, which in turn are the required parameters to resolve present-day problems in describing the energy and momentum coupling between the ionosphere-magnetosphere and ionosphere-thermosphere. This model database has been successfully created for one geophysical condition; winter, solar maximum with disturbed geophysical conditions, specifically a substorm. Using this data set, visualizations (movies) were created to contrast dynamics of the different measurable parameters. Specifically, the rapidly varying magnetospheric E and auroral electron precipitation versus the slower varying ionospheric F-region electron density, but rapidly responding E-region density.

A Process Algebra Approach to Quantum Electrodynamics

NASA Astrophysics Data System (ADS)

Sulis, William

2017-12-01

The process algebra program is directed towards developing a realist model of quantum mechanics free of paradoxes, divergences and conceptual confusions. From this perspective, fundamental phenomena are viewed as emerging from primitive informational elements generated by processes. The process algebra has been shown to successfully reproduce scalar non-relativistic quantum mechanics (NRQM) without the usual paradoxes and dualities. NRQM appears as an effective theory which emerges under specific asymptotic limits. Space-time, scalar particle wave functions and the Born rule are all emergent in this framework. In this paper, the process algebra model is reviewed, extended to the relativistic setting, and then applied to the problem of electrodynamics. A semiclassical version is presented in which a Minkowski-like space-time emerges as well as a vector potential that is discrete and photon-like at small scales and near-continuous and wave-like at large scales. QED is viewed as an effective theory at small scales while Maxwell theory becomes an effective theory at large scales. The process algebra version of quantum electrodynamics is intuitive and realist, free from divergences and eliminates the distinction between particle, field and wave. Computations are carried out using the configuration space process covering map, although the connection to second quantization has not been fully explored.

Gossamer sails for satellite de-orbiting: Mission analysis and applications

NASA Astrophysics Data System (ADS)

Visagie, Lourens

The requirement for satellites to have a mitigation or deorbiting strategy has been brought about by the ever increasing amount of debris in Earth orbit. Studies have been used to formulate space debris mitigation guidelines, and adherence to these guidelines would theoretically lead to a sustainable environment for future satellite launches and operations. Deployable sail designs that have traditionally been studied and used for solar sails are increasingly being considered for de-orbit applications. Such sail designs benefit from a low mass and large surface area to achieve efficient thrust. A sail has the potential to be used for drag augmentation, to reduce the time until re-entry, or as an actual solar sail - to deorbit from higher orbits. A number of concerns for sail-based deorbiting are addressed in this thesis. One of these concerns is the ability of a sail to mitigate the risk of a collision. By investigating both the area-time-product (ATP) and collision probability it is shown that a gossamer sail used for deorbiting will lead to a reduction in overall collision risk. The extent to which the risk is reduced is investigated and the contributing factors assessed. Another concern is that of attitude stability of a host satellite and deorbit sail. One of the biggest benefits of drag augmentation is the fact that it can achieve the deorbiting goal with an inactive host satellite. There is thus no need for active control, communications or power after deployment. But a simple 2D sail will lose efficiency as a deorbiting device if it is not optimally oriented. It was found in this research that it is possible for a host satellite with attached sail to maintain a stable attitude under passive conditions in a drag deorbiting mode. Finally, in order to fully prove the benefit of sail-based deorbiting it is shown that in certain scenarios this alternative might be more efficient at reducing collision risk, weighs less, and has less operational requirements than other alternatives such as electrodynamic tethers and conventional propulsion. This thesis aims to cover the fundamental concerns of a sail-based deorbiting device at mission level by firstly addressing the mission analysis aspects and then applying it to specific scenarios. The theory and methods required to perform mission analysis for a sail-based deorbiting strategy is presented. These methods are then used to demonstrate passive attitude stability for a drag sail, and reduction in collision risk, both in terms of the Area-Time-Product and collision probability. The analysis results are then further applied by identifying scenarios to which the proposed deorbiting device applies, and then performing a meaningful comparison by analysing a number of case studies. The application is made more concrete by comparison with likely contenders - traditional propulsion, electrodynamic tethers and an inflatable sphere.

Desert Research and Technology Studies Exposure of Lotus Coated Electrodynamic Shield Samples

NASA Technical Reports Server (NTRS)

Rodriquez, Marcello; Peters, Wanda C.; Straka, Sharon A.; Jones, Craig B.

2011-01-01

The Lotus dust mitigation coating and the electrodynamic shield (EDS) are two new technologies currently being developed by NASA as countermeasures for addressing dust accumulation for long-duration human space exploration. These combined technologies were chosen by the Habitation Demonstration Unit (HDU) program for desert dust exposure at the Desert Research and Technologies Studies (D-RaTS) test site in Arizona. Characterization of these samples was performed prior to, during and post D-RaTS exposure.

Elastic-Tether Suits for Artificial Gravity and Exercise

NASA Technical Reports Server (NTRS)

Torrance, Paul; Biesinger, Paul; Rybicki, Daniel D.

2005-01-01

Body suits harnessed to systems of elastic tethers have been proposed as means of approximating the effects of normal Earth gravitation on crewmembers of spacecraft in flight to help preserve the crewmembers physical fitness. The suits could also be used on Earth to increase effective gravitational loads for purposes of athletic training. The suit according to the proposal would include numerous small tether-attachment fixtures distributed over its outer surface so as to distribute the artificial gravitational force as nearly evenly as possible over the wearer s body. Elastic tethers would be connected between these fixtures and a single attachment fixture on a main elastic tether that would be anchored to a fixture on or under a floor. This fixture might include multiple pulleys to make the effective length of the main tether great enough that normal motions of the wearer cause no more than acceptably small variations in the total artificial gravitational force. Among the problems in designing the suit would be equalizing the load in the shoulder area and keeping tethers out of the way below the knees to prevent tripping. The solution would likely include running tethers through rings on the sides. Body suits with a weight or water ballast system are also proposed for very slight spinning space-station scenarios, in which cases the proposed body suits will easily be able to provide the equivalency of a 1-G or even greater load.

The Arctic Lower Troposphere Observed Structure (ALTOS) Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verlinde, J

2010-10-18

The ALTOS campaign focuses on operating a tethered observing system for routine in situ sampling of low-level (< 2 km) Arctic clouds. It has been a long-term hope to fly tethered systems at Barrow, Alaska, but it is clear that the Federal Aviation Administration (FAA) will not permit in-cloud tether systems at Barrow, even if unmanned aerial vehicle (UAV) operations are allowed in the future. We have provided the scientific rationale for long-term, routine in situ measurements of cloud and aerosol properties in the Arctic. The existing restricted air space at Oliktok offers an opportunity to do so.

Dynamics and Control of Tethered Satellite Formations for the Purpose of Space-Based Remote Sensing

DTIC Science & Technology

2006-08-01

remote sensing mission. Energy dissipation is found to have an adverse effect on foundational rigid body (Likins-Pringle) equilibria. It is shown that a continuously earth-facing equilibrium condition for a fixed-length tethered system does not exist since the spin rate required for the proper precession would not be high enough to maintain tether tension. The range of required spin rates for steady-spin motion is numerically defined here, but none of these conditions can meet the continuously earth-facing criteria. Of particular note is the discovery that applying certain

VLF space transmitter

NASA Technical Reports Server (NTRS)

Olsen, R. C.; Thompson, G. C.

1989-01-01

A practical operational system for communicating with submarines located at high latitudes, particularly those under the ice cap, is described. A 10-20-km dipole is deployed which utilized tether technology and which operated at 1-3 kHz. A pair of hollow-cathode-based plasma sources, establishing contact between the ends of the tether system and the ambient plasma, allows utilization of the natural dynamo effect of the tether. It is suggested that a 12-satellite constellation in quasi-polar orbit at 500-1000 km altitude could provide coverage for a 4 million sq km area at 75 percent duty cycle.

Parametric control of maneuver of a space tether system

NASA Astrophysics Data System (ADS)

Bezglasnyi, S. P.; Piyakina, E. E.

2015-07-01

Planar motion of a space tether system (STS) simulated by a massless rod with two masses fixed on its edges and a third mass moving along the rod is considered. An equation of the pendulum-controlled motion of the system in an elliptical orbit is obtained. Problems of parametric control that takes the STS from one stable radial equilibrium state to another and stabilizes it with respect to planar excitations of two diametrically opposite positions of the relative equilibrium of the STS in a circular orbit are investigated. The control is a continuous law of motion for a moving mass along the tether on the swing principle. The solution is obtained in a closed form based on the second method of the classical stability theory by the construction of the corresponding Lyapunov functions. Asymptotic convergence of solutions is confirmed by the results of numerical modeling of the system motion.

A tether tension control law for tethered subsatellites deployed along local vertical. [space shuttle orbiters - satellite control/towed bodies

NASA Technical Reports Server (NTRS)

Rupp, C. C.

1975-01-01

A tethered subsatellite deployed along the local vertical is in stable equilibrium. This applies equally to subsatellites deployed in the direction towards the earth from the main spacecraft or away from the earth. Momentary perturbations from this stable equilibrium will result in a swinging motion, which decays very slowly if passive means are relied upon to provide damping. A control law is described which actively damps the swinging motion by employing a reel, or other mechanism, to apply appropriate tension as a function of tetherline length, rate of change of length, and desired length. The same control law is shown to be useful for deployment and retrieval of tethered subsatellites in addition to damping to steady state.

The mechanics of motorised momentum exchange tethers when applied to active debris removal from LEO

NASA Astrophysics Data System (ADS)

Caldecott, Ralph; Kamarulzaman, Dayangku N. S.; Kirrane, James P.; Cartmell, Matthew P.; Ganilova, Olga A.

2014-12-01

The concept of momentum exchange when applied to space tethers for propulsion is well established, and a considerable body of literature now exists on the on-orbit modelling, the dynamics, and also the control of a large range of tether system applications. The authors consider here a new application for the Motorised Momentum Exchange Tether by highlighting three key stages of development leading to a conceptualisation that can subsequently be developed into a technology for Active Debris Removal. The paper starts with a study of the on-orbit mechanics of a full sized motorised tether in which it is shown that a laden and therefore highly massasymmetrical tether can still be forced to spin, and certainly to librate, thereby confirming its possible usefulness for active debris removal (ADR). The second part of the paper concentrates on the modelling of the centripetal deployment of a symmetrical MMET in order to get it initialized for debris removal operations, and the third and final part of the paper provides an entry into scale modelling for low cost mission design and testing. It is shown that the motorised momentum exchange tether offers a potential solution to the removal of large pieces of orbital debris, and that dynamic methodologies can be implemented to in order to optimise the emergent design.

Modelling Tethered Enzymatic Reactions

NASA Astrophysics Data System (ADS)

Solis Salas, Citlali; Goyette, Jesse; Coker-Gordon, Nicola; Bridge, Marcus; Isaacson, Samuel; Allard, Jun; Maini, Philip; Dushek, Omer

Enzymatic reactions are key to cell functioning, and whilst much work has been done in protein interaction in cases where diffusion is possible, interactions of tethered proteins are poorly understood. Yet, because of the large role cell membranes play in enzymatic reactions, several reactions may take place where one of the proteins is bound to a fixed point in space. We develop a model to characterize tethered signalling between the phosphatase SHP-1 interacting with a tethered, phosphorylated protein. We compare our model to experimental data obtained using surface plasmon resonance (SPR). We show that a single SPR experiment recovers 5 independent biophysical/biochemical constants. We also compare the results between a three dimensional model and a two dimensional model. The work gives the opportunity to use known techniques to learn more about signalling processes, and new insights into how enzyme tethering alters cellular signalling. With support from the Mexican Council for Science and Technology (CONACyT), the Public Education Secretariat (SEP), and the Mexican National Autonomous University's Foundation (Fundacion UNAM).

Special Relativity

NASA Astrophysics Data System (ADS)

Dixon, W. G.

1982-11-01

Preface; 1. The physics of space and time; 2. Affine spaces in mathematics and physics; 3. Foundations of dynamics; 4. Relativistic simple fluids; 5. Electrodynamics of polarisable fluids; Appendix: Vector and dyadic notation in three dimensions; Publications referred to in the text; Summary and index of symbols and conventions; Subject index.

EMC Test Report Electrodynamic Dust Shield

NASA Technical Reports Server (NTRS)

Carmody, Lynne M.; Boyette, Carl B.

2014-01-01

This report documents the Electromagnetic Interference E M I evaluation performed on the Electrodynamic Dust Shield (EDS) which is part of the MISSE-X System under the Electrostatics and Surface Physics Laboratory at Kennedy Space Center. Measurements are performed to document the emissions environment associated with the EDS units. The purpose of this report is to collect all information needed to reproduce the testing performed on the Electrodynamic Dust Shield units, document data gathered during testing, and present the results. This document presents information unique to the measurements performed on the Bioculture Express Rack payload; using test methods prepared to meet SSP 30238 requirements. It includes the information necessary to satisfy the needs of the customer per work order number 1037104. The information presented herein should only be used to meet the requirements for which it was prepared.

KSC-2013-3900

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dr. Carlos Calle, senior research scientist on the Electrodynamic Dust Shield for Dust Mitigation project, manages the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. Electrodynamic dust shield, or EDS, technology is based on concepts originally developed by NASA as early as 1967 and later by the University of Tokyo. In 2003, NASA, in collaboration with the University of Arkansas at Little Rock, started development of the EDS for dust particle removal from solar panels to be used on future missions to the moon, an asteroid or Mars. A flight experiment to expose the dust shields to the space environment currently is under development. For more information, visit: http://www.nasa.gov/content/scientists-developing-ways-to-mitigate-dust-problem-for-explorers/ Photo credit: NASA/Dan Casper

A Convective Coordinate Approach to Continuum Mechanics with Application to Electrodynamics

DTIC Science & Technology

2013-01-01

7 3. Differential Operators in Curvilinear Spaces 9 3.1 The Covariant...the particles in an arbitrary (perhaps initial or even fictitious) configuration, and a set of spatial coordinates that fixes locations in space (that...of field quantities defined in such spaces . 2.1 The Background Cartesian System Before defining the physical coordinate systems at the heart of this

GEMINI-TITAN (GT)-12 - EARTH SKY - AGENA ON TETHER - OUTER SPACE

NASA Image and Video Library

1966-11-13

S66-63517 (13 Nov. 1966) --- The Gulf of California area as seen from the Gemini-12 spacecraft during its 30th revolution of Earth. Baja California Sur is the peninsula on the left. At lower left is the mainland of Mexico. A 100-foot tether line connects the Agena Target Docking Vehicle with the Gemini-12 spacecraft. View is looking south. Photo credit: NASA

KSC-2013-4284

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander has been lifted by a tether and hovers above a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The lander’s engine begins firing for a tethered test that includes lifting it 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

KSC-2013-4282

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander has been attached to a tether and is being raised from a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The tethered test includes lifting the lander 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

Morpheus Lander Testing Campaign

NASA Technical Reports Server (NTRS)

Hart, Jeremy J.; Mitchell, Jennifer D.

2011-01-01

NASA s Morpheus Project has developed and tested a prototype planetary lander capable of vertical takeoff and landing designed to serve as a testbed for advanced spacecraft technologies. The Morpheus vehicle has successfully performed a set of integrated vehicle test flights including hot-fire and tether tests, ultimately culminating in an un-tethered "free-flight" This development and testing campaign was conducted on-site at the Johnson Space Center (JSC), less than one year after project start. Designed, developed, manufactured and operated in-house by engineers at JSC, the Morpheus Project represents an unprecedented departure from recent NASA programs and projects that traditionally require longer development lifecycles and testing at remote, dedicated testing facilities. This paper documents the integrated testing campaign, including descriptions of test types (hot-fire, tether, and free-flight), test objectives, and the infrastructure of JSC testing facilities. A major focus of the paper will be the fast pace of the project, rapid prototyping, frequent testing, and lessons learned from this departure from the traditional engineering development process at NASA s Johnson Space Center.

High voltage plasma sheath analysis related to TSS-1

NASA Technical Reports Server (NTRS)

Sheldon, John W.

1991-01-01

On the first mission of the Tethered Satellite System (TSS-1), a 1.8 m diameter spherical satellite will be deployed a distance of 20 km above the space shuttle Orbiter on an insulated conducting tether. The satellite will be held at electric potentials up to 5000 volts positive with respect to the ambient plasma. Due to the passage of the conducting tether through the Earth's magnetic field, an emf will be created, driving electrons down the tether to the orbiter, out through an electron gun into the ionosphere and back into the positive biased satellite. Instrumentation on the satellite will measure electron flow to the surface at several locations, but these detectors have a limited range of acceptance angle. The problem addressed herein is the determination of the electron current distribution over the satellite surface and the angle of incidence of the incoming electrons relative to the surface normal.

The TSS-1R Results - the Physics of Current Collection in Magnetized Plasmas Revised

NASA Astrophysics Data System (ADS)

Papadopoulos, Konstantinos

1996-11-01

The Tethered Satellite System (TSS-1R) was deployed from the space shuttle "Columbia" (STS-75 Mission) on February 24, 1996. The satellite was deployed to a distance of 19.7 km above the shuttle. The system operated nominally over its deployment phase which lasted 5.5 hours. A defect in the tether insulation inside the orbiter caused a local discharge which led to a tether break. Data collected before and during the break revealed a host of new physics phenomena concerning the current collection by charged bodies in space moving at orbital velocities. The maximum EMF observed during the mission was 3.8 kV and the maximum current exceeded 1A. Power generation of several kW's was demonstrated. The current collected was significantly larger than expected by space charged limited flow in magnetized and even unmagnetized plasmas. For example the 1A current was collected with less than 1 kV potential instead of the 20 kV given by previous theories. The presentation will review the fascinating results of the TSS-1R and will discuss the ongoing physics analysis of the observed phenomena. *In collaboration with A. Drobot and C.L. Chang of SAIC.

Velior Petrovich

NASA Astrophysics Data System (ADS)

Ness, Norman

Dr. Velior Petrovich Shabansky, aged 58, the head of the Laboratory of Cosmic Electrodynamics, Institute of Nuclear Physics, Moscow State University, suddenly passed away on November 16, 1985, of a heart attack. He was one of the founders of theoretical ideas in physics of interplanetary and near-earth space. Shabansky obtained his education at the Moscow State University and joined the P. N. Lebedev Physical Institute, Academy of Sciences of the U.S.S.R., as a postgraduate. He obtained his Candidate's Degree in theory of conductivity of metals in strong electric fields, with V. L. Ginsburg as his advisor, in 1954. During 1954-1958, Shabansky continued investigation of nonlinear properties of plasma in metals. For the next 2 years, he worked at the Crimean Astrophysical Observatory. Shabansky left the Crimean Observatory to go to the Institute of Nuclear Physics, Moscow State University, where he investigated the earth's radiation belts, the plasma of the earth's magnetosphere, finished his doctoral dissertation, and received his degree in 1966. From 1966, he headed the Laboratory of Cosmic Electrodynamics, Institute of Nuclear Physics, Moscow State University. He is best known to the scientific community in the Soviet Union as chief of the Seminar on Cosmic Electrodynamics. Shabansky elaborated a special course of lectures on space physics that has been delivered for many years at the Physical Faculty, Moscow State University. He taught a large number of Soviet physicists, experts in cosmic electrodynamics. An enthusiastic, talented, and many-sided personality, he carried away everybody who knew him. He was known to the U.S. space physics community because of his own work, because of the work of his colleagues and students, a n d because of his infectious and spirited personality. Having died an untimely death, he left a deeply mourning widow and a 23-year-old son. Friends and colleagues will keep the bright image of Dr. Shabansky in their memory forever.

Definition of ground test for verification of large space structure control

NASA Technical Reports Server (NTRS)

Glaese, John R.

1994-01-01

Under this contract, the Large Space Structure Ground Test Verification (LSSGTV) Facility at the George C. Marshall Space Flight Center (MSFC) was developed. Planning in coordination with NASA was finalized and implemented. The contract was modified and extended with several increments of funding to procure additional hardware and to continue support for the LSSGTV facility. Additional tasks were defined for the performance of studies in the dynamics, control and simulation of tethered satellites. When the LSSGTV facility development task was completed, support and enhancement activities were funded through a new competitive contract won by LCD. All work related to LSSGTV performed under NAS8-35835 has been completed and documented. No further discussion of these activities will appear in this report. This report summarizes the tether dynamics and control studies performed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caldecott, Ralph; Kamarulzaman, Dayangku N. S.; Kirrane, James P.

The concept of momentum exchange when applied to space tethers for propulsion is well established, and a considerable body of literature now exists on the on-orbit modelling, the dynamics, and also the control of a large range of tether system applications. The authors consider here a new application for the Motorised Momentum Exchange Tether by highlighting three key stages of development leading to a conceptualisation that can subsequently be developed into a technology for Active Debris Removal. The paper starts with a study of the on-orbit mechanics of a full sized motorised tether in which it is shown that amore » laden and therefore highly massasymmetrical tether can still be forced to spin, and certainly to librate, thereby confirming its possible usefulness for active debris removal (ADR). The second part of the paper concentrates on the modelling of the centripetal deployment of a symmetrical MMET in order to get it initialized for debris removal operations, and the third and final part of the paper provides an entry into scale modelling for low cost mission design and testing. It is shown that the motorised momentum exchange tether offers a potential solution to the removal of large pieces of orbital debris, and that dynamic methodologies can be implemented to in order to optimise the emergent design.« less

Multibody dynamics driving GNC and system design in tethered nets for active debris removal

NASA Astrophysics Data System (ADS)

Benvenuto, Riccardo; Lavagna, Michèle; Salvi, Samuele

2016-07-01

Debris removal in Earth orbits is an urgent issue to be faced for space exploitation durability. Among different techniques, tethered-nets present appealing benefits and some open points to fix. Former and latter are discussed in the paper, supported by the exploitation of a multibody dynamics tool. With respect to other proposed capture mechanisms, tethered-net solutions are characterised by a safer capturing distance, a passive angular momentum damping effect and the highest flexibility to unknown shape, material and attitude of the target to interface with. They also allow not considering the centre of gravity alignment with thrust axis as a constraint, as it is for any rigid link solution. Furthermore, the introduction of a closing thread around the net perimeter ensures safer and more reliable grasping and holding. In the paper, a six degrees of freedom multibody dynamics simulator is presented: it was developed at Politecnico di Milano - Department of Aerospace Science and Technologies - and it is able to describe the orbital and attitude dynamics of tethered-nets systems and end-bodies during different phases, with great flexibility in dealing with different topologies and configurations. Critical phases as impact and wrapping are analysed by simulation to address the tethered-stack controllability. It is shown how the role of contact modelling is fundamental to describe the coupled dynamics: it is demonstrated, as a major novel contribution, how friction between the net and a tumbling target allows reducing its angular motion, stabilizing the system and allowing safer towing operations. Moreover, the so-called tethered space tug is analysed: after capture, the two objects, one passive and one active, are connected by the tethered-net flexible link, the motion of the system being excited by the active spacecraft thrusters. The critical modes prevention during this phase, by means of a closed-loop control synthesis is shown. Finally, the connection between flexible dynamics and capture system design is highlighted, giving engineering answers to most challenging open points to lead to a ready to flight solution.

KSC-2013-3901

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dr. Carlos Calle, senior research scientist on the Electrodynamic Dust Shield for Dust Mitigation project, demonstrates equipment used in his experiments in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. Electrodynamic dust shield, or EDS, technology is based on concepts originally developed by NASA as early as 1967 and later by the University of Tokyo. In 2003, NASA, in collaboration with the University of Arkansas at Little Rock, started development of the EDS for dust particle removal from solar panels to be used on future missions to the moon, an asteroid or Mars. A flight experiment to expose the dust shields to the space environment currently is under development. For more information, visit: http://www.nasa.gov/content/scientists-developing-ways-to-mitigate-dust-problem-for-explorers/ Photo credit: NASA/Dan Casper

USMP-3 satellite moves into CITE stand

NASA Technical Reports Server (NTRS)

1996-01-01

The United States Microgravity Payload-3 (USMP-3) is readied by KSC workers for its move from the Cargo Interface Test Equipment (CITE) stand in the Operations and Checkout (O&C) Building and installation into a payload canister along with the Tethered Satellite System-1R (TSS-1R). Once in the canister, both payloads were transported to Launch Pad 39B to be integrated into the payload bay of the Space Shuttle Orbiter Columbia during final preparations for the STS-75 mission. During the 12-day, 16-hour space flight, the 5-foot (1.6 meter)-in-diameter TSS-1R satellite will be deployed from its pallet in Columbia's payload bay to a distance of 12.4 miles (20.7) kilometers) above the orbiter as an attached, electrically-conductive tether the diameter of a wooden matchstick unwinds from a motorized reel. The objectives of the TSS program are to demonstrate the ability to deploy and control satellites on long tethers in space and to conduct space plasma experiments that include the generation of electrical power. The USMP-3 is a continuation of NASA's microgravity research program to provide advances in the fields of materials science and condensed matter physics. Four major USMP-3 experiment packages are in Columbia's payload bay, while three combustion experimetns will be conducted by the crew in a Glovebox facility located in the orbiter's middeck area.

Space Shuttle Projects

NASA Image and Video Library

1984-01-01

The Space Shuttle Challenger, making its fourth space flight, highlights the 41B insignia. The reusable vehicle is flanked in the oval by an illustration of a Payload Assist Module-D solid rocket motor (PAM-D) for assisted satellite deployment; an astronaut making the first non-tethered extravehicular activity (EVA); and eleven stars.

Space Science Research and Technology at NASA's Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Johnson, Charles L.

2007-01-01

This presentation will summarize the various projects and programs managed in the Space Science Programs and Projects Office at NASA's Marshall Space Flight Center in Huntsville, Alabama. Projects in the portfolio include NASA's Chandra X-Ray telescope, Hinode solar physics satellite, various advanced space propulsion technologies, including solar sails and tethers, as well as NASA's Discovery and New Frontiers Programs.

Conceptual Design of an Electric Sail Technology Demonstration Mission Spacecraft

NASA Technical Reports Server (NTRS)

Wiegmann, Bruce M.

2017-01-01

There is great interest in examining the outer planets of our solar system and Heliopause region (edge of Solar System) and beyond regions of interstellar space by both the Planetary and Heliophysics communities. These needs are well docu-mented in the recent National Academy of Sciences Decadal Surveys. There is significant interest in developing revolutionary propulsion techniques that will enable such Heliopause scientific missions to be completed within 10 to15 years of the launch date. One such enabling propulsion technique commonly known as Electric Sail (E-Sail) propulsion employs positively charged bare wire tethers that extend radially outward from a rotating spacecraft spinning at a rate of one revolution per hour. Around the positively charged bare-wire tethers, a Debye Sheath is created once positive voltage is applied. This sheath stands off of the bare wire tether at a sheath diameter that is proportional to the voltage in the wire coupled with the flux density of solar wind ions within the solar system (or the location of spacecraft in the solar system. The protons that are expended from the sun (solar wind) at 400 to 800 km/sec are electrostatically repelled away from these positively charged Debye sheaths and propulsive thrust is produced via the resulting momentum transfer. The amount of thrust produced is directly proportional to the total wire length. The Marshall Space Flight Center (MSFC) Electric Sail team is currently funded via a two year Phase II NASA Innovative Advanced Concepts (NIAC) awarded in July 2015. The team's current activities are: 1) Developing a Particle in Cell (PIC) numeric engineering model from the experimental data collected at MSFC's Solar Wind Facility on the interaction between simulated solar wind interaction with a charged bare wire that can be applied to a variety of missions, 2) The development of the necessary tether deployers and tethers to enable successful de-ployment of multiple, multi km length bare tethers, 3) Controllability of the space-craft via a voltage bias to steer itself through the solar system to destinations of discovery. These activities once demonstrated analytically, will require a technology demonstration mission (TDM) around the year2020 to demonstrate that all systems work together seamlessly before a Heliophysics Electrostatic Rapid Transit System (HERTS) mission could be initiated. A notional TDM spacecraft that meets the requirements of such a mission will be showcased in this paper.

KSC-2013-4257

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander has been attached to a tether and is being prepared for placement on a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The lander will be prepared for a tethered test that includes lifting it 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2013-4260

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, technicians and engineers assist as the Project Morpheus prototype lander is attached to a tether and lowered onto a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The lander will be prepared for a tethered test that includes lifting it 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2013-4280

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – Inside a control room at NASA’s Kennedy Space Center in Florida, engineers monitor the progress as the Project Morpheus prototype lander is being prepared for a tether test on a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The tethered test will include lifting it 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

KSC-2013-4258

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander has been attached to a tether and is being lowered onto a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The lander will be prepared for a tethered test that includes lifting it 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

Overload control of artificial gravity facility using spinning tether system for high eccentricity transfer orbits

NASA Astrophysics Data System (ADS)

Gou, Xing-wang; Li, Ai-jun; Tian, Hao-chang; Wang, Chang-qing; Lu, Hong-shi

2018-06-01

As the major part of space life supporting systems, artificial gravity requires further study before it becomes mature. Spinning tether system is a good alternative solution to provide artificial gravity for the whole spacecraft other than additional devices, and its longer tether length could significantly reduce spinning velocity and thus enhance comfortability. An approximated overload-based feedback method is proposed to provide estimated spinning velocity signals for controller, so that gravity level could be accurately controlled without complicated GPS modules. System behavior in high eccentricity transfer orbits is also studied to give a complete knowledge of the spinning stabilities. The application range of the proposed method is studied in various orbit cases and spinning velocities, indicating that it is accurate and reliable for most of the mission phases especially for the final constant gravity level phase. In order to provide stable gravity level for transfer orbit missions, a sliding mode controller based on estimated angular signals is designed for closed-loop control. Numerical results indicate that the combination of overload-based feedback and sliding mode controller could satisfy most of the long-term artificial gravity missions. It is capable of forming flexible gravity environment in relatively good accuracy even in the lowest possible orbital radiuses and high eccentricity orbits of crewed space missions. The proposed scheme provides an effective tether solution for the artificial gravity construction in interstellar travel.

Dynamics and stability of spinning flexible space tether systems

NASA Astrophysics Data System (ADS)

Tyc, George

This dissertation focuses on a detailed dynamical investigation of a previously unexplored tether configuration that involves a spinning two-body tethered system with flexible appendages on each end-body where the spin axis is nominally aligned along the tether. The original motivation for this work came after the flight of the first Canadian sub-orbital tether mission OEDIPUS-A in 1989 which employed this spinning tethered configuration. To everyone's surprise, one of the end-bodies was observed to exhibit a rapid divergence of its nutation angle. It was clear after this flight that there were some fundamental mechanisms associated with the interaction between the tether and the end-body that were not fully understood at that time. Hence, a Tether Dynamics Experiment (TDE) was formed and became a formal part of the scientific agenda for the follow-on mission OEDIPUS-C which flew in 1995. This dissertation describes the work that was conducted as part of the TDE and involves: theoretical investigations into the dynamics of this spinning tethered flexible body system; ground testing to validate the models and establish the tether properties; application of the models to develop a stabilization approach for OEDIPUS-C, and comparisons between theory and flight data from both OEDIPUS-A and OEDIPUS-C. Nonlinear equations of motion are developed for a spinning tethered system where the tether could be either spinning with the end-bodies or attached to small de-spun platforms on the end-bodies. Since the tether used for the OEDIPUS missions is not a string, as is often assumed, but rather a wire that has some bending stiffness, albeit small, the tether bending was also taken into account in the formulation. Two sets of ground tests are described that were used to validate the stability conditions and gain confidence in the mathematical models. One set involved hanging a body by a tether and spinning at different speeds to investigate the end-body stability. The other set used a tethered spinning end-body suspended on a set of gimbals and had a means to measure the end-body attitude in real-time. The mathematical models were then applied to investigate suitable stabilization approaches for OEDIPUS-C. In general, very good agreement was found between the theory and both the ground experiments and flight data. One of the surprising results from this work is the significance of the tether root bending effects. It is shown that it is this subtle effect that caused the rapid divergence in one of the end-bodies in the OEDIPUS-A mission which was unstable. For OEDIPUS-C, the situation was rectified by adding the booms to ensure "short term" stability and also by not spinning as rapidly. The OEDIPUS-C was very successful as all systems worked as planned and hence a superb set of flight dynamics data was collected. (Abstract shortened by UMI.)

Determination of design and operation parameters for upper atmospheric research instrumentation to yield optimum resolution with deconvolution. Appendix 7. [Transform Domain Skiprope Observer for tethered satellites

NASA Technical Reports Server (NTRS)

Ioup, George E.; Ioup, Juliette W.

1993-01-01

Because of the interesting science which can be performed using a satellite attached by a very long tether to a mother vehicle in orbit, such as the Space Shuttle, NASA will deploy TSS-1 (Tethered Satellite System) in 1992. A very long tether (20 km in this case) has the possibility of undergoing oscillations of several different types, or modes, and higher harmonics of these modes. The purpose of this document is to describe a method for detecting the amplitude, frequency, and phase (and predicting future motion in the steady state) of these modes, in particular, the skiprope mode, using tethered satellite dynamics measurements. Specifically the rotation rate data about two orthogonal axes, calculated from output from satellite gyroscopes, are used. The data of interest are the satellite pitch and roll rate measurements. NASA has determined to use two methods to diagnose skiprope properties and predict future values. One of these, a Fourier transform domain approach, is the subject of this notebook. The main program and all subroutines are described along with the test plan for evaluating the Frequency Domain Skiprope Observer.

Results from a tethered rocket experiment (Charge-2)

NASA Astrophysics Data System (ADS)

Kawashima, N.; Sasaki, S.; Oyama, K. I.; Hirao, K.; Obayashi, T.; Raitt, W. J.; White, A. B.; Williamson, P. R.; Banks, P. M.; Sharp, W. F.

A tethered payload experiment (Charge-2) was carried out as an international program between Japan and the USA using a NASA sounding rocket at White Sands Missile Range. The objective of the experiment was to perform a new type of active experiment in space by injecting an electron beam from a mother-daughter rocket system connected with a long tether wire. The electron beam with voltage and current up to 1 kV and 80 mA (nominal) was injected from the mother payload. An insulated conductive wire of 426 m length connected the two payloads, the longest tether system flown so far. The electron gun system and diagnostic instruments (plasma, optical, particle and wave) functioned correctly throughout the flight. The potential rise of the mother payload during the electron beam emission was measured with respect to the daughter payload. The beam trajectory was detected by a camera onboard the mother rocket. Wave generation and current induction in the wire during the beam emission were also studied.

KSC-2013-4225

NASA Image and Video Library

2013-12-04

CAPE CANAVERAL, Fla. – The Project Morpheus prototype lander is attached to a tether at the launch platform located at the north end of the Shuttle Landing Facility at NASA’s Kennedy Space Center in Florida. Morpheus is being prepared for a dress rehearsal of a tethered flight test. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

Tethered Formation Configurations: Meeting the Scientific Objectives of Large Aperture and Interferometric Science

NASA Technical Reports Server (NTRS)

Farley, Rodger E.; Quinn, David A.; Brodeur, Stephen J. (Technical Monitor)

2001-01-01

With the success of the Hubble Space Telescope, it has become apparent that new frontiers of science and discovery are made every time an improvement in imaging resolution is made. For the HST working primarily in the visible and near-visible spectrum, this meant designing, building, and launching a primary mirror approximately three meters in diameter. Conventional thinking tells us that accomplishing a comparable improvement in resolution at longer wavelengths for Earth and Space Science applications requires a corresponding increase in the size of the primary mirror. For wavelengths in the sub-millimeter range, a very large telescope with an effective aperture in excess of one kilometer in diameter would be needed to obtain high quality angular resolution. Realistically a single aperture this large is practically impossible. Fortunately such large apertures can be constructed synthetically. Possibly as few as three 34 meter diameter mirrors flying in precision formation could be used to collect light at these longer wavelengths permitting not only very large virtual aperture science to be carried out, but high-resolution interferometry as well. To ensure the longest possible mission duration, a system of tethered spacecraft will be needed to mitigate the need for a great deal of propellant. A spin-stabilized, tethered formation will likely meet these requirements. Several configurations have been proposed which possibly meet the needs of the Space Science community. This paper discusses two of them, weighing the relative pros and cons of each concept. The ultimate goal being to settle on a configuration which combines the best features of structure, tethers, and formation flying to meet the ambitious requirements necessary to make future large synthetic aperture and interferometric science missions successful.

Tethered Formation Configurations: Meeting the Scientific Objectives of Large Aperture and Interferometric Science

NASA Technical Reports Server (NTRS)

Farley, Rodger E.; Quinn, David A.

2004-01-01

With the success of the Hubble Space Telescope, it has become apparent that new frontiers of science and discovery are made every time an improvement in imaging resolution is made. For the HST working primarily in the visible and near-visible spectrum, this meant designing, building and launching a primary mirror approximately three meters in diameter. Conventional thinking tells us that accomplishing a comparable improvement in resolution at longer wavelengths for Earth and Space Science applications requires a corresponding increase in the size of the primary mirror. For wavelengths in the sub-millimeter range, a very large telescope with an effective aperture in excess of one kilometer in diameter would be needed to obtain high quality angular resolution. Realistically a single aperture this large is practically impossible. Fortunately such large apertures can be constructed synthetically. Possibly as few as three 3 - 4 meter diameter mirrors flying in precision formation could be used to collect light at these longer wavelengths permitting not only very large virtual aperture science to be carried out, but high-resolution interferometry as well. To ensure the longest possible mission duration, a system of tethered spacecraft will be needed to mitigate the need for a great deal of propellant. A spin-stabilized, tethered formation will likely meet these requirements. Several configurations have been proposed which possibly meet the needs of the Space Science community. This paper discusses two of them, weighing the relative pros and cons of each concept. The ultimate goal being to settle on a configuration which combines the best features of structure, tethers and formation flying to meet the ambitious requirements necessary to make future large synthetic aperture and interferometric science missions successful.

KSC-2013-3906

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities.

Holographic insulator/superconductor transition with exponential nonlinear electrodynamics probed by entanglement entropy

NASA Astrophysics Data System (ADS)

Yao, Weiping; Yang, Chaohui; Jing, Jiliang

2018-05-01

From the viewpoint of holography, we study the behaviors of the entanglement entropy in insulator/superconductor transition with exponential nonlinear electrodynamics (ENE). We find that the entanglement entropy is a good probe to the properties of the holographic phase transition. Both in the half space and the belt space, the non-monotonic behavior of the entanglement entropy in superconducting phase versus the chemical potential is general in this model. Furthermore, the behavior of the entanglement entropy for the strip geometry shows that the confinement/deconfinement phase transition appears in both insulator and superconductor phases. And the critical width of the confinement/deconfinement phase transition depends on the chemical potential and the exponential coupling term. More interestingly, the behaviors of the entanglement entropy in their corresponding insulator phases are independent of the exponential coupling factor but depends on the width of the subsystem A.

Technology Development and Demonstration Concepts for the Space Elevator

NASA Technical Reports Server (NTRS)

Smitherman, David V., Jr.

2004-01-01

During the 1990s several discoveries and advances in the development of carbon nano-tube (CNT) materials indicated that material strengths many times greater than common high-strength composite materials might be possible. Progress in the development of this material led to renewed interest in the space elevator concept for construction of a tether structure from the surface of the Earth through a geostationary orbit (GEO) and thus creating a new approach to Earth-to-orbit transportation infrastructures. To investigate this possibility the author, in 1999, managed for NASA a space elevator work:hop at the Marshall Space Flight Center to explore the potential feasibility of space elevators in the 21 century, and to identify the critical technologies and demonstration missions needed to make development of space elevators feasible. Since that time, a NASA Institute for Advanced Concepts (NIAC) funded study of the Space Elevator proposed a concept for a simpler first space elevator system using more near-term technologies. This paper will review some of the latest ideas for space elevator development, the critical technologies required, and some of the ideas proposed for demonstrating the feasibility for full-scale development of an Earth to GEO space elevator. Critical technologies include CNT composite materials, wireless power transmission, orbital object avoidance, and large-scale tether deployment and control systems. Numerous paths for technology demonstrations have been proposed utilizing ground experiments, air structures. LEO missions, the space shuttle, the international Space Station, GEO demonstration missions, demonstrations at the lunar L1 or L2 points, and other locations. In conclusion, this paper finds that the most critical technologies for an Earth to GEO space elevator include CNT composite materials development and object avoidance technologies; that lack of successful development of these technologies need not preclude continued development of space elevator systems in general; and that the critical technologies required for the Earth to GEO space elevator are not required for similar systems at the Moon, Mars, Europa, or for orbital tether systems at GEO, Luna, and other locations.

Compact Q-balls and Q-shells in a scalar electrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arodz, H.; Lis, J.

2009-02-15

We investigate spherically symmetric nontopological solitons in electrodynamics with a scalar field self-interaction U{approx}|{psi}| taken from the complex signum-Gordon model. We find Q-balls for small absolute values of the total electric charge Q, and Q-shells when |Q| is large enough. In both cases the charge density exactly vanishes outside certain compact regions in the three-dimensional space. The dependence of the total energy E of small Q-balls on the total electric charge has the form E{approx}|Q|{sup 5/6}, while in the case of very large Q-shells, E{approx}|Q|{sup 7/6}.

The Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

Lorenzini, Enrico C.; Estes, Robert D.; Cosmo, Mario L.

2001-01-01

This is the Annual Report #2 entitled "The Propulsive Small Expendable Deployer System (ProSEDS)" prepared by the Smithsonian Astrophysical Observatory for NASA Marshall Space Flight Center. This report covers the period of activity from 1 August 2000 through 30 July 2001. The topics include: 1) Updated System Performance; 2) Mission Analysis; 3) Updated Dynamics Reference Mission; 4) Updated Deployment Control Profiles and Simulations; 5) Comparison of ED tethers and electrical thrusters; 6) Kalman filters for mission estimation; and 7) Delivery of interactive software for ED tethers.

Electrodynamic Dust Shield for Surface Exploration Activities on the Moon and Mars

NASA Technical Reports Server (NTRS)

Calle, C. I.; Immer, C. D.; Clements, J. S.; Chen, A.; Buhler, C. R.; Lundeen, P.; Mantovani, J. G.; Starnes, J. W.; Michalenko, M.; Mazumder, M. K.

2006-01-01

The Apollo missions to the moon showed that lunar dust can hamper astronaut surface activities due to its ability to cling to most surfaces. NASA's Mars exploration landers and rovers have also shown that the problem is equally hard if not harder on Mars. In this paper, we report on our efforts to develop and electrodynamic dust shield to prevent the accumulation of dust on surfaces and to remove dust already adhering to those surfaces. The parent technology for the electrodynamic dust shield, developed in the 1970s, has been shown to lift and transport charged and uncharged particles using electrostatic and dielectrophoretic forces. This technology has never been applied for space applications on Mars or the moon due to electrostatic breakdown concerns. In this paper, we show that an appropriate design can prevent the electrostatic breakdown at the low Martian atmospheric pressures. We are also able to show that uncharged dust can be lifted and removed from surfaces under simulated Martian environmental conditions. This technology has many potential benefits for removing dust from visors, viewports and many other surfaces as well as from solar arrays. We have also been able to develop a version of the electrodynamic dust shield working under. hard vacuum conditions. This version should work well on the moon.

Experimental detection of long-distance interactions between biomolecules through their diffusion behavior: numerical study.

PubMed

Nardecchia, Ilaria; Spinelli, Lionel; Preto, Jordane; Gori, Matteo; Floriani, Elena; Jaeger, Sebastien; Ferrier, Pierre; Pettini, Marco

2014-08-01

The dynamical properties and diffusive behavior of a collection of mutually interacting particles are numerically investigated for two types of long-range interparticle interactions: Coulomb-electrostatic and dipole-electrodynamic. It is shown that when the particles are uniformly distributed throughout the accessible space, the self-diffusion coefficient is always lowered by the considered interparticle interactions, irrespective of their attractive or repulsive character. This fact is also confirmed by a simple model to compute the correction to the Brownian diffusion coefficient due to the interactions among the particles. These interactions are also responsible for the onset of dynamical chaos and an associated chaotic diffusion which still follows an Einstein-Fick-like law for the mean-square displacement as a function of time. Transitional phenomena are observed for Coulomb-electrostatic (repulsive) and dipole-electrodynamic (attractive) interactions considered both separately and in competition. The outcomes reported in this paper clearly indicate a feasible experimental method to probe the activation of resonant electrodynamic interactions among biomolecules.

Asymptotically (A)dS dilaton black holes with nonlinear electrodynamics

NASA Astrophysics Data System (ADS)

Hajkhalili, S.; Sheykhi, A.

It is well known that with an appropriate combination of three Liouville-type dilaton potentials, one can construct charged dilaton black holes in an (anti)-de Sitter [(A)dS] spaces in the presence of linear Maxwell field. However, asymptotically (A)dS dilaton black holes coupled to nonlinear gauge field have not been found. In this paper, we construct, for the first time, three new classes of dilaton black hole solutions in the presence of three types of nonlinear electrodynamics, namely Born-Infeld (BI), Logarithmic (LN) and Exponential nonlinear (EN) electrodynamics. All these solutions are asymptotically (A)dS and in the linear regime reduce to the Einstein-Maxwell-dilaton (EMd) black holes in (A)dS spaces. We investigate physical properties and the causal structure, as well as asymptotic behavior of the obtained solutions, and show that depending on the values of the metric parameters, the singularity can be covered by various horizons. We also calculate conserved and thermodynamic quantities of the obtained solutions. Interestingly enough, we find that the coupling of dilaton field and nonlinear gauge field in the background of (A)dS spaces leads to a strange behavior for the electric field. We observe that the electric field is zero at singularity and increases smoothly until reaches a maximum value, then it decreases smoothly until goes to zero as r →∞. The maximum value of the electric field increases with increasing the nonlinear parameter β or decreasing the dilaton coupling α and is shifted to the singularity in the absence of either dilaton field (α = 0) or nonlinear gauge field (β →∞).

Effective metrics and a fully covariant description of constitutive tensors in electrodynamics

NASA Astrophysics Data System (ADS)

Schuster, Sebastian; Visser, Matt

2017-12-01

Using electromagnetism to study analogue space-times is tantamount to considering consistency conditions for when a given (meta-) material would provide an analogue space-time model or—vice versa—characterizing which given metric could be modeled with a (meta-) material. While the consistency conditions themselves are by now well known and studied, the form the metric takes once they are satisfied is not. This question is mostly easily answered by keeping the formalisms of the two research fields here in contact as close to each other as possible. While fully covariant formulations of the electrodynamics of media have been around for a long while, they are usually abandoned for (3 +1 )- or six-dimensional formalisms. Here we use the fully unified and fully covariant approach. This enables us even to generalize the consistency conditions for the existence of an effective metric to arbitrary background metrics beyond flat space-time electrodynamics. We also show how the familiar matrices for permittivity ɛ , permeability μ-1, and magnetoelectric effects ζ can be seen as the three independent pieces of the Bel decomposition for the constitutive tensor Za b c d, i.e., the components of an orthogonal decomposition with respect to a given observer with four-velocity Va. Finally, we use the Moore-Penrose pseudoinverse and the closely related pseudodeterminant to then gain the desired reconstruction of the effective metric in terms of the permittivity tensor ɛa b, the permeability tensor [μ-1]a b, and the magnetoelectric tensor ζa b, as an explicit function geff(ɛ ,μ-1,ζ ).

Space-Based Solar Power As an Opportunity for Strategic Security: Phase 0 Architecture Feasibility Study

DTIC Science & Technology

2007-10-10

levitation ( MAGLEV ) followed by rocket,  airbreathing/airborne oxygen enrichment, as well as electromagnetic launch, hybrid launch to  tethers, and...to‐orbit (TSTO) rocket powered vertical launch horizontal landing  (VTHL) to  Maglev  assisted airbreathing or airborne oxygen enrichment horizontal...takeoff and landing  (HOTOL).  Further alternatives include gun launch (typically electromagnetic, or  MagLev ), a space  elevator, or a hybrid tether

Photon momentum transfer plane for asteroid, meteoroid, and comet orbit shaping

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor)

2004-01-01

A spacecraft docks with a spinning and/or rotating asteroid, meteoroid, comet, or other space object, utilizing a tether shaped in a loop and utilizing subvehicles appropriately to control loop instabilities. The loop is positioned about a portion of the asteroid and retracted thereby docking the spacecraft to the asteroid, meteoroid, comet, or other space object. A deployable rigidized, photon momentum transfer plane of sufficient thickness may then be inflated and filled with foam. This plane has a reflective surface that assists in generating a larger momentum from impinging photons. This plane may also be moved relative to the spacecraft to alter the forces acting on it, and thus on the asteroid, meteoroid, comet, or other space object to which it is attached. In general, these forces may be utilized, over time, to alter the orbits of asteroids, meteoroids, comets, or other space objects. Sensors and communication equipment may be utilized to allow remote operation of the rigidized, photon momentum transfer plane and tether.

Swarms: Optimum aggregations of spacecraft

NASA Technical Reports Server (NTRS)

Mayer, H. L.

1980-01-01

Swarms are aggregations of spacecraft or elements of a space system which are cooperative in function, but physically isolated or only loosely connected. For some missions the swarm configuration may be optimum compared to a group of completely independent spacecraft or a complex rigidly integrated spacecraft or space platform. General features of swarms are induced by considering an ensemble of 26 swarms, examples ranging from Earth centered swarms for commercial application to swarms for exploring minor planets. A concept for a low altitude swarm as a substitute for a space platform is proposed and a preliminary design studied. The salient design feature is the web of tethers holding the 30 km swarm in a rigid two dimensional array in the orbital plane. A mathematical discussion and tutorial in tether technology and in some aspects of the distribution of services (mass, energy, and information to swarm elements) are included.

Materials samples face rigors of space.

PubMed

Flinn, Edward D

2002-07-01

The Materials International Space Station Experiment (MISSE) is described. This project is designed to conduct long duration materials tests on samples attached to the ISS. A batch of 750 material samples were delivered on STS-105 and attached to the ISS airlock. They will be exposed to the space environment for 18 months and are slated to return on STS-114. A second batch of 750 samples is being prepared. The experiment containers were used originally for the Mir Environmental Effects Payload, which tested a variety of substances, including some slated for use on the ISS. Researchers are particularly interested in the effects of atomic oxygen on the samples. Some samples are being tested to determine their use in radiation protection. As part of the MISSE project, ultrathin tether materials are being tested for use on the Propulsive Small Expendable Depoloyer System (ProSEDS), which will use a tether system to change a satellite's orbital altitude.

Magnetoplasma sheath waves on a conducting tether in the ionosphere with applications to EMI propagation on large space structures

NASA Technical Reports Server (NTRS)

Balmain, K. G.; James, H. G.; Bantin, C. C.

1991-01-01

A recent space experiment confirmed sheath-wave propagation of a kilometer-long insulated wire in the ionosphere, oriented parallel to the Earth's magnetic field. This space tether experiment, Oedipus-A, showed a sheath-wave passband up to about 2 MHz and a phase velocity somewhat slower than the velocity of light in a vacuum, and also demonstrated both ease of wave excitation and low attenuation. The evidence suggests that, on any large structure in low Earth orbit, transient or continuous wave electromagnetic interference, once generated, could propagate over the structure via sheath waves, producing unwanted signal levels much higher than in the absence of the ambient plasma medium. Consequently, there is a need for a review of both electromagnetic interference/electromagnetic compatibility standards and ground test procedures as they apply to large structures in low Earth orbit.

Rational design and synthesis of androgen receptor-targeted nonsteroidal anti-androgen ligands for the tumor-specific delivery of a doxorubicin-formaldehyde conjugate.

PubMed

Cogan, Peter S; Koch, Tad H

2003-11-20

The synthesis and preliminary evaluation of a doxorubicin-formaldehyde conjugate tethered to the nonsteroidal antiandrogen, cyanonilutamide (RU 56279), for the treatment of prostate cancer are reported. The relative ability of the targeting group to bind to the human androgen receptor was studied as a function of tether. The tether served to attach the antiandrogen to the doxorubicin-formaldehyde conjugate via an N-Mannich base of a salicylamide derivative. The salicylamide was selected to serve as a trigger release mechanism to separate the doxorubicin-formaldehyde conjugate from the targeting group after it has bound to the androgen receptor. The remaining part of the tether consisted of a linear group that spanned from the 5-position of the salicylamide to the 3'-position of cyanonilutamide. The structures explored for the linear region of the tether were derivatives of di(ethylene glycol), tri(ethylene glycol), N,N'-disubstituted-piperazine, and 2-butyne-1,4-diol. Relative binding affinity of the tethers bound to the targeting group for human androgen receptor were measured using a (3)H-Mibolerone competition assay and varied from 18% of nilutamide binding for the butynediol-based linear region to less than 1% for one of the piperazine derivatives. The complete targeted drug with the butynediol-based linear region has a relative binding affinity of 10%. This relative binding affinity is encouraging in light of the cocrystal structure of human androgen receptor ligand binding domain bound to the steroid Metribolone which predicts very limited space for a tether connecting the antiandrogen on the inside to the cytotoxin on the outside.

A Status of the Advanced Space Transportation Program from Planning to Action

NASA Technical Reports Server (NTRS)

Lyles, Garry; Griner, Carolyn

1998-01-01

A Technology Plan for Enabling Commercial Space Business was presented at the 48th International Astronautical Congress in Turin, Italy. This paper presents a status of the program's accomplishments. Technology demonstrations have progressed in each of the four elements of the program; (1) Low Cost Technology, (2) Advanced Reusable Technology, (3) Space Transfer Technology and (4) Space Transportation Research. The Low Cost Technology program element is primarily focused at reducing development and acquisition costs of aerospace hardware using a "design to cost" philosophy with robust margins, adapting commercial manufacturing processes and commercial off-the-shelf hardware. The attributes of this philosophy for small payload launch are being demonstrated at the component, sub-system, and system level. The X-34 "Fastrac" engine has progressed through major component and subsystem demonstrations. A propulsion system test bed has been implemented for system-level demonstration of component and subsystem technologies; including propellant tankage and feedlines, controls, pressurization, and engine systems. Low cost turbopump designs, commercial valves and a controller are demonstrating the potential for a ten-fold reduction in engine and propulsion system costs. The Advanced Reusable Technology program element is focused on increasing life through high strength-to-weight structures and propulsion components, highly integrated propellant tanks, automated checkout and health management and increased propulsion system performance. The validation of rocket based combined cycle (RBCC) propulsion is pro,-,ressing through component and subsystem testing. RBCC propulsion has the potential to provide performance margin over an all rocket system that could result in lower gross liftoff weight, a lower propellant mass fraction or a higher payload mass fraction. The Space Transfer Technology element of the program is pursuing technology that can improve performance and dramatically reduce the propellant and structural mass of orbit transfer and deep space systems. Flight demonstration of ion propulsion is progressing towards launch. Ion propulsion is the primary propulsion for Deep Space 1; a flyby of comet West-kohoutek-lkemura and asteroid 3352 McAuliffe. Testing of critical solar-thermal propulsion subsystems have been accomplished and planning is continuing for the flight demonstration of an electrodynamic tether orbit transfer system. The forth and final element of the program, Space Transportation Research, has progressed in several areas of propulsion research. This element of the program is focused at long-term (25 years) breakthrough concepts that could bring launch costs to a factor of one hundred below today's cost or dramatically expand planetary travel and enable interstellar travel.

Early Program Development

NASA Image and Video Library

1970-01-01

Managed by Marshall Space Flight Center, the Space Tug was a reusable multipurpose space vehicle designed to transport payloads to different orbital inclinations. Utilizing mission-specific combinations of its three primary modules (crew, propulsion, and cargo) and a variety of supplementary kits, the Space Tug was capable of numerous space applications. This 1970 artist's concept depicts the Space Tug during a satellite repair mission with the contact and de-spin attachment kit in place. An astronaut can be seen tethered to the Tug.

Invited Article: Electric solar wind sail: Toward test missions

NASA Astrophysics Data System (ADS)

Janhunen, P.; Toivanen, P. K.; Polkko, J.; Merikallio, S.; Salminen, P.; Haeggström, E.; Seppänen, H.; Kurppa, R.; Ukkonen, J.; Kiprich, S.; Thornell, G.; Kratz, H.; Richter, L.; Krömer, O.; Rosta, R.; Noorma, M.; Envall, J.; Lätt, S.; Mengali, G.; Quarta, A. A.; Koivisto, H.; Tarvainen, O.; Kalvas, T.; Kauppinen, J.; Nuottajärvi, A.; Obraztsov, A.

2010-11-01

The electric solar wind sail (E-sail) is a space propulsion concept that uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form, the E-sail consists of a number of long, thin, conducting, and centrifugally stretched tethers, which are kept in a high positive potential by an onboard electron gun. The concept gains its efficiency from the fact that the effective sail area, i.e., the potential structure of the tethers, can be millions of times larger than the physical area of the thin tethers wires, which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in the rather near future, providing a revolutionary level of propulsive performance (specific acceleration) for travel in the solar system. Here we give a review of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies, and dynamical and orbital simulations.

Multimodal transport and dispersion of organelles in narrow tubular cells

NASA Astrophysics Data System (ADS)

Mogre, Saurabh S.; Koslover, Elena F.

2018-04-01

Intracellular components explore the cytoplasm via active motor-driven transport in conjunction with passive diffusion. We model the motion of organelles in narrow tubular cells using analytical techniques and numerical simulations to study the efficiency of different transport modes in achieving various cellular objectives. Our model describes length and time scales over which each transport mode dominates organelle motion, along with various metrics to quantify exploration of intracellular space. For organelles that search for a specific target, we obtain the average capture time for given transport parameters and show that diffusion and active motion contribute to target capture in the biologically relevant regime. Because many organelles have been found to tether to microtubules when not engaged in active motion, we study the interplay between immobilization due to tethering and increased probability of active transport. We derive parameter-dependent conditions under which tethering enhances long-range transport and improves the target capture time. These results shed light on the optimization of intracellular transport machinery and provide experimentally testable predictions for the effects of transport regulation mechanisms such as tethering.

Invited article: Electric solar wind sail: toward test missions.

PubMed

Janhunen, P; Toivanen, P K; Polkko, J; Merikallio, S; Salminen, P; Haeggström, E; Seppänen, H; Kurppa, R; Ukkonen, J; Kiprich, S; Thornell, G; Kratz, H; Richter, L; Krömer, O; Rosta, R; Noorma, M; Envall, J; Lätt, S; Mengali, G; Quarta, A A; Koivisto, H; Tarvainen, O; Kalvas, T; Kauppinen, J; Nuottajärvi, A; Obraztsov, A

2010-11-01

The electric solar wind sail (E-sail) is a space propulsion concept that uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form, the E-sail consists of a number of long, thin, conducting, and centrifugally stretched tethers, which are kept in a high positive potential by an onboard electron gun. The concept gains its efficiency from the fact that the effective sail area, i.e., the potential structure of the tethers, can be millions of times larger than the physical area of the thin tethers wires, which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in the rather near future, providing a revolutionary level of propulsive performance (specific acceleration) for travel in the solar system. Here we give a review of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies, and dynamical and orbital simulations.

TSS-1R satellite integration in O&C Building

NASA Technical Reports Server (NTRS)

1995-01-01

John Powell (left) and Jim Nail (second from right) of McDonnell Douglas Space and Defense Systems prepare the satellite element of the Tethered Satellite System-1R (TSS-1R) for integration with its support unit in the Operations and Checkout (O&C) Building. The TSS-1R is one of two primary payloads scheduled to fly aboard the Orbiter Columbia during the STS-75 mission in early 1996. The TSS program is a joint venture between NASA and the Agenzia Spaziale Italiana, or Italian Space Agency. The 'R' designation indicates a reflight. The TSS-1 flew aboard Atlantis during the STS-46 mission in July 1992 and achieved only a partial success when its tether reel mechanism became jammed after only approximately 840 feet of the 12-mile-long tether had been unwound as the satellite rose from its cradle in the orbiter's payload bay. Once deployed to the 12-mile height on the STS-75 mission, the satellite will be used to validate theories that such a system could possibly be used in the future to generate electrical power to power orbital systems, raise and lower spacecraft, study atmospheric conditions at several different heights and for many other applications.

A new approach to explore the binding space of polysaccharide-based ligands: selectin antagonists.

PubMed

Calosso, Mickael; Charpentier, Daniel; Vaillancourt, Marc; Bencheqroun, Mohammed; St-Pierre, Gabrielle; Wilkes, Brian C; Guindon, Yvan

2012-12-13

The discovery of molecules that interfere with the binding of a ligand to a receptor remains a topic of great interest in medicinal chemistry. Herein, we report that a monosaccharide unit of a polysaccharide ligand can be replaced advantageously by a conformationally locked acyclic molecular entity. A cyclic component of the selectin ligand Sialyl Lewis(x), GlcNAc, is replaced by an acyclic tether, tartaric esters, which link two saccharide units. The conformational bias of this acyclic tether originates from the minimization of intramolecular dipole-dipole interaction and the gauche effect. The evaluation of the binding of these derivatives to P-selectin was measured by surface plasmon resonance spectroscopy. The results obtained in our pilot study suggest that the discovery of tunable tethers could facilitate the exploration of the carbohydrate recognition domain of various receptors.

Reduced Dirac equation and Lamb shift as off-mass-shell effect in quantum electrodynamics

NASA Astrophysics Data System (ADS)

Ni, Guang-Jiong; Xu, Jian-Jun; Lou, Sen-Yue

2011-02-01

Based on the accurate experimental data of energy-level differences in hydrogen-like atoms, especially the 1S—2S transitions of hydrogen and deuterium, the necessity of introducing a reduced Dirac equation with reduced mass as the substitution of original electron mass is stressed. Based on new cognition about the essence of special relativity, we provide a reasonable argument for the reduced Dirac equation to have two symmetries, the invariance under the (newly defined) space-time inversion and that under the pure space inversion, in a noninertial frame. By using the reduced Dirac equation and within the framework of quantum electrodynamics in covariant form, the Lamb shift can be evaluated (at one-loop level) as the radiative correction on a bound electron staying in an off-mass-shell state—-a new approach eliminating the infrared divergence. Hence the whole calculation, though with limited accuracy, is simplified, getting rid of all divergences and free of ambiguity.

KSC-2013-3908

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dust particles scatter during an experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The fabricated material is designed to mimic the dust on the lunar surface. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities.

KSC-2013-3904

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dust particle experiments are conducted for Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. Electrodynamic dust shield, or EDS, technology is based on concepts originally developed by NASA as early as 1967 and later by the University of Tokyo. In 2003, NASA, in collaboration with the University of Arkansas at Little Rock, started development of the EDS for dust particle removal from solar panels to be used on future missions to the moon, an asteroid or Mars. A flight experiment to expose the dust shields to the space environment currently is under development. For more information, visit: http://www.nasa.gov/content/scientists-developing-ways-to-mitigate-dust-problem-for-explorers/ Photo credit: NASA/Dan Casper

KSC-2013-3907

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dust particles are readied for an experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The fabricated material is designed to mimic the dust on the lunar surface. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities.

Space physics missions handbook

NASA Technical Reports Server (NTRS)

Cooper, Robert A. (Compiler); Burks, David H. (Compiler); Hayne, Julie A. (Editor)

1991-01-01

The purpose of this handbook is to provide background data on current, approved, and planned missions, including a summary of the recommended candidate future missions. Topics include the space physics mission plan, operational spacecraft, and details of such approved missions as the Tethered Satellite System, the Solar and Heliospheric Observatory, and the Atmospheric Laboratory for Applications and Science.

Analysis of a rotating advanced-technology space station for the year 2025

NASA Technical Reports Server (NTRS)

Queijo, M. J.; Butterfield, A. J.; Cuddihy, W. F.; King, C. B.; Stone, R. W.; Garn, P. A.

1988-01-01

An analysis is made of several aspects of an advanced-technology rotating space station configuration generated under a previous study. The analysis includes examination of several modifications of the configuration, interface with proposed launch systems, effects of low-gravity environment on human subjects, and the space station assembly sequence. Consideration was given also to some aspects of space station rotational dynamics, surface charging, and the possible application of tethers.

Desert Research and Technology Studies Exposure of Lotus Coated Electrodynamic Shield Samples. Part 2

NASA Technical Reports Server (NTRS)

Margiotta, Danielle V.; McKittrick, Kristin R.; Straka, Sharon A.; Jones, Craig B.

2012-01-01

The passive Lotus dust mitigation coating currently being developed at NASA's Goddard Space Flight Center (GSFC), was selected by the Habitation Demonstration Unit Deep Space Habitat (HDU-DSH) for participation in the 2011 Desert Research and Technology Studies (D-RaTS). Based on the unique surface architecture of the Lotus leaf, the nano-engineered Lotus coating seeks to replicate these structures on space flight and habitation surfaces. By decreasing both the surface energy and area for particle attachment, the Lotus coating greatly diminishes dust accumulation on surfaces. This is a problem that can be encountered on lunar, Martian, and asteroid missions. Two different application methods of this coating were tested in summer 2011 at the D-RaTS site: the wet chemistry applied version and combustion chemical vapor deposition (CCVD) applied version. These Lotus coatings, along with two common thermal control coatings, were combined with the active dust mitigation electrodynamic shield (EDS) technology developed at Kennedy Space Center (KSC). The EDS technology uses an electrified grid to remove dust particles from the surface of a Kapton (Trademark) substrate. The Lotus coating and thermal control coatings were applied to these Kapton (Trademark) substrates for testing. The combination of these two innovations was theorized to be an applicable countermeasure for addressing dust accumulation during long-duration human space exploration. This theory was tested and characterized prior to, during, and after D-RaTS exposure.

Tether Transportation System Study

NASA Technical Reports Server (NTRS)

Bangham, M. E.; Lorenzini, E.; Vestal, L.

1998-01-01

The projected traffic to geostationary earth orbit (GEO) is expected to increase over the next few decades. At the same time, the cost of delivering payloads from the Earth's surface to low earth orbit (LEO) is projected to decrease, thanks in part to the Reusable Launch Vehicle (RLV). A comparable reduction in the cost of delivering payloads from LEO to GEO is sought. The use of in-space tethers, eliminating the requirement for traditional chemical upper stages and thereby reducing the launch mass, has been identified as such an alternative. Spinning tethers are excellent kinetic energy storage devices for providing the large delta vee's required for LEO to GEO transfer. A single-stage system for transferring payloads from LEO to GEO was proposed some years ago. The study results presented here contain the first detailed analyses of this proposal, its extension to a two-stage system, and the likely implementation of the operational system.

Revisiting Einstein's Happiest Thought: On Ernst Mach and the Early History of Relativity

NASA Astrophysics Data System (ADS)

Staley, Richard

2016-03-01

This paper argues we should distinguish three phases in the formation of relativity. The first involved relational approaches to perception, and physiological and geometrical space and time in the 1860s and 70s. The second concerned electrodynamics and mechanics (special relativity). The third concerned mechanics, gravitation, and physical and geometrical space and time. Mach's early work on the Doppler effect, together with studies of visual and motor perception linked physiology, physics and psychology, and offered new approaches to physiological space and time. These informed the critical conceptual attacks on Newtonian absolutes that Mach famously outlined in The Science of Mechanics. Subsequently Mach identified a growing group of ``relativists,'' and his critiques helped form a foundation for later work in electrodynamics (in which he did not participate). Revisiting Mach's early work will suggest he was still more important to the development of new approaches to inertia and gravitation than has been commonly appreciated. In addition to what Einstein later called ``Mach's principle,'' I will argue that a thought experiment on falling bodies in Mach's Science of Mechanics also provided a point of inspiration for the happy thought that led Einstein to the equivalence principle.

Kohn-Sham approach to quantum electrodynamical density-functional theory: Exact time-dependent effective potentials in real space.

PubMed

Flick, Johannes; Ruggenthaler, Michael; Appel, Heiko; Rubio, Angel

2015-12-15

The density-functional approach to quantum electrodynamics extends traditional density-functional theory and opens the possibility to describe electron-photon interactions in terms of effective Kohn-Sham potentials. In this work, we numerically construct the exact electron-photon Kohn-Sham potentials for a prototype system that consists of a trapped electron coupled to a quantized electromagnetic mode in an optical high-Q cavity. Although the effective current that acts on the photons is known explicitly, the exact effective potential that describes the forces exerted by the photons on the electrons is obtained from a fixed-point inversion scheme. This procedure allows us to uncover important beyond-mean-field features of the effective potential that mark the breakdown of classical light-matter interactions. We observe peak and step structures in the effective potentials, which can be attributed solely to the quantum nature of light; i.e., they are real-space signatures of the photons. Our findings show how the ubiquitous dipole interaction with a classical electromagnetic field has to be modified in real space to take the quantum nature of the electromagnetic field fully into account.

Laboratory electron exposure of TSS-1 thermal control coating

NASA Technical Reports Server (NTRS)

Vaughn, J. A.; Mccollum, M.; Carruth, M. R., Jr.

1995-01-01

RM400, a conductive thermal control coating, was developed for use on the exterior shell of the tethered satellite. Testing was performed by the Engineering Physics Division to quantify effects of the space environment on this coating and its conductive and optical properties. Included in this testing was exposure of RM400 to electrons with energies ranging from 0.1 to 1 keV, to simulate electrons accelerated from the ambient space plasma when the tethered satellite is fully deployed. During this testing, the coating was found to luminesce, and a prolonged exposure of the coating to high-energy electrons caused the coating to darken. This report describes the tests done to quantify the degradation of the thermal control properties caused by electron exposure and to measure the luminescence as a function of electron energy and current density to the satellite.

Guidebook for analysis of tether applications

NASA Technical Reports Server (NTRS)

Carroll, J. A.

1985-01-01

This guidebook is intended as a tool to facilitate initial analyses of proposed tether applications in space. The guiding philosophy is that a brief analysis of all the common problem areas is far more useful than a detailed study in any one area. Such analyses can minimize the waste of resources on elegant but fatally flawed concepts, and can identify the areas where more effort is needed on concepts which do survive the initial analyses. The simplified formulas, approximations, and analytical tools included should be used only for preliminary analyses. For detailed analyses, the references with each topic and in the bibliography may be useful.

Realtime Space Weather Forecasts Via Android Phone App

NASA Astrophysics Data System (ADS)

Crowley, G.; Haacke, B.; Reynolds, A.

2010-12-01

For the past several years, ASTRA has run a first-principles global 3-D fully coupled thermosphere-ionosphere model in real-time for space weather applications. The model is the Thermosphere-Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM). ASTRA also runs the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) in real-time. Using AMIE to drive the high latitude inputs to the TIMEGCM produces high fidelity simulations of the global thermosphere and ionosphere. These simulations can be viewed on the Android Phone App developed by ASTRA. The SpaceWeather app for the Android operating system is free and can be downloaded from the Google Marketplace. We present the current status of realtime thermosphere-ionosphere space-weather forcasting and discuss the way forward. We explore some of the issues in maintaining real-time simulations with assimilative data feeds in a quasi-operational setting. We also discuss some of the challenges of presenting large amounts of data on a smartphone. The ASTRA SpaceWeather app includes the broadest and most unique range of space weather data yet to be found on a single smartphone app. This is a one-stop-shop for space weather and the only app where you can get access to ASTRA’s real-time predictions of the global thermosphere and ionosphere, high latitude convection and geomagnetic activity. Because of the phone's GPS capability, users can obtain location specific vertical profiles of electron density, temperature, and time-histories of various parameters from the models. The SpaceWeather app has over 9000 downloads, 30 reviews, and a following of active users. It is clear that real-time space weather on smartphones is here to stay, and must be included in planning for any transition to operational space-weather use.

Nanosatellite Potential for Unique Research and Education

NASA Astrophysics Data System (ADS)

Voss, H. D.; Dailey, J. F.; Voss, D.

2009-12-01

With the recent advances in low-power miniaturized electronics, sensors, and wireless technology, powerful new ways are available for collecting multipoint measurements in Geospace and the Upper Atmosphere. At our undergraduate university, three nanosatellites were developed that demonstrate the exceptional capability of nanosatellites for research and education. TUSat 1 was a dual CubeSat (1.8 kg) that included 1) a novel tether system for stabilization and electrodynamics studies, 2) a plasma probe on a boom, 3) a 3-axis magnetometer, 4) a VLF receiver, and 5) a 56 kB spread spectrum (902-928 MHz) data/E-mail communication system with an amateur radio beacon. The Thunderstorm Effects in Space and Technology (TEST) nanosatellite was a partnership between Taylor University and the University of Illinois (UI) and was part of the AFOSR nanosat program. TEST was a 27 CubeSat module design that included 1) 3-axis stabilization and power system, 2) plasma probe, 3) UI photometer and spectrometer, 4) transient photometer, 5) dual energetic particle spectrometers, 6) VLF receiver, 7) educational pods, and 8) spread spectrum and amateur radio communication. Recently we participated in the AFOSR Boston University nanosatellite (BUSat) providing instruments and a communication system. Nanosatellites provide a new way of advancing space science since they 1) foster creativity, 2) make multipoint measurements (improve global math models and understanding), and 3) study the unexplored lower thermosphere space environment and ionosphere and distant interplanetary objects. The low-cost and state-of-the- art technology associated with constellations of nanosatelites make them ideal for Low Earth Orbit (LEO) altitudes (120 - 500 km) where paucity of data and the orbit decay rate are high. Orbital debris pollution is also relatively unimportant in low LEO orbits. For nanosats to be successful a rigorous program needs to be established for testing, calibration, and quality assurance. The High-Altitude Research Platform (HARP) has now launched over 200 balloon flights with 100% real-time telemetry and recovery at Taylor University. The HALO program demonstrated the reliability of an intra-balloon mesh network by simultaneously launching 13 payloads separated by over 500 miles at altitudes of 25 km. The educational outcomes from nanosatellite experiments are strong for STEM education and directing students professionally into space science.

NASA's In Space Propulsion Technology Program Accomplishments and Lessons Learned

NASA Technical Reports Server (NTRS)

Johnson, Les C.; Harris, David

2008-01-01

NASA's In-Space Propulsion Technology (ISPT) Program was managed for 5 years at the NASA MSFC and significant strides were made in the advancement of key transportation technologies that will enable or enhance future robotic science and deep space exploration missions. At the program's inception, a set of technology investment priorities were established using an NASA-wide, mission-driven prioritization process and, for the most part, these priorities changed little - thus allowing a consistent framework in which to fund and manage technology development. Technologies in the portfolio included aerocapture, advanced chemical propulsion, solar electric propulsion, solar sail propulsion, electrodynamic and momentum transfer tethers, and various very advanced propulsion technologies with significantly lower technology readiness. The program invested in technologies that have the potential to revolutionize the robotic exploration of deep space. For robotic exploration and science missions, increased efficiencies of future propulsion systems are critical to reduce overall life-cycle costs and, in some cases, enable missions previously considered impossible. Continued reliance on conventional chemical propulsion alone will not enable the robust exploration of deep space - the maximum theoretical efficiencies have almost been reached and they are insufficient to meet needs for many ambitious science missions currently being considered. By developing the capability to support mid-term robotic mission needs, the program was to lay the technological foundation for travel to nearby interstellar space. The ambitious goals of the program at its inception included supporting the development of technologies that could support all of NASA's missions, both human and robotic. As time went on and budgets were never as high as planned, the scope of the program was reduced almost every year, forcing the elimination of not only the broader goals of the initial program, but also of funding for over half of the technologies in the original portfolio. In addition, the frequency at which the application requirements for the program changed exceeded the development time required to mature technologies: forcing sometimes radical rescoping of research efforts already halfway (or more) to completion. At the end of its fifth year, both the scope and funding of the program were at a minimum despite the program successfully meeting all of it's initial high priority objectives. This paper will describe the program, its requirements, technology portfolio, and technology maturation processes. Also discussed will be the major technology milestones achieved and the lessons learned from managing a $100M+ technology program.

KSC-2013-4286

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander’s engine begins to fire during a tether test at the north end of the Shuttle Landing Facility. During the test, the lander is lifted 20 feet by crane, and will ascend another 10 feet, maneuver backwards 10 feet, and then fly forward and descend to its original position, landing at the end of the tether onto a transportable launch platform. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

KSC-2013-4295

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander’s engine has completed its firing during a tether test at the north end of the Shuttle Landing Facility. During the test, the lander was lifted 20 feet by crane, and then ascended another 10 feet, maneuvered backwards 10 feet, and then flew forward. It will descend to its original position, landing at the end of the tether onto a transportable launch platform. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

KSC-2013-4289

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, smoke fills the air as the Project Morpheus prototype lander’s engine fires during a tether test at the north end of the Shuttle Landing Facility. During the test, the lander was lifted 20 feet by crane, and then ascended another 10 feet, maneuvered backwards 10 feet, and then flew forward. It will descend to its original position, landing at the end of the tether onto a transportable launch platform. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

KSC-2013-4292

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, smoke fills the air as the Project Morpheus prototype lander’s engine fires during a tether test at the north end of the Shuttle Landing Facility. During the test, the lander was lifted 20 feet by crane, and then ascended another 10 feet, maneuvered backwards 10 feet, and then flew forward. It will descend to its original position, landing at the end of the tether onto a transportable launch platform. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

KSC-2013-4256

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, the Project Morpheus prototype lander is being prepared for placement on a transportable launch platform positioned at the north end of the Shuttle Landing Facility. The lander will be prepared for a tethered test that includes lifting it 20 feet by crane, ascending another 10 feet, maneuvering backwards 10 feet, and then flying forward and descending to its original position, landing at the end of the tether. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2013-4290

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, smoke fills the air as the Project Morpheus prototype lander’s engine fires during a tether test at the north end of the Shuttle Landing Facility. During the test, the lander was lifted 20 feet by crane, and then ascended another 10 feet, maneuvered backwards 10 feet, and then flew forward. It will descend to its original position, landing at the end of the tether onto a transportable launch platform. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

KSC-2013-4291

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, smoke fills the air as the Project Morpheus prototype lander’s engine fires during a tether test at the north end of the Shuttle Landing Facility. During the test, the lander was lifted 20 feet by crane, and then ascended another 10 feet, maneuvered backwards 10 feet, and then flew forward. It will descend to its original position, landing at the end of the tether onto a transportable launch platform. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

In-Space Propulsion: Connectivity to In-Space Fabrication and Repair

NASA Technical Reports Server (NTRS)

Johnson, L.; Harris, D.; Trausch, A.; Matloff, G. L.; Taylor, T.; Cutting, K.

2005-01-01

The connectivity between new in-space propulsion technologies and the ultimate development of an in-space fabrication and repair infrastructure are described in this Technical Memorandum. A number of advanced in-space propulsion technologies are being developed by NASA, many of which are directly relevant to the establishment of such an in-space infrastructure. These include aerocapture, advanced solar-electric propulsion, solar-thermal propulsion, advanced chemical propulsion, tethers, and solar photon sails. Other, further-term technologies have also been studied to assess their utility to the development of such an infrastructure.

Debye mass in de Sitter space

NASA Astrophysics Data System (ADS)

Popov, Fedor K.

2018-06-01

We calculate the one-loop contributions to the polarization operator for scalar quantum electrodynamics in different external electromagnetic and gravitational fields. In the case of gravity, de Sitter space and its different patches were considered. It is shown that the Debye mass appears only in the case of alpha-vacuum in the Expanding Poincare Patch. It can be shown either by direct computations or by using analytical and causal properties of the de Sitter space. Also, the case of constant electric field is considered and the Debye mass is calculated.

Phase Space Tweezers for Tailoring Cavity Fields by Quantum Zeno Dynamics

NASA Astrophysics Data System (ADS)

Raimond, J. M.; Sayrin, C.; Gleyzes, S.; Dotsenko, I.; Brune, M.; Haroche, S.; Facchi, P.; Pascazio, S.

2010-11-01

We discuss an implementation of quantum Zeno dynamics in a cavity quantum electrodynamics experiment. By performing repeated unitary operations on atoms coupled to the field, we restrict the field evolution in chosen subspaces of the total Hilbert space. This procedure leads to promising methods for tailoring nonclassical states. We propose to realize “tweezers” picking a coherent field at a point in phase space and moving it towards an arbitrary final position without affecting other nonoverlapping coherent components. These effects could be observed with a state-of-the-art apparatus.

Development of the SEASIS instrument for SEDSAT

NASA Technical Reports Server (NTRS)

Maier, Mark W.

1996-01-01

Two SEASIS experiment objectives are key: take images that allow three axis attitude determination and take multi-spectral images of the earth. During the tether mission it is also desirable to capture images for the recoiling tether from the endmass perspective (which has never been observed). SEASIS must store all its imagery taken during the tether mission until the earth downlink can be established. SEASIS determines attitude with a panoramic camera and performs earth observation with a telephoto lens camera. Camera video is digitized, compressed, and stored in solid state memory. These objectives are addressed through the following architectural choices: (1) A camera system using a Panoramic Annular Lens (PAL). This lens has a 360 deg. azimuthal field of view by a +45 degree vertical field measured from a plan normal to the lens boresight axis. It has been shown in Mr. Mark Steadham's UAH M.S. thesis that his camera can determine three axis attitude anytime the earth and one other recognizable celestial object (for example, the sun) is in the field of view. This will be essentially all the time during tether deployment. (2) A second camera system using telephoto lens and filter wheel. The camera is a black and white standard video camera. The filters are chosen to cover the visible spectral bands of remote sensing interest. (3) A processor and mass memory arrangement linked to the cameras. Video signals from the cameras are digitized, compressed in the processor, and stored in a large static RAM bank. The processor is a multi-chip module consisting of a T800 Transputer and three Zoran floating point Digital Signal Processors. This processor module was supplied under ARPA contract by the Space Computer Corporation to demonstrate its use in space.

Momentum harvesting techniques for solar system travel

NASA Technical Reports Server (NTRS)

Willoughby, Alan J.

1991-01-01

Astronomers are lately estimating there are 400,000 earth visiting asteroids larger than 100 meters in diameter. These asteroids are uniquely accessible sources of building materials, propellants, oxygen, water, and minerals. They also constitute a huge momentum reserve, potentially usable for travel throughout the solar system. To use this momentum, these stealthy objects must be tracked and the ability to extract the desired momentum obtained. Momentum harvesting by momentum transfer from asteroid to spacecraft, and by using the momentum of the extraterrestrial material to help deliver itself to its destination is discussed. The purpose is neither to quantify nor justify the momentum exchange processes, but to stimulate collective imaginations with some intriguing possibilities which emerge when momentum as well as material is considered. A net and tether concept is the suggested means of asteroid capture, the basic momentum exchange process. The energy damping characteristics of the tether determines the velocity mismatch that can be tolerated, and hence the amount of momentum that can be harvested per capture. As the tether plays out of its reel, drag on the tether steadily accelerates the spacecraft and dilutes, in time, the would-be collision. A variety of concepts for riding and using asteroids after capture are introduced. The hitchhiker uses momentum transfer only. The beachcomber, the caveman, the swinger, the prospector, and the rock wrecker also take advantage of raw asteroid materials. The chemist and the hijacker go further, they process the asteroid into propellants. Or, an asteroid railway system could be constructed with each hijacked asteroid becoming a scheduled train. Travelers could board this space railway system assured that water, oxygen propellants, and shielding await them. Austere space travel could give way to comforts, with a speed and economy impossible without nature's gift of earth visiting asteroids.

Advanced interdisciplinary technologies

NASA Technical Reports Server (NTRS)

Anderson, John L.

1990-01-01

The following topics are presented in view graph form: (1) breakthrough trust (space research and technology assessment); (2) bionics (technology derivatives from biological systems); (3) biodynamics (modeling of human biomechanical performance based on anatomical data); and (4) tethered atmospheric research probes.

European Space Agency (ESA) Mission Specialist Nicollier trains in JSC's WETF

NASA Technical Reports Server (NTRS)

1987-01-01

European Space Agency (ESA) Mission Specialist (MS) Claude Nicollier (left) is briefed by Randall S. McDaniel on Space Shuttle extravehicular activity (EVA) tools and equipment prior to donning an extravehicular mobility unit and participating in an underwater EVA simulation in JSC's Weightless Environment Training Facility (WETF) Bldg 29 pool. Nicollier is holding the EMU mini workstation. Other equipment on the table includes EVA tool caddies and EVA crewmember safety tethers.

McDonnell Douglas Space Systems worker checks STS-46 TSS wiring at KSC O and C

NASA Technical Reports Server (NTRS)

1991-01-01

In the Kennedy Space Center (KSC) Operations and Checkout (O and C) Building, a McDonnell Douglas Space Systems technician Hugh Beins, wearing a clean suit, inspects a complex array of wiring for the Tethered Satellite System (TSS) scheduled to fly on STS-46 aboard Atlantis, Orbiter Vehicle (OV) 104. Other technicians work on the spacelab enhanced multiplexer/demultiplexer pallet (EMP) and support struts in the background.

de Broglie-Proca and Bopp-Podolsky massive photon gases in cosmology

NASA Astrophysics Data System (ADS)

Cuzinatto, R. R.; de Morais, E. M.; Medeiros, L. G.; Naldoni de Souza, C.; Pimentel, B. M.

2017-04-01

We investigate the influence of massive photons on the evolution of the expanding universe. Two particular models for generalized electrodynamics are considered, namely de Broglie-Proca and Bopp-Podolsky electrodynamics. We obtain the equation of state (EOS) P=P(\\varepsilon) for each case using dispersion relations derived from both theories. The EOS are inputted into the Friedmann equations of a homogeneous and isotropic space-time to determine the cosmic scale factor a(t). It is shown that the photon non-null mass does not significantly alter the result a\\propto t1/2 valid for a massless photon gas; this is true either in de Broglie-Proca's case (where the photon mass m is extremely small) or in Bopp-Podolsky theory (for which m is extremely large).

Thermodynamics of third-order Lovelock-AdS black holes in the presence of Born-Infeld type nonlinear electrodynamics

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Dehghani, A.

2015-03-01

In this paper, we obtain topological black hole solutions of third-order Lovelock gravity coupled with two classes of Born-Infeld-type nonlinear electrodynamics with anti-de Sitter asymptotic structure. We investigate geometric and thermodynamics properties of the solutions and obtain conserved quantities of the black holes. We examine the first law of thermodynamics and find that the conserved and thermodynamic quantities of the black hole solutions satisfy the first law of thermodynamics. Finally, we calculate the heat capacity and determinant of the Hessian matrix to evaluate thermal stability in both canonical and grand canonical ensembles. Moreover, we consider the extended phase space thermodynamics to obtain a generalized first law of thermodynamics as well as the extended Smarr formula.

Electrodynamic Dust Shield for Space Applications

NASA Technical Reports Server (NTRS)

Mackey, P. J.; Johansen, M. R.; Olsen, R. C.; Raines, M. G.; Phillips, J. R., III; Pollard, J. R. S.; Calle, C. I.

2016-01-01

The International Space Exploration Coordination Group (ISECG) has chosen dust mitigation technology as a Global Exploration Roadmap (GER) critical technology need in order to reduce life cycle cost and risk, and increase the probability of mission success. NASA has also included Particulate Contamination Prevention and Mitigation as a cross-cutting technology to be developed for contamination prevention, cleaning and protection. This technology has been highlighted due to the detrimental effect of dust on both human and robotic missions. During manned Apollo missions, dust caused issues with both equipment and crew. Contamination of equipment caused many issues including incorrect instrument readings and increased temperatures due to masking of thermal radiators. The astronauts were directly affected by dust that covered space suits, obscured face shields and later propagated to the cabin and into the crew's eyes and lungs. Robotic missions on Mars were affected when solar panels were obscured by dust thereby reducing the effectiveness of the solar panels. The Electrostatics and Surface Physics Lab in Swamp Works at the Kennedy Space Center has been developing an Electrodynamic Dust Shield (EDS) to remove dust from multiple surfaces, including glass shields and thermal radiators. This technology has been tested in lab environments and has evolved over several years. Tests of the technology include reduced gravity flights (one-sixth g) in which Apollo Lunar dust samples were successfully removed from glass shields while under vacuum (10(exp -6) kPa).

A gridded global description of the ionosphere and thermosphere for 1996 - 2000

NASA Astrophysics Data System (ADS)

Ridley, A.; Kihn, E.; Kroehl, H.

The modeling and simulation community has asked for a realistic representation of the near-Earth space environment covering a significant number of years to be used in scientific and engineering applications. The data, data management systems, assimilation techniques, physical models, and computer resources are now available to construct a realistic description of the ionosphere and thermosphere over a 5 year period. DMSP and NOAA POES satellite data and solar emissions were used to compute Hall and Pederson conductances in the ionosphere. Interplanetary magnetic field measurements on the ACE satellite define average electrostatic potential patterns over the northern and southern Polar Regions. These conductances, electric field patterns, and ground-based magnetometer data were input to the Assimilative Mapping of Ionospheric Electrodynamics model to compute the distribution of electric fields and currents in the ionosphere. The Global Thermosphere Ionosphere Model (GITM) used the ionospheric electrodynamic parameters to compute the distribution of particles and fields in the ionosphere and thermosphere. GITM uses a general circulation approach to solve the fundamental equations. Model results offer a unique opportunity to assess the relative importance of different forcing terms under a variety of conditions as well as the accuracies of different estimates of ionospheric electrodynamic parameters.

NASA Bluetooth Wireless Communications

NASA Technical Reports Server (NTRS)

Miller, Robert D.

2007-01-01

NASA has been interested in wireless communications for many years, especially when the crew size of the International Space Station (ISS) was reduced to two members. NASA began a study to find ways to improve crew efficiency to make sure the ISS could be maintained with limited crew capacity and still be a valuable research testbed in Low-Earth Orbit (LEO). Currently the ISS audio system requires astronauts to be tethered to the audio system, specifically a device called the Audio Terminal Unit (ATU). Wireless communications would remove the tether and allow astronauts to freely float from experiment to experiment without having to worry about moving and reconnecting the associated cabling or finding the space equivalent of an extension cord. A wireless communication system would also improve safety and reduce system susceptibility to Electromagnetic Interference (EMI). Safety would be improved because a crewmember could quickly escape a fire while maintaining communications with the ground and other crewmembers at any location. In addition, it would allow the crew to overcome the volume limitations of the ISS ATU. This is especially important to the Portable Breathing Apparatus (PBA). The next generation of space vehicles and habitats also demand wireless attention. Orion will carry up to six crewmembers in a relatively small cabin. Yet, wireless could become a driving factor to reduce launch weight and increase habitable volume. Six crewmembers, each tethered to a panel, could result in a wiring mess even in nominal operations. In addition to Orion, research is being conducted to determine if Bluetooth is appropriate for Lunar Habitat applications.

KSC-2013-3905

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dr. Carlos Calle, senior research scientist on the Electrodynamic Dust Shield for Dust Mitigation project, demonstrates a dust particle experiment in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. Electrodynamic dust shield, or EDS, technology is based on concepts originally developed by NASA as early as 1967 and later by the University of Tokyo. In 2003, NASA, in collaboration with the University of Arkansas at Little Rock, started development of the EDS for dust particle removal from solar panels to be used on future missions to the moon, an asteroid or Mars. A flight experiment to expose the dust shields to the space environment currently is under development. For more information, visit: http://www.nasa.gov/content/scientists-developing-ways-to-mitigate-dust-problem-for-explorers/ Photo credit: NASA/Dan Casper

KSC-2013-3903

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dr. Carlos Calle, senior research scientist on the Electrodynamic Dust Shield for Dust Mitigation project, demonstrates a dust particle experiment in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. Electrodynamic dust shield, or EDS, technology is based on concepts originally developed by NASA as early as 1967 and later by the University of Tokyo. In 2003, NASA, in collaboration with the University of Arkansas at Little Rock, started development of the EDS for dust particle removal from solar panels to be used on future missions to the moon, an asteroid or Mars. A flight experiment to expose the dust shields to the space environment currently is under development. For more information, visit: http://www.nasa.gov/content/scientists-developing-ways-to-mitigate-dust-problem-for-explorers/ Photo credit: NASA/Dan Casper

Technical Evaluation Report on the Flight Mechanics Panel Symposium on the Flight Mechanics Panel Symposium on Space Vehicle Flight Mechanics (La Mecanique du Vol des Vehicules Spatiaux)

DTIC Science & Technology

1990-11-01

control and including final recovery for a wide range of space vehicles from tethered satellite systems and flexible space structures to the space plane...flight mechanics, members from the Fluid Dynamics Panel, the Guidance and Control Panel, the Propulsion and Energetics Panel and the Structures and... Structures and Materials which should be overcome for a successful realization of a human Space Transportation System in the 21st century. He

Large space structures and systems in the space station era: A bibliography with indexes (supplement 03)

NASA Technical Reports Server (NTRS)

1991-01-01

Bibliographies and abstracts are listed for 1221 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and June 30, 1991. Topics covered include large space structures and systems, space stations, extravehicular activity, thermal environments and control, tethering, spacecraft power supplies, structural concepts and control systems, electronics, advanced materials, propulsion, policies and international cooperation, vibration and dynamic controls, robotics and remote operations, data and communication systems, electric power generation, space commercialization, orbital transfer, and human factors engineering.

Molecular dynamics simulation study of the role of evenly spaced poly(ethylene oxide) tethers on the aggregation of C60 fullerenes in water.

PubMed

Bedrov, Dmitry; Smith, Grant D; Li, Liwei

2005-06-07

The aggregation behavior of C60 fullerenes and C60 fullerenes with six symmetrically tethered poly(ethylene oxide) oligomers [(PEO)-6-C60] in aqueous solutions has been studied using implicit solvent molecular dynamics simulations. Our simulations reveal that while the attraction between two (PEO)-6-C60 fullerenes in aqueous solution is stronger and longer range than that between two bare C60 fullerenes, the (PEO)-6-C60 fullerenes do not phase-separate in water but rather aggregate in chain-like clusters at concentrations where unmodified fullerenes completely phase-separate.

Speculations on future opportunities to evolve Brayton powerplants aboard the space station

NASA Technical Reports Server (NTRS)

English, Robert E.

1987-01-01

The Space Station provides a unique, low-risk environment in which to evolve new capabilities. In this way, the Space Station will grow in capacity, in its range of capabilities, and its economy of operation as a laboratory and as a center for space operations. Although both Rankine and Brayton cycles, two concepts for solar dynamic power generation, now compete to power the station, this paper confines its attention to the Brayton cycle using a mixture of He and Xe as its working fluid. Such a Brayton powerplant to supply the station's increasing demands for both electric power and heat has the potential to gradually evolve higher and higher performance by exploiting already-evolved materials (ASTAR-811C and molten-Li heat storage), its peak cycle temperature rising ultimately to 1500 K. Adapting the station to exploit long tethers (200 to 300 km long) could yield increases in payloads to LEO, to GEO, and to distant destinations in the solar system. Such tethering of the Space Station would not only require additional power for electric propulsion but also would so increase nuclear safety that nuclear powerplants might provide this power. From an 8000-kWt SP-100 reactor, thermoelectric power generation could produce 300 kWe, or adapted solar-Brayton cycle, 2400 to 2800 kWe.

The 17th Aerospace Mechanisms Symposium

NASA Technical Reports Server (NTRS)

1983-01-01

The proceedings of the Aerospace Mechanisms Symposium are reported. Technological areas covered include space lubrication, aerodynamic devices, spacecraft/Shuttle latches, deployment, positioning, and pointing. Devices for spacecraft tether, magnetic bearing suspension, explosive welding, and a deployable/retractable mast are also described.

Measuring functional connectivity using MEG: Methodology and comparison with fcMRI

PubMed Central

Brookes, Matthew J.; Hale, Joanne R.; Zumer, Johanna M.; Stevenson, Claire M.; Francis, Susan T.; Barnes, Gareth R.; Owen, Julia P.; Morris, Peter G.; Nagarajan, Srikantan S.

2011-01-01

Functional connectivity (FC) between brain regions is thought to be central to the way in which the brain processes information. Abnormal connectivity is thought to be implicated in a number of diseases. The ability to study FC is therefore a key goal for neuroimaging. Functional connectivity (fc) MRI has become a popular tool to make connectivity measurements but the technique is limited by its indirect nature. A multimodal approach is therefore an attractive means to investigate the electrodynamic mechanisms underlying hemodynamic connectivity. In this paper, we investigate resting state FC using fcMRI and magnetoencephalography (MEG). In fcMRI, we exploit the advantages afforded by ultra high magnetic field. In MEG we apply envelope correlation and coherence techniques to source space projected MEG signals. We show that beamforming provides an excellent means to measure FC in source space using MEG data. However, care must be taken when interpreting these measurements since cross talk between voxels in source space can potentially lead to spurious connectivity and this must be taken into account in all studies of this type. We show good spatial agreement between FC measured independently using MEG and fcMRI; FC between sensorimotor cortices was observed using both modalities, with the best spatial agreement when MEG data are filtered into the β band. This finding helps to reduce the potential confounds associated with each modality alone: while it helps reduce the uncertainties in spatial patterns generated by MEG (brought about by the ill posed inverse problem), addition of electrodynamic metric confirms the neural basis of fcMRI measurements. Finally, we show that multiple MEG based FC metrics allow the potential to move beyond what is possible using fcMRI, and investigate the nature of electrodynamic connectivity. Our results extend those from previous studies and add weight to the argument that neural oscillations are intimately related to functional connectivity and the BOLD response. PMID:21352925

High voltage plasma sheath analysis related to TSS-1

NASA Technical Reports Server (NTRS)

Sheldon, John W.

1990-01-01

On the first mission of the Tethered Satellite System (TSS-1), a 1.8 m diameter spherical satellite will be deployed a distance of 20 km above the Space Shuttle Orbiter on an insulated conducting tether. The satellite will be held at electric potentials up to 5000 volts positive with respect to the ambient plasma. Due to the passage of the conducting tether through the Earth's magnetic field, an electromagnetic field (EMF) will be created, driving electrons down the tether to the Orbiter, out through an electron gun into the ionosphere and back into the positive-biased satellite. The main problem addressed here is the current-voltage characteristics of the ionospheric interaction with the satellite. The first problem is that while the satellite will be capable of measuring charged particle flow to the surface at several locations, the detectors have a limited range of acceptance angle. The second problem is that the angle of incidence of the incoming electrons will have to be relative to the local normal. This will be important in order to predict the magnitude of the detectable current at each detector location so the detector gain can be pre-set to the correct range. The plasma sheath was analyzed mathematically, and subroutines were written to solve relevant finite element, Taylor-Vlasov, and Poisson equations.

Initiation of Coronal Mass Ejections by Tether-Cutting Reconnection

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Sterling, Alphonse C.; Falconer, David A.; Six, N. Frank (Technical Monitor)

2002-01-01

We present and interpret examples of the eruptive motion and flare brightening observed in the onset of magnetic explosions that produce coronal mass ejections. The observations are photospheric magnetograms and sequences of coronal and/or chromospheric images. In our examples, the explosion is apparently driven by the ejective eruption of a sigmoidal sheared-field flux rope from the core of an initially closed bipole. This eruption is initiated (triggered and unleashed) by reconnection located either (1) internally, low in the sheared core field, or (2) externally, at a magnetic null above the closed bipole. The internal reconnection is commonly called 'tether-cutting" reconnection, and the external reconnection is commonly called "break-out' reconnection. We point out that break-out reconnection amounts to external tether cutting. In one example, the eruptive motion of the sheared core field starts several minutes prior to any detectable brightening in the coronal images. We suggest that in this case the eruption is triggered by internal tether-cutting reconnection that at first is too slow and/or too localized to produce detectable heating in the coronal images. This work is supported by NASA's Office of Space Science through its Solar & Heliospheric Physics Supporting Research & Technology program and its Sun-Earth Connection Guest Investigator program.

NASA's Electric Sail Propulsion System Investigations over the Past Three Years

NASA Technical Reports Server (NTRS)

Wiegmann, Bruce M.

2017-01-01

Personnel from NASA's MSFC have been investigating the feasibility of an advanced propulsion system known as the Electric Sail for future scientific missions of exploration. This team initially won a NASA Space Technology Mission Directorate (STMD) Phase I NASA Innovative Advanced Concept (NIAC) award and then a two year follow-on Phase II NIAC award. This paper documents the findings from this three year investigation. An Electric sail propulsion system is a propellant-less and extremely fast propulsion system that takes advantage of the ions that are present in the solar wind to provide very rapid transit speeds whether to deep space or to the inner solar system. Scientific spacecraft could arrive to Pluto in 5 years, to the boundary of the solar system in ten to twelve years vs. thirty five plus years it took the Voyager spacecraft. The team's recent focused activities are: 1) Developing a Particle in Cell (PIC) numeric engineering model from the experimental data collected at MSFC's Solar Wind Facility on the interaction between simulated solar wind interaction with a charged bare wire that can be applied to a variety of missions, 2) The development of the necessary tether deployers/tethers to enable successful deployment of multiple, multi km length bare tethers, 3) Determining the different missions that can be captured from this revolutionary propulsion system 4) Conceptual designs of spacecraft to reach various destinations whether to the edge of the solar system, or as Heliophysics sentinels around the sun, or to trips to examine a multitude of asteroids These above activities, once demonstrated analytically, will require a technology demonstration mission (2021 to 2023) to demonstrate that all systems work together seamlessly before a Heliophysics Electrostatic Rapid Transit System (HERTS) could be given the go-ahead. The proposed demonstration mission will require that a small spacecraft must first travel to cis-lunar space as the Electric Sail must be outside of Earth's Magnetic fields to produce thrust. The paper will outline what was done over the past three years from performing various plasma chamber tests to obtain data for the PIC model development, investigation of tether material trades, and conceptual designs of proposed spacecraft.

Space science/space station attached payload pointing accommodation study: Technology assessment white paper

NASA Technical Reports Server (NTRS)

Lin, Richard Y.; Mann, Kenneth E.; Laskin, Robert A.; Sirlin, Samuel W.

1987-01-01

Technology assessment is performed for pointing systems that accommodate payloads of large mass and large dimensions. Related technology areas are also examined. These related areas include active thermal lines or power cables across gimbals, new materials for increased passive damping, tethered pointing, and inertially reacting pointing systems. Conclusions, issues and concerns, and recommendations regarding the status and development of large pointing systems for space applications are made based on the performed assessments.

SEDS1 mission software verification using a signal simulator

NASA Technical Reports Server (NTRS)

Pierson, William E.

1992-01-01

The first flight of the Small Expendable Deployer System (SEDS1) is schedule to fly as the secondary payload of a Delta 2 in March, 1993. The objective of the SEDS1 mission is to collect data to validate the concept of tethered satellite systems and to verify computer simulations used to predict their behavior. SEDS1 will deploy a 50 lb. instrumented satellite as an end mass using a 20 km tether. Langley Research Center is providing the end mass instrumentation, while the Marshall Space Flight Center is designing and building the deployer. The objective of the experiment is to test the SEDS design concept by demonstrating that the system will satisfactorily deploy the full 20 km tether without stopping prematurely, come to a smooth stop on the application of a brake, and cut the tether at the proper time after it swings to the local vertical. Also, SEDS1 will collect data which will be used to test the accuracy of tether dynamics models used to stimulate this type of deployment. The experiment will last about 1.5 hours and complete approximately 1.5 orbits. Radar tracking of the Delta II and end mass is planned. In addition, the SEDS1 on-board computer will continuously record, store, and transmit mission data over the Delta II S-band telemetry system. The Data System will count tether windings as the tether unwinds, log the times of each turn and other mission events, monitor tether tension, and record the temperature of system components. A summary of the measurements taken during the SEDS1 are shown. The Data System will also control the tether brake and cutter mechanisms. Preliminary versions of two major sections of the flight software, the data telemetry modules and the data collection modules, were developed and tested under the 1990 NASA/ASEE Summer Faculty Fellowship Program. To facilitate the debugging of these software modules, a prototype SEDS Data System was programmed to simulate turn count signals. During the 1991 summer program, the concept of simulating signals produced by the SEDS electronics systems and circuits was expanded and more precisely defined. During the 1992 summer program, the SEDS signal simulator was programmed to test the requirements of the SEDS Mission software, and this simulator will be used in the formal verification of the SEDS Mission Software. The formal test procedures specification was written which incorporates the use of the signal simulator to test the SEDS Mission Software and which incorporates procedures for testing the other major component of the SEDS software, the Monitor Software.

Design and Calibration of an Electrodynamic Driver for the Space Thermoacoustic Refrigerator

DTIC Science & Technology

1989-06-01

University, 1982 Submitted in partial fulfillment of the requirements for the degree of MAST£et OF SCIENCE IN ENGINEERING ACOUSTICS from the NAVAL...A5oustickAcademic Committee Gordon E. Schacher Dean of Science and Engineering ii ABSTRACT The objective of the STAR project is to test and space qualify a...definition of the subject matter to the study of heat engines in which a net 1 heat transport in some gaseous medium is related to the acoustic

KSC-2013-4288

NASA Image and Video Library

2013-12-06

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, smoke fills the air as the Project Morpheus prototype lander’s engine fires during a tether test at the north end of the Shuttle Landing Facility. During the test, the lander was lifted 20 feet by crane, and then ascended another 10 feet. The lander will maneuver backwards 10 feet, and then fly forward and descend to its original position, landing at the end of the tether onto a transportable launch platform. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Daniel Casper

Renormalizable Electrodynamics of Scalar and Vector Mesons. Part II

DOE R&D Accomplishments Database

Salam, Abdus; Delbourgo, Robert

1964-01-01

The "gauge" technique" for solving theories introduced in an earlier paper is applied to scalar and vector electrodynamics. It is shown that for scalar electrodynamics, there is no {lambda}φ*2φ2 infinity in the theory, while with conventional subtractions vector electrodynamics is completely finite. The essential ideas of the gauge technique are explained in section 3, and a preliminary set of rules for finite computation in vector electrodynamics is set out in Eqs. (7.28) - (7.34).

Local U(2,2) symmetry in relativistic quantum mechanics

NASA Astrophysics Data System (ADS)

Finster, Felix

1998-12-01

Local gauge freedom in relativistic quantum mechanics is derived from a measurement principle for space and time. For the Dirac equation, one obtains local U(2,2) gauge transformations acting on the spinor index of the wave functions. This local U(2,2) symmetry allows a unified description of electrodynamics and general relativity as a classical gauge theory.

A-3 Test Stand

NASA Image and Video Library

2012-06-08

A tethered Stennis Space Center employee climbs an A-3 Test Stand ladder June 8, 2012, against the backdrop of the A-2 and B-1/B-2 stands. The new A-3 Test Stand will enable simulated high-altitude testing of next-generation rocket engines.

A-3 Test Stand

NASA Image and Video Library

2012-06-08

A tethered Stennis Space Center employee climbs an A-3 Test Stand ladded June 8, 2012, against the backdrop of the A-2 and B-1/B-2 stands. The new A-3 Test Stand will enable simulated high-altitude testing of next-generation rocket engines.

76 FR 41526 - Centennial Challenges 2011 Strong Tether Challenge

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-14

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice (11-063)] Centennial Challenges 2011 Strong... scheduled and teams that wish to compete may register. Centennial Challenges is a program of prize... NASA Centennial Challenges Program please visit: http://www.nasa.gov/challenges . General questions and...

Inflight - STS-11/41B (MISSION CONTROL CENTER [MCC]) - JSC

NASA Image and Video Library

1984-02-08

S84-26503 (7 Feb 1984) --- This wide angle, overall view of activity in the mission operations control room in the Johnson Space Center?s mission control center, was photographed during the first even non-tethered extravehicular activity (EVA) in space. The large MOCR monitor and those at individual consoles feed to ground controllers the spectacular scene of Astronaut Bruce McCandless II ?suspended? I space above the blue and white Earth. The scene was photographed at 7:30 a.m. (CST), February 7, 1984.

OV-104's RMS grapples EURECA-1L and holds it in deployment position above PLB

NASA Image and Video Library

1992-08-08

STS046-102-021 (1 Aug 1992) --- The European Space Agency's (ESA) EURECA satellite remains in the grasp of the Space Shuttle Atlantis' Remote Manipulator System (RMS) as the Space Shuttle passes over the Persian Gulf. Most of the theater of the recent war is visible in the frame. Parts of Kuwait, Iraq, Iran and Saudi Arabia can be delineated. The Tethered Satellite System (TSS) remains stowed in the aft cargo bay of Atlantis.

Telemetric Sensors for the Space Life Sciences

NASA Technical Reports Server (NTRS)

Hines, John W.; Somps, Chris J.; Madou, Marc; Jeutter, Dean C.; Singh, Avtar; Connolly, John P. (Technical Monitor)

1996-01-01

Telemetric sensors for monitoring physiological changes in animal models in space are being developed by NASA's Sensors 2000! program. The sensors measure a variety of physiological measurands, including temperature, biopotentials, pressure, flow, acceleration, and chemical levels, and transmit these signals from the animals to a remote receiver via a wireless link. Thus physiologic information can be obtained continuously and automatically without animal handling, tethers, or percutaneous leads. We report here on NASA's development and testing of advanced wireless sensor systems for space life sciences research.

The Potential for Ambient Plasma Wave Propulsion

NASA Technical Reports Server (NTRS)

Gilland, James H.; Williams, George J.

2016-01-01

A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at frequencies below the ion cyclotron frequency. They have been observed in both laboratory and astrophysical settings. On Earth, they are being investigated as a possible means for plasma heating, current drive, and momentum addition in magnetic confinement fusion systems. In addition, Alfven waves have been proposed as a mechanism for acceleration of the solar wind away from the sun.

Ferroelectric Emission Cathodes for Low-Power Electric Propulsion

NASA Technical Reports Server (NTRS)

Kovaleski, Scott D.; Burke, Tom (Technical Monitor)

2002-01-01

Low- or no-flow electron emitters are required for low-power electric thrusters, spacecraft plasma contactors, and electrodynamic tether systems to reduce or eliminate the need for propellant/expellant. Expellant-less neutralizers can improve the viability of very low-power colloid thrusters, field emission electric propulsion devices, ion engines, Hall thrusters, and gridded vacuum arc thrusters. The NASA Glenn Research Center (GRC) is evaluating ferroelectric emission (FEE) cathodes as zero expellant flow rate cathode sources for the applications listed above. At GRC, low voltage (100s to approx. 1500 V) operation of FEE cathodes is examined. Initial experiments, with unipolar, bipolar, and RF burst applied voltage, have produced current pulses 250 to 1000 ns in duration with peak currents of up to 2 A at voltages at or below 1500 V. In particular, FEE cathodes driven by RF burst voltages from 1400 to 2000 V peak to peak, at burst frequencies from 70 to 400 kHz, emitted average current densities from 0.1 to 0.7 A/sq cm. Pulse repeatability as a function of input voltage has been initially established. Reliable emission has been achieved in air background at pressures as high as 10(exp -6) Torr.

Self field electromagnetism and quantum phenomena

NASA Astrophysics Data System (ADS)

Schatten, Kenneth H.

1994-07-01

Quantum Electrodynamics (QED) has been extremely successful inits predictive capability for atomic phenomena. Thus the greatest hope for any alternative view is solely to mimic the predictive capability of quantum mechanics (QM), and perhaps its usefulness will lie in gaining a better understanding of microscopic phenomena. Many ?paradoxes? and problematic situations emerge in QED. To combat the QED problems, the field of Stochastics Electrodynamics (SE) emerged, wherein a random ?zero point radiation? is assumed to fill all of space in an attmept to explain quantum phenomena, without some of the paradoxical concerns. SE, however, has greater failings. One is that the electromagnetic field energy must be infinit eto work. We have examined a deterministic side branch of SE, ?self field? electrodynamics, which may overcome the probelms of SE. Self field electrodynamics (SFE) utilizes the chaotic nature of electromagnetic emissions, as charges lose energy near atomic dimensions, to try to understand and mimic quantum phenomena. These fields and charges can ?interact with themselves? in a non-linear fashion, and may thereby explain many quantum phenomena from a semi-classical viewpoint. Referred to as self fields, they have gone by other names in the literature: ?evanesccent radiation?, ?virtual photons?, and ?vacuum fluctuations?. Using self fields, we discuss the uncertainty principles, the Casimir effects, and the black-body radiation spectrum, diffraction and interference effects, Schrodinger's equation, Planck's constant, and the nature of the electron and how they might be understood in the present framework. No new theory could ever replace QED. The self field view (if correct) would, at best, only serve to provide some understanding of the processes by which strange quantum phenomena occur at the atomic level. We discuss possible areas where experiments might be employed to test SFE, and areas where future work may lie.

KSC-2013-3902

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dr. Carlos Calle, senior research scientist on the Electrodynamic Dust Shield for Dust Mitigation project, works with dust fabricated for use in his experiments in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The fabricated material is designed to mimic the dust on the lunar surface. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. Electrodynamic dust shield, or EDS, technology is based on concepts originally developed by NASA as early as 1967 and later by the University of Tokyo. In 2003, NASA, in collaboration with the University of Arkansas at Little Rock, started development of the EDS for dust particle removal from solar panels to be used on future missions to the moon, an asteroid or Mars. A flight experiment to expose the dust shields to the space environment currently is under development. For more information, visit: http://www.nasa.gov/content/scientists-developing-ways-to-mitigate-dust-problem-for-explorers/ Photo credit: NASA/Dan Casper

The Biomechanics of Exercise Countermeasures

NASA Technical Reports Server (NTRS)

Cavanagh, Peter R.; Arnold, Steven; Derr, Janice; Sharkey, Neil; Wu, Ge

1999-01-01

The Penn State Zero-gravity Simulator (PSZS) is a device developed by the Center for Locomotion Studies (CELOS) to enable ground studies of exercise countermeasures for the bone loss that has been shown to occur during long-term exposure to zero gravity (0G). The PSZS simulates 0G exercise by providing a suspension system that holds an individual in a horizontal (supine) position above the floor in order to enable exercise on a wall-mounted treadmill. Due to this orientation, exercise performed in the PSZS is free of the force of -ravity in the direction that would normally contribute to ground reaction forces. In order for movements to be more similar to those in 0G, a constant force suspension of each segment (equal to the segment weight) is provided regardless of limb position. During the preliminary development of the PSZS, CELOS researchers also designed an optional gravity-replacement simulation feature for the PSZS. This feature was a prototype tethering system that consisted of a spring tension system to pull an exercising individual toward the treadmill. The immediate application of the tethering system was to be the provision of gravity-replacement loading so that exercise in 0G- and 1G-loading conditions could be compared, and the PSZS could then be used to evaluate exercise countermeasures for bone loss during space flight. This tethering system would also be a model for the further refinement of gravity-replacement systems provided for astronaut usage while performing prescribed exercise countermeasures for bone loss during long-term space flights.

Tunable Artificial Receptor as a Chemical Sensor for V- and G-agents

DTIC Science & Technology

2012-06-01

shows the design concept for a fluorescent tether. The highly electrophilic nature of fluorescein required the used of carefully selected protecting...atoms removed for clarity) and a space-filling model (Key to figures: carbon: grey; oxygen: red; nitrogen: blue; phosphorus: orange; fluorine : yellow

Derivation of the Lorentz force law, the magnetic field concept and the Faraday Lenz and magnetic Gauss laws using an invariant formulation of the Lorentz transformation

NASA Astrophysics Data System (ADS)

Field, J. H.

2006-06-01

It is demonstrated how the right-hand sides of the Lorentz transformation equations may be written, in a Lorentz-invariant manner, as 4-vector scalar products. This implies the existence of invariant length intervals analogous to invariant proper time intervals. An important distinction between the physical meanings of the space time and energy momentum 4-vectors is pointed out. The formalism is shown to provide a short derivation of the Lorentz force law of classical electrodynamics, and the conventional definition of the magnetic field, in terms of spatial derivatives of the 4-vector potential, as well as the Faraday Lenz law and the Gauss law for magnetic fields. The connection between the Gauss law for the electric field and the electrodynamic Ampère law, due to the 4-vector character of the electromagnetic potential, is also pointed out.

Italian aerospace company Alenia prepare TSS-1R in O&C

NASA Technical Reports Server (NTRS)

1995-01-01

Employees of the Italian aerospace company Alenia Spazio S.p.A. prepare the Tethered Satellite System-1R (TSS-1R) that is one of two primary payloads scheduled to fly aboard the Orbiter Columbia during the STS-75 mission in early 1996 for a series of tests in the Operations and Checkout (O&C) Building. The TSS program is a joint venture between NASA and the Agenzia Spaziale Italiana, or Italian Space Agency. The 'R' designation indicates a reflight. The TSS-1 flew aboard Atlantis during the STS-46 mission in July 1992 and achieved only a partial success when its tether reel mechanism became jammed after only approximately 840 feet of the 12-mile-long tether had been unwound as the satellite rose from its cradle in the orbiter's payload bay. Once deployed to the 12- mile height on the STS-75 mission, the satellite will be used to validate theories that such a system could possibly be used in the future to generate electrical power to power orbital systems, raise and lower spacecraft, study atmospheric conditions at several different heights and for many other applications.

Use of control umbilicals as a deployment mode for free flying telerobotic work systems

NASA Technical Reports Server (NTRS)

Kuehn, J. S.; Selle, E. D.

1987-01-01

Work to date on telerobotic work systems for use in space generally consider two deployment modes, free flying, or fixed within a limited work envelope. Control tethers may be employed to obtain a number of operational advantages and added flexibility in the basing and deployment of telerobotic work systems. Use of a tether allows the work system to be separated into two major modules, the remote work package and the control module. The Remote Work Package (RWP) comprises the free flying portion of the work system while the Control Module (CM) remains at the work system base. The chief advantage of this configuration is that only the components required for completion of the work task must be located at the work site. Reaction mass used in free flight is stored at the Control module and supplied to the RWP through the tether, eliminating the need for the RWP to carry it. The RWP can be made less massive than a self contained free flying work system. As a result, reaction mass required for free flight is lower than for a self contained free flyer.

Analysis of thermionic bare tether operation regimes in passive mode

NASA Astrophysics Data System (ADS)

Sanmartín, J. R.; Chen, Xin; Sánchez-Arriaga, G.

2017-01-01

A thermionic bare tether (TBT) is a long conductor coated with a low work-function material. In drag mode, a tether segment extending from anodic end A to a zero-bias point B, with the standard Orbital-motion-limited current collection, is followed by a complex cathodic segment. In general, as bias becomes more negative in moving from B to cathodic end C, one first finds space-charge-limited (SCL) emission covering up to some intermediate point B*, then full Richardson-Dushman (RD) emission reaching from B* to end C. An approximate analytical study, which combines the current and voltage profile equations with results from asymptotic studies of the Vlasov-Poisson system for emissive probes, is carried out to determine the parameter domain covering two limit regimes, which are effectively controlled by just two dimensionless parameters involving ambient plasma and TBT material properties. In one such limit regime, no point B* is reached and thus no full RD emission develops. In an opposite regime, SCL segment BB* is too short to contribute significantly to the current balance.

Atmospheric Electricity and Tethered Aerostats, Volume 2

DTIC Science & Technology

1976-05-11

vs Altitude (Non- conducting or Conducting Tethers...Effect of Corona Charge Plume 15 3.1 Tether Current vs Balloon Altitude , BJ+3 - 25 Sep 73 20 3.2 Tether Current vs Balloon Altitude , Baldy - 17 Oct 73 21...3.3 Tether Current vs Balloon Altitude , Baldy - 31 Oct 73 22 3.4 Tether Current vs Balloon Altitude , Baldy - 2 Nov 73 23 3.5 Tether Current vs

Middle atmosphere electrodynamics: Report of the workshop on the Role of the Electrodynamics of the Middle Atmosphere on Solar Terrestrial Coupling

NASA Technical Reports Server (NTRS)

Maynard, N. C. (Editor)

1979-01-01

Significant deficiencies exist in the present understanding of the basic physical processes taking place within the middle atmosphere (the region between the tropopause and the mesopause), and in the knowledge of the variability of many of the primary parameters that regulate Middle Atmosphere Electrodynamics (MAE). Knowledge of the electrical properties, i.e., electric fields, plasma characteristics, conductivity and currents, and the physical processes that govern them is of fundamental importance to the physics of the region. Middle atmosphere electrodynamics may play a critical role in the electrodynamical aspects of solar-terrestrial relations. As a first step, the Workshop on the Role of the Electrodynamics of the Middle Atmosphere on Solar-Terrestrial Coupling was held to review the present status and define recommendations for future MAE research.

Use of top tethers with forward-facing child restraints: observations and driver interviews.

PubMed

Eichelberger, Angela H; Decina, Lawrence E; Jermakian, Jessica S; McCartt, Anne T

2014-02-01

Despite the safety benefits, many parents do not use top tethers with forward-facing child restraints. Detailed information was collected about why parents are not using tethers. The sample included 479 drivers who had forward-facing child restraints installed in passenger vehicles equipped with tether anchors. The survey was conducted primarily at shopping centers, recreation facilities, child care facilities, car seat check events, and health care facilities in mostly suburban areas surrounding Philadelphia, Washington, DC, Fredericksburg (VA), and Seattle. Drivers were surveyed about their knowledge and use of tethers and experience with child restraints. Tether use was observed to verify whether tethers were being used correctly. Fifty-six percent of forward-facing child restraints were installed with the tether; 39% were installed with the tether used correctly. The tether was used with 71% of LATCH lower anchor installations and 33% of seat belt installations. Drivers who installed child restraints without tethers most often said they did not know about the tether or how to use it. Although the tether use rate was slightly higher in the current research than in previous studies, many parents and caregivers still use forward-facing child restraints without attaching the tether. Because the main problem is lack of awareness of the tether or how to use it, public education should focus specifically on the safety benefits of tethers and how to use them. Information about why caregivers fail to use top tethers is potentially useful to child restraint manufacturers, child passenger safety technicians, and others who work with parents to improve motor vehicle safety. Copyright © 2013 Elsevier Ltd and National Safety Council. All rights reserved.

Discussion meeting on Gossamer spacecraft (ultralightweight spacecraft)

NASA Technical Reports Server (NTRS)

Brereton, R. G. (Editor)

1980-01-01

Concepts, technology, and application of ultralightweight structures in space are examined. Gossamer spacecraft represented a generic class of space vehicles or structures characterized by a low mass per unit area (approximately 50g/m2). Gossamer concepts include the solar sail, the space tether, and various two and three dimensional large lightweight structures that were deployed or assembled in space. The Gossamer Spacecraft had a high potential for use as a transportation device (solar sail), as a science instrument (reflecting or occulting antenna), or as a large structural component for an enclosure, manned platform, or other human habitats. Inflatable structures were one possible building element for large ultralightweight structures in space.

A New Approach Towards Deployment of Far Side Lunar SETI Using a Tethered Link to a Near Side Antenna

NASA Astrophysics Data System (ADS)

Datta, L. V.; Guven, U.; Goel, E.

2017-10-01

Keeping in pace with the recent growth in interest in deployable space telescopes for detection of extra-solar objects, we suggest a feasible approach to make a lunar far side SETI mission a reality with the technology. available today.

The Vehicle Control Systems Branch at the Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Barret, Chris

1990-01-01

This paper outlines the responsibility of the Vehicle Control Systems Branch at the Marshall Space Flight Center (MSFC) to analyze, evaluate, define, design, verify, and specify requirements for advanced launch vehicles and related space projects, and to conduct research in advanced flight control concepts. Attention is given to branch responsibilities which include Shuttle-C, Shuttle-C Block II, Shuttle-Z, lunar cargo launch vehicles, Mars cargo launch vehicles, orbital maneuvering vehicle, automatic docking, tethered satellite, aeroassisted flight experiment, and solid rocket booster parachute recovery system design.

Life sciences biomedical research planning for Space Station

NASA Technical Reports Server (NTRS)

Primeaux, Gary R.; Michaud, Roger; Miller, Ladonna; Searcy, Jim; Dickey, Bernistine

1987-01-01

The Biomedical Research Project (BmRP), a major component of the NASA Life Sciences Space Station Program, incorporates a laboratory for the study of the effects of microgravity on the human body, and the development of techniques capable of modifying or counteracting these effects. Attention is presently given to a representative scenario of BmRP investigations and associated engineering analyses, together with an account of the evolutionary process by which the scenarios and the Space Station design requirements they entail are identified. Attention is given to a tether-implemented 'variable gravity centrifuge'.

Tethers as Debris: Simulating Impacts of Kevlar Tethers on Shuttle Tiles

NASA Technical Reports Server (NTRS)

Evans, Steven W.

2004-01-01

In a previous paper I examined the effects of impacts of polymer tethers on aluminum plates using the SPHC hydrodynamic code. In this paper I apply tether models to a new target - models of Space Shuttle tiles developed during the STS 107 accident investigation. In this three-dimensional simulation, a short tether fragment strikes a single tile supported on an aluminum backing plate. A tile of the LI-900 material is modeled. Penetration and damage to the tile and the backwall are characterized for three normal impact velocities. The tether is modeled as a bundle of eight 1-mm strands, with the bundle having dimensions 2-mm x 4-mm x 20-cm. The bulk material properties used are those of Kevlar(TradeMark) 49, for which a Mie-Gruneisen multiphase equation of state (eos) is used. In addition, the strength model is applied in a linear sense, such that tensile loads along the strand length are supported, but there is no strength in the lateral directions. Tile models include the various layers making up the tile structure. The outermost layer is a relatively dense borosilicate glass, known as RCG, 0.5-mm thick. The RCG layer is present on the top and four sides of the tile. Below this coating is the bulk of the tile, 1.8- in thick, made of LI-900, a product consisting of rigidized fiberous silica with a density of 9 lWft3. Below the main insulating layer is a bottom layer of the same material that has been treated to increase its density by approximately 69% to improve its strength. This densified layer is bonded to a Strain Isolation Pad (SIP), modeled as a refractory felt fabric. The SIP is bonded to an aluminum 2024 wall 0.1-in thick. The tile and backwall materials use a Me-Gruneisen multiphase eos, with the exception of the SIP felt, which uses a fabric equation of state. Fabrics must be crushed to the full bulk material density before bulk material properties and a Mie-Gruneisen eos are applied. Tether fragment impact speeds of 3,7, and 10 km/s are simulated, with impact velocities normal to the tile face. Damage results are presented in tabular format.

Multisubunit tethering complexes in higher plants.

PubMed

Ravikumar, Raksha; Steiner, Alexander; Assaad, Farhah F

2017-12-01

Tethering complexes mediate the initial, specific contact between donor and acceptor membranes. This review focuses on the modularity and function of multisubunit tethering complexes (MTCs) in higher plants. One emphasis is on molecular interactions of plant MTCs. Here, a number of insights have been gained concerning interactions between different tethering complexes, and between tethers and microtubule-associated proteins. The roles of tethering complexes in abiotic stress responses appear indirect, but in the context of biotic stress responses it has been suggested that some tethers are direct targets of pathogen effectors or virulence factors. In light of the central roles tethering complexes play in plant development, an emerging concept is that tethers may be co-opted for plant adaptive responses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modelling of Tethered Space-Web Structures

NASA Astrophysics Data System (ADS)

McKenzie, D. J.; Cartnell, M. P.

Large structures in space are an essential milestone in the path of many projects, from solar power collectors to space stations. In space, as on Earth, these large projects may be split up into more manageable sections, dividing the task into multiple replicable parts. Specially constructed spider robots could assemble these structures piece by piece over a membrane or space- web, giving a method for building a structure while on orbit. The modelling and applications of these space-webs are discussed, along with the derivation of the equations of motion of the structure. The presentation of some preliminary results from the solution of these equations will show that space-webs can take a variety of different forms, and give some guidelines for configuring the space-web system.

Notes on Born-Infeld-type electrodynamics

NASA Astrophysics Data System (ADS)

Kruglov, S. I.

2017-11-01

We propose a new model of nonlinear electrodynamics (NLED) with three parameters. Born-Infeld (BI) electrodynamics and exponential electrodynamics are particular cases of this model. The phenomenon of vacuum birefringence in the external magnetic field is studied. We show that there is no singularity of the electric field at the origin of point-like charged particles. The corrections to Coulomb’s law at r →∞ are obtained. We calculate the total electrostatic energy of charges, for different parameters of the model, which is finite.

Remarks on Heisenberg-Euler-type electrodynamics

NASA Astrophysics Data System (ADS)

Kruglov, S. I.

2017-05-01

We consider Heisenberg-Euler-type model of nonlinear electrodynamics with two parameters. Heisenberg-Euler electrodynamics is a particular case of this model. Corrections to Coulomb’s law at r →∞ are obtained and energy conditions are studied. The total electrostatic energy of charged particles is finite. The charged black hole solution in the framework of nonlinear electrodynamics is investigated. We find the asymptotic of the metric and mass functions at r →∞. Corrections to the Reissner-Nordström solution are obtained.

Visco-Elastic Membrane Tethers Extracted from Escherichia coli by Optical Tweezers

PubMed Central

Jauffred, Liselotte; Callisen, Thomas Hønger; Oddershede, Lene Broeng

2007-01-01

Tethers were created between a living Escherichia coli bacterium and a bead by unspecifically attaching the bead to the outer membrane and pulling it away using optical tweezers. Upon release, the bead returned to the bacterium, thus showing the existence of an elastic tether between the bead and the bacterium. These tethers can be tens of microns long, several times the bacterial length. Using mutants expressing different parts of the outer membrane structure, we have shown that an intact core lipopolysaccharide is a necessary condition for tether formation, regardless of whether the beads were uncoated polystyrene or beads coated with lectin. A physical characterization of the tethers has been performed yielding visco-elastic tether force-extension relationships: for first pull tethers, a spring constant of 10–12 pN/μm describes the tether visco-elasticity, for subsequent pulls the spring constant decreases to 6–7 pN/μm, and typical relaxation timescales of hundreds of seconds are observed. Studies of tether stability in the presence of proteases, lipases, and amylases lead us to propose that the extracted tether is primarily composed of the asymmetric lipopolysaccharide containing bilayer of the outer membrane. This unspecific tethered attachment mechanism could be important in the initiation of bacterial adhesion. PMID:17704145

SPECS: The Kilometer-baseline Far-IR Interferometer in NASA's Space Science Roadmap Presentation

NASA Technical Reports Server (NTRS)

Abel, Tom; Allen, Ron; Benford, Dominic; Blain, Andrew; Bombardelli, Claudio; Calzetti, Daniela; DiPirro, Michael J.; Ehrenfreund, Pascale; Evans, Neal; Fischer, Jackie

2004-01-01

A viewgraph presentation describing the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) mission is shown. The topics include: 1) Context: community planning and study status; 2) Science goals; 3) Mission requirements; 4) Mission concepts for SPIRIT and SPECS; and 5) Tethered formation flying, a key enabling technology.

KSC-2013-4226

NASA Image and Video Library

2013-12-04

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, technicians prepare to load the Project Morpheus Prototype Lander with propellant at the launch platform located at the north end of the Shuttle Landing Facility. Morpheus is being prepared for a dress rehearsal of a tethered flight test. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2013-4195

NASA Image and Video Library

2013-12-03

CAPE CANAVERAL, Fla. -- At NASA’s Kennedy Space Center in Florida, a team of engineers and technicians assist as a tether is used to lower the Project Morpheus prototype lander onto a launch platform at the north end of the Shuttle Landing Facility. Testing of the prototype lander has been ongoing at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2013-4227

NASA Image and Video Library

2013-12-04

CAPE CANAVERAL, Fla. – At NASA’s Kennedy Space Center in Florida, technicians have loaded the Project Morpheus Prototype Lander with propellant at the launch platform located at the north end of the Shuttle Landing Facility. Morpheus is being prepared for a dress rehearsal of a tethered flight test. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2013-4194

NASA Image and Video Library

2013-12-03

CAPE CANAVERAL, Fla. -- At NASA’s Kennedy Space Center in Florida, a team of engineers and technicians assist as a tether is used to move the Project Morpheus prototype lander to a launch platform at the north end of the Shuttle Landing Facility. Testing of the prototype lander has been ongoing at NASA’s Johnson Space Center in Houston in preparation for tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

KSC-2013-4192

NASA Image and Video Library

2013-12-03

CAPE CANAVERAL, Fla. -- At NASA’s Kennedy Space Center in Florida, a team of engineers and technicians attaches a tether to the Project Morpheus prototype lander near the north end of the Shuttle Landing Facility. Testing of the prototype lander was performed at NASA’s Johnson Space Center in Houston in preparation for Morpheus’ tethered and free flight testing at Kennedy. The landing facility will provide the lander with the kind of field necessary for realistic testing, complete with rocks, craters and hazards to avoid. Morpheus utilizes an autonomous landing and hazard avoidance technology, or ALHAT, payload that will allow it to navigate to clear landing sites amidst rocks, craters and other hazards during its descent. Project Morpheus is being managed under the Advanced Exploration Systems, or AES, Division in NASA’s Human Exploration and Operations Mission Directorate. The efforts in AES pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future human missions beyond Earth orbit. For more information on Project Morpheus, visit http://morpheuslander.jsc.nasa.gov. Photo credit: NASA/Kim Shiflett

Distinct constrictive processes, separated in time and space, divide caulobacter inner and outer membranes.

PubMed

Judd, Ellen M; Comolli, Luis R; Chen, Joseph C; Downing, Kenneth H; Moerner, W E; McAdams, Harley H

2005-10-01

Cryoelectron microscope tomography (cryoEM) and a fluorescence loss in photobleaching (FLIP) assay were used to characterize progression of the terminal stages of Caulobacter crescentus cell division. Tomographic cryoEM images of the cell division site show separate constrictive processes closing first the inner membrane (IM) and then the outer membrane (OM) in a manner distinctly different from that of septum-forming bacteria. FLIP experiments had previously shown cytoplasmic compartmentalization (when cytoplasmic proteins can no longer diffuse between the two nascent progeny cell compartments) occurring 18 min before daughter cell separation in a 135-min cell cycle so the two constrictive processes are separated in both time and space. In the very latest stages of both IM and OM constriction, short membrane tether structures are observed. The smallest observed pre-fission tethers were 60 nm in diameter for both the inner and outer membranes. Here, we also used FLIP experiments to show that both membrane-bound and periplasmic fluorescent proteins diffuse freely through the FtsZ ring during most of the constriction procession.

Power transmission studies for tethered SP-100

NASA Technical Reports Server (NTRS)

Bents, David J.

1988-01-01

The tether and/or transmission line connecting the SP-100 to space station presents some unorthodox challenges in high voltage engineering, power transmission, and distribution. The line, which doubles as a structural element of this unusual spacecraft, will convey HVDC from SP-100 to the platform in low Earth orbit, and environment where the local plasma is sufficient to cause breakdown of exposed conductors at potentials of only a few hundred volts. Its anticipated several years operation, and continuously accumulating exposure to meteoroids and debris, raises an increasing likelihood that mechanical damage, including perforation, will be sustained in service. The present concept employs an array of gas insulated solid wall aluminum coaxial tubes; a conceptual design which showed basic feasibility of the SP-100 powered space station. Practical considerations of launch, deployment and assembly have lead to investigation of reel deployable, dielectric insulated coaxial cables. To be competitive, the dielectric would have to operate reliably in a radiation environment under electrical stresses exceeding 50 kV/cm. The SP-100 transmission line high voltage interfaces are also considered.

Power transmission studies for tethered SP-100

NASA Technical Reports Server (NTRS)

Bents, David J.

1988-01-01

The tether and/or transmission line connecting the SP-100 to Space Station presents some unorthodox challenges in high voltage engineering, power transmission, and distribution. The line, which doubles as a structural element of this unusual spacecraft, will convey HVDC from SP-100 to the platform in low Earth orbit, and environment where the local plasma is sufficient to cause breakdown of exposed conductors at potentials of only a few hundred volts. Its anticipated several years operation, and continuously accumulating exposure to meteoroids and debris, raises an increasing likelihood that mechanical damage, including perforation, will be sustained in service. The present concept employs an array of gas insulated solid wall aluminum coaxial tubes; a conceptual design which showed basic feasibility of the SP-100 powered Space Station. Practical considerations of launch, deployment and assembly have led to investigation of reel deployable, dielectric insulated coaxial cables. To be competitive, the dielectric would have to operate reliably in a radiation environment under electrical stresses exceeding 50 kV/cm. The SP-100 transmission line high voltage interfaces are also considered.

The plasma properties and electron emission characteristics of near-zero differential resistance of hollow cathode-based plasma contactors with a discharge chamber

NASA Astrophysics Data System (ADS)

Xie, Kan; Farnell, Casey C.; Williams, John D.

2014-08-01

The formation of electron emission-bias voltage (I-V) characteristics of near-zero differential resistance in the cathodic plasma contactor for bare electrodynamic tether applications, based on a hollow cathode embedded in a ring-cusp ionization stage, is studied. The existence of such an I-V regime is important to achieve low impedance performance without being affected by the space plasma properties for a cathodic plasma contactor. Experimental data on the plasma structure and properties downstream from the ionization stage are presented as functions of the xenon flow rate and the electron emission current. The electrons were emitted from the cathode to the cylindrical vacuum chamber wall (r = 0.9 m) under ≈10-5 Torr of vacuum pressure. The ring-cusp configuration selected for the plasma contactor created a 125-Gauss axial field near the cathode orifice, along with a large-volume 50-Gauss magnitude pocket in the stage. A baseline ion energy cost of ≈300 eV/ion was measured in the ionization stage when no electrons were emitted to the vacuum chamber wall. In addition, the anode fall growth limited the maximum propellant unitization to below ≈75% in the discharge loss curves for this ion stage. Detailed measurements on the plasma properties were carried out for the no-electron emission and 3 A emission conditions. The experimental data are compared with 1-D models, and the effectiveness of the model is discussed. The four key issues that played important roles in the process of building the near-zero different resistance I-V regime are: a significant amount of ionization by the emission electrons, a decrease in the number of reflected electrons in the plume, the electron-temperature increment, and low initial ion energy at the source outlet.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez-Monroy, J.A., E-mail: antosan@gmail.com; Quimbay, C.J., E-mail: cjquimbayh@unal.edu.co; Centro Internacional de Fisica, Bogota D.C.

In the context of a semiclassical approach where vectorial gauge fields can be considered as classical fields, we obtain exact static solutions of the SU(N) Yang-Mills equations in an (n+1)-dimensional curved space-time, for the cases n=1,2,3. As an application of the results obtained for the case n=3, we consider the solutions for the anti-de Sitter and Schwarzschild metrics. We show that these solutions have a confining behavior and can be considered as a first step in the study of the corrections of the spectra of quarkonia in a curved background. Since the solutions that we find in this work aremore » valid also for the group U(1), the case n=2 is a description of the (2+1) electrodynamics in the presence of a point charge. For this case, the solution has a confining behavior and can be considered as an application of the planar electrodynamics in a curved space-time. Finally we find that the solution for the case n=1 is invariant under a parity transformation and has the form of a linear confining solution. - Highlights: Black-Right-Pointing-Pointer We study exact static confining solutions of the SU(N) Yang-Mills equations in an (n+1)-dimensional curved space-time. Black-Right-Pointing-Pointer The solutions found are a first step in the study of the corrections on the spectra of quarkonia in a curved background. Black-Right-Pointing-Pointer A expression for the confinement potential in low dimensionality is found.« less

Exploring the notion of space coupling propulsion

NASA Technical Reports Server (NTRS)

Millis, Marc G.

1990-01-01

All existing methods of space propulsion are based on expelling a reaction mass (propellant) to induce motion. Alternatively, 'space coupling propulsion' refers to speculations about reacting with space-time itself to generate propulsive forces. Conceivably, the resulting increases in payload, range, and velocity would constitute a breakthrough in space propulsion. Such speculations are still considered science fiction for a number of reasons: (1) it appears to violate conservation of momentum; (2) no reactive media appear to exist in space; (3) no 'Grand Uniform Theories' exist to link gravity, an acceleration field, to other phenomena of nature such as electrodynamics. The rationale behind these objectives is the focus of interest. Various methods to either satisfy or explore these issues are presented along with secondary considerations. It is found that it may be useful to consider alternative conventions of science to further explore speculations of space coupling propulsion.

The Implications of Reduced Ground Reaction Forces During Space Flight for Bone Strains

NASA Technical Reports Server (NTRS)

Peterman, Marc M.; Hamel, Andrew J.; Sharkey, Neil A.; Piazza, Stephen J.; Cavanagh, Peter R.

1998-01-01

The specific mechanisms regulating bone mass are not known, but most investigators agree that bone maintenance is largely dependent upon mechanical demand and the resultant local bone strains. During space flight, bone loss such as that reported by LeBlanc et al. may result from failure to effectively load the skeleton and generate sufficient localized bone strains. In microgravity, a gravity replacement system can be used to tether an exercising subject to a treadmill. It follows that the ability to prevent bone loss is critically dependent upon the external ground reaction forces (GRFs) and skeletal loads imparted by the tethering system. To our knowledge, the loads during orbital flight have been measured only once (on STS 81). Based on these data and data from ground based experiments, it appears likely that interventions designed to prevent bone loss in micro-gravity generate GRFs substantially less than body weight. It is unknown to what degree reductions in external GRFs will affect internal bone strain and thus the bone maintenance response. To better predict the efficacy of treadmill exercise in micro-gravity we used a unique cadaver model to measure localized bone strains under conditions representative of those that might be produced by a gravity replacement system in space.

Tether fundamentals

NASA Technical Reports Server (NTRS)

Carroll, J. A.

1986-01-01

Some fundamental aspects of tethers are presented and briefly discussed. The effects of gravity gradients, dumbbell libration in circular orbits, tether control strategies and impact hazards for tethers are among those fundamentals. Also considered are aerodynamic drag, constraints in momentum transfer applications and constraints with permanently deployed tethers. The theoretical feasibility of these concepts are reviewed.

Atmospheric tether mission analyses

NASA Technical Reports Server (NTRS)

1996-01-01

NASA is considering the use of tethered satellites to explore regions of the atmosphere inaccessible to spacecraft or high altitude research balloons. This report summarizes the Lockheed Martin Astronautics (LMA) effort for the engineering study team assessment of an Orbiter-based atmospheric tether mission. Lockheed Martin responsibilities included design recommendations for the deployer and tether, as well as tether dynamic analyses for the mission. Three tether configurations were studied including single line, multistrand (Hoytether) and tape designs.

Tethered body problems and relative motion orbit determination

NASA Technical Reports Server (NTRS)

Eades, J. B., Jr.; Wolf, H.

1972-01-01

Selected problems dealing with orbiting tethered body systems have been studied. In addition, a relative motion orbit determination program was developed. Results from these tasks are described and discussed. The expected tethered body motions were examined, analytically, to ascertain what influence would be played by the physical parameters of the tether, the gravity gradient and orbit eccentricity. After separating the motion modes these influences were determined; and, subsequently, the effects of oscillations and/or rotations, on tether force, were described. A study was undertaken, by examining tether motions, to see what type of control actions would be needed to accurately place a mass particle at a prescribed position relative to a main vehicle. Other applications for tethers were studied. Principally these were concerned with the producing of low-level gee forces by means of stabilized tether configurations; and, the initiation of free transfer trajectories from tether supported vehicle relative positions.

Electrodynamics of Moving Conductors in Magnetic Fields: Off the Beaten Track with Paul Lorrain

ERIC Educational Resources Information Center

Bringuier, E.

2012-01-01

The paper is about the appearance of space charge in an ohmic conductor moving in a magnetic field, as pointed out in this journal by Lorrain (1990 "Eur. J. Phys." 11 94-8) and earlier by van Bladel (1973 "Proc. IEEE" 61 260-8). The phenomenon is reinvestigated here in the light of energy balance considerations, in the particular case of a…

Validated simulator for space debris removal with nets and other flexible tethers applications

NASA Astrophysics Data System (ADS)

Gołębiowski, Wojciech; Michalczyk, Rafał; Dyrek, Michał; Battista, Umberto; Wormnes, Kjetil

2016-12-01

In the context of active debris removal technologies and preparation activities for the e.Deorbit mission, a simulator for net-shaped elastic bodies dynamics and their interactions with rigid bodies, has been developed. Its main application is to aid net design and test scenarios for space debris deorbitation. The simulator can model all the phases of the debris capturing process: net launch, flight and wrapping around the target. It handles coupled simulation of rigid and flexible bodies dynamics. Flexible bodies were implemented using Cosserat rods model. It allows to simulate flexible threads or wires with elasticity and damping for stretching, bending and torsion. Threads may be combined into structures of any topology, so the software is able to simulate nets, pure tethers, tether bundles, cages, trusses, etc. Full contact dynamics was implemented. Programmatic interaction with simulation is possible - i.e. for control implementation. The underlying model has been experimentally validated and due to significant gravity influence, experiment had to be performed in microgravity conditions. Validation experiment for parabolic flight was a downscaled process of Envisat capturing. The prepacked net was launched towards the satellite model, it expanded, hit the model and wrapped around it. The whole process was recorded with 2 fast stereographic camera sets for full 3D trajectory reconstruction. The trajectories were used to compare net dynamics to respective simulations and then to validate the simulation tool. The experiments were performed on board of a Falcon-20 aircraft, operated by National Research Council in Ottawa, Canada. Validation results show that model reflects phenomenon physics accurately enough, so it may be used for scenario evaluation and mission design purposes. The functionalities of the simulator are described in detail in the paper, as well as its underlying model, sample cases and methodology behind validation. Results are presented and typical use cases are discussed showing that the software may be used to design throw nets for space debris capturing, but also to simulate deorbitation process, chaser control system or general interactions between rigid and elastic bodies - all in convenient and efficient way. The presented work was led by SKA Polska under the ESA contract, within the CleanSpace initiative.

Quantitative modeling and optimization of magnetic tweezers.

PubMed

Lipfert, Jan; Hao, Xiaomin; Dekker, Nynke H

2009-06-17

Magnetic tweezers are a powerful tool to manipulate single DNA or RNA molecules and to study nucleic acid-protein interactions in real time. Here, we have modeled the magnetic fields of permanent magnets in magnetic tweezers and computed the forces exerted on superparamagnetic beads from first principles. For simple, symmetric geometries the magnetic fields can be calculated semianalytically using the Biot-Savart law. For complicated geometries and in the presence of an iron yoke, we employ a finite-element three-dimensional PDE solver to numerically solve the magnetostatic problem. The theoretical predictions are in quantitative agreement with direct Hall-probe measurements of the magnetic field and with measurements of the force exerted on DNA-tethered beads. Using these predictive theories, we systematically explore the effects of magnet alignment, magnet spacing, magnet size, and of adding an iron yoke to the magnets on the forces that can be exerted on tethered particles. We find that the optimal configuration for maximal stretching forces is a vertically aligned pair of magnets, with a minimal gap between the magnets and minimal flow cell thickness. Following these principles, we present a configuration that allows one to apply > or = 40 pN stretching forces on approximately 1-microm tethered beads.

Quantitative Modeling and Optimization of Magnetic Tweezers

PubMed Central

Lipfert, Jan; Hao, Xiaomin; Dekker, Nynke H.

2009-01-01

Abstract Magnetic tweezers are a powerful tool to manipulate single DNA or RNA molecules and to study nucleic acid-protein interactions in real time. Here, we have modeled the magnetic fields of permanent magnets in magnetic tweezers and computed the forces exerted on superparamagnetic beads from first principles. For simple, symmetric geometries the magnetic fields can be calculated semianalytically using the Biot-Savart law. For complicated geometries and in the presence of an iron yoke, we employ a finite-element three-dimensional PDE solver to numerically solve the magnetostatic problem. The theoretical predictions are in quantitative agreement with direct Hall-probe measurements of the magnetic field and with measurements of the force exerted on DNA-tethered beads. Using these predictive theories, we systematically explore the effects of magnet alignment, magnet spacing, magnet size, and of adding an iron yoke to the magnets on the forces that can be exerted on tethered particles. We find that the optimal configuration for maximal stretching forces is a vertically aligned pair of magnets, with a minimal gap between the magnets and minimal flow cell thickness. Following these principles, we present a configuration that allows one to apply ≥40 pN stretching forces on ≈1-μm tethered beads. PMID:19527664

Development and analysis of a novel cytokine biosensor concept for astronaut immune system monitoring

NASA Astrophysics Data System (ADS)

Aponte, Vanessa M.

The dynamics of how astronauts' immune systems respond to space flight have been studied extensively, but the complex process has not to date been thoroughly characterized, nor have the underlying principles of what causes the immune system to change in microgravity been fully determined. To obtain statistically significant results regarding overall immunological effects in space, collecting in vivo data during flight is desirable, but no sensor is currently capable of performing such function in this environment. The aims of this research were to establish appropriate markers for in-flight monitoring of the immune system and develop a novel approach for a benchtop sensor to measure them. Quartz Crystal Microbalances (QCMs) were used as platforms to study a surface biochemistry process selective towards cytokines, which are used as stress-related immune markers in space and ground medicine. Pilot studies elucidated that a thiolated streptavidin-biotinylated antibody surface assembly did not form the protein monolayer necessary for stable cytokine sensing. Improved experiments incorporated self-assembled monolayers (SAMs) by using di-thiol tethers at the base of a dual antibody sandwich and fluorophore assembly. The goals of the improved experiments were to achieve a stable monolayer of covalently bound tethers, to enhance sensitivity by the addition of a second monoclonal antibody, and to have a fluorescence tether attached to the last antibody layer as a way to corroborate the amount of proteins attached to the surface by using confocal fluorescence microscopy (CFM). Atomic Force Microscopy (AFM) results confirmed the formation of an even protein monolayer at the surface of the QCM, while CFM corroborated that the entire sandwich assembly had been achieved. Frequency changes increased directly proportional to concentration of cytokines, adhering to non-linear behavior explained by viscoelastic fluid models. Results point to the promising use of this surface chemistry within an optical platform such as Surface Plasmon Resonance (SPR), rather than a piezoelectric device. Consideration is given to the potential application of this concept to MEMS/NEMS devices.

Flow around a tethered cylinder, the effect of tether length at high layover angles

NASA Astrophysics Data System (ADS)

Ryan, Kris

2011-07-01

Tethered cylinder systems constitute a natural extension of the lightly damped, hydro-elastically mounted cylinder. In this case, the cylinder is constrained to travel along an arc prescribed by the tether length. The analysis of the tethered cylinder system is hampered by the dependence of the natural frequency of the system on both the fluid forces acting on the system and the curved motion (which in turn alters the added mass coefficient away from unity). These difficulties have precluded prior studies considering the natural frequency or reduced velocity as a controlling parameter, making direct comparison with the hydro-elastically mounted cylinder system difficult.This investigation considers the case of a tethered cylinder at low Reynolds number (Re=200) for a mass ratio m*=0.2. It notes a local maximum in the amplitude of oscillation when the normalized tether length L*≃2.0, in agreement with prior studies. By instead considering the amplitude of oscillation in a rotational framework, we are able to explain the existence of this peak, and identify two regions of amplitude response, the first region exists for very small tether lengths (L*≲0.3), while the second exists for larger tether lengths. The transition from small tether lengths to large tether lengths exhibits the highest amplitude angular oscillations.Several wake states are also considered for a tethered cylinder which is oscillating about a horizontal mean layover angle. By considering these wake states, coupled with the definition of the natural frequency, an estimate of the added mass coefficient is made. Here we predict that CA≃0.5 for a tether length of L*=1.5. This prediction is based not only on the tether length, but also on the amplitude of oscillation, and hence is Reynolds number dependent.

Advanced In-Space Propulsion: "Exploring the Solar System"

NASA Technical Reports Server (NTRS)

Johnson, Les

2003-01-01

This viewgraph presentation reviews a number of advanced propulsion technologies for interplanetary spacecraft. The objective of the In Space Propulsion Technology Projects Office is to develop in-space propulsion technologies that can enable and/or benefit near and mid-term NASA science missions by significantly reducing cost, mass, and/or travel times. The technologies profiled are divided into several categories: High Priority (aerocapture, next generation ion propulsion, solar sails); Medium Priority (advanced chemical propulsion, solar electric propulsion, Hall thrusters); Low Priority (solar thermal propulsion); and High Payoff/High Risk (1 g/sq m solar sails, momentum exchange tethers, and plasma sails).

View of Endeavour's STBD longeron and MEPSI deploy during STS-113

NASA Image and Video Library

2002-12-02

STS113-370-012 (2 December 2002) --- The horizon of a blue and white Earth and the blackness of space form the backdrop for this view, as two miniature satellites are released from the Space Shuttle Endeavour as part of an experiment referred to as MEPSI. Funded by the Defense Advance Research Projects Agency (DARPA), the two small satellites, which are tethered together, were released from Endeavour’s payload bay (visible in foreground) to fly free for three days as a technology demonstration of the launcher and use of micro- and nano-technologies in space systems.

Introduction to Electrodynamics

NASA Astrophysics Data System (ADS)

Griffiths, David J.

2017-06-01

1. Vector analysis; 2. Electrostatics; 3. Potentials; 4. Electric fields in matter; 5. Magnetostatics; 6. Magnetic fields in matter; 7. Electrodynamics; 8. Conservation laws; 9. Electromagnetic waves; 10. Potentials and fields; 11. Radiation; 12. Electrodynamics and relativity; Appendix A. Vector calculus in curvilinear coordinates; Appendix B. The Helmholtz theorem; Appendix C. Units; Index.

Conceptual Assessment Tool for Advanced Undergraduate Electrodynamics

ERIC Educational Resources Information Center

Baily, Charles; Ryan, Qing X.; Astolfi, Cecilia; Pollock, Steven J.

2017-01-01

As part of ongoing investigations into student learning in advanced undergraduate courses, we have developed a conceptual assessment tool for upper-division electrodynamics (E&M II): the Colorado UppeR-division ElectrodyNamics Test (CURrENT). This is a free response, postinstruction diagnostic with 6 multipart questions, an optional 3-question…

Assessing the Capabilities and Limitations of Physics-Based Models in Capturing the Ionosphere and Thermosphere Storm-Time Response

NASA Astrophysics Data System (ADS)

Fedrizzi, M.; Fuller-Rowell, T. J.; Maruyama, N.; Fang, T. W.; Codrescu, M.

2016-12-01

The Sun can directly impact the Earth's environment during solar storms when the interaction between their magnetic fields can severely modify the quiet-time electric fields and current patterns in the ionosphere, which in turn affect neutral temperature, density, winds and composition, and plasma density. The nature of the various solar wind features and their interaction with the upper atmosphere is likely to channel the response into different pathways. Depending on whether the forcing is impulsive or gradual, of long or short durations, intense or moderate, the partitioning of the energy will be different. For instance, a sudden onset of energy deposition is likely to generate a more intense wave field at the expense of the energy being partitioned into local heating, thermal expansion, and composition change. The net electrodynamic and ionospheric response is likely to be significantly different in the two cases. As the ionosphere and thermosphere constituents are controlled by gravity, diffusion, chemical reactions, and bulk transport, it is essential to understand how these processes determine global responses in O and N2 after heating occurs at high latitudes. Since these disturbances are superimposed on a solar EUV-driven circulation system that is mainly ordered in a geographic coordinate frame that varies with local time and season, the interactions can be complex, and ionosphere-thermosphere responses are very different depending on prevailing conditions. The relative abundances of O and N2 are fundamental to understanding local plasma densities and total mass densities, both of which are key parameters underlying space weather forecast needs. In this study, the Coupled model of the Thermosphere, Ionosphere, Plasmasphere and electrodynamics (CTIPe) and the recently developed Ionosphere-Plasmasphere-Electrodynamics (IPE) models are used to quantitatively assess how well the models reproduce the structure of the O/N2 changes and the negative phase observed during geomagnetic storm events. Various datasets from ground and space are used to validate the model results.

Future geodesy missions: Tethered systems and formation flying

NASA Astrophysics Data System (ADS)

Fontdecaba, Jordi; Sanjurjo, Manuel; Pelaez, Jesus; Metris, Gilles; Exertier, Pierre

Recent gravity field determination missions have shown the possibility of improving our Earth knowledge from space. GRACE has helped to the determination of temporal variations of low and mean degrees of the field while GOCE will improve the precision in the determination of higher degrees. But there is still some needs for geophysics which are not satisfied by these missions. Two areas where improvements must be done are (i) perenniality of the observations, and (ii) determination of temporal variations of higher degrees of the gravity field. These improvements can be achieved thanks to new measurement technologies with higher precision, but also using new observables. Historically, space determination of the gravity field has been done observing the perturbations of the orbit of the satellites. More recently, GRACE has introduced the use of satellite-tosatellite ranging. Goce will use onboard gradiometry. The authors have explored the possibilities of two new technologies for the determination of the gravity field: (i) tethered systems, and (ii) formation flying for all kind of configurations (not just leader-follower). To analyze the possibilities of these technologies, we obtain the covariance matrix of the coefficients of the gravity field for the different observables. This can be done providing some very reasonable hypothesis are accepted. This matrix contains a lot of information concerning the behavior of the observable. In order to obtain the matrix, we use the so-called lumped coefficients approach. We have used this method for three observables (i) tethered systems, (ii) formation flying and (iii) gradiometry (for comparison purposes). Tethers appear as a very long base gradiometers, with very interesting properties, but also very challenging from a technological point of view. One of the major advantages of the tethered systems is their multitask design. Indeed, the same cable can be used for propulsion purposes in some phases of the mission, and for geodesy purposes in other phases. Several studies have been presented using formation flying, but none of them is exhaustive in terms of number of satellites, configuration, and plan of the motion. We study formation flying using differential orbital elements in order to be as general as possible. The advantage of this representation is the possibility to study all sort of initial conditions and reference orbits with a posterior analysis of covariance matrices. Our results show the intrinsic possibilities of these new two systems and their comparison with existing ones. We also define some baseline scenarios for future missions.

System protection from atmospheric electricity for aerostats with conducting tethers

NASA Astrophysics Data System (ADS)

Wheeler, M. S.; Beach, G. R.; Jakubowski, P. R.; Fisher, F. A.

1988-04-01

Aerostat power tethers have demonstrated survival of lightning strikes, but they usually have to be reterminated or replaced afterward. Two requirements are given for the prevention of lightning damage to the tether to about 100 kA: installation of a metal-to-metal contact on the outer tether surface to ground the tether at the base flying sheave at typical flying positions; and installation of a shielding band within the outer tether jacket with a weight of about 0.05 lb/ft for a half-inch tether. This determination was made in part by high current tests and in part by electrical modeling.

Development of the command data system and ground software for the SEDSAT-1 microsatellite

NASA Technical Reports Server (NTRS)

Wells, B. Earl

1996-01-01

SEDSAT-1 is designed to be a low cost scientific satellite which is to be used to perform a minimum of five tasks which include: (1) the acquisition of a number of important parameters associated with the tethering processes from the payloads perspective (such as accelerations incurred and imaging data of the tether during deployment), (2) to act as a remote sensing platform for making measurements of the Earth's Atmosphere (allowing research to be performed in such areas as vertical lightning observation, visible light spectrography, and cloud cover studies, (3) to act as a general purpose amateur radio communication satellite relaying information back to earth, (4) to demonstrate the feasibility of the deployment in low earth orbit of advanced technology such as the Gallium Arsenide Solar Cells, Nickel Metal Hydride batteries, and multi-chip module technology and, (5) to support student's active participation in applying the disciplines of engineering and science to space-based hardware platforms. The project includes the Three-axis Accelerometer System, TAS, Experiment which is designed to report the accelerations that the satellite undergoes during the tethering operations and during the second phase of the mission when the free floating satellite comes in contact with orbit debris. The SEASIS (SEDS Earth, Atmosphere, and Space Imaging System) is another SEDSAT experiment designed to provide images of the tether during its deployment and the earth during the second phase of the mission. To control these experiments and virtually all other satellite operations the Command Data System, CDS is employed. This system utilizes a moderate complexity micro-controller controlled by tasks operating under a real-time operating system to dynamically monitor and control the satellite. The scope of this researchers efforts has been in the general area of coordinating and assisting the student researchers with the development of the CDS and ground station interfaces. This included the low level CDS hardware design and the formulization of a general software plan and schedule for both the CDS and ground station portions of the project.

Three-dimensional stochastic model of actin–myosin binding in the sarcomere lattice

PubMed Central

Kayser-Herold, Oliver; Stojanovic, Boban; Nedic, Djordje; Irving, Thomas C.; Geeves, Michael A.

2016-01-01

The effect of molecule tethering in three-dimensional (3-D) space on bimolecular binding kinetics is rarely addressed and only occasionally incorporated into models of cell motility. The simplest system that can quantitatively determine this effect is the 3-D sarcomere lattice of the striated muscle, where tethered myosin in thick filaments can only bind to a relatively small number of available sites on the actin filament, positioned within a limited range of thermal movement of the myosin head. Here we implement spatially explicit actomyosin interactions into the multiscale Monte Carlo platform MUSICO, specifically defining how geometrical constraints on tethered myosins can modulate state transition rates in the actomyosin cycle. The simulations provide the distribution of myosin bound to sites on actin, ensure conservation of the number of interacting myosins and actin monomers, and most importantly, the departure in behavior of tethered myosin molecules from unconstrained myosin interactions with actin. In addition, MUSICO determines the number of cross-bridges in each actomyosin cycle state, the force and number of attached cross-bridges per myosin filament, the range of cross-bridge forces and accounts for energy consumption. At the macroscopic scale, MUSICO simulations show large differences in predicted force-velocity curves and in the response during early force recovery phase after a step change in length comparing to the two simplest mass action kinetic models. The origin of these differences is rooted in the different fluxes of myosin binding and corresponding instantaneous cross-bridge distributions and quantitatively reflects a major flaw of the mathematical description in all mass action kinetic models. Consequently, this new approach shows that accurate recapitulation of experimental data requires significantly different binding rates, number of actomyosin states, and cross-bridge elasticity than typically used in mass action kinetic models to correctly describe the biochemical reactions of tethered molecules and their interaction energetics. PMID:27864330

Three-dimensional stochastic model of actin–myosin binding in the sarcomere lattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mijailovich, Srboljub M.; Kayser-Herold, Oliver; Stojanovic, Boban

2016-11-18

The effect of molecule tethering in three-dimensional (3-D) space on bimolecular binding kinetics is rarely addressed and only occasionally incorporated into models of cell motility. The simplest system that can quantitatively determine this effect is the 3-D sarcomere lattice of the striated muscle, where tethered myosin in thick filaments can only bind to a relatively small number of available sites on the actin filament, positioned within a limited range of thermal movement of the myosin head. Here we implement spatially explicit actomyosin interactions into the multiscale Monte Carlo platform MUSICO, specifically defining how geometrical constraints on tethered myosins can modulatemore » state transition rates in the actomyosin cycle. The simulations provide the distribution of myosin bound to sites on actin, ensure conservation of the number of interacting myosins and actin monomers, and most importantly, the departure in behavior of tethered myosin molecules from unconstrained myosin interactions with actin. In addition, MUSICO determines the number of cross-bridges in each actomyosin cycle state, the force and number of attached cross-bridges per myosin filament, the range of cross-bridge forces and accounts for energy consumption. At the macroscopic scale, MUSICO simulations show large differences in predicted force-velocity curves and in the response during early force recovery phase after a step change in length comparing to the two simplest mass action kinetic models. The origin of these differences is rooted in the different fluxes of myosin binding and corresponding instantaneous cross-bridge distributions and quantitatively reflects a major flaw of the mathematical description in all mass action kinetic models. Consequently, this new approach shows that accurate recapitulation of experimental data requires significantly different binding rates, number of actomyosin states, and cross-bridge elasticity than typically used in mass action kinetic models to correctly describe the biochemical reactions of tethered molecules and their interaction energetics.« less

Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer

PubMed Central

Lundt, Nils; Klembt, Sebastian; Cherotchenko, Evgeniia; Betzold, Simon; Iff, Oliver; Nalitov, Anton V.; Klaas, Martin; Dietrich, Christof P.; Kavokin, Alexey V.; Höfling, Sven; Schneider, Christian

2016-01-01

Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light–matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe2, hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy–momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons. PMID:27796288

Absorbing Boundary Conditions in Quantum Relativistic Mechanics for Spinless Particles Subject to a Classical Electromagnetic Field

NASA Astrophysics Data System (ADS)

Sater, Julien

The theory of Artificial Boundary Conditions described by Antoine et al. [2,4-6] for the Schrodinger equation is applied to the Klein-Gordon (KG) in two-dimensions (2-D) for spinless particles subject to electromagnetic fields. We begin by providing definitions for a basic understanding of the theory of operators, differential geometry and wave front sets needed to discuss the factorization theorem thanks to Nirenberg and Hormander [14, 16]. The laser-free Klein-Gordon equation in 1-D is then discussed, followed by the case including electrodynamics potentials, concluding with the KG equation in 2-D space with electrodynamics potentials. We then consider numerical simulations of the laser-particle KG equation, which includes a brief analysis of a finite difference scheme. The conclusion integrates a discussion of the numerical results, the successful completion of the objective set forth, a declaration of the unanswered encountered questions and a suggestion of subjects for further research.

Chiral dynamos and magnetogenesis induced by torsionful Maxwell-Chern Simons electrodynamics

NASA Astrophysics Data System (ADS)

de Andrade, L. C. Garcia

2018-03-01

Recently chiral anomalous currents have been investigated by Boyarsky et al. and Brandenburg et al. with respect to applications to the early universe. In this paper we show that these magnetic field anomalies, which can give rise to dynamo magnetic field amplification can also be linked to spacetime torsion through the use of a chemical potential and Maxwell electrodynamics with torsion firstly proposed by de Sabbata and Gasperini. When the axial torsion is constant this electrodynamics acquires the form of a Maxwell-Chern-Simmons (MCS) equations where the chiral current appears naturally and the zero component of torsion plays the role of a chemical potential, while the other components play the role of anisotropic conductivity. The chiral dynamo equation in torsionful spacetime is derived here from MSC electrodynamics. Here we have used a recently derived a torsion LV bound of T0˜ {10^{-26}} GeV and the constraint that this chiral magnetic field is a seed for galactic dynamo. This estimate is weaker than the one obtained from the chiral battery seed of ˜ {10^{30}} G without making use of Cartan torsion. The torsion obtained here was derived at 500 pc coherence scale. When a chiral MF is forced to seed a galactic dynamo one obtains a yet weaker MF, of the order of B˜ {10^{12}} G, which is the value of a MF at nucleosynthesis. By the use of chiral dynamo equations from parity-violating torsion one obtains a seed field of B˜ {10^{27}} G, which is a much stronger MF closer to the one obtained by making use of chiral batteries. Chiral vortical currents in non-Riemannian spacetimes derived in Riemannian spaces previously by Flaschi and Fukushima are extended to include minimal coupling with torsion. The present universe yields B˜ {10^{-24}} G, still sufficient to seed galactic dynamos.

Propulsion Options for the Global Precipitation Measurement Core Satellite

NASA Technical Reports Server (NTRS)

Cardiff, Eric H.; Davis, Gary T.; Folta, David C.

2003-01-01

This study was conducted to evaluate several propulsion system options for the Global Precipitation Measurement (GPM) core satellite. Orbital simulations showed clear benefits for the scientific data to be obtained at a constant orbital altitude rather than with a decay/reboost approach. An orbital analysis estimated the drag force on the satellite will be 1 to 12 mN during the five-year mission. Four electric propulsion systems were identified that are able to compensate for these drag forces and maintain a circular orbit. The four systems were the UK-10/TS and the NASA 8 cm ion engines, and the ESA RMT and RITl0 EVO radio-frequency ion engines. The mass, cost, and power requirements were examined for these four systems. The systems were also evaluated for the transfer time from the initial orbit of 400 x 650 km altitude orbit to a circular 400 km orbit. The transfer times were excessive, and as a consequence a dual system concept (with a hydrazine monopropellant system for the orbit transfer and electric propulsion for drag compensation) was examined. Clear mass benefits were obtained with the dual system, but cost remains an issue because of the larger power system required for the electric propulsion system. An electrodynamic tether was also evaluated in this trade study.

Impact of mitral valve geometry on hemodynamic efficacy of surgical repair in secondary mitral regurgitation.

PubMed

Padala, Muralidhar; Gyoneva, Lazarina I; Thourani, Vinod H; Yoganathan, Ajit P

2014-01-01

Mitral valve geometry is significantly altered secondary to left ventricular remodeling in non-ischemic and ischemic dilated cardiomyopathies. Since the extent of remodeling and asymmetry of dilatation of the ventricle differ significantly between individual patients, the valve geometry and tethering also differ. The study aim was to determine if mitral valve geometry has an impact on the efficacy of surgical repairs to eliminate regurgitation and restore valve closure in a validated experimental model. Porcine mitral valves (n = 8) were studied in a pulsatile heart simulator, in which the mitral valve geometry can be precisely altered and controlled throughout the experiment. Baseline hemodynamics for each valve were measured (Control), and the valves were tethered in two distinct ways: annular dilatation with 7 mm apical papillary muscle (PM) displacement (Tether 1, symmetric), and annular dilatation with 7 mm apical, 7 mm posterior and 7 mm lateral PM displacement (Tether 2, asymmetric). Mitral annuloplasty was performed on each valve (Annular Repair), succeeded by anterior leaflet secondary chordal cutting (Sub-annular Repair). The efficacy of each repair in the setting of a given valve geometry was quantified by measuring the changes in mitral regurgitation (MR), leaflet coaptation length, tethering height and area. At baseline, none of the valves was regurgitant. Significant leaflet tethering was measured in Tether 2 over Tether 1, but both groups were significantly higher compared to baseline (60.9 +/- 31 mm2 for Control versus 129.7 +/- 28.4 mm2 for Tether 1 versus 186.4 +/- 36.3 mm2 for Tether 2). Consequently, the MR fraction was higher in Tether 2 group (23.0 +/- 5.7%) than in Tether 1 (10.5 +/- 5.5%). Mitral annuloplasty reduced MR in both groups, but remnant regurgitation after the repair was higher in Tether 2. After chordal cutting a similar trend was observed with trace regurgitation in Tether 1 group at 3.6 +/- 2.8%, in comparison to 18.6 +/- 4.2% in the Tether 2 group. In this experimental model, the tethering geometry of the mitral valve impacts the valve hemodynamics after annuloplasty and chordal cutting. The quantitative assessment of valve geometry may help in tailoring a repair to the specific tethering pattern.

Modelling of auroral electrodynamical processes: Magnetosphere to mesosphere

NASA Technical Reports Server (NTRS)

Chiu, Y. T.; Gorney, D. J.; Kishi, A. M.; Newman, A. L.; Schulz, M.; Walterscheid, R. L.; CORNWALL; Prasad, S. S.

1982-01-01

Research conducted on auroral electrodynamic coupling between the magnetosphere and ionosphere-atmosphere in support of the development of a global scale kinetic plasma theory is reviewed. Topics covered include electric potential structure in the evening sector; morning and dayside auroras; auroral plasma formation; electrodynamic coupling with the thermosphere; and auroral electron interaction with the atmosphere.

Advanced propulsion concepts

NASA Technical Reports Server (NTRS)

Frisbee, Robert H.

1991-01-01

A variety of Advanced Propulsion Concepts (APC) is discussed. The focus is on those concepts that are sufficiently near-term that they could be developed for the Space Exploration Initiative. High-power (multi-megawatt) electric propulsion, solar sails, tethers, and extraterrestrial resource utilization concepts are discussed. A summary of these concepts and some general conclusions on their technology development needs are presented.

The propagator of stochastic electrodynamics

NASA Astrophysics Data System (ADS)

Cavalleri, G.

1981-01-01

The "elementary propagator" for the position of a free charged particle subject to the zero-point electromagnetic field with Lorentz-invariant spectral density ~ω3 is obtained. The nonstationary process for the position is solved by the stationary process for the acceleration. The dispersion of the position elementary propagator is compared with that of quantum electrodynamics. Finally, the evolution of the probability density is obtained starting from an initial distribution confined in a small volume and with a Gaussian distribution in the velocities. The resulting probability density for the position turns out to be equal, to within radiative corrections, to ψψ* where ψ is the Kennard wave packet. If the radiative corrections are retained, the present result is new since the corresponding expression in quantum electrodynamics has not yet been found. Besides preceding quantum electrodynamics for this problem, no renormalization is required in stochastic electrodynamics.

P-Tether-Mediated, Iterative SN2'-Cuprate Alkylation Strategy to Skipped Polyol Stereotetrads: Utility of an Oxidative "Function Switch" with Phosphite-Borane Tethers.

PubMed

Markley, Jana L; Hanson, Paul R

2017-05-19

The development of a P-tether-mediated, iterative S N 2'-cuprate alkylation protocol for the formation of 1,3-skipped polyol stereotetrads is reported. This two-directional synthetic strategy builds molecular complexity from simple, readily prepared C 2 -symmetric dienediols and unites the chemistry of both temporary phosphite-borane tethers and temporary phosphate tethers-through an oxidative "function switch" of the P-tether itself-to generate intermediates that were previously inaccessible via either method alone.

Bekenstein inequalities and nonlinear electrodynamics

NASA Astrophysics Data System (ADS)

Peñafiel, M. L.; Falciano, F. T.

2017-12-01

Bekenstein and Mayo proposed a generalized bound for the entropy, which implies some inequalities between the charge, energy, angular momentum, and size of the macroscopic system. Dain has shown that Maxwell's electrodynamics satisfies all three inequalities. We investigate the validity of these relations in the context of nonlinear electrodynamics and show that Born-Infeld electrodynamics satisfies all of them. However, contrary to the linear theory, there is no rigidity statement in Born-Infeld. We study the physical meaning and the relationship between these inequalities, and in particular, we analyze the connection between the energy-angular momentum inequality and causality.

Simulations of momentum transfer process between solar wind plasma and bias voltage tethers of electric sail thruster

NASA Astrophysics Data System (ADS)

Xia, Guangqing; Han, Yajie; Chen, Liuwei; Wei, Yanming; Yu, Yang; Chen, Maolin

2018-06-01

The interaction between the solar wind plasma and the bias voltage of long tethers is the basic mechanism of the electric sail thruster. The momentum transfer process between the solar wind plasma and electric tethers was investigated using a 2D full particle PIC method. The coupled electric field distribution and deflected ion trajectory under different bias voltages were compared, and the influence of bias voltage on momentum transfer process was analyzed. The results show that the high potential of the bias voltage of long tethers will slow down, stagnate, reflect and deflect a large number of ions, so that ion cavities are formed in the vicinity of the tether, and the ions will transmit the axial momentum to the sail tethers to produce the thrust. Compared to the singe tether, double tethers show a better thrust performance.

Altering surface fluctuations by blending tethered and untethered chains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J. K.; Akgun, B.; Jiang, Z.

"Partially tethering" a thin film of a polymer melt by covalently attaching to the substrate a fraction of the chains in an unentangled melt dramatically increases the relaxation time of the surface height fluctuations. This phenomenon is observed even when the film thickness, h, is 20 times the unperturbed chain radius, R g,tethered, of the tethered chains, indicating that partial tethering is more influential than any physical attraction with the substrate. Furthermore, a partially tethered layer of a low average molecular weight of 5k showed much slower surface fluctuations than did a reference layer of pure untethered chains of muchmore » greater molecular weight (48k), so the partial tethering effect is stronger than the effects of entanglement and increase in glass transition temperature, Tg, with molecular weight. Partial tethering offers a means of tailoring these fluctuations which influence wetting, adhesion, and tribology of the surface.« less