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5-4 Space Forecast in the Future Manned Space Era

TOMITA Fumihiko

Space weather is the conditions of the and in the solar , , iono- sphere and that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human and animal life or health. In 2050, everyone will be able to enjoy his/her space tour. The space weather research will transform into more and more practical science in that future manned space era. Keywords Space weather forecast, Manned space activities, Space environment

1 Introduction are applied to forecasting space weather in a practical and useful manner[1]. Space weather refers to various physical This paper describes an overview of and chemical phenomena that occur naturally space-weather applications, addressing issues in a region that extends from an altitude of a such as how space-weather research and fore- few tens of kilometers into the , in casting will benefit humanity, and possible which the main component is . There- near-future uses in the context of full opera- fore, space-weather research is an interdisci- tion of the International Space Station (the plinary and interactive research field ranging "ISS") and applications involving manned from geophysics to astronomy, covering Mars explorations and , envi- , , and . sioned for the middle of this century. However, as is the case in the fields of geophysics, space-weather research holds 2 Sources of space-weather vari- practical interest in terms of the ways in which ation the natural environment (in this case extend- ing from the to the Sun) affects human In order to ensure human safety and pro- activities. It is in this context that the term tect various man-made systems, it is essential space "weather" was coined. to research and understand the sources and From this viewpoint, the definition of global structure of space weather, which has a Space weather is as follows: "Conditions on significant effect on such safety and systems. the Sun and in the , magnetosphere, Since individual research achievements relat- and thermosphere that can influ- ing to the area from the upper atmosphere to ence the performance and reliability of space- the Sun have been discussed in detail by other borne and ground-based technological systems authors, this paper will summarize the primary and can endanger human life or health." sources of space-weather variation (Fig.1). A prime example of space weather activity The Sun is the greatest energy source in can be found in forecasting research, in which the region from the upper atmosphere into the a wide range of research activities―from the solar system. most basic research to complex applications― In the surroundings of the geomagneto-

TOMITA Fumihiko 159 Fig.1 Sources of space-weather variation that affect human activities on Earth and in space sphere, the "solar wind" constantly blows 3 Influence on the ground from the Sun into the solar system, accompa- nied by a magnetic field. The characteristics 3.1 Radio communications of the solar wind vary significantly, temporally All communications using radio waves are and spatially, in the region of its origin near influenced by space weather. In particular, the Sun, creating disturbances in the geomag- short-wave (HF band) radio waves in the netosphere and the upper atmosphere. region are sometimes absorbed by the iono- Furthermore, sudden eruptions of "plasma sphere when appear and do not return clouds" (referred to as coronal mass ejections, to the ground. or "CMEs") and a "flare" are generated in Frequencies of mobile wireless terminals active regions on the surface of the Sun, often have already been shifted to the UHF and SHF resulting in space-weather variations. bands, and it is expected that in the future ter- Additional factors other than those origi- restrial communications will no longer rely nating in the Sun also lead to space-weather strictly on the HF band. Nevertheless, numer- variation; these include galactic cosmic rays, ous ham radio stations around the world meteorites, and debris. remain active, and since these involve rela- We will describe the ways in which space- tively simple transmitter/receiver systems, weather variation originating from such HF-band radio communications are expected sources affects human life in Fig.2. to play a number of continued roles: in inter- national short-wave broadcasting, information communication in regions of low population

160 Journal of the Communications Research Laboratory Vol.49 No.4 2002 Fig.2 Space weather factors affecting various human activities Such variation may, in some cases, be life-threatening densities, communications at the time of a dis- direction of radio-wave propagation is nearly aster or emergency, communications for mili- parallel to the direction of the Sun's rays, solar tary purposes, and in backup communication radio bursts are extremely likely to have direct systems. Therefore, in order to support safe undesirable effects on broadcasting operations in these and other contexts, an and communications, especially on communi- understanding of the nature of ionospheric cations between geostationary and storms and the prediction thereof will play a the ground. necessary role continuously into the future. Space weather also affects users of cellular As a point of note, although mainstream navi- (i.e., mobile) phones, whose numbers have gation communications for aircraft and ships increased explosively in recent years. It is are gradually moving toward satellite commu- predicted that the frequency of failed calls, in nications, many users today continue to which a cellular-phone user cannot reach his employ VHF-band (short-distance) and HF- or her party due to increased noise level band (long-distance) communications with caused by solar radio bursts, is at least once ground/land facilities. every 3.5 days at the time of , Although satellite broadcasting and com- and at least once every 18.5 days during solar munications between satellites and the ground minimum[2]. Furthermore, cellular phones have become an essential part of modern life, may become more susceptible to the undesir- ionospheric storms have undesirable effects on able effects of space weather variations in the satellite-related radio-wave propagation from future through reduction in the transmitting/ the VHF band to the SHF band, as the propa- receiving electric power used (for purposes of gation paths of these bands through the safety and further miniaturization of telephone ionosphere. Specifically, in cases in which the sets). Most interference in communication

TOMITA Fumihiko 161 between base stations and cellular phones due avoided. to solar radio bursts occurs at sunrise and sun- set, when solar altitude is low. 3.3 Terrestrial long-distance wired Although the undesirable effect of natural communication lines, power lines, etc. phenomena such as magnetospheric/ionos- In 1849, the influence of space weather on pheric storms on radio communications and man-made systems was reported; specifically, broadcasting cannot be avoided even with the electromagnetic induction phenomenon highly accurate space weather forecasts, dam- accompanying geomagnetic storms and affect- age can be minimized by suspending impor- ing terrestrial cable communication (tele- tant communications at the predicted times graph) was noted. Today the roles of medi- and, if necessary, by switching to other way of um/long-distance communications have been communications, such as satellite circuits, taken over by satellite communications and optical fiber lines, or cable. fiber-optical communications (after brief experimentation in microwave communica- 3.2 Navigation tions and other technologies); however, the For ship navigation systems that use the influence of space weather remains strong, in LF and VLF bands for LORAN, OMEGA, its effects on satellite communications as and so on, it is important to determine ionos- described above as well as on optical fiber pheric height precisely. Variation in the communications, insofar as the latter relies on heights of ionospheric layers at the time of long-distance power transmission to repeaters magnetospheric/ionospheric storms can result (as will be described later). in errors on the order of km in positional cal- Modern life relies heavily on electric culation. power, generated primarily through hydraulic, GPS (Global Positioning System) technol- thermal, and nuclear power, with a small but ogy has become an indispensable element of growing contribution from wind power, geot- daily life due to the popularization of automo- hermal energy, and solar power. Consumption bile navigation systems and other applications, of electricity is extremely localized depending while more advanced uses of highly accurate on population density, and it is often the case and reliable positional information is envi- that the sites of power consumption are far sioned―in aircraft takeoff and landings and in from the sites of production, to minimize the control of distance between automobiles, for pollution from power plant facilities on resi- example. Since the sudden change in the elec- dential areas. This has resulted in the expan- tron density of the ionosphere accompanying a sion―both within and between nations―of magnetospheric/ generates a long-distance power lines carrying vast short-period radio-wave variation referred to amounts of electric power. as scintillation, with an undesirable effect on Long-distance electric power lines are GPS signals, space weather forecasts will be affected by induced currents caused by varia- indispensable in the development of positional tions in the geomagnetic field. The effects can measurement systems requiring greater accu- be serious, especially in high-latitude regions, racy. It is worth noting that the United States where variation in the geomagnetic field is and a number of other countries are already large. For example, a nine-hour power failure applying space weather forecasts to high-pre- occurred in Canada in March, 1989, affecting cision military GPS applications. about 6 million people. Fig.3 shows the inte- With an accurate space weather forecast or rior of a transformer that was burnt out by the an awareness of the instantaneous state of same magnetic storm in a power plant in New communications (positional error informa- Jersey, U.S. tion), serious accidents otherwise attributable The damage was caused by a magnetic to reliance on GPS navigation alone can be storm on March 13, 1989 (Photograph taken

162 Journal of the Communications Research Laboratory Vol.49 No.4 2002 by U.S. Electric Power Research Institute). Some fish, birds, and mammals have organs for geomagnetic detection, located near the olfactory organs; it is well known, for example, that carrier pigeons and dolphins alike rely on detection of the Earth's magnetic field. In one case, numerous pigeons in an inter- national carrier-pigeon race were lost due to a large . Today such races are scheduled with reference to space weather forecasts. Moreover, research on the influence of magnetic-field variation on the human body has also begun[3]. Fig.3 Coil inside an electric power trans- former burnt out by space storm (Pho- tograph courtesy of the United States Electric Power Research Institute) 3.5 forecast for sightseeing Since Gauss first measured the total mag- In order to minimize the effects of this netic force of the Earth at the beginning of the induced current (referred to as a geomagnetic 18th century, the Earth's magnetism has tend- induced current, or "GIC"), electric power ed to decrease steadily. Estimation show that companies and other relevant parties world- if this decrease continues at this rate, in about wide are carrying out various research and 700 years, auroras will be seen even in Japan, development projects, including those relating and 500 years after that, the Earth's magnetism to space weather, and at the same time are will have been reduced to zero. This also cooperating to establish multiple route net- means that dangerous high-energy particles works and systems to supply electric power will increasingly penetrate to Earth surface via safe routes during high-risk periods. from space. Therefore, it is becoming possible to prepare Auroras, natural phenomena occurring in for the worst, avoiding electric power failure the high-latitude regions, have become objects by selecting routes that are less susceptible to of sightseeing in Alaska and Northern Europe, geomagnetic disturbances and by establishing etc. In order to view these curtain-like auroras backup lines that are always available in the rippling in the skies, and in particular to event of magnetic storms. Such preparation, enable viewing of auroral expansions, it will however, depends upon the availability of help to predict the arrival of geomagnetic advance magnetic storm data obtained via storms through space weather forecasts, space weather forecasts. enabling those who wish to view these phe- Long-distance pipelines from oil fields to nomena to head to high-latitude regions at the power-generation facilities, especially those in ideal times. high-latitude regions, are similarly affected by geomagnetic storms. Because induced current 3.6 Influence on terrestrial semicon- on the surface of a metallic pipe promotes cor- ductor devices rosion of junction or grounding components of Most radiation on the ground originates the pipe, oil-mining enterprises and trans- from the ground, buildings, air, foods, and portation enterprises are conducting research other materials containing radioactive sub- and development of effective methods of pro- stances; the proportion of radiation from space cessing the induced current. represents about 1/3 of the whole at Earth sur- face. Most of this radiation comes in the form 3.4 Magnetic-field-sensing capabili- of high-energy particle showers originating in ties of animals and human beings galactic cosmic rays (GCRs); variations in

TOMITA Fumihiko 163 GCR of 10 % or so cannot be said to exert a 4 Influence on aircraft significant influence on terrestrial life. However, technological development is As mentioned above, space weather leading to greater miniaturization of semicon- affects direct short-wave radio communica- ductor devices, integrated circuits, and similar tions and satellite communications between devices, resulting each year in greater integra- aircraft and base stations, and GPS navigation; tion and sophistication (as will be described in this context this chapter will discuss the later in discussion of the influence of high- influence of high-energy particles on aircraft energy particles on devices aboard aircraft and in the space radiation environment. ). Furthermore, higher-performance As the number of international airline devices are configured to work with smaller flights continues to grow, with increasing pas- currents; as a result, the influence of high- senger numbers, it has become difficult to energy particles on semiconductor devices and ignore the influence of space radiation on the integrated circuits is becoming increasingly crew and passengers aboard aircrafts, espe- non-negligible even in terrestrial applications. cially in planes that pass over regions of high While the variable component of space latitude in a "great-circle track." In these weather does not exert a particularly large cases, applicable sources of space radiation influence on terrestrial events, care must be include GCR, present on a near-constant basis; taken to mitigate the influence of constant radiation belt particles, permanently present radiation from space. For example, in order to but in varying intensity; and solar energetic store high-precision semiconductor devices, particles (SEP), which arrive suddenly and CCDs, etc., safely for long periods, shielded exert a significant influence for several days. rooms made of concrete or equivalent materi- It has been reported that if either a crew mem- als are required. ber or passenger flies a number of high-lati- tude flights, his/her annual exposure to radia- 3.7 Influence on climatic variation tion may exceed 1 mSv. Space weather includes the upper-atmos- Particularly in the case of a crew member pheric environment of the Earth, and this subject to continual high-latitude exposure in upper atmosphere connects continuously with the course of his/her work, exposures as high the terrestrial atmosphere. Therefore, it is as 3 mSv/year have been reported, and in the expected that variations in space weather case of passengers spending in excess of sev- attributable to galactic cosmic rays and solar eral hundred hours per year on high-latitude activity affect the and weather of the routes, radiation exposure rates cannot be Earth. Currently research is underway to look ignored[6]. If the aircraft happens to for correlations between various elements of encounter a (SPE) while weather data and variations in the galactic cos- flying at high altitudes over a high-latitude mic rays and solar energetic particles, while region, there will be a spike in exposure dur- additional research is focusing on the effect of ing that flight; therefore, in the case of a high- solar activity (e.g., numbers of ) and latitude and high-altitude passenger airplane geomagnetism on climatic variation[4][5]. such as the Concorde, space weather forecasts However, in order to determine the magni- have led to alteration of course and/or altitude. tude of the effects of space-weather variation Furthermore, in light of the continued on weather and climate―in terms of factors enhancement of performance and integration such as trace atmospheric components, of electronic parts used for aircraft control, aerosols, clouds (vapor), oceans, wind sys- research and development in these areas is tems, the Earth's axis, and in terms of the also focusing on resistance to space radiation, interaction among these factors―continuous as with the case of space-borne devices, to be observation and research is required. described in next chapter.

164 Journal of the Communications Research Laboratory Vol.49 No.4 2002 5 Influence on spacecraft increase effective shield thicknesses; however, no method has been found to cope adequately 5.1 Influence of high-energy particle with more than an occasional increase in elec- particles on devices aboard space- tron flux of more than a few MeV. craft Continued technical development has led High-energy particles damage electronic to greater miniaturization and integration of devices in satellites, generate erroneous sig- circuits. These high-performance integrated nals (as with the "single event effect," or circuits are configured to operate with a small- "SEE"), and quickly degrade or disable com- er current, which means that higher-perform- ponent functions. Moreover, accumulated ance circuits are more susceptible to the single exposure (the total dose effect) shortens the event effect, deep dielectric charge, and so on; lives of devices, especially those installed on therefore continued improvement in the radia- satellite surfaces, such as solar panels. In one tion resistance of such circuits will be increas- case a single SPE accelerated the degradation ingly important in the future. It is worth not- of a solar cell panel by a few years or more. ing that the high radiation resistance of such If the arrival of high-energy particles and components leads to poor cost-performance the conditions of the plasma environment sur- due to the restricted range of applications of rounding a satellite could be predicted in these items, contributing to the elevation of advance, damage could be minimized by turn- overall satellite costs. Therefore, establish- ing off high-voltage power supplies, initiating ment of appropriate radiation-environment backup calculation modes, or temporarily models and the development of the most accu- housing solar-cell panels. rate technology for prediction of radiation A plasma environment of comparatively damage (allowing, for example, prediction of low energy in the surroundings of a satellite a single event effect generation rate) stands as can trigger erroneous operation due to electro- an important target of technological develop- static discharge ("ESD"), which is caused by ment, that will bring direct benefits to space- excess charge on the satellite surface, poten- craft design and cost. tially shortening the life of the satellite itself. Today, it has become possible to avoid much 5.2 Influence of atmosphere on orbit of the damage caused by surface charging and control of spacecraft abnormal discharge phenomena through the Increased heat (amounting to 1013 Wat incorporation of conductivity and insulation maximum) generated by auroras and solar design into satellite construction (using anti- radiation (mainly ultraviolet light) change static coatings, etc.). atmospheric density (composition and temper- On the other hand, in recent years a signif- ature) and wind systems in the upper atmos- icant problem has been known in the form of a phere. Therefore, especially in orbiting satel- phenomenon referred to as "deep dielectric lites with perigees at altitudes of a few hun- charge" or "bulk charge," attributed to a group dred kilometers, satellite orbits and attitudes of high-energy "killer" electrons in the outer will be subject to abnormal conditions, due to radiation belt. With this phenomenon, high- variations in atmospheric drag. This influence energy electrons (over a few hundreds of keV) will appear as excessive thruster injection in enter a satellite in the form of accumulated orbital maintenance in the short term, and will inside the dielectrics of cables, manifest itself in shortened satellite life in the semiconductor devices, etc.; when the charge long term. In the worst case, these phenome- surpasses insulation limits, an abnormal cur- na may lead to earlier-than-anticipated failure rent pulse is generated. To cope with this phe- and descent of the satellite. Moreover, at the nomenon, efforts have been made to conduct time of atmospheric entry of manned space- careful grounding of devices and cables and to craft (such as the ), if calculations

TOMITA Fumihiko 165 do not take these effects into consideration, moon's surface, and on Mars. Fatal accidents the lives of space crews will be at risk. due to radiation exposure cannot be ruled out. At an altitude of approximately 400 km, 5.3 Influence of geomagnetism on with an orbital inclination of 51.6û, the ISS attitude control of spacecraft has now begun to host long-term manned Geomagnetic storms exert undesirable space operations, introducing a detailed model effects on satellites that perform attitude con- of radiation-exposure using the data collected trol using geomagnetic sensors. If the influ- onboard various space shuttles and the ence is deadly strong, various satellite func- space station. The results have led to the pre- tions that depend on the attitude are temporari- diction that when an stays onboard ly paralyzed; thruster fuel is then required for the ISS under normal environmental condi- frequent attitude recovery. Such effects ulti- tions (with no SPEs), the effective exposure is mately have an influence on satellite service about 1 mSv/day, and that during several days life. of an SPE, the value increases by a factor of In such cases, damage can be minimized approximately ten to one hundred times the by temporarily interrupting the geomagnetic- above case. Moreover, during extra-vehicular sensor attitude-control mechanism in accor- activity ("EVA"), the exposure rises to several dance with space weather forecasts. times that of onboard activities, and the expo- sure of skin and organs near the body surface 5.4 Influence on human activities in increases accordingly. space As shown in Fig.4, ordinary people on the The high-energy particles that come from ground are exposed to radiation of approxi- space (space radiation) exert not only an unde- mately 1 mSv for one X-ray photograph, and a sirable influence on devices aboard satellites reference value of annual exposure is set to 5 and spacecraft but also have serious harmful mSv. The reference value for radiation work- effects on human activities on the ISS, on the ers in nuclear-power facilities in Japan and Radiation dose equivalent (cSv)

Fig.4 Comparison between expected values and reference values for radiation exposure in space

166 Journal of the Communications Research Laboratory Vol.49 No.4 2002 Table 1 Exposure limit for Japanese aboard ISS

similar personnel is set to ten times that of Protection and Measurements) and the ordinary individuals, in consideration of the NASDA (National Space Development risks of the work involved, whereas in the case Agency of Japan) have come to the conclusion of astronauts in NASA (U.S. National Aero- that it is appropriate to set up an exposure nautics and Space Administration), the refer- limit for astronauts based on a lifetime excess ence value for annual exposure is 500 mSv risk of cancer mortality of 3 % (normally the (0.5 Sv/year) for bone marrow, in light of the risk is 15-18 %). The results are shown in special nature of their duties[7][8]. Table 1[9]. The vertical axis denotes dose equivalent The upper figure shows career effective (unit: cSv, centisievert) expressed in logarith- dose limits. The lower figure shows equiva- mic form. lent dose limits for the critical organs. Cited In the case of an astronaut onboard the from a report of Space Radiation Health Sub- ISS, even in the absence of a sudden event committee of Manned Sup- (such as an SPE) or any EVA, it is expected port Committee of National Space Develop- that exposure over several months exceeds the ment Agency of Japan. reference value for radiation workers in Japan. It is anticipated that from 2020 to 2050 This leads to the question of where to set the and after, manned spacecraft will travel out- standards for risk in terms of radiation expo- side the magnetosphere of the Earth, and that sure for professionals engaged in special mis- manned Moon operations and exploration of sions, such as manned space experimentation Mars will be carried out. In these cases, or exploration of the Moon or of Mars. although exposure to radiation belt particles The NCRP (National Council on Radiation may be eliminated, the exposure to GCRs and

TOMITA Fumihiko 167 SPE will increase, as space travelers will no lished, when a warning of a significant distur- longer be protected by the magnetospheric bance is issued by the SEC, the warning is barrier. Consequently, the total exposure dose transferred immediately to space-shuttle mis- when not encountering SPE will range from sion control through SRAG (or directly), 300 mSv to 700 mSv. However, in these allowing those in charge to make a prompt cases, unlike the case of the ISS―in which the decision, such as suspension of EVA. Russia, astronaut can go back to Earth on the space for its part, has established the Institute for shuttle or the like with comparative ease―the Biomedical Problems, with the influence of astronaut can encounter significant SPE, the space radiation environment as one of its depending on the period of solar activity; major research themes, ranking alongside the therefore countermeasures must be established influence of zero gravity and other such in advance. At the least, space weather fore- topics[10]. casts (featuring highly accurate SPE predic- Measures required for safe utilization of tion), in-situ radiation measurement, and the ISS include monitoring of the exposure installation of a shelter for emergency evacua- doses of individual astronauts at all stages― tion will be required. before boarding the ISS, while onboard, and "Space tourism" in the vicinity of the after boarding; these results are then recorded Earth will also likely become reality. Accord- for use in radiobiological research. While ingly, it can be imagined that a reference value astronauts are onboard, not only is individual for radiation exposure will be set for such dose monitoring required, but the energetic- sightseers, according to length of stay (in particle environment in several positions days) in space, with the above-mentioned ISS inside and outside the ISS must be measured reference value as an upper limit. If the sight- comprehensively and continuously (in terms seers encountered (or were likely to of types of particles, energy spectra, etc.). encounter) SPE, they would be returned to Along with the above, space-weather mon- Earth as soon as possible. itoring is also required; specifically, forecast- ing and "nowcasting" (determinations of cur- 6 International space station rent states) of factors that affect the space radi- operation in the near future ation environment in the vicinity of the ISS (such as SPEs) must be conducted periodical- A system of protecting astronauts from ly, with greater frequency as required. exposure to space radiation was established by It is conceivable that an ISS operation sys- NASA in the U.S. when the Gemini program tem will be agreed upon among the participat- was first underway, and the system entered ing countries within a few years. An operation full use when the began; thus system such as the one shown in Fig.5 can be it may be said that space weather information imagined, based on the current system was first applied to manned space activities employed by the U.S. The roles of the com- during this period. Currently, the Space Envi- ponent system elements indicated in Fig.5 is ronment Center (SEC) of the National Ocean- shown in Table 2. ic and Atmospheric Administration (NOAA) Space weather is continuously monitored of the Department of Commerce, and the 55th by the ISES (International Weather Squadron (55th WX) of the United Service), and nowcasting and forecasting States Air Force (USAF) are jointly responsi- information is also issued every few hours. ble for space weather forecasts. During space- The results are sent to SRAG, an international shuttle missions, the SEC and the Space Radi- organization that analyzes and examines the ation Analysis Group (SRAG) of the Johnson radiation weather specifically in the vicinity of Space Center (JSC) exchange information on the ISS, and as a result of consultations a 24-hour basis. In the system thus estab- between the ISES and SRAG, the nowcast and

168 Journal of the Communications Research Laboratory Vol.49 No.4 2002 Fig.5 Anticipated ISS operation support system

Table 2 Various component system elements for ISS operations support and their roles

the forecast for the radiation weather in the a group of aerospace medical specialists vicinity of ISS are recorded. The recorded (flight surgeons). information is sent to an international group of Based on the information, analytical aerospace medical specialists, and is used to results, and advice provided, the flight director evaluate astronauts' health. The results are communicates with the ISS crew via CAP- then reported to the flight director, the final COM and determines a detailed schedule of person in charge of ISS operations. Addition- manned space activities, such as EVA, to be ally, since biomedical factors other than the executed by the astronauts. space radiation environment―such as zero gravity and long-term confinement in an 7 Space weather forecast as part enclosed space―have complex effects on the of the infrastructure in 2050 human body in the ISS, analysis of these fac- tors and related predictions are performed by As stated previously, space weather various expert biomedical engineers (BME) to already affects the daily life and health of

TOMITA Fumihiko 169 Fig.6 Overall scenario of manned space activities (draft). Cited from a report of the Space Infra- structure Study Group of Japan human beings through its influence on a vari- countries, such as China, and on islands in the ety of artificial systems. International short- Pacific Ocean), the use of communication wave broadcasting, radio communications for satellites forms an essential part of the societal aircraft and sea vessels with no alternate infrastructure. The use of a global-scale high- means of communication, long-distance power speed space-communication network using transmission in high-latitude regions, high- inter-satellite communication, in addition to precision GPS navigation, and a host of other global environmental monitoring using multi applications may be strongly affected by satellites, may also be expected to grow in space-weather variations. Space-weather importance and scope. In terms of more nowcasting and forecasting will prove sophisticated advanced satellite use, more extremely useful in the safe operation of these satellites will be launched into new kinds of systems, albeit naturally less important in orbits (such as quasi-zenith orbits), and a solar practice than ground-weather reports. power satellite will become reality as well. It is the author's opinion that it will take Moreover, it is predicted that space applica- until between 2020 and 2050 for people to sense tions will also be pursued simply to ensure a close daily connection with space weather greater global safety. Since space weather forecasts and consequently view related may often have serious undesirable effects on research as practical and necessary in society. satellites in the vicinity of the Earth, space- Today the use of meteorological and weather forecasts will become increasingly broadcasting satellites has become a part of indispensable in the operation of increasingly daily life, and more and more people are rely- diverse satellites. ing on navigation using satellites. Further, in Furthermore, as can be seen from Fig.6 many regions (particularly in Southeast Asian taken from a report of the Space Infrastructure

170 Journal of the Communications Research Laboratory Vol.49 No.4 2002 Study Group of Japan, and also in light of the time a planet was formed of such convenient prediction that China will become the third dimensions and location as to produce Earth- nation to achieve manned space flight around type life―Earth. Less than one billion years 2003, space-environment activity and develop- after Earth's formation, life first appeared; sea ment may easily be expected to progress dra- plants began to emit oxygen into the atmos- matically[11]. phere, and an ozone layer was formed; then The mystery of the evolution of life on the flora appeared on land, followed by the Earth may be illuminated by manned explo- fauna. Then, approximately one million years ration of Mars, the only other planet in the ago, one creature came to evolve a relatively solar system likely to have traces of life. Such large brain, allowing it to consider and imag- exploration must be accomplished by astro- ine its future. If the time from the Earth's nauts, as there is a limit to the discoveries birth to the present were viewed in terms of a afforded by unmanned exploration alone. In single year, man's emergence at this time this context, during the slightly more than two would have taken place at 10:53 pm on years of space flight required for a round trip to December 31. Evolution to date has developed Mars, the safety of the crew must be protected gradually in most cases, although occasionally through reliance on space-weather forecasts. significant events have led to rapid changes, Observations of Earth by manned space- affecting the history of the entire Earth. craft may also be carried out to enable us to Humans, with their large brains, have come to cope flexibly and effectively with a number of create a small history of their own against the critical situations. Moreover, it is also likely backdrop of the vast expanse of Earth's histo- that transportation technologies, such as those ry, and in very little time have managed to related to the space shuttle, will progress fur- have an impact on the entire Earth, affecting ther; sightseeing businesses may spring up to even the atmospheric environment, resulting cater to civilian space travel, and consequently in the world we are faced with today. the number of people traveling into space may In the flow of history, human beings came increase dramatically. There is also the possi- to learn that their planet is round; Vasco da bility that mankind may return to the Moon, as Gama, Magellan, Columbus, and others thus a site of resource exploration and to perform set off to navigate the vast oceans, acquiring various observations and experiments. The new knowledge through their explorations, at safety of these people, orbiting the Earth or the same time expanding the sphere of human working on the Moon, must also be protected habitation. through space-weather forecasts. Reflecting on this history, I would argue In light of the above, it can be concluded that Gagarin's manned space flight in April, that space-weather forecasting, a field current- 1961 and the landing of Apollo 11 on the ly in the phase of basic research and develop- Moon in July, 1969 are more significant ment of necessary technologies, will eventual- events for mankind than the discovery of the ly form an indispensable element of the socie- American continent by Columbus in October, tal infrastructure. 1492. We are lucky to have lived in the 20th century and to have had the opportunity to 8 Concluding remarks witness such historical events, and I feel com- pelled to say that we must make strenuous Long ago―4.55 billion years before the efforts to conduct further space development, current era―our solar system was created as a to pass such good fortune on to the next gener- planetary system following several genera- ation. Space is waiting for mankind, promis- tions of such system development throughout ing ever-increasing knowledge and further the universe following the Big Bang; at this evolution.

TOMITA Fumihiko 171 References 1 Wave Summit Course, Science of Space Environment, Ohmusha, March, 2001. 2 American Geophysical Union NEWS, American Geophysical Union / Bell Laboratories / New Jersey Institute of Technology Joint Release, 6, March, 2002 AGU RELEASE NO. 02-08. 3 Physics in Solar-Planetary Environment, Hiroshi Maeda, Kyohritsu Pub. co. ltd., December, 1982. (in Japan- ese) 4 Tinsley, B. A., and Deen, G. W., Apparent tropospheric response to MeV-GeV particle flux variations: A con- nection via electrofreezing of supercooled water in high-level clouds?, J. Geophys. Res., 96, 22283-22296, 1991. 5 Watanabe, T., and Fujita, E., Meteorological correlation with solar-terrestrial phenomena: a provisional study, Proc. NIPR Symp. On Upper Atmos. Phys., No. 7, 60, 1994. 6 Study of Radiation Fields and Dosimetry at Aviation Altitudes, Contract Number: F14P-CT950011, Final Report January 1996- June 1999. NCRP, Guidance on Radiation Received in Space Activities, National Council on Radiation Protection and Measurements, Report-98, 1989. 7 NCRP, Guidance on Radiation Received in Space Activities, National Council on Radiation Protection and Measurements, Report-98, 1989. 8 NCRP, Acceptability of risk from radiation - Application to human space flight, National Council on Radia- tion Protection and Measurements, Symposium Proceedings No. 3, 1997. 9 Report of Space Radiation Health Subcommittee of Manned Space Technology Support Committee of National Space Development Agency of Japan (NASDA), December, 2001 (in Japanese) and private com- munication with NASDA. 10 Bioscience in Space, Ken-ichi, Ijiri, Asakura Pub. co. ltd., December, 2001. (in Japanese) 11 Final Report of Committee on Space Infrastructure, May, 2000. (in Japanese)

TOMITA Fumihiko, Ph. D. Head, Research Planning Office, Strategic Planning Division Space Weather Science for Manned Space Activities

172 Journal of the Communications Research Laboratory Vol.49 No.4 2002