ELECTROMAGNETIC EFFECTS & SPACECRAFT CHARGING

D.C. Ferguson and G.B. Hillard, LEO Spacecraft Charging Design Guidelines, NASA/TP-2003-212287, NASA Marshall Space Flight Center, AL 35812, January 2003, pp. 366

Keywords: charging, electron, spacecraft, ion, mitigation, volt, voltage, solar, array, potential, snapover, current, plasma, arc, arcing

Abstract: This report is intended as a design guideline for high-voltage space power systems (>55 volts) that must operate in the plasma environment associated with Low Earth Orbit (LEO).  Such power systems, particularly solar arrays, may interact with this environment in a number of ways that are potentially destructive to themselves as well as to the platform or vehicle that has deployed them.  The first objective is to present an overview of current understanding of the various plasma interactions that may result when a high voltage system is operated in the earth's ionosphere.  A second objective is to reference common design practices that have exacerbated plasma interactions in the past and to recommend standard practices to eliminate or mitigate such reactions.  This report is intended as a guideline for design applications and is not requirements specification instrument.

Berki, J.M. and Sargent, SEE Design Guide and Requirements for Electrical Deadfacing, NASA/CR-2002-211839, NASA Marshall Space Flight Center, AL 35812, July 2002, pp. 72

Keywords: de-mating, mating powered electrical connectors, deadfacing, electro-magnetic interference, radio frequency

Abstract:  The purpose of this design guide is to present information for understanding and mitigating the potential hazards associated with de-mating and mating powered electrical connectors on space flight vehicles. The process of staging is a necessary function in the launching of space vehicles and in the deployment of satellites, and now in manned assembly of systems in space. During this electrical interconnection process, various environments may be encountered that warrant the restriction of the voltage and current present across the pins of an electrical connector prior to separation, mating, or in a static open non-mated configuration. This process is called deadfacing. These potentially hazardous environments encompass the obvious explosive fuel vapors and human shock hazard, to multiple Electro-Magnetic Interference (EMI) phenomena related to the rapid rate of change in current as well as exposure to Radio Frequency (RF) fields.

V. Smith, Comparison of Commercial Electromagnetic Interference Test Techniques to NASA Electromagnetic Interference Test Techniques, NASA/CR-2000-210400, NASA Marshall Space Flight Center, AL  35812, November 2000, pp. 70

Keywords:  EMI, EMC, test standards, comparison, space systems, commercial, COTS equipment

Abstract:  This report documents the development of analytical techniques required for interpreting and comparing space systems electromagnetic interference test data with commercial electromagnetic interference test data using NASA Specification SSP 30237A "Space Systems Electromagnetic Emission and Susceptibility Requirements for Electromagnetic Compatibility."  The PSpice computer simulation results and the laboratory measurements for the test setups under study compare well.  The study results, however, indicate that the transfer function required to translate test results of one setup to another is highly dependent on cables and their actual layout in the test setup.  Since cables are equipment specific and are not specified in the test standards, developing a transfer function that would cover all cable types (random, twisted, or coaxial), sizes (gauge number and length), and layouts (distance from the ground plane) is not practical.

J.G. Sketoe, Integrated Circuit Electromagnetic Immunity Handbook, NASA/CR-2000-210017, NASA Marshall Space Flight Center, AL  35812, August 2000, pp. 64

Keywords: conducted susceptibility, electromagnetic compatibility, electromagnetic interference, EMC, EMI, IC, immunity, integrated circuit, lab view, susceptibility, test fixture, TTL

Abstract: This handbook presents the results of the Boeing Company effort for NASA under contract NAS8-98217. Immunity level data for certain integrated circuit parts are discussed herein, along with analytical techniques for applying the data to electronics systems. This handbook is built heavily on the one produced in the seventies by McDonnell Douglas Astronautics Company (MDAC, MDC Report E1929 of 1 August 1978, entitled Integrated Circuit Electromagnetic Susceptibility Handbook, known commonly as the ICES Handbook, which has served countless systems designers for over 20 years).

K. Javor, Investigation Into the Effects of Microsecond Power Line Transients on Line-Connected Capacitors, NASA/CR-2000-209906, K. Javor NASA Marshall Space Flight Center, AL  35812, February 2000, pp. 33

Keywords: electromagnetic effects, capacitors, power line transients

Abstract: An investigation was conducted into the effect of power-line transients on capacitors used by NASA and installed on platform primary power inputs to avionics. The purpose was to investigate whether capacitor voltage ratings needs to be derated for expected spike potentials. Concerns had been voiced in the past by NASA suppliers that MIL-STD-461 CS06-like requirements were overly harsh and led to physically large capacitors.

The author had previously predicted that electrical-switching spike requirements representative of actual power-line transient potentials, durations, and source impedance would require no derating. This investigation bore out that prediction. It was further determined that traditional low source impedance CS06-like transients also will not damage a capacitor, although the spikes themselves are not nearly as well filtered.

This report should be used to allay fears that CS06-like requirements drive capacitor voltage derating. Only that derating required by the relatively long duration transients in power quality specification need concern the equipment designer.

K. Javor, Specification, Measurement, and Control of Electrical Switching Transients, NASA/CR-1999-209574, NASA Marshall Space Flight Center, AL 35812, September 1999, pp. 51.

Keywords: Switching Transients, Transient Switching Control, Power Bus Transients.

Abstract: There have been several instances of susceptibility to switching transients. The Space Shuttle Spacelab Remote Acquisition Unit (RAU- a standard interface between Spacelab payloads and the Shuttle communications system) will shut down if the input 28 VDC bus drops below 22 volts for more than 80 us. Although A MIL-STD-461 derivative CS06 requirement was levied on the RAU, it failed to find this susceptibility. A heavy payload on one aircraft sags the 28 volt bus below 20 volts for milliseconds. DC-dc converteres have an operating voltage. A typical 28 Vdc-to-5 Vdc converter operates within tolerance when input potential is between 17-40 Vdc. A hold-up capacitor can be used to extend the time this range is presented to the converter when the line potential sags or surges outside this range. The designer must know the range of normal transients in order to choose the correct value of hod-up.

This report describes the phenomena of electrical power bus transients induced by the switching of loads both on and off the bus, and control thereof.

M. L. Wheeler, Spread Spectrum Received Electromagnetic Interference (EMI) Test Guide, NASA/CR-1998-208535, NASA Marshall Space Flight Center, AL 35812, July 1998, pp. 46.

Abstract:  The objective of this test guide is to document appropriate unit level test methods and techniques for the performance of EMI testing of Direct Sequence (DS) spread spectrum receivers.  Consideration of EMI test methods tailored for spread spectrum receivers utilizing frequency spreading techniques other than direct sequence (such as frequency hopping, frequencing chirping, and various hybrid methods) is beyond the scope of this test guide development program and is not addressed as part of this document.  EMI test requirements for NASA programs are primarily developed based on the requirements contained in MIL-STD-461D (or earlier revisions of MIL-STD-461).  The corresponding test method guidelines for the MIL-STD-461D tests are provided in MIL-STD-462D.  These test methods are well documented with the exception of the receiver antenna port susceptibility tests (intermodulation, cross modulation, and rejection of undesired signals) which must be tailored to the specific type of receiver that is being tested.  Thus, test methods addressed in this guide consist only of antenna port tests designed to evaluate receiver susceptibility characteristics.  MIL-STD-462D should be referred for guidance pertaining to test methods for EMI tests other than the antenna port tests.

The scope of this test guide includes:  (1) a discussion of generic DS receiver performance characteristics;  (2) a summary of S-band TDRSS receiver operation;   (3) a discussion of DS receiver EMI susceptibility mechanisms and characteristics;   (4) a summary of military standard test guidelines;  (5) recommended test approach and methods; and (6) general conclusions and recommendations for future studies in the area of spread spectrum receiver testing.

R. W. Evans, Electrical Bonding: A Survey of Requirements, Methods, and Specification, NASA/CR-1998-207400, NASA Marshall Space Flight Center, AL 35812 by Computer Science Corp. Huntsville, Alabama, March 1998, pp. 56.

Keywords: Electrical Bonding, Electromagnetic Compatibility

Abstract: This document provides information helpful to engineers imposing electrical bonding requirements, reviewing waiver requests, or modifying specifications on various space programs. Electrical bonding discusses the specifications and some of the processes used in the United States have been reviewed. This document discusses the specifications, the bonds, the intent of each and the basic requirements where possible. Additional topics discussed are resistance verus impedance, bond straps, corrosion, finishes, and special applications.

John K. Daher and Mark L. Wheeler, International Space Station Electric Field Measurement Package (EFMP), Georgia Tech Research Institute, prepared for the Space Environments and Effects Program, Marshall Space Flight Center, AL 35812, January 1998, pp. 58

Keywords: electromagnetic interference, antenna, spectrum analyzer

Abstract: This document is a concept study to develop an implementation plan for a flight experiment on the International Space Station (ISS) to measure the on-orbit electric field environment. The experiment will: (1) provide accurate measurement of the on-orbit electric field environment across the applicable frequency range of significant ground and ISS transmitters; (2) provide publishable measurement results and data for U.S. military and commercial spacecraft and payload developers; (3) be compatible with
interface requirements (such as size and power) for an ISS external payload attach site; (4) meet the applicable qualification requirements of ISS attached payloads.

R .M. Lawton, System Guidelines for EMC Safety--Critical Circuits: Design, Selection, and Margin Demonstration, NASA CR-4759, Prepared for NASA Marshall Space Flight Center, AL 35812, Contract NAS8-40259, by GB Tech, Inc. 2200 Space Park Drive, Suite 400, Houston, TX 77058, October 1996, pp. 76

Keywords: EMC critical circuits, electromagnetic interference safety margins, pyrotechnic or electroexplosive device testing, RF susceptibility of critical circuits

Abstract: Demonstration of required safety margins on critical electrical/electronic circuits in large complex systems has become an implementation and cost problem. These margins are the difference between the activation level of the circuit and the electrical noise on the circuit in the actual operating environment. This document discusses the origin of the requirement and gives a detailed process flow for the identification of the system electromagnetic compatibility (EMC) critical circuit list. The process flow discusses the roles of engineering disciplines such as systems engineering, safety, and EMC. Design and analysis guidelines are provided to assist the designer in assuring the system design has a high probability of meeting the margin requirements.   Examples of approaches used on actual programs (Skylab and Space Shuttle Solid Rocket Booster) are provided to show how variations of the approach can be used successfully.

R.W. Evans, Test Report - Fault Current Through Graphite Filament Reinforced Plastic, NASA CR-4774, Prepared for Systems Analysis and Integration Laboratory, Science and Engineering Division NASA Marshall Space Flight Center, AL 35812, Contract NAS8-39983, by Tec-Masters, Inc., 1500 Perimeter Parkway, Huntsville, AL 35806, April 1997, pp. 36.

Keywords: electrical fault, fault current, electrical bonding, composite materials, electromagnetic compatibility

Abstract: Tests were performed to determine the damage to samples of composite material when a current carrying wire is shorted to the surface of the composite material, and to determine whether enough current can flow through the material to blow a fuse before damage can occur. Fault current tests were performed on samples of graphite epoxy materials. Samples consisted of six layers of IM7 graphite fiber mat in Hercules 8552 epoxy resin. A variable power supply provided up to 35 amps of current. The high voltage side of the power supply was attached to a wire at the end of a hinged arm, and the low side was attached to the edge of the sample. To test joints, the return was connected to the edge of one sample, and the high side was shorted to the top of the other sample. Tests show that when current exceeds approximately 5 amps, the graphite glows, and the epoxy melts out at the shorted contact. At higher current levels the epoxy burns. At voltages above 15 volts the epoxy outer coat is easily broken, and fire, flame, and a rise in current occur suddenly. When joints are introduced, resistance is increased, and the maximum current resulting from a short circuit to the graphite epoxy is reduced. This condition can easily result in fault current lower than the circuit breaker limit and higher than the 5 amp ignition level. The shorting contact and the joint become hot spots with melting epoxy, smoke, and fire.

R.W. Evans*, Test Report-Direct and Indirect Lightning Effects on Composite Materials, NASA CR-4783, Prepared for Systems Analysis and Integration Laboratory, Science and Engineering Division NASA Marshall Space Flight Center, AL 35812, Contract NAS8-39983, by *Tec-Masters, Inc., 1500 Perimeter Parkway, Huntsville, AL 35806, July 1997, pp. 86.

Keywords: lightning, composite materials

Abstract: Lightning tests were performed on composite materials as a part of an investigation of electromagnetic effects on the materials. Samples were subjected to direct and remote simulated lightning strikes. Samples included various thickness of graphite filament reinforced plastic (GFRP), material enhanced by expanded aluminum foil layers, and material with an aluminum honeycomb core. Shielding properties of the material and damage to the sample surfaces and joints were investigated. Adding
expanded aluminum foil layers and increasing the thickness of GFRP improves the shielding effectiveness against lightning induced fields and the ability to withstand lightning strikes. A report describing the lightning strike tests performed by the U.S. Army Redstone Technical Test Center, Redstone Arsenal, AL, STERT-TE-E-EM, is included as an appendix.

R.W. Evans*, Design Guidelines for Shielding Effectiveness, Current Carrying Capability, and the Enhancement of Conductivity of Composite Materials, NASA CR-4784, Prepared for Systems Analysis and Integration Laboratory, Science and Engineering Division NASA Marshall Space Flight Center, AL 35812, Contract NAS8-39983, by *Tec-Masters, Inc., 1500 Perimeter Parkway, Suite 400, Huntsville, AL 35806, August 1997, pp. 69.

Keywords: natural space environment, electromagnetic compatibility, electrical

Abstract: These guidelines address the electrical properties of composite materials which may have an effect on electromagnetic compatibility (EMC). The main topics of the guidelines include the electrical shielding, fault current return, and lightning protection capabilities of graphite reinforced polymers, since they are somewhat conductive but may require enhancement to be adequate for EMC purposes. Shielding effectiveness depends heavily upon the conductivity of the material. Graphite epoxy can
provide useful shielding against RF signals, but it is approximately 1,000 times more resistive than good conductive metals. The reduced shielding effectiveness is significant but is still useful in many cases. The primary concern is with gaps and seams in the material just as it is with metal. Current carrying capability of graphite epoxy is adequate for dissipation static charges, but fault currents through graphite epoxy may cause fire at the shorting contact and at joints. The effect of lightning on selected graphite epoxy material and mating surfaces is described, and protection methods are reviewed. shielding, fault current, electrical and lightning effects on composites.

Apirian, Lloyd, and Baummer, Philip, Space Vehicle RF Environments, JSC-CR-06-070, DCA100-00-C-4012, NASA MSFC Electromagnetic Environmental Effects and Electrical Integration Branch Huntsville, AL  35812, P2375

Abstract: Marshall Space Flight Center (MSFC) requested that the Joint Spectrum Center evaluate the radio frequency (RF) environments for a space vehicle in orbit.  This request was made in response to MSFC concerns about potential degradation to space vehicle operations due to electromagnetic effects from communications-electronics emitters in the environment that operate between 2 MHz and 40 GHz.  MSFC will use the Joint Spectrum Center results to evaluate RF-hardening requirements for systems/subsystems and payloads aboard a space vehicle.  Date used in this report was current as of May 2006.

J.A. Vaughn, M. McCollum, and M.R. Carruth, Jr., Laboratory Electron Exposure of TSS-1 Thermal Control Coating, NASA TM-108503, Systems Analysis and Integration Laboratory, Science and Engineering Directorate, Electromagnetics and Environments Branch NASA Marshall Space Flight Center, AL 35812, December 1995, pp. 15.

Keywords: tethered satellite, electron, space environment, conductivity, thermal control

Abstract: 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 luminance, 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.

R.D. Leach and M. B. Alexander, Editor, Electronic Systems Failures and Anomalies Attributed to Electromagnetic Interference, NASA RP-1374, Systems Analysis and Integration Laboratory, Science and Engineering Directorate, Electromagnetics and Environments Branch NASA Marshall Space Flight Center, AL 35812, July 1995, pp. 31.

Keywords: electromagnetic compatibility, electromagnetic interference, spacecraft,

Abstract: The effects of electromagnetic interference can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are electrically compatible is an important engineering function necessary to assure mission success. This reference publication will acquaint the reader with spacecraft electronic systems failures and anomalies caused by electromagnetic interference and will show the importance of electromagnetic compatibility activities in conjunction with space flight programs. It is also hoped that the report will illustrate that evolving electronic systems are increasingly sensitive to electromagnetic interference and that NASA personnel must continue to diligently pursue electromagnetic compatibility on space flight systems. electronic systems, anomalies, failures

T.L. Clark, M.B. McCollum, D.H. Trout and K. Javor*, Marshall Space Flight Center Electromagnetic Compatibility Design and Interference Control (MEDIC) Handbook (MSFC Center Director's Discretionary Fund Final Report, Project 93-15), NASA RP-1368, Electromagnetics and Environments Branch of MSFC's Systems Analysis and Integration Laboratory, NASA Marshall Space Flight Center, AL 35812, *Sverdrup Technology Inc., June 1995, pp. 161.

Keywords: electromagnetic compatibility (EMC), electromagnetic interference (EMI), electrical design guidelines, noise reduction, electronic/electrical systems

Abstract: The purpose of the MEDIC Handbook is to provide practical and helpful information in the design of electrical equipment for electromagnetic compatibility (EMC). Included is the definition of electromagnetic interference (EMI) terms and units as well as an explanation of the basic EMI interactions. An overview of typical NASA EMI test requirements and associated test setups is given. General design techniques to minimize the risk of EMI and EMI suppression techniques at the board and equipment interface levels are presented. The Handbook contains specific EMI test compliance design techniques and retrofit fixes for noncompliant equipment. Also presented are special tests that are useful in the design process or in instances of specification noncompliance.

    
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