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1、Ob95534 O002083 T T 4 = Special Copy right Notice 1994 by the American Institute of Aeronautics and Astronautics. All rights reserved. COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Institute of Aeronautics and Astronautics L
2、icensed by Information Handling Services A I A A SP-Ob9 94 = Ob95534 0003797 T78 AIAA SP-069-1994 Contemporary Models of the Orbital Envi ron ment COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Institute of Aeronautics and As
3、tronautics Licensed by Information Handling Services A I A A SP-Ob7 74 W Ob75534 OOOL778 TOY AIAA SP-069- 1994 Special Project Report Contemporary Models of the Orbital Environment Robert A. Skrivanek, Editor Abstract The six papers included in this Special Report were presented at the AIAA Aerospac
4、e Sciences Meeting in January 1994. They provide state-of-the-art knowledge about ionospheric, radiation, neutral density, space debris, and thermal environments. The papers will be employed in the development of standard models for these aspects of the orbital environment. COPYRIGHT American Instit
5、ute of Aeronautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services A I A A SP-Ob9 94 Ob95534 0003777 840 Published by American Institute of Aeronautics and Astronautics 370 LEnfant Prome
6、nade, SW, Washington, DC 20024 Copyright O 1994 American Institute of Aeronautics and Astronautics All rights reserved No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Printed in the United S
7、tates of America COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services A I A A SP-Ob9 94 = 0675534 OOOLBOO 392 H AMA SP-069-1994 CONTENTS Foreword .
8、 . 1 Ionospheric Models The Space Radiation Environment 29 65 Neutral Density Models for Aerospace Applications 81 Orbital Debris Environment: An Update . Space Debris Reentry Risk Analysis . Thermal Environment in Space for Engineering Applications . 89 105 . 111 COPYRIGHT American Institute of Aer
9、onautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services A I A A SP-Ob9 94 m Ob95534 OOOLBOL 229 m AIAA SP-069-1994 iv COPYRIGHT American Institute of Aeronautics and Astronautics Licens
10、ed by Information Handling Services COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services A I A A SP-Ob7 74 m Ob75534 0001802 1b5 Foreword The Air Force and NASA Co-leaders of the Space Technology Interdependency Group (STIG) have noted recently that
11、more effort is needed to encourage the application of available knowledge toward specifying and modeling the interaction and effect of the space environment on space systems. This need exists despite the significant amount of progress that has been achieved mutually by both organizations in measurin
12、g and model- ing the physical and chemical properties of near Earth space. Our ability to measure, understand, and specify the detailed characteristics of the space environment has improved steadily since the first simplified measurements were made using research balloons and sounding rockets. The l
13、ead agencies for sponsoring and performing many of the these measure- ments have been the US Air Force and NASA. Each of these agencies has had its own requirements and priorities for obtain- ing the various specific measurements of the space environment. Through the years each has accumulated a com
14、prehensive collection of data sets and models. This information, as it was being collected, analyzed, and assembled, has been used by the spacecraft design groups in government agencies and industrial concerns throughout the United States. Hundreds of military and civilian satellites, designed and b
15、uilt for both research and operational purposes, have benefited from this evolving data over the last 30 years. The space environment data that was used by these satellite designers has not always been easily accessible nor easily understood. In most cases the data or models were gen- erated by scie
16、ntists who were driven more by their desire to understand particular geo- physical phenomena than they were to de- velop an engineering guide or translate a space measurement into a systems design standard. Generally speaking, the space sci - entists have been very successful. We are still surprised
17、 occasionally by a new space environment measurement, but by and large, space scientists have provided us with an AIAA SP469-1994 excellent understanding of near Earth space that may well continue to be refined, but is not likely to change dramatically. As mentioned, the Co-leaders of the Air ForceN
18、ASA group concerned with the in- terdependency of their space programs feel that more effort is needed to encourage the interaction between NASA and Air Force working level scientists and the hands-on space systems engineers in industry and government that design, build, and operate space systems. A
19、 technical meeting, at which a series of survey papers describing the characteristics of available empirical and theoretical models in select areas of interest to the space systems community seemed to be a reasonable approach. It was decided that a well-attended, national, AIAA meet- ing, with its d
20、iverse participation that in- clude some scientists, as well as a large number of engineers and managers from industry and government, would provide a very appropriate forum. I had the privilege of being asked to orga- nize one technical session for the 1994 Aerospace Sciences Meeting. In this ses-
21、sion, a small group of scientists, each well established and respected in his field, would present the characteristics of available on- orbit space environment models. The speakers would describe which models were appropriate under which conditions, what assumptions were made within a particular mod
22、el, and the effect of these assumptions on the models product. The session con- tained six papers and attracted an audience twice as large as expected. The consensus of the audience was that the presented mate- rial was interesting, useful to the engineering community, and that the program should be
23、 expanded to include additional types of space data and models the following year. This publication, based on the papers in that session, is another step toward facilitating the availability of space environment data and models to the designers and builders of civilian and military space systems. Wh
24、ile this material addresses a limited number of topics, it is comprehensive and up to date for the specific areas covered and should of use of the space systems community. V COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Inst
25、itute of Aeronautics and Astronautics Licensed by Information Handling Services A I A A SP-Ob9 94 Ob95534 0001803 O T 1 D AIAA SP-069-1994 vi COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Institute of Aeronautics and Astrona
26、utics Licensed by Information Handling Services - A I A A SP-Ob9 94 m Ob95534 0001804 T38 AIAA SP-069-1994 IONOSPHERIC MODELS H. C. Carlson, Jr. R. W. Schunk USAF Phillips Utah State Laboratory University Hanscom AFB, MA Logan. UT Abstract We seek here to provide a frame of reference for assessing t
27、he present status of iono- spheric modeling, and for determining which models may best serve a particular user need. This choice depends not only on the geo- graphic region, and time of concern (post analysis, nowcast, forecast), but on the accu- racy required by the user, and the ionospheric parame
28、ters of greatest concern. Introduction Development of ionospheric models has been a preoccupation of scientists and engineers for some decades. The continuing interest of the engineers (communications, surveillance) has been motivated by continuing improve- ment of commercial and military systems de
29、- pendent on the ionosphere as a component of the total system. This in turn has generated recurring need for further accuracy and re- finement of ionospheric modeling, specifica- tion, and prediction capability, as rf systems saw recurring advances to meet ever more stringent demands. The continuin
30、g interest of scientists has been motivated by the rapid pace of discovery of different regions of the global ionosphere, controlled by very differ- ent physical processes. Furthermore, many global regions exhibit a character often driven by coupling to often very remote regions of space, by a rich
31、complex of interactive mech- anisms. In the earliest days empirical and climatologi- cal models were adequate for many purposes. Greater accuracy was afforded, at least for over-head or nearby specification, by adding local measurement for real time scaling or calibration of the empirical statistica
32、l model. Today this is still true for certain applications, and for some regions of the globe it is diffi- cult to improve on this approach. For many R. A. Heelis Sa. Basu University of Texas USAF Phillips at Dallas Laboratory Richardson, TX Hanscom AFB, MA purposes however, particularly those invol
33、v- ing larger sectors of the global ionosphere, physical models are the only way to achieve the accuracies required by the needs of today. This is true not only as a particularly effective way of identifying mechanisms controlling ionospheric behavior, but for practical appli- cations as well. For t
34、he latter purposes, the trend is now clearly towards models driven by real time data. To enhance operating speed, and reduce computational cost, these are often streamlined to the form of analytic or semi-empirical models. These then also form the basis of predictive models, where the challenge is t
35、o break beyond the realm of prediction by persistence. Governing processes: For even simple models, the minimum set of parameters re- quired as input to drive the model are: solar activity, geomagnetic activity, time of day (in general both universal and local time), sea- son, and latitude (in gener
36、al both geomag- netic and geographic). To achieve accuracies of tens of percent or better in electron density requires periodic input of measured iono- spheric parameters, with crucial dependence on correlation distances and times. Figure 1 shows a representative midlatitude ionospheric profile, dem
37、onstrating some common nominclature. F region plasma typically has chemical lifetimes of hours and is dominated by transport between production and loss; lower altitude plasma has chemical lifetimes of minutes and less, and is domi- nated by local production (solar radiation and energetic particles)
38、 and chemical recombina- tion. Quite different morphologies and physical processes distinguish between equatorial, midlatitude, near auroral, and polar cap iono- spheric conditions. For instance, the equato- rial ionosphere is characterized by strongly enhanced peak electron densities roughly 10- 1
39、COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services COPYRIGHT American Institute of Aeronautics and Astronautics Licensed by Information Handling Services A I A A SP-Ob9 94 M Ob95534 0001805 974 AIAA SP-069-1994 20 degrees either side of the equator
40、 (the Appleton anomaly). These occur on many, but not all days, depending on a variable equatorial electric-field-driven upward trans- port term. Midlatitude ionospheric electron densities exhibit: strong seasonal variations due in large part to changing upper atmo- spheric composition; and consider
41、able day to day variability due largely but not solely to variable vertical transport driven by variable horizontal upper atmospheric winds and elecmc fields. Auroral ionospheric electron densities may be anomalously enhanced in the E region by particle production, and de- pleted in the F region by
42、velocity dependent chemical loss rates. Because polar iono- spheric F region plasma (with typical life- times of hours) commonly has anti-sunward horizontal transport velocities of order a W s , the polar cap is characterized by large plasma densities which typically come from source regions thousan
43、ds of km away. This ionospheric transport is driven by forces originating in the solar wind, and transmitted via interaction through the magnetosphere. Consequently, the character of the polar ionosphere is critically dependent on the in- terplanetary magnetic field (IMF). The IMF, particularly its
44、vertical component, in fact dominates the polar cap ionospheric electro- dynamics and energetics, and threrby its plasma densities, thermal structure, and com- position. Despite these complexities, physical models of ionospheric electron densities, when driven by real time data, can produce real tim
45、e global models with nominal accuracies of a few tens of percent, within correlation distances less than about a thousand km, and correlation times of a fraction of an hour. Approaches to modeling: Empirical or statis- tical models have been widely used over the last decade, based on a large body of
46、 mea- surements, binned by known dependent pa- rameters, and generally analytically fit. The most comprehensive of these is the International Reference Ionosphere, the RI. It provides a model of the global distribution of electron density , ion composition, and electron and ion temperature and drift
47、. Empirical models also exist for ionospheric high latitude convection, plasma structuring, auroral particle precipitation, and field aligned currents. Physical models are very effective research tools for identifying missing physical pro- cesses and mechanisms controlling iono- spheric behavior, an
48、d for applications are generally the best way to extrapolate and in- terpolate between direct measurements of de- sired parameters. Ab initio calculations grow steadily more accurate as increasingly com- prehensive global data sets and refined mod- els are iterated The model usually solves the conti
49、nuity, momentum, and energy equations for the electrons and ions, as a function of altitude along curved magnetic field lines, to derive plasma densities, flow velocities, temperatures, and composition. Analytical models can make much of the power of physical models available to a much broader community of users than otherwise economically feasible. An extensive set of physical model outputs is fit by sets of rela- tively simple analytic functions, tagged to key parameters, so that the “physical model data“ can be more quickly and easily accessed, us- ing a much smaller and less expe
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