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1 Introduction

Space weather refers to various physicaland chemical phenomena that occur naturallyin a region that extends from an altitude of afew tens of kilometers into the solar system, inwhich the main component is plasma. There-fore, space-weather research is an interdisci-plinary and interactive research field rangingfrom geophysics to astronomy, coveringaeronomy, space physics, and solar physics.

However, as is the case in the fields ofgeophysics, space-weather research holdspractical interest in terms of the ways in whichthe natural environment (in this case extend-ing from the Earth to the Sun) affects humanactivities. It is in this context that the termspace "weather" was coined.

From this viewpoint, the definition ofSpace weather is as follows: "Conditions onthe Sun and in the solar wind, magnetosphere,ionosphere and thermosphere that can influ-ence the performance and reliability of space-borne and ground-based technological systemsand can endanger human life or health."

A prime example of space weather activitycan be found in forecasting research, in whicha wide range of research activities―from themost basic research to complex applications―

are applied to forecasting space weather in apractical and useful manner[1].

This paper describes an overview ofspace-weather applications, addressing issuessuch as how space-weather research and fore-casting will benefit humanity, and possiblenear-future uses in the context of full opera-tion of the International Space Station (the"ISS") and applications involving mannedMars explorations and space tourism, envi-sioned for the middle of this century.

2 Sources of space-weather vari-ation

In order to ensure human safety and pro-tect various man-made systems, it is essentialto research and understand the sources andglobal structure of space weather, which has asignificant effect on such safety and systems.Since individual research achievements relat-ing to the area from the upper atmosphere tothe Sun have been discussed in detail by otherauthors, this paper will summarize the primarysources of space-weather variation (Fig.1).

The Sun is the greatest energy source inthe region from the upper atmosphere into thesolar system.

In the surroundings of the geomagneto-

TOMITA Fumihiko

5-4 Space Weather Forecast in the FutureManned Space Era

TOMITA Fumihiko

Space weather is the conditions of the Sun and in the solar wind, magnetosphere, iono-sphere and thermosphere that can influence the performance and reliability of space-borneand ground-based technological systems and can endanger human and animal life orhealth. In 2050, everyone will be able to enjoy his/her space tour. The space weatherresearch will transform into more and more practical science in that future manned spaceera.

Keywords Space weather forecast, Manned space activities, Space radiation environment

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sphere, the "solar wind" constantly blowsfrom the Sun into the solar system, accompa-nied by a magnetic field. The characteristicsof the solar wind vary significantly, temporallyand spatially, in the region of its origin nearthe Sun, creating disturbances in the geomag-netosphere and the upper atmosphere.

Furthermore, sudden eruptions of "plasmaclouds" (referred to as coronal mass ejections,or "CMEs") and a "flare" are generated inactive regions on the surface of the Sun, oftenresulting in space-weather variations.

Additional factors other than those origi-nating in the Sun also lead to space-weathervariation; these include galactic cosmic rays,meteorites, and debris.

We will describe the ways in which space-weather variation originating from suchsources affects human life in Fig.2.

3 Influence on the ground

3.1 Radio communicationsAll communications using radio waves are

influenced by space weather. In particular,short-wave (HF band) radio waves in the polarregion are sometimes absorbed by the iono-sphere when auroras appear and do not returnto the ground.

Frequencies of mobile wireless terminalshave already been shifted to the UHF and SHFbands, and it is expected that in the future ter-restrial communications will no longer relystrictly on the HF band. Nevertheless, numer-ous ham radio stations around the worldremain active, and since these involve rela-tively simple transmitter/receiver systems,HF-band radio communications are expectedto play a number of continued roles: in inter-national short-wave broadcasting, informationcommunication in regions of low population

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Sources of space-weather variation that affect human activities on Earth and in spaceFig.1

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densities, communications at the time of a dis-aster or emergency, communications for mili-tary purposes, and in backup communicationsystems. Therefore, in order to support safeoperations in these and other contexts, anunderstanding of the nature of ionosphericstorms and the prediction thereof will play anecessary role continuously into the future.As a point of note, although mainstream navi-gation communications for aircraft and shipsare gradually moving toward satellite commu-nications, many users today continue toemploy VHF-band (short-distance) and HF-band (long-distance) communications withground/land facilities.

Although satellite broadcasting and com-munications between satellites and the groundhave become an essential part of modern life,ionospheric storms have undesirable effects onsatellite-related radio-wave propagation fromthe VHF band to the SHF band, as the propa-gation paths of these bands pass through theionosphere. Specifically, in cases in which the

direction of radio-wave propagation is nearlyparallel to the direction of the Sun's rays, solarradio bursts are extremely likely to have directundesirable effects on satellite broadcastingand communications, especially on communi-cations between geostationary satellites andthe ground.

Space weather also affects users of cellular(i.e., mobile) phones, whose numbers haveincreased explosively in recent years. It ispredicted that the frequency of failed calls, inwhich a cellular-phone user cannot reach hisor her party due to increased noise levelcaused by solar radio bursts, is at least onceevery 3.5 days at the time of solar maximum,and at least once every 18.5 days during solarminimum[2]. Furthermore, cellular phonesmay become more susceptible to the undesir-able effects of space weather variations in thefuture through reduction in the transmitting/receiving electric power used (for purposes ofsafety and further miniaturization of telephonesets). Most interference in communication

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Space weather factors affecting various human activities Such variation may, in somecases, be life-threatening

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between base stations and cellular phones dueto solar radio bursts occurs at sunrise and sun-set, when solar altitude is low.

Although the undesirable effect of naturalphenomena such as magnetospheric/ionos-pheric storms on radio communications andbroadcasting cannot be avoided even withhighly accurate space weather forecasts, dam-age can be minimized by suspending impor-tant communications at the predicted timesand, if necessary, by switching to other way ofcommunications, such as satellite circuits,optical fiber lines, or cable.

3.2 NavigationFor ship navigation systems that use the

LF and VLF bands for LORAN, OMEGA,and so on, it is important to determine ionos-pheric height precisely. Variation in theheights of ionospheric layers at the time ofmagnetospheric/ionospheric storms can resultin errors on the order of km in positional cal-culation.

GPS (Global Positioning System) technol-ogy has become an indispensable element ofdaily life due to the popularization of automo-bile navigation systems and other applications,while more advanced uses of highly accurateand reliable positional information is envi-sioned―in aircraft takeoff and landings and incontrol of distance between automobiles, forexample. Since the sudden change in the elec-tron density of the ionosphere accompanying amagnetospheric/ionospheric storm generates ashort-period radio-wave variation referred toas scintillation, with an undesirable effect onGPS signals, space weather forecasts will beindispensable in the development of positionalmeasurement systems requiring greater accu-racy. It is worth noting that the United Statesand a number of other countries are alreadyapplying space weather forecasts to high-pre-cision military GPS applications.

With an accurate space weather forecast oran awareness of the instantaneous state ofcommunications (positional error informa-tion), serious accidents otherwise attributableto reliance on GPS navigation alone can be

avoided.

3.3 Terrestrial long-distance wiredcommunication lines, power lines, etc.

In 1849, the influence of space weather onman-made systems was reported; specifically,the electromagnetic induction phenomenonaccompanying geomagnetic storms and affect-ing terrestrial cable communication (tele-graph) was noted. Today the roles of medi-um/long-distance communications have beentaken over by satellite communications andfiber-optical communications (after briefexperimentation in microwave communica-tions and other technologies); however, theinfluence of space weather remains strong, inits effects on satellite communications asdescribed above as well as on optical fibercommunications, insofar as the latter relies onlong-distance power transmission to repeaters(as will be described later).

Modern life relies heavily on electricpower, generated primarily through hydraulic,thermal, and nuclear power, with a small butgrowing contribution from wind power, geot-hermal energy, and solar power. Consumptionof electricity is extremely localized dependingon population density, and it is often the casethat the sites of power consumption are farfrom the sites of production, to minimize thepollution from power plant facilities on resi-dential areas. This has resulted in the expan-sion―both within and between nations―oflong-distance power lines carrying vastamounts of electric power.

Long-distance electric power lines areaffected by induced currents caused by varia-tions in the geomagnetic field. The effects canbe serious, especially in high-latitude regions,where variation in the geomagnetic field islarge. For example, a nine-hour power failureoccurred in Canada in March, 1989, affectingabout 6 million people. Fig.3 shows the inte-rior of a transformer that was burnt out by thesame magnetic storm in a power plant in NewJersey, U.S.

The damage was caused by a magneticstorm on March 13, 1989 (Photograph taken

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by U.S. Electric Power Research Institute).

In order to minimize the effects of thisinduced current (referred to as a geomagneticinduced current, or "GIC"), electric powercompanies and other relevant parties world-wide are carrying out various research anddevelopment projects, including those relatingto space weather, and at the same time arecooperating to establish multiple route net-works and systems to supply electric powervia safe routes during high-risk periods.Therefore, it is becoming possible to preparefor the worst, avoiding electric power failureby selecting routes that are less susceptible togeomagnetic disturbances and by establishingbackup lines that are always available in theevent of magnetic storms. Such preparation,however, depends upon the availability ofadvance magnetic storm data obtained viaspace weather forecasts.

Long-distance pipelines from oil fields topower-generation facilities, especially those inhigh-latitude regions, are similarly affected bygeomagnetic storms. Because induced currenton the surface of a metallic pipe promotes cor-rosion of junction or grounding components ofthe pipe, oil-mining enterprises and trans-portation enterprises are conducting researchand development of effective methods of pro-cessing the induced current.

3.4 Magnetic-field-sensing capabili-ties of animals and human beings

Some fish, birds, and mammals haveorgans for geomagnetic detection, located nearthe olfactory organs; it is well known, forexample, that carrier pigeons and dolphinsalike rely on detection of the Earth's magneticfield.

In one case, numerous pigeons in an inter-national carrier-pigeon race were lost due to alarge geomagnetic storm. Today such racesare scheduled with reference to space weatherforecasts. Moreover, research on the influenceof magnetic-field variation on the human bodyhas also begun[3].

3.5 Aurora forecast for sightseeingSince Gauss first measured the total mag-

netic force of the Earth at the beginning of the18th century, the Earth's magnetism has tend-ed to decrease steadily. Estimation show thatif this decrease continues at this rate, in about700 years, auroras will be seen even in Japan,and 500 years after that, the Earth's magnetismwill have been reduced to zero. This alsomeans that dangerous high-energy particleswill increasingly penetrate to Earth surfacefrom space.

Auroras, natural phenomena occurring inthe high-latitude regions, have become objectsof sightseeing in Alaska and Northern Europe,etc. In order to view these curtain-like aurorasrippling in the skies, and in particular toenable viewing of auroral expansions, it willhelp to predict the arrival of geomagneticstorms through space weather forecasts,enabling those who wish to view these phe-nomena to head to high-latitude regions at theideal times.

3.6 Influence on terrestrial semicon-ductor devices

Most radiation on the ground originatesfrom the ground, buildings, air, foods, andother materials containing radioactive sub-stances; the proportion of radiation from spacerepresents about 1/3 of the whole at Earth sur-face. Most of this radiation comes in the formof high-energy particle showers originating ingalactic cosmic rays (GCRs); variations in

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Coil inside an electric power trans-former burnt out by space storm (Pho-tograph courtesy of the United StatesElectric Power Research Institute)

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GCR of 10 % or so cannot be said to exert asignificant influence on terrestrial life.

However, technological development isleading to greater miniaturization of semicon-ductor devices, integrated circuits, and similardevices, resulting each year in greater integra-tion and sophistication (as will be describedlater in discussion of the influence of high-energy particles on devices aboard aircraft andspacecraft). Furthermore, higher-performancedevices are configured to work with smallercurrents; as a result, the influence of high-energy particles on semiconductor devices andintegrated circuits is becoming increasinglynon-negligible even in terrestrial applications.

While the variable component of spaceweather does not exert a particularly largeinfluence on terrestrial events, care must betaken to mitigate the influence of constantradiation from space. For example, in order tostore high-precision semiconductor devices,CCDs, etc., safely for long periods, shieldedrooms made of concrete or equivalent materi-als are required.

3.7 Influence on climatic variationSpace weather includes the upper-atmos-

pheric environment of the Earth, and thisupper atmosphere connects continuously withthe terrestrial atmosphere. Therefore, it isexpected that variations in space weatherattributable to galactic cosmic rays and solaractivity affect the climate and weather of theEarth. Currently research is underway to lookfor correlations between various elements ofweather data and variations in the galactic cos-mic rays and solar energetic particles, whileadditional research is focusing on the effect ofsolar activity (e.g., numbers of Sunspots) andgeomagnetism on climatic variation[4][5].

However, in order to determine the magni-tude of the effects of space-weather variationon weather and climate―in terms of factorssuch as trace atmospheric components,aerosols, clouds (vapor), oceans, wind sys-tems, the Earth's axis, and in terms of theinteraction among these factors―continuousobservation and research is required.

4 Influence on aircraft

As mentioned above, space weatheraffects direct short-wave radio communica-tions and satellite communications betweenaircraft and base stations, and GPS navigation;in this context this chapter will discuss theinfluence of high-energy particles on aircraftin the space radiation environment.

As the number of international airlineflights continues to grow, with increasing pas-senger numbers, it has become difficult toignore the influence of space radiation on thecrew and passengers aboard aircrafts, espe-cially in planes that pass over regions of highlatitude in a "great-circle track." In thesecases, applicable sources of space radiationinclude GCR, present on a near-constant basis;radiation belt particles, permanently presentbut in varying intensity; and solar energeticparticles (SEP), which arrive suddenly andexert a significant influence for several days.It has been reported that if either a crew mem-ber or passenger flies a number of high-lati-tude flights, his/her annual exposure to radia-tion may exceed 1 mSv.

Particularly in the case of a crew membersubject to continual high-latitude exposure inthe course of his/her work, exposures as highas 3 mSv/year have been reported, and in thecase of passengers spending in excess of sev-eral hundred hours per year on high-latituderoutes, radiation exposure rates cannot beignored [6]. If the aircraft happens toencounter a solar particle event (SPE) whileflying at high altitudes over a high-latituderegion, there will be a spike in exposure dur-ing that flight; therefore, in the case of a high-latitude and high-altitude passenger airplanesuch as the Concorde, space weather forecastshave led to alteration of course and/or altitude.

Furthermore, in light of the continuedenhancement of performance and integrationof electronic parts used for aircraft control,research and development in these areas isalso focusing on resistance to space radiation,as with the case of space-borne devices, to bedescribed in next chapter.

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5 Influence on spacecraft

5.1 Influence of high-energy particleparticles on devices aboard space-craft

High-energy particles damage electronicdevices in satellites, generate erroneous sig-nals (as with the "single event effect," or"SEE"), and quickly degrade or disable com-ponent functions. Moreover, accumulatedexposure (the total dose effect) shortens thelives of devices, especially those installed onsatellite surfaces, such as solar panels. In onecase a single SPE accelerated the degradationof a solar cell panel by a few years or more.

If the arrival of high-energy particles andthe conditions of the plasma environment sur-rounding a satellite could be predicted inadvance, damage could be minimized by turn-ing off high-voltage power supplies, initiatingbackup calculation modes, or temporarilyhousing solar-cell panels.

A plasma environment of comparativelylow energy in the surroundings of a satellitecan trigger erroneous operation due to electro-static discharge ("ESD"), which is caused byexcess charge on the satellite surface, poten-tially shortening the life of the satellite itself.Today, it has become possible to avoid muchof the damage caused by surface charging andabnormal discharge phenomena through theincorporation of conductivity and insulationdesign into satellite construction (using anti-static coatings, etc.).

On the other hand, in recent years a signif-icant problem has been known in the form of aphenomenon referred to as "deep dielectriccharge" or "bulk charge," attributed to a groupof high-energy "killer" electrons in the outerradiation belt. With this phenomenon, high-energy electrons (over a few hundreds of keV)enter a satellite in the form of accumulatedelectric charge inside the dielectrics of cables,semiconductor devices, etc.; when the chargesurpasses insulation limits, an abnormal cur-rent pulse is generated. To cope with this phe-nomenon, efforts have been made to conductcareful grounding of devices and cables and to

increase effective shield thicknesses; however,no method has been found to cope adequatelywith more than an occasional increase in elec-tron flux of more than a few MeV.

Continued technical development has ledto greater miniaturization and integration ofcircuits. These high-performance integratedcircuits are configured to operate with a small-er current, which means that higher-perform-ance circuits are more susceptible to the singleevent effect, deep dielectric charge, and so on;therefore continued improvement in the radia-tion resistance of such circuits will be increas-ingly important in the future. It is worth not-ing that the high radiation resistance of suchcomponents leads to poor cost-performancedue to the restricted range of applications ofthese items, contributing to the elevation ofoverall satellite costs. Therefore, establish-ment of appropriate radiation-environmentmodels and the development of the most accu-rate technology for prediction of radiationdamage (allowing, for example, prediction ofa single event effect generation rate) stands asan important target of technological develop-ment, that will bring direct benefits to space-craft design and cost.

5.2 Influence of atmosphere on orbitcontrol of spacecraft

Increased heat (amounting to 1013 W atmaximum) generated by auroras and solarradiation (mainly ultraviolet light) changeatmospheric density (composition and temper-ature) and wind systems in the upper atmos-phere. Therefore, especially in orbiting satel-lites with perigees at altitudes of a few hun-dred kilometers, satellite orbits and attitudeswill be subject to abnormal conditions, due tovariations in atmospheric drag. This influencewill appear as excessive thruster injection inorbital maintenance in the short term, and willmanifest itself in shortened satellite life in thelong term. In the worst case, these phenome-na may lead to earlier-than-anticipated failureand descent of the satellite. Moreover, at thetime of atmospheric entry of manned space-craft (such as the space shuttle), if calculations

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do not take these effects into consideration,the lives of space crews will be at risk.

5.3 Influence of geomagnetism onattitude control of spacecraft

Geomagnetic storms exert undesirableeffects on satellites that perform attitude con-trol using geomagnetic sensors. If the influ-ence is deadly strong, various satellite func-tions that depend on the attitude are temporari-ly paralyzed; thruster fuel is then required forfrequent attitude recovery. Such effects ulti-mately have an influence on satellite servicelife.

In such cases, damage can be minimizedby temporarily interrupting the geomagnetic-sensor attitude-control mechanism in accor-dance with space weather forecasts.

5.4 Influence on human activities inspace

The high-energy particles that come fromspace (space radiation) exert not only an unde-sirable influence on devices aboard satellitesand spacecraft but also have serious harmfuleffects on human activities on the ISS, on the

moon's surface, and on Mars. Fatal accidentsdue to radiation exposure cannot be ruled out.

At an altitude of approximately 400 km,with an orbital inclination of 51.6˚, the ISShas now begun to host long-term mannedspace operations, introducing a detailed modelof radiation-exposure using the data collectedonboard various space shuttles and the Mirspace station. The results have led to the pre-diction that when an astronaut stays onboardthe ISS under normal environmental condi-tions (with no SPEs), the effective exposure isabout 1 mSv/day, and that during several daysof an SPE, the value increases by a factor ofapproximately ten to one hundred times theabove case. Moreover, during extra-vehicularactivity ("EVA"), the exposure rises to severaltimes that of onboard activities, and the expo-sure of skin and organs near the body surfaceincreases accordingly.

As shown in Fig.4, ordinary people on theground are exposed to radiation of approxi-mately 1 mSv for one X-ray photograph, and areference value of annual exposure is set to 5mSv. The reference value for radiation work-ers in nuclear-power facilities in Japan and

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Comparison between expected values and reference values for radiation exposure inspace

Fig.4

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se e

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similar personnel is set to ten times that ofordinary individuals, in consideration of therisks of the work involved, whereas in the caseof astronauts in NASA (U.S. National Aero-nautics and Space Administration), the refer-ence value for annual exposure is 500 mSv(0.5 Sv/year) for bone marrow, in light of thespecial nature of their duties[7][8].

The vertical axis denotes dose equivalent(unit: cSv, centisievert) expressed in logarith-mic form.

In the case of an astronaut onboard theISS, even in the absence of a sudden event(such as an SPE) or any EVA, it is expectedthat exposure over several months exceeds thereference value for radiation workers in Japan.This leads to the question of where to set thestandards for risk in terms of radiation expo-sure for professionals engaged in special mis-sions, such as manned space experimentationor exploration of the Moon or of Mars.

The NCRP (National Council on Radiation

Protection and Measurements) and theNASDA (National Space DevelopmentAgency of Japan) have come to the conclusionthat it is appropriate to set up an exposurelimit for astronauts based on a lifetime excessrisk of cancer mortality of 3 % (normally therisk is 15-18 %). The results are shown inTable 1[9].

The upper figure shows career effectivedose limits. The lower figure shows equiva-lent dose limits for the critical organs. Citedfrom a report of Space Radiation Health Sub-committee of Manned Space Technology Sup-port Committee of National Space Develop-ment Agency of Japan.

It is anticipated that from 2020 to 2050and after, manned spacecraft will travel out-side the magnetosphere of the Earth, and thatmanned Moon operations and exploration ofMars will be carried out. In these cases,although exposure to radiation belt particlesmay be eliminated, the exposure to GCRs and

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Exposure limit for Japanese astronauts aboard ISSTable 1

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SPE will increase, as space travelers will nolonger be protected by the magnetosphericbarrier. Consequently, the total exposure dosewhen not encountering SPE will range from300 mSv to 700 mSv. However, in thesecases, unlike the case of the ISS―in which theastronaut can go back to Earth on the spaceshuttle or the like with comparative ease―theastronaut can encounter significant SPE,depending on the period of solar activity;therefore countermeasures must be establishedin advance. At the least, space weather fore-casts (featuring highly accurate SPE predic-tion), in-situ radiation measurement, andinstallation of a shelter for emergency evacua-tion will be required.

"Space tourism" in the vicinity of theEarth will also likely become reality. Accord-ingly, it can be imagined that a reference valuefor radiation exposure will be set for suchsightseers, according to length of stay (indays) in space, with the above-mentioned ISSreference value as an upper limit. If the sight-seers encountered (or were likely toencounter) SPE, they would be returned toEarth as soon as possible.

6 International space stationoperation in the near future

A system of protecting astronauts fromexposure to space radiation was established byNASA in the U.S. when the Gemini programwas first underway, and the system enteredfull use when the Apollo program began; thusit may be said that space weather informationwas first applied to manned space activitiesduring this period. Currently, the Space Envi-ronment Center (SEC) of the National Ocean-ic and Atmospheric Administration (NOAA)of the Department of Commerce, and the 55thWeather Squadron (55th WX) of the UnitedStates Air Force (USAF) are jointly responsi-ble for space weather forecasts. During space-shuttle missions, the SEC and the Space Radi-ation Analysis Group (SRAG) of the JohnsonSpace Center (JSC) exchange information ona 24-hour basis. In the system thus estab-

lished, when a warning of a significant distur-bance is issued by the SEC, the warning istransferred immediately to space-shuttle mis-sion control through SRAG (or directly),allowing those in charge to make a promptdecision, such as suspension of EVA. Russia,for its part, has established the Institute forBiomedical Problems, with the influence ofthe space radiation environment as one of itsmajor research themes, ranking alongside theinfluence of zero gravity and other suchtopics[10].

Measures required for safe utilization ofthe ISS include monitoring of the exposuredoses of individual astronauts at all stages―before boarding the ISS, while onboard, andafter boarding; these results are then recordedfor use in radiobiological research. Whileastronauts are onboard, not only is individualdose monitoring required, but the energetic-particle environment in several positionsinside and outside the ISS must be measuredcomprehensively and continuously (in termsof types of particles, energy spectra, etc.).

Along with the above, space-weather mon-itoring is also required; specifically, forecast-ing and "nowcasting" (determinations of cur-rent states) of factors that affect the space radi-ation environment in the vicinity of the ISS(such as SPEs) must be conducted periodical-ly, with greater frequency as required.

It is conceivable that an ISS operation sys-tem will be agreed upon among the participat-ing countries within a few years. An operationsystem such as the one shown in Fig.5 can beimagined, based on the current systememployed by the U.S. The roles of the com-ponent system elements indicated in Fig.5 isshown in Table 2.

Space weather is continuously monitoredby the ISES (International Space EnvironmentService), and nowcasting and forecastinginformation is also issued every few hours.The results are sent to SRAG, an internationalorganization that analyzes and examines theradiation weather specifically in the vicinity ofthe ISS, and as a result of consultationsbetween the ISES and SRAG, the nowcast and

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the forecast for the radiation weather in thevicinity of ISS are recorded. The recordedinformation is sent to an international group ofaerospace medical specialists, and is used toevaluate astronauts' health. The results arethen reported to the flight director, the finalperson in charge of ISS operations. Addition-ally, since biomedical factors other than thespace radiation environment―such as zerogravity and long-term confinement in anenclosed space―have complex effects on thehuman body in the ISS, analysis of these fac-tors and related predictions are performed byvarious expert biomedical engineers (BME) to

a group of aerospace medical specialists(flight surgeons).

Based on the information, analyticalresults, and advice provided, the flight directorcommunicates with the ISS crew via CAP-COM and determines a detailed schedule ofmanned space activities, such as EVA, to beexecuted by the astronauts.

7 Space weather forecast as partof the infrastructure in 2050

As stated previously, space weatheralready affects the daily life and health of

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Various component system elements for ISS operations support and their rolesTable 2

Anticipated ISS operation support systemFig.5

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human beings through its influence on a vari-ety of artificial systems. International short-wave broadcasting, radio communications foraircraft and sea vessels with no alternatemeans of communication, long-distance powertransmission in high-latitude regions, high-precision GPS navigation, and a host of otherapplications may be strongly affected byspace-weather variations. Space-weathernowcasting and forecasting will proveextremely useful in the safe operation of thesesystems, albeit naturally less important inpractice than ground-weather reports.

It is the author's opinion that it will takeuntil between 2020 and 2050 for people to sensea close daily connection with space weatherforecasts and consequently view relatedresearch as practical and necessary in society.

Today the use of meteorological andbroadcasting satellites has become a part ofdaily life, and more and more people are rely-ing on navigation using satellites. Further, inmany regions (particularly in Southeast Asian

countries, such as China, and on islands in thePacific Ocean), the use of communicationsatellites forms an essential part of the societalinfrastructure. The use of a global-scale high-speed space-communication network usinginter-satellite communication, in addition toglobal environmental monitoring using multisatellites, may also be expected to grow inimportance and scope. In terms of moresophisticated advanced satellite use, moresatellites will be launched into new kinds oforbits (such as quasi-zenith orbits), and a solarpower satellite will become reality as well.Moreover, it is predicted that space applica-tions will also be pursued simply to ensuregreater global safety. Since space weathermay often have serious undesirable effects onsatellites in the vicinity of the Earth, space-weather forecasts will become increasinglyindispensable in the operation of increasinglydiverse satellites.

Furthermore, as can be seen from Fig.6taken from a report of the Space Infrastructure

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Overall scenario of manned space activities (draft). Cited from a report of the Space Infra-structure Study Group of Japan

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Study Group of Japan, and also in light of theprediction that China will become the thirdnation to achieve manned space flight around2003, space-environment activity and develop-ment may easily be expected to progress dra-matically[11].

The mystery of the evolution of life onEarth may be illuminated by manned explo-ration of Mars, the only other planet in thesolar system likely to have traces of life. Suchexploration must be accomplished by astro-nauts, as there is a limit to the discoveriesafforded by unmanned exploration alone. Inthis context, during the slightly more than twoyears of space flight required for a round trip toMars, the safety of the crew must be protectedthrough reliance on space-weather forecasts.

Observations of Earth by manned space-craft may also be carried out to enable us tocope flexibly and effectively with a number ofcritical situations. Moreover, it is also likelythat transportation technologies, such as thoserelated to the space shuttle, will progress fur-ther; sightseeing businesses may spring up tocater to civilian space travel, and consequentlythe number of people traveling into space mayincrease dramatically. There is also the possi-bility that mankind may return to the Moon, asa site of resource exploration and to performvarious observations and experiments. Thesafety of these people, orbiting the Earth orworking on the Moon, must also be protectedthrough space-weather forecasts.

In light of the above, it can be concludedthat space-weather forecasting, a field current-ly in the phase of basic research and develop-ment of necessary technologies, will eventual-ly form an indispensable element of the socie-tal infrastructure.

8 Concluding remarks

Long ago―4.55 billion years before thecurrent era―our solar system was created as aplanetary system following several genera-tions of such system development throughoutthe universe following the Big Bang; at this

time a planet was formed of such convenientdimensions and location as to produce Earth-type life―Earth. Less than one billion yearsafter Earth's formation, life first appeared; seaplants began to emit oxygen into the atmos-phere, and an ozone layer was formed; thenthe flora appeared on land, followed by thefauna. Then, approximately one million yearsago, one creature came to evolve a relativelylarge brain, allowing it to consider and imag-ine its future. If the time from the Earth'sbirth to the present were viewed in terms of asingle year, man's emergence at this timewould have taken place at 10:53 pm onDecember 31. Evolution to date has developedgradually in most cases, although occasionallysignificant events have led to rapid changes,affecting the history of the entire Earth.Humans, with their large brains, have come tocreate a small history of their own against thebackdrop of the vast expanse of Earth's histo-ry, and in very little time have managed tohave an impact on the entire Earth, affectingeven the atmospheric environment, resultingin the world we are faced with today.

In the flow of history, human beings cameto learn that their planet is round; Vasco daGama, Magellan, Columbus, and others thusset off to navigate the vast oceans, acquiringnew knowledge through their explorations, atthe same time expanding the sphere of humanhabitation.

Reflecting on this history, I would arguethat Gagarin's manned space flight in April,1961 and the landing of Apollo 11 on theMoon in July, 1969 are more significantevents for mankind than the discovery of theAmerican continent by Columbus in October,1492. We are lucky to have lived in the 20thcentury and to have had the opportunity towitness such historical events, and I feel com-pelled to say that we must make strenuousefforts to conduct further space development,to pass such good fortune on to the next gener-ation. Space is waiting for mankind, promis-ing ever-increasing knowledge and furtherevolution.

TOMITA Fumihiko

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

TOMITA Fumihiko, Ph. D.

Head, Research Planning Office,Strategic Planning Division

Space Weather Science for MannedSpace Activities

References1 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)