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Space Plasma Physics: The Study of Solar-System Plasmas (1978)

Chapter: Impacts of Solar System Environment on Man and Man on the Environment

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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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Suggested Citation:"Impacts of Solar System Environment on Man and Man on the Environment." National Research Council. 1978. Space Plasma Physics: The Study of Solar-System Plasmas. Washington, DC: The National Academies Press. doi: 10.17226/18481.
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IMPACTS OF SOLAR SYSTEM ENVIRONMENT ON MAN AND MAN ON THE ENVIRONMENT by P.A. Sturrock The first seven chapters of this report review various plasma processes which are known to occur in the magnetosphere and the solar system. Some of the known technological effects of these plasma processes were discussed in the previous section. Any one who had been out of touch with these topics for more than a few years would no doubt be surprised at some of these effects. It was a distinct surprise when the association between magnetic storms and power outages was first realized. Moreover, it is unlikely that engineers planning cable communications or petroleum exploration realized, from the outset, that the functioning of their equipment might be affected by fluctuations of the geomagnetic field. This realization inevitably poses the following question: Are we now overlooking comparable effects? In other words, are there further important effects of the solar system environment on human life and technology or, conversely, does our terrestrial technology have significant effects beyond the known effects in the lower atmosphere — for instance, effects upon the ionosphere, plasmasphere or magnetosphere? Such questions are among the most intriguing and challenging issues with which scientists may be faced. As with any other branch of science, one may initiate either an experimental (or observational) attack or a theoretical attack. In the first case, one looks for puzzling facts (or quasi-facts) which may 1269

1270 possibly be related to the search; in the latter case, one begins to speculate on consequences of present-day theoretical knowledge. Neither approach is by itself likely to yield firm new scientific information. To use a categorization of scientific activities proposed by Morrison , these approaches may yield only "new intelligence". The later stage, which he terms "consolidation of newly occupied territory", will typically involve mutually supportive observational and theoretical activities. Perhaps the most striking example of a possible effect of the type we are considering, which originated in analysis of observational data, is a possible association between solar variability and terrestrial o weather and/or climate. Wilcox notes that claims for a connection between the variable sun and the earth's weather can be found in well over 1,000 papers published during the past century, many of these papers written by illustrious scientists. Nevertheless, the subject has tended to remain on the fringes of respectable science. The near coincidence, for some 10 cycles, between severe drought in the high prairies and sunspot minima strikes some scientists as remarkable, but remains unimpressive to other scientists. Rightly or wrongly, scientists tend to ask "How can there possibly be a real cause-and-effect relation- ship?" An important development in the history of this controversy has been the work of Wilcox and his collaborators showing that there is an apparent association between the vorticity area index in the Northern Hemisphere and sector boundaries in the solar wind. Since this correlation occurs on the time scale of days, rather than decades, one

1271 can accumulate within a few years far more evidence on this association than one could on an association between cycles with an 11-year or 22-year period. Another important aspect of these findings is that one is associating a large-scale terrestrial index with an index of the near-earth environment. Such an association is valuable in any search for a causal chain of mechanisms relating solar variability to terrestrial weather. The attitude of funding agencies towards the more speculative areas of scientific research is crucial. If financial support is available, this in itself tends to make the topic respectable; in addition, it clearly facilitates further research which will lead eventually to a validation or refutation of these speculations. On the other hand, it is unlikely that a Federal agency funding scientific research will give an implicit stamp of approval to a subject which is considered by most scientists to be of dubious respectability. One way to break this mutually restrictive cycle is for an agency to appoint a committee charged with the responsibility of assessing the existing evidence. For instance, such a committee recently met at the request of NASA to 4 study the relationship between solar activity and terrestrial weather . This committee concluded that there is a prima facie case for influence of the sun on terrestrial weather on a time scale of a few days and made recommendations concerning research likely to lead to a more definitive evaluation. On the one hand, further statistical analysis of solar and terrestrial variables is desirable to evaluate the proposed 11-year and 22-year associations and to search for possible causal chains. On the other hand, theoretical

1272 study and computer modeling are desirable to evaluate possible mechanisms which may be involved in a chain of mechanisms coupling variations of the sun's atmosphere to variations of the earth's atmosphere. Although study of the association between solar variability and terrestrial weather is in danger of becoming respectable, some other proposed correlations do not yet run this risk. For instance, a number of Russian scientists have claimed that there is a real associa- tion between geomagnetic storms and the incidence of various human diseases ' ' . In particular, Gnevyshev and Novikova claim that there is a correlation between solar activity and both myocardial infarc- tion and stroke. Since such an association, if real, might point to g hitherto unrecognized hazards to human health, my colleaques and I have investigated this hypothesis in terms of U.S. data. We found no evidence for a correlation of the type proposed by Gnevyshev and Novikova. If further analyses show that the Russian claims are, nevertheless, well founded, it will be necessary to determine whether the effect is sensitive to geographical location or some other parameter which might distinguish the Soviet data from the U.S. data. 9 Over forty years ago, Dull and Dull carried out an analysis claiming to demonstrate a relationship between the incidence of nervous and mental diseases and suicides, on the one hand, and magnetic storms on the other hand. Friedman, Becker and Bachman decided to test the possibility of psychological disturbances associated with magnetic storms. They therefore searched for a correlation between daily

1273 admissions to several psychiatric hospitals in New York State and magnetic activity in that area. The authors claim that their results show the existence of a statistically significant relationship between geomagnetic parameters and a gross measure of human disturbance. In a later article , the same scientists searched instead for a correlation between psychiatric hospital admissions and cosmic ray activity. Their claim is that cosmic ray indexes provide more significant parameters of geophysical events related to human behavior measures than do the more typical measures of geomagnetic activity, such as the K-index or Ap. These are provocative findings but, to the best of my knowledge, these important questions have not been pursued. Most scientific research is concerned with projects of fairly high probability of success and fairly low payoff. In deciding whether or not to study topics such as those so far mentioned in this chapter, a scientist must decide whether to invest any time and effort into a topic which may appear to have a low probability of success (in terms of proving beyond doubt the existence of a significant phenomenon), when success would imply a high "payoff" in the sense that the unequivocal demonstration of such an effect would be highly significant. The true importance may not be in the established association (there is little we can do to avoid magnetic storms!), but it would surely lead to new knowledge if the problem is pursued to the point that we have a complete understanding of the association. We may find, for instance, that certain electric or magnetic fluctuations have adverse effects (or possibly beneficial effects) on human beings. On the other hand, the

1274 association may be due to some other unsuspected environmental changes which are associated with but different from electric and magnetic fluctuations. Scientists involved in the study of electromagnetic aspects of the earth's environment may also be alert to the inverse class of effects; possible effects on the ionosphere, plasmasphere and magnetosphere due to man's activities. We saw, in the preceding chapter, that magnetic storms have a significant influence on power systems. There is some evidence for the inverse process, disturbances of the magnetosphere by radiation from power lines. A recent search for such an effect has 12 been carried out by Dr. A. Fraser-Smith who has analyzed many years of geomagnetic data to see if the geomagnetic Ap index displays a weekly variation. His positive conclusion is that this index shows enhancement of approximately 7% at weekends, which one may reasonably associate with the fact that power consumption is lower (by 30%) on weekends. It has been known for some time that VLF chorus emissions are 13 influenced by power line radiation . Since VLF electromagnetic waves play an important role in the precipitation of particles from the magneto- 14 15 sphere into the ionosphere ' ' , it is perhaps not too far-fetched to speculate that power line radiation may lead to precipitation which in turn produces ionospheric effects. Variations of the ionosphere can, of course, have important effects on radio communication systems. The effect of power line radiation on VLF properties of the magneto- sphere seem to be quite subtle. It has recently been learned that the amplification of one VLF signal in a magnetospheric duct may be drastically

1275 suppressed by the presence of another VLF signal. Not only may power line radiations directly influence the magnetosphere, but it may change the response of the magnetosphere to electromagnetic disturbances of natural origin. We have already witnessed large-scale changes in the earth's radiation belts due to human activity: namely, the "Starfish" experiment of exploding nuclear bombs above the ionosphere. Not only was the Intensity of radiation in the inner belt substantially enhanced, but we discovered that this enhanced radiation took several years to decay. Substantially enhanced radiation may be a danger to astronauts. In addition, the enhanced rate of dumping of energetic particles into the ionosphere, which may follow such a perturbation of the radiation belts, is likely to cause changes in the D and E layers, and possibly magnetic pulsations which may interfere with power control systems and telephone communication systems. Such questions deserve careful study before related experiments are undertaken, such as the injection of high-energy particles into the magnetosphere by an AMPS type experiment, or the injection of large amounts of electromagnetic energy which may either precipitate large fluxes of magnetospheric particles into the ionosphere or accelerate ionospheric particles, some of which may migrate into the magnetosphere. Dr. Francis Perkins of Princeton University has recently made the specific suggestion that if 3 MW of radio power at 700 kHz were beamed upwards into the ionosphere, a large fraction would be absorbed at a height of about 1400 km, principally by accelerating electrons which would then be injected into the magnetosphere. It has recently been learned that explosive chemical combustion may have drastic effects on the ionosphere. In particular, an iono-

1276 spheric "hole" was produced as a result of the rocket burn which put the Skylab spacecraft into orbit. Will similar, or possibly more drastic, perturbations be caused by rocket burns required to put the Space Shuttle into orbit or bring it down to earth? Intriguing scientific questions arise not only from the rational pursuit of existing knowledge, but also from the study of possible associations of seemingly unrelated variables, and from studying the implications of man's increasing capability to perturb his environment.

1277 REFERENCES 1. Morrison, P., 1975, Opportunities and Choices in Space Sciences, 1974 (Space Science Board, National Academy of Sciences), p. 21. 2. Wilcox, J.M., Solar structure and terrestrial weather. Science 192, 745-748, 1976. 3. Wilcox, J.M., P.H. Scherrer, L. Svalgaard, W.O. Roberts, R.H. Olson, Solar magnetic sector structure: relation to circulation of the earth's atmosphere. Science 180, 185-186, 1973. 4. Sturrock, P.A., G.E. Brueckner, R.E. Dickinson, N. Fukuta, L.J. Lanzerotti, R.S. Lindzen, C.G. Park, and J.M. Wilcox, "Study of the Relationship Between Solar Activity and Terrestrial Weather" (SUIPR Report No. 671, Stanford University), 1976. 5. Chizheviskii, A.L., One aspect of the specific bioactive or Z-radia- tion from the sun, in The Earth in the Universe, ed. by V.V. Fedynskii (NASA TT F-345 TT 66-51025), pp. 280-307, 1968. 6. Gnevyshev, M.N. and K.F. Novikova, The influence of solar activity on the earth's biosphere. J. Interdiscipl. Cycle Res. ^, 99- 104, 1972. 7. Spreiter, J.R., Shock waves in the solar system. Astronautica Acta 17, 321-338, 1972. 8. Lipa, B.J., P.A. Sturrock, and E. Rogot, Search for correlation between geomagnetic disturbances and mortality. Nature 259, 302-304, 1976. 9. Dull, T. and B. Dull, Zusammenhange zwischen Storungen des Erdmag- nestismus und Haufungen von Todesfallen, Deutsch. med Wschr., 61, 95, 1935.

1278 10. Friedman, H., R.O. Becker, and C.H. Bachman, Geomagnetic parameters and psychiatric hospital admission. Nature 200, 626-628, 1963. 11. Friedman, H., R.O. Becker, and C.H. Bachman, Psychiatric ward be- havior and geophysical parameters. Nature 205, 1050-1052, 1965. 12. Fraser-Smith, A., A weekend increase of geomagnetic activity. EOS Trans. A.G.U. _58_, 470 (Abstract //SM26), 1977. 13. Helliwell, R.A., J.P. Katsufrakis, T.F. Bell, and R. Raghuram, VLF line radiation in the earth's magnetosphere and its association with power system radiation. J. Geophys. Res. 80, 4249-4258, 1975. 14. Rosenberg, T.J., R.A. Helliwell, and J.P. Katsufrakis, Electron pre- cipitation associated with discrete very-low-frequency emissions. J. Geophys. Res. 7_6, 8445-8452, 1971. 15. Helliwell, R.A., J.P. Katsufrakis, and M.L. Trimpi, Whistler-induced amplitude perturbation in VLF propagation. J. Geophys. Res. 78, 4679-4688, 1973.

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The space age began exactly 20 years ago with the launch of Sputnik I and Explorer I. The Explorer spacecraft discovered regions of trapped radiation around the earth—the van Allen belts. This was the beginning of the study of particles and fields in space, or space plasma physics. A large part of the effort in the early years of the space program was devoted to the mapping of the magnetosphere, the measurements of time variations in particles and fields, and the exploration of the solar wind.

From these studies a sophisticated empirical knowledge of phenomena in space plasma physics has emerged. with the attainment of this observational maturity in the field, NASA funding for space plasma physics has declined as priorities have shifted to other exploratory ventures. The present study of space plasma physics was requested by NASA to obtain guidance for future directions in the subject.

The Committee on Space Physics of the Space Science Board was charged with the responsibility for soliciting technical review papers on a large number of topics in space plasma physics. These reviews are Volume 2 of the report; they constitute a most valuable resource for those working in the field.

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