IONOSPHERE AND THERMOSPHERE

Plasma

R.D. Leach,* Author and M.B. Alexander, Editor, Failures and Anomalies Attributed to Spacecraft Charging, NASA RP-1375 , Electromagnetics and Environments Branch, Systems Analysis and Integration Laboratory, Science and Engineering Directorate, NASA Marshall Space Flight Center, AL 35812 and *Computer Sciences Corporation, Huntsville, AL., August 1995, pp. 30.

Keywords: plasma, spacecraft charging, spacecraft, electronic systems, anomalies, failures, EMI, arc-discharge, satellite

Abstract: The effects of spacecraft charging can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are protected against charging is an important engineering function necessary to assure mission success. Spacecraft charging is expected to have a significant role in future space activities and programs. Objectives of this reference publication are to present a brief overview of spacecraft charging, to acquaint the reader with charging history, including illustrative cases of charging anomalies, and to introduce current spacecraft charging prevention activities of the Electromagnetics and Environments Branch, Marshall Space Flight Center (MSFC), National Aeronautics and Space Administration (NASA).

J.L. Herr* and M.B. McCollum , Spacecraft Environments Interactions: Protecting Against the Effects of Spacecraft Charging, NASA RP-1354, Systems Analysis and Integration Laboratory, Science and Engineering Directorate, Electromagnetics and Environments Branch. NASA Marshall Space Flight Center, AL 35812 , November 1994 , pp. 19 .

Keywords: spacecraft charging, Spacecraft Charging Effects Protection Plan, natural space plasma

Abstract: The effects of the natural space environments on spacecraft design, development, and operation are the topic of a series of NASA Reference Publications currently being developed by the Electromagnetics and Environments Branch, Systems Analysis and Integration Laboratory, Marshall Space Flight Center. This primer, second in the series, describes the interactions between a spacecraft and the natural space plasma. Under certain environmental/spacecraft conditions, these interactions result in the phenomenon known as spacecraft charging. It is the focus of this publication to describe the phenomenon of spacecraft charging and its possible adverse effects on spacecraft and to present the key elements of a Spacecraft Charging Effects Protection Plan.

Boris V. Vayner and Dale C. Ferguson, Electromagnetic Radiation in the Plasma Environment Around the Shuttle, NASA TM-106891, National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio 44135-3191, March 1995, pp. 21.

Keywords: Shuttle; Plasma; Electromagnetic environment; SAMPIE; Arcing

ABSTRACT: As part of the SAMPIE (The Solar Array Module Plasma Interaction Experiment) program, the Langmuir probe (LP) was employed to measure plasma characteristics during the flight STS-62. The whole set of data could be divided into two parts: i) low frequency sweeps to determine voltage-current characteristics and to find electron temperature and number density; ii) high frequency turbulence (HFT dwells) data caused by electromagnetic noise around the shuttle. The broadband noise was observed at frequencies 250-20,000 Hz. Measurements were performed in ram conditions; thus, it seems reasonable to believe that the influence of spacecraft operations on plasma parameters was minimized. The average spectrum of fluctuations is in agreement with theoretical predictions. According to purposes of SAMPIE, the samples of solar cells were placed in the cargo bay of the shuttle, and high negative bias voltages were applied to them to initiate arcing between these cells and surrounding plasma. The arcing onset was registered by special counters, and data were obtained that included the amplitudes of current, duration of each arc, and the number of arcs per one experiment. The LP data were analyzed for two different situations: with arcing and without arcing. Electrostatic noise spectra for both situations and theoretical explanation of the observed features are presented in this report.

Boris V. Vayner and Dale C. Ferguson, Electrostatic Noise in the Plasma Environment Around the Shuttle, National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio 44135-3191, NASA TM-106856 AIAA-95-1944, February 1995, pp. 9.

Keywords: Plasma turbulence; Langmuir probe; Spectrum; Arcing; Solar cells

ABSTRACT: The Langmuir probe flown as part of the SAMPIE package aboard the space shuttle flight STSÜ62 was used to determine plasma potential fluctuations in the vicinity of the shuttle. The broadband noise was observed at frequencies 250Ü20,000 Hz. Measurements were performed in ram conditions; thus, it seems reasonable to believe that the influence of spacecraft operations on plasma parameters was absolutely negligible. The average spectrum of fluctuations is in agreement with theoretical predictions. The influence on the observed spectra of arcing generated by high negative bias voltages applied to solar cell samples is briefly discussed.

THERMOSPHERE

Solar Conditions

W. W. Vaughan*, K. O. Niehuss and M. B. Alexander, Spacecraft Environments Interactions: Solar Activity and Effects on Spacecraft, NASA RP-1396, Electromagnetics and Aerospace Environments Branch, Systems Analysis and Integration Laboratory, Science and Engineering Directorate. NASA Marshall Space Flight Center, AL 35812 and *University of Alabama in Huntsville, Huntsville, Alabama, November 1996, pp. 32.

Keywords: natural space environment, spacecraft environment, environmental effects and impacts, solar activity influences, effects, and prediction

Abstract: The natural space environment is characterized by many complex and subtle phenomena hostile to spacecraft. The effects of these phenomena impact spacecraft design, development, and operations. Space systems become increasingly susceptible to the space environment as use of composite materials and smaller, faster electronics increases. This trend makes an understanding of the natural space environment essential to accomplish overall mission objectives, especially in the current climate of better/cheaper/faster. This primer provides an overview of solar activity and interaction with the space environment. Under certain conditions, these interactions result in significant effects on the performance of a spacecraft. This publication describes some of these effects and presents key solar activity elements responsible for them. This primer is one in a series of NASA Reference Publications currently being developed by the Electromagnetics and Aerospace Environments Branch, Systems Analysis and Integration Laboratory, Marshall Space Flight Center (MSFC), National Aeronautics and Space Administration (NASA).

R.M. Wilson, On the Variation of the Nimbus7 Total Solar Irradiance, NASA TP-3316 , Space Science Laboratory, NASA Marshall Space Flight Center, AL 35812, December 1992, (N93-15532).

Abstract: For the interval December 1978 to April 1991, the value of the mean total solar irradiance, as measured by the NimbusÐ7 Earth Radiation Budget Experiment channel 10C, was 1,372.02 WmÐ2, having a standard deviation of 0.65 WmÐ2, a coefficient of variation (mean divided by the standard deviation) of 0.047 percent, and a normal deviate z (a measure of the randomness of the data) of Ð8.019 (inferring a highly significant nonrandom variation in the solar irradiance measurements, presumably related to the action of the solar cycle). Comparison of the 12-month moving average (also called the 13-month running mean) of solar irradiance to those of the usual descriptors of the solar cycle (i.e., sunspot number, 10.7-cm solar radio flux, and total corrected sunspot area) suggests possibly significant temporal differences. For example, solar irradiance is found to have been greatest on or before mid 1979 (leading solar maximum for cycle 21), lowest in early 1987 (lagging solar minimum for cycle 22), and was rising again through late 1990 (thus, lagging solar maximum for cycle 22), having last reported values below those that were seen in 1979 (even though cycles 21 and 22 were of comparable strength). Presuming a genuine correlation between solar irradiance and the solar cycle (in particular, sunspot number) one infers that the correlation is weak (having a coefficient of correlation r <0.84) and that major excursions (both as ÒexcessesÓ and ÒdeficitsÓ) have occurred (about every 2 to 3 years, perhaps suggesting a pulsating Sun).

J.E. Smith, NASA Marshall Space Flight Center Solar Observatory Report-July-December 1992, NASA TM-108396 , Space Science Laboratory, NASA Marshall Space Flight Center, AL 35812, February 1993, (N93-22665).
 

Abstract: This report provides a description of the NASA Marshall Space Flight Center's Solar Vector Magnetograph Facility and gives a summary of its observations and data reduction during July to December 1992. The systems that make up the facility are a magnetograph telescope, an H-alpha telescope, a Questar telescope, and a computer code.
 

J.E. Smith, NASA Marshall Space Flight Center Solar Observatory Report-January-June 1993, NASA TM-108417 , Space Science Laboratory, NASA Marshall Space Flight Center, AL 35812, July 1993, (N94-10866).

Abstract: This report provides a description of the NASA Marshall Space Flight Center's Solar Vector Magnetograph Facility and gives a summary of its observations and data reduction during January to June 1993. The systems that make up the facility are a magnetograph telescope, an H-alpha telescope, a Questar telescope, and a computer code.
 

J.E. Smith, NASA Marshall Space Flight Center Solar Observatory Report-July-October 1993, NASA TM-108448 , Space Sciences Laboratory, NASA Marshall Space Flight Center, AL 35812, April 1994, (N94-29470).

Abstract: This report provides a description of the NASA Marshall Space Flight Center's Solar Vector Magnetograph Facility and gives a summary of its observations and data reduction during June-October 1993. The systems that make up the facility are a magnetograph telescope, an H-a telescope, a Questar telescope, and a computer code.
 

M. Herrmann and L. Johnson, Inner Magnetosphere Imager (IMI) Solar Terrestrial Probe Class Mission Preliminary Design Study Report, NASA TM-108464 , Program Development Directorate, NASA Marshall Space Flight Center, AL 35812, August 1994.

Abstract: For three decades, magnetospheric field and plasma measurements have been made by diverse instruments flown on spacecraft in many different orbits, widely separated in space and time, and under various solar and magnetospheric conditions. Scientists have used this information to piece together an intricate, yet incomplete view of the magnetosphere. A simultaneous global view, using various light wavelengths and energetic neutral atoms, could reveal exciting new data and help explain complex magnetospheric processes, thus providing us with a clear picture of this region of space. The George C. Marshall Space Flight Center (MSFC) is responsible for defining the IMI mission which will study this region of space. NASA's Space Physics Division of the Office of Space Science placed the IMI third in its queue of Solar Terrestrial Probe missions for launch in the 1990's. A core instrument complement of three images (with the potential addition of one or more mission enhancing instruments) will fly in an elliptical, polar Earth orbit with a apogee of 44,600 km and a perigee of 4,800 km. This paper will address the mission objectives, spacecraft design considerations, interim results of the MSFC concept definition study, and future plans.
 

J.E. Smith, NASA Marshall Space Flight Center Solar Observatory Report - March-May 1994, NASA TM-108471, Space Sciences Laboratory, Science and Engineering Directorate NASA Marshall Space Flight Center, AL 35812, December 1994, pp. 41.

Keywords: Solar Observatory, Vector Magnetograph, H- Telescope, Questar Telescope

Abstract: This report provides a description of the NASA Marshall Space Flight Center's Solar Vector Magnetograph Facility and gives a summary of its observations and data reduction during March-May 1994. The systems that make up the facility are a magnetograph telescope, an H- telescope, a Questar telescope, and a computer code.

    
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