Download or read book Radio frequency Emissions from Hypervelocity Impacts on Charged Spacecraft written by Andrew Michael Nuttall and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The space environment is a complex interactive system that deals with the dynamic processes and effects that can occur above the protective cocoon of Earth's atmosphere. Many extreme conditions found in space can pose significant mechanical and electrical risks to spacecraft systems. Space truly is an area of extremes, where spacecraft in orbit around Earth are immersed in the plasmasphere, where solar weather shapes our magnetosphere, and where meteoroids and asteroids careen past spacecraft at hypervelocity shock inducing speeds. We study these phenomena and others to understand how best to design spacecraft and missions to minimize the risks and hazards they are exposed to while operating in this extreme environment. The specific focus of this research is on the effects and hazards generated by collisions between electrically charged spacecraft and hypervelocity impactors. Spacecraft in orbit around Earth can naturally accrue strong surface charging conditions from the high energy electron populations that exist in regions of Earth's plasmasphere. We focus on the effects that occur when these strong spacecraft charging conditions coincide with hypervelocity impacts from meteoroid and orbital debris collisions with spacecraft. The strong shock waves that are generated from hypervelocity impacts compress, heat, and ionize the affected media and produce a plasma at the site of impact. The plasma formation process is predominately an effect of impact velocity and can persist across impactors of all sizes and masses. This plasma acts as a conduit for many different unwanted electrical phenomena. This thesis strives to understand the potential for hazardous radio-frequency electromagnetic pulses to be emitted from the impact plasma when impacts occur on electrically biased spacecraft surfaces. This research is motivated in part by case studies of spacecraft electrical subsystem failures during peak meteoroid shower activity. The expansion and evolution of a hypervelocity impact plasma and its potential to emit radio-frequency electromagnetic pulses is driven in large part by the initial conditions of the impact event and the boundary conditions imposed by the space environment and the charged spacecraft surfaces. This thesis presents novel research on the high energy shock physics that describe the formation of the initial impact plasma, with a specific focus on how material properties and impact conditions affect the thermodynamic states of the shocked media. Following the formation of the impact plasma we show how the expansion process in the presence of a strong negative external electric field can lead to conditions where the bulk of the plasma's electrons are accelerated away from the spacecraft. This bulk acceleration creates a wide-band radio-frequency emission which scales with the amount of plasma produced, the plasma temperature, and the bias conditions on the spacecraft. We corroborate these findings with experimental campaigns at electrostatic accelerator and light gas gun impact facilities. In these experiments we observe for the first time wide-band RF emissions from hypervelocity impacts with charged surfaces. A scaling analysis of the emission strength shows that spacecraft can be exposed to wide-band emissions in excess of $\SI{1}{\watt}$ effective isotropic radiated power for high energy collisions. These emission strengths, which are many orders of magnitude outside of the expectation on spurious emissions and radio-frequency interference, represent a risk for sensitive spacecraft electronics.
Download or read book Understanding Spacecraft Electrical Anomalies written by Nicolas Nik Lee and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Small meteoroids, with masses less than a microgram, are common within the solar system and routinely impact spacecraft. In Earth orbit, human-made debris also presents a risk of impact. This thesis provides the first characterization of the threat of electrical damage from these hypervelocity impacts. When an impactor encounters a spacecraft (typically at 60 km/s for meteoroids or 10 km/s for debris), its kinetic energy is converted over a very short timescale into energy of vaporization and ionization, resulting in a small, dense plasma. This plasma can produce radio frequency (RF) emission, causing electrical anomalies within the spacecraft. The behavior of hypervelocity impact plasmas was studied through ground-based experiments and a corresponding plasma expansion model to interpret the data. The experiments were conducted using a Van de Graaff dust accelerator at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Impacts of iron projectiles ranging from 0.1 fg to 10 pg at speeds of up to 70 km/s were studied using a variety of target materials. Novel plasma sensors were designed and built to characterize the plasma expansion from impacts on these targets under a range of surface charging conditions representative of space environment effects. Impact plasmas associated with bare metal targets as well as spacecraft materials were studied. The expansion behavior of the impact plasma was found to depend strongly on the surface charge of the target. From a correlation of experimental measurements with theoretical models, the dependence of plasma composition and temperature on target material, impact speed, and surface charge was analyzed. This work includes three major results. First, the initial temperature of the impact plasma is at least an order of magnitude lower than previously reported, providing conditions more favorable for sustained RF emission. Second, the composition of impact plasmas from glass targets, unlike that of impact plasmas from tungsten, has low dependence on impact speed, indicating a charge production mechanism that is significant down to orbital debris speeds. Finally, negative ion formation has a strong dependence on target material. These new results can inform the design and operation of satellites in order to prevent impact-related electrical anomalies. Since spacecraft charging is strongly dependent on orientation and surface material, deleterious electrical effects of hypervelocity impacts can be mitigated through design and operational practices that account for the influence of spacecraft geometry and the space environment on the behavior of impact plasmas.
Download or read book Seeking Radio Emissions from Hypervelocity Micrometeoroid Impacts Early Experimental Results from the Ground written by and published by . This book was released on 2006 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-velocity impact experiments have been conducted to look for radio frequency (RF) emissions from impact-produced plasmas that could be used to identify micrometeoroid impacts to spacecraft in orbit. Launched by a three-stage light gas gun, 17 mm diameter by 0.9 mm thick Ti6Al-4V flyer plates impacted 0.75 mm thick indium (In) foil at more than 10 km s( -1). The resulting collision presumably ionized some fraction of the vaporized in cloud, which was accelerated to about 12 km s( -1). This weak In plasma then passed through a wide-band detection system that looked for RF emissions. Over the course of five shots during the experiment, no conclusive plasma emissions from the In were detected. However, strong evidence indicates that significant charge is accumulated on the flyer plate during acceleration and flight, possibly producing Paschen discharge to the chamber walls. Finally, plasma may be produced by the launcher secondary to launching the plate, leading to further contamination of the results. These effects have significant consequences for RF experiments attempted in launching systems of this type.
Download or read book Detection and Analysis of the Electromagnetic Pulse from Hypervelocity Impact Plasma Expansion written by Theresa Lynn Johnson and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hypervelocity dust particles, including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (10^25/m^3), but rapidly expand into the surrounding vacuum. This research was the first to detect radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity dust particle impacts in ground-based experiments. These micro particles that produced RF are 15 orders of magnitude less massive than previously observed. We find that one mechanism for EMP production is the result of the growth of the unstable Weibel mode in the plasma and that the EMP detection rate is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. This mode grows from a plasma temperature anisotropy driven by the impact ionization process combined with the external electric field. Upon expansion, the Weibel mode grows, producing RF emission within nanoseconds. In particular, impacts of the fastest particles (speed> 15 km/s) occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. The sensor design and analysis that led to this discovery is discussed. This phenomenon may provide a source for unexplained RF measurements and satellite electrical anomalies.
Download or read book Dusty Plasma Effects in Hypervelocity Impacts written by Gil Shohet and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Meteoroids routinely impact bodies in space, such as spacecraft and small planetary bodies. Orbital debris also threaten spacecraft near Earth. These hypervelocity impacts occur at velocities of a few to tens of km/s, and the rapid conversion of kinetic energy to internal and thermal energy upon impact leads to fracturing, melting, vaporization, and ionization, producing a dense plasma. As the plasma expands from the impact crater, oscillations and instabilities can generate electromagnetic emissions in the radio frequency (RF) range and a broadband electromagnetic pulse (EMP). Moreover, condensed phase (solid and liquid) ejecta, referred to as dust, may acquire a surface charge due to interactions with the plasma, resulting in a dusty plasma. Hypervelocity impact plasmas generated by ground-based light gas gun impacts, which overlap the mass and velocity range of orbital debris, have been described as dusty for decades. Experimental plasma data and hydrodynamic simulations suggest dust charging as a possible explanation for anomalous plasma measurements. The degree of charge attachment and effect on plasma observations, however, remains unquantified. This thesis makes the first quantitative estimate of charge attachment in light gas gun impacts. We use thin-film witness plates to produce the first measurements of microscopic ejecta 1-50 microns in diameter generated by light gas gun impacts on aluminum and powdered regolith simulant targets, which serve as analogues for spacecraft and small solar system bodies, respectively. We then extend dust charging models based on orbital motion limited (OML) theory to the impact environment and build a novel semi-analytic model for dust charging and dynamics across the many orders of magnitude of space, time, and density spanned by the expanding plasma. Combining ejecta measurements, empirical and analytic models for the expanding plasma, and the dust evolution model enables predictions of the charge state of impact debris throughout the expansion. We quantify and propagate experimental and model uncertainties and use stochastic methods to produce bounded estimates of quantities of interest. This work led to a number of key findings. First, extrapolations from measurements of macroscopic ejecta poorly predict the flux of microscopic debris, and the computed particle size distribution predicts a flux of dust to the co-located plasma sensors that agrees in order of magnitude with the number of impulses, indicative of dust, in the plasma signals. Second, the dust charging model suggests that enough electrons attach to ejecta that dusty plasma phenomena are likely. These may affect electromagnetic emissions generated by hypervelocity impacts, especially on granular bodies, such as asteroids and comets. Third, the evolution model, with reasonable inputs, predicts similar arrival times and a surface charge that agrees in sign with experimental plasma measurements. Thermionic emission by hot debris can explain the observation of positively charged dust in impacts on granular regolith analogues. Finally, the ambient environment plays an important role in the charging and evolution of ejecta, and the neutral background present in many light gas gun facilities augments the tendency of debris to charge positively.
Download or read book Hazards of Hypervelocity Impacts on Spacecraft written by Shu T. Lai and published by . This book was released on 2002 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hypervelocity impacts by space particles, such as meteoroids and debris, pose hazards to spacecraft. The limits of velocity of meteoroid and debris are derived. Characteristic properties of hypervelocity impacts are momentum transfer, penetration, plasma production, localization, and suddenness. Using McDonnell's empirical formulas derived from laboratory experiments, impact penetrations and plasma production rates in the space environment are calculated. When the critical temperature theorem for Maxwellian space plasmas is used, the energy of the plasma generated is shown to be too low to induce any significant spacecraft charging. The plasma generated, however, can induce a transient, sustained or avalanche discharge between differentially charged surfaces. The discharge current depends not only on the plasma density generated but also on the neutral gas released on impact. A scenario of impact induced hazard following days of passage of a high-energy plasma cloud, such as a coronal mass ejection cloud, is discussed. Some mitigation methods are discussed. Finally, we discuss whether electrons can be accelerated to high energies in a meteor trail.
Download or read book Harnessing Energy in the Space Environment for Spacecraft Operations written by Sean Alden Quigg Young and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Exploration of the outer solar system is an expensive endeavor. Although these missions typically involve large monolithic spacecraft, interplanetary small spacecraft -- especially CubeSats -- have the potential to reduce hardware costs while increasing the science return. Spacecraft in the outer solar system generally have access to far less power than their counterparts in the inner solar system. The extreme distance from the sun necessitates the use of large deployable solar photovoltaic arrays to capture useful amounts of power, but threats from trapped radiation and microscopic particulate environments decrease their effectiveness. Radioisotope thermoelectric generators (RTGs), the typical solution in the outer solar system, are tremendously more expensive and do not scale well to small spacecraft. A different paradigm is required to enable these missions. This thesis proposes concepts for harvesting energy from the space environment, surface charging due to space plasmas and radio emissions from hypervelocity impacts in particular. A survey of the plasma and debris environments throughout the solar system is presented with estimates of the energy content. This survey is used to identify the most favorable environments in the solar system for energy harvesting. Using experimental data and theoretical models, more sophisticated energy harvesting estimates are constructed. Measurements of emission polarization and frequency spectrum from a hypervelocity impact experimental campaign conducted at the NASA Ames Vertical Gun Range (AVGR) are compared with theories of electromagnetic pulse emission and used to place an upper bound on the electromagnetic energy emitted in usable bands. A general theory for harvesting from differential charging is derived and presented. An Orbit-Motion-Limited (OML) charging model is used to determine how the harvested power scales with plasma properties and spacecraft design parameters. Surfaces with highly disparate secondary electron yields charge differentially without the use of electron emitters and can be used as anodes and cathodes to supply current to an instrument. The model suggests that load impedances and anode-to-cathode area ratios can be varied to optimize the power intake from the ambient plasma. Optimal loads are simply impedance matches to the background plasma characteristics, while large anodes are favored to capture the most electrons. These theories are used to estimate the energy harvested in two outer solar system environments: Jupiter and Saturn. The former has warm dense plasma (n ~ 1e4/cm3, T ~ 50 eV) ideal for harvesting from surface charging, while the latter has a well-studied, dense (n ~ 3.5e-8/cm3) dust environment in its ring system. Results from the OML model agree well with predictions from the Spacecraft Plasma Interaction Software (SPIS). Harvesting from hypervelocity impact electromagnetic pulses is found to be inefficient and impractical for powering spacecraft. On the other hand, differential charging generates areal power densities on the order of 0.1--10 mW/m2 at Jupiter but may require deployable surfaces to maximize the system efficiently. Although neither power source improves upon the performance of solar panels or RTGs, they may be more robust in the face of radiation and hypervelocity impacts.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book NASA Scientific and Technical Reports written by United States. National Aeronautics and Space Administration Scientific and Technical Information Division and published by . This book was released on 1966 with total page 1440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Literature 1969 Part 2 written by Siegfried Böhme and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts, which appears in semi-annual volumes, is devoted to the re cording, summarizing and indexing of astronomical publications throughout the world. It aims to pre sent a comprehensive documentation of literature in all fields of astronomy and astrophysics. Every effort will be made to ensure that the average time interval between the date of receipt of the original literature and publication of the abstracts will not exceed eight months. This time interval is near to that achieved by monthly issued abstracting journals, compared to which our system of accumulating abstracts for about six months offers the advantage of greater convenience for the user. Volume 2 contains literature published in 1969 and received before March 15, 1970; some older lite rature which was received late and which is not recorded in Volume 1 is also included. The authors of papers who have sent us abstracts on request have effectively contributed to the suc cess of our service. We should like to express our gratitude to them. We acknowledge with thanks con tributions to this volume by Dr. J. Bou~a, who surveyed journals and publications in Czech language and supplied us with abstracts in English, by Dr. B. Onderlicka, Brno, for providing English ab stracts of Russian papers, and by the Commonwealth Scientific and Industrial Research Organization (C.S.I.R.O.), Sydney, for providing titles and abstracts of papers on radio astronomy.
Download or read book Literature 1989 Part 1 written by Astronomisches Rechen-Institut and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1433 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the reviews: "Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundemental publications in the fields of astronomy, astrophysics and neighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. ...The abstracts are classified under more than a hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world." Space Science Review# "Dividing the whole field plus related subjects into 108 categories, each work is numbered and most are accompanied by brief abstracts. Fairly comprehensive cross-referencing links relevant papers to more than one category, and exhaustive author and subject indices are to be found at the back, making the catalogues easy to use. The series appears to be so complete in its coverage and always less than a year out of date that I shall certainly have to make a little more space on those shelves for future volumes." The Observatory Magazine#
Download or read book Shock and Vibration Environment written by Wendell L. Hercules and published by . This book was released on 1962 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thesaurus of Engineering and Scientific Terms written by Engineers Joint Council and published by . This book was released on 1967 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book U S Government Research Reports written by and published by . This book was released on 1962 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Space Weather written by Paul Song and published by American Geophysical Union. This book was released on 2001-01-09 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Space weather is considered to be conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the reliability and performance of space-borne or ground- based technological systems. Song (environmental earth and atmospheric sciences, U. of Massachusetts), Singer (Space Environment Center, National Oceanic and Atmospheric Administration), and Siscoe (Center for Space Physics, Boston U.) present 50 articles on current understanding and advances in the description and prediction of space weather. Nine of the articles, accessible to non-specialists, touch upon broad issues of space weather in the area of technology, science, industry, and commerce. The remaining articles are geared more towards the scientific community and address the sun and its influence on space weather, specification and prediction of the magnetosphere, and specification and prediction of the ionosphere and thermosphere. Annotation copyrighted by Book News, Inc., Portland, OR.
Download or read book Research and Technology Program Digest written by United States. National Aeronautics and Space Administration and published by . This book was released on with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spacecraft Operations written by Florian Sellmaier and published by Springer Nature. This book was released on 2022-06-14 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the basic concepts of spacecraft operations for both manned and unmanned missions. The first part of the book provides a brief overview of the space segment. The next four parts deal with the classic areas of space flight operations: mission operations, communications and infrastructure, the flight dynamics system, and the mission planning system. This is followed by a part describing the operational tasks of the various subsystems of a classical satellite in Earth orbit. The last part describes the special requirements of other mission types due to the presence of astronauts, the approach of a satellite to another target satellite, or leaving Earth orbit in interplanetary missions and landing on other planets and moons. The 2nd edition is published seven years after the first edition. It contains four new chapters on flight procedures, the human factors, ground station operation, and software and systems. In addition, several chapters have been extensively expanded. The entire book has been brought up to date and the language has been revised. This book is based on the “Spacecraft Operations Course” held at the German Space Operations Center. However, the target audience of this book is not only the participants of the course, but also students of technical and scientific courses, as well as technically interested people who want to gain a deeper understanding of spacecraft operations.
