I CONTENTS

'A great solar flare is truly beautiful event that captivates the onlooker and fills him with a sense of awe. He may witness, over the space of an hour, the release of an enormous quantity of energy— the largest in the solar system - and its transformation into an incredibly complex variety of forms. Afterwards, he may wonder: how did it all begin?"

E. P. Priest University of St. Andrews, Scotland The Challenge: Understanding Solar Activity ...... 1 The Key: Solar Magnetism ...... 5 The Solution: SAMEX - Solar Activity Measurements Experiments ...... 7 SAMEX Research: Scientific Objectives and Observational Requirements ...... 11 SAMEX Instruments: State-of-the-Ad Solar Observations ...... 15 Shared Benefits: A Broad Community of Users ...... 19 A Current Need: Planning for the 21st Century ...... 23 The Challenge: Understanding Solar Activity

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1 A broad endeavor of solar understanding of more distant research is to understand the various celestial objects is limited by weaker aspects of solar activity, ranging from signals and lack of spatial resolution, the sporadic, explosive energy we can see and measure solar releases in flares to the ubiquitous phenomena with considerable clarity. heating of the corona. This quest is Many of the features we now take for important for guiding and testing our granted as characteristic of stars - understanding of magnetoplasma flares, coronae, spots - were phenomena in more remote discovered by first observing them on astrophysical objects as well as for the Sun. Solar observations are the understanding the Sun's modulation foundation of many of today's of Earth's space environment and astrophysical theories, and the Sun is atmosphere. a model for understanding other stars. The Sun is the only star near Our explanations of active galaxies enough to be observed in detail. By and exotic phenomena, such as studying it, we gain insight into stellar quasars and black holes, owe much features and processes elsewhere in to our observations of solar activity. the universe. While our physical Studying the Sun also gives us insight into events occurring nearby, in Earth's space environment and atmosphere. Observations of sunspots, flares, and the extended solar corona and detection of the solar wind in interplanetary space are the foundation of solar-terrestrial physics. It is evident that solar activity profoundly affects Earth and that improved solar observations are needed to understand and predict these relationships. The root cause of solar activity lies in the interaction between the ionized solar gases and the magnetic field generated by convective and rotational motions in the solar interior. Manifestations of this interaction include: The solar cycle • Emerging magnetic flux • Active regions and sunspots • Spicules • Coronal heating • Active filaments, surges, and sprays • Flares, coronal transients, and mass ejections. 2 The Sun is an important Space age research has laboratory for studying matter and transformed solar science, yet we are energy under extreme conditions that still developing a basic understanding cannot be duplicated on Earth. The of many fundamental solar basic laws of physics can be tested phenomena such as flares, coronal and refined through observations of holes, and magnetic field evolution. intense solar magnetic fields, To test current theories and answer explosive processes, and the unsolved questions, scientists need behavior of matter and energy across long-term, high-resolution the Sun's tremendous temperature observations of solar activity. scale. We have used a variety of PERPLEXING QUESTIONS observational techniques - from the The data base for solar science ground and from spacecraft - to today is two decades' worth of develop our understanding of solar extensive ground-based observations activity. The contributions to and spectacular, but occasional, knowledge from solar astronomy in observations from space. While some space are impressive. of the details of solar astrophysics are The first astrophysical X-ray now familiar, many basic questions observations were made by rocket- are still unanswered: borne instruments observing the Sun. These early results pointed the way to • What causes the sunspot cycle? the Skylab solar observatory (1973- • How do subsurface fields become 1974). Skylab provided the buoyant, emerge, diverge, and opportunity for prolonged, extensive submerge? views of the high-temperature solar - How (why) do sunspots form, chromosphere and corona, a plasma persist, and then disintegrate? threaded by magnetic fields. Coronal • What are spicules? holes were discovered and related to • How is the corona heated? the magnetic field patterns. • What causes filaments to activate and erupt? The Orbiting Solar Observatory (OSO) satellites extended knowledge • What is the basic mechanism that of the temperature structure of the leads to the explosive release of solar atmosphere. Later observations magnetic energy in the form of by the Solar Maximum Mission (SMM, energetic particles and radiation? 1980's) expanded our understanding • Why does the energy release occur of solar flares, explosive phenomena at places where there is no vertical fueled by the transformation of mag- magnetic field? netic energy. In 1985, Spacelab 2 • What are the dynamics and solar observations revealed new evolution of the coronal structure timescale features of the interplay above active regions? between magnetic fields and The common thread in all these convection in the photosphere. questions is the solar magnetic field.

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4 The Key: Solar Magnetism 74 051603 UT 1436 UI 06 1423 C. 13

a. Full disk magnetogram, 31 July 1985 National Solar Observatory, Kitt Peak b.Magnetogram showing details of magnetic field, 31 July 1985 AS4 Marsra Soace Flight Cere,

Region 80 July b. S . . -.

5 The answers to our questions In the visible layers of the solar are rooted in the Sun's magnetic field, atmosphere, we see this field shaping the single most important force in the and controlling the solar plasma, solar atmosphere. Since George originating with the convective Ellery Hale first demonstrated the motions of the subsurface plasma to existence of magnetic fields on the produce the solar activity cycle, Sun, we have come to realize the appearing in the supergranular cells pervasive influence of magnetism in as subarcsecond concentrations of the physics of solar activity. We can kilogauss fields, forming sunspots, trace its influence from the solar and providing the energy source for c. Magnetogram, interior up into the solar atmosphere the explosive phenomenon of solar 5-6 April 1980 and beyond, even to the surface of flares. NASA Marshall Space Flight Center our planet Earth. The X-ray, extreme ultraviolet d. Ha comparison, (XUV), and coronagraph images from 5-6 April 1980 Skylab forcefully demonstrated that Solar Optical Observing Network the entire outer solar atmosphere is largely a consequence of the magnetic fields extending above the photosphere. The structure, heating, and dynamics of the chromosphere and corona, from global scales down to the smallest scales yet resolved, are seen to be strongly controlled and basically caused by the magnetic Coronal loop structure LI S Naval Research Laboratory field. Thus, the key to understanding solar activity lies in detailed examination of the solar magnetic field and its interaction with the solar plasma. Observations must provide thorough knowledge of the vector field, its evolution and cyclic jf variations, and the process by which , magnetic energy is stored, converted, and released as solar activity. Ground-based observations • E) have provided some clues, but the 1. definitive observations must be made • -r;• •-• - from space. X-rays and most , :, ultraviolet radiation do not penetrate JK I.r:4Ty ,c the atmosphere, and it is impossible to achieve from ground-based observations the extreme sensitivity & ' • and high spatial resolution required *: •.• • :•' over long periods of time. Yet, to date, no space observations have been dedicated to this important purpose.

6 The Solution: SAMEX - Solar Activity Measurements Experiments

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Morphology: Magnetic Field Configuration Sunspot Magnetic Structure Topology: Current-Carrying Fields Magnetic Shear Across Neutral Lines Evolution: Changing Magnetic Fields Emerging-Submerging Magnetic Flux Kinematics: Photospheric Bulk Shearing Motions Dynamics: Pre-Flare Heating Flux Tube Interactions Magnetic Energy r4 MEETING THE SCIENTIFIC OBJECTIVES To address the fundamental problems of solar activity, we must WITH SAMEX explore the nature of the Sun's magnetic field. The Solar Activity SOLAR REQUIRED SAMEX Measurements Experiments (SAMEX) PHENOMENA OBSERVATION INSTRUMENTATION will be the first spacecraft mission dedicated to the study of solar New Emerging-Flux B, V magnetic fields and their role in solar • Photospheric Shearing activity. It will provide observations of Motions Vector Magnetograph the magnetic field through the solar • Flux tube interaction atmosphere in three dimensions, • Field cancellations using a highly sensitive vector Electric Currents B, V magnetograph to study the • Energy storage rates photosphere, a hydrogen-alpha • Coronal field configuration Magnetic Field Geometry telescope for observations of the chromosphere, and an XUV imager to • Photosphere B viewthe corona and transition region. -Chromosphere Ha J- Hu Telescope -Transition region XUV Lines The key scientific objectives of Soft 7 -Corona XUV, X-ray F XUVlmager SAMEX are: Flare Onset • To place on a quantitive basis our (early recognition) XUV, Soft X-ray understanding of the buildup and Ha, continuum- Ha Telescope storage of energy in the magnetic field and its relationship to structures at all levels in the solar atmosphere. • To identify the necessary conditions for release of energy in various solar transient phenomena. • To determine whether this knowledge is sufficient to predict where, when, how much, and in what form the energy will be released.

Chromosphere

U S Naval Research Laboratory (photo) 8 NASA Marshall Space Flight Center (spacecraft) Sunspot Group

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"Fiare The key features of SAMEX are: • Simultaneous observations with • Quantitative measurements of the three cospatial imaging instruments three-dimensional vector magnetic • Long periods of continuous field with three coaligned, cospatial observations over an extended instruments: mission lifetime. - Photospheric vector magnetograph SAMEX will provide data on magnetodynamic and magneto- - Chromospheric Ha imager - Coronal XUV imager hydrodynamic processes fundamental to all areas of • Unprecedented accuracy in these astrophysics: magnetic flux quantitative measurements: emergence, dynamic field - Measurement of the photospheric reconfigurations, reconnection and line-of-sight component to 1 G or magnetic instabilities, magneto- better acceleration of plasma and particles, - Measurement of the photospheric wave propagation, field-aligned transverse component to 30 G or current configurations and effects, better and the structure and general • High spatial and temporal dynamics of magnetoplasmas. resolution: SAMEX is envisaged as a joint, open project of the National - 0.5 arcsecond spatial resolution Aeronautics and Space over a 4 x 8 arcminute field of view - 5 minute or better temporal Administration (NASA) and the United resolution States Air Force (USAF).

Features Linked to the Solar Magnetic Field

Layer Quiet Sun Evolving Sun Dynamic Sun Photosphere Granules Pores Flares (white light) Network Sunspots Stressed Fields Umbral Dots Plage Convective Motions Supergranules Emerging Flux Evolving Flux Active Regions

Chromosphere & Fibrils Plage Flares Transition Region Spicules Filaments Active Filaments Prominences Arch Filament Systems Microflares Sunspot Structure UV Bright Points

Corona Coronal Loops Coronal Holes Flares Streamers X-Ray Bright Points Eruptive Prominences Post-Flare Loops Coronal Mass Ejections 10 SAMEX Research: Scientific Objectives and Observational Requirements

Corona (1,500,000 K) X-Rays

Chromosphere/Corona Transition Region (30,000 - 500,000 K) Ultraviolet

Im The SAMEX mission will allow The study of flare evolution is scientists to take advantage of the the focus of the SAMEX mission. latest technology and solar data to Questions to be asked include: investigate the processes that give • What is the magnetic field rise to intense solar activity. With configuration prior to solar flares? coordinated, high-resolution How is this pre-flare configuration observations from Earth orbit, the formed? SAMEX instruments will focus on the evolution of the solar magnetic field, • How is the magnetic field observing it at all levels simultane- destabilized? ously: the field itself in the Related questions about other photosphere, field-aligned structures phenomena will be addressed and in the chromosphere, and X-ray/XUV will benefit from the long-term emissions in the million-degree measurements of solar magnetic field plasmas that fill the closed field activity: structures in the transition region and e (5,000 - 10,000 K) corona. • How do sunspots form? How do nd I JItrvirilt they disappear? • How do magnetic field structures vary with the solar cycle? The data from SAMEX observations will allow scientists to reformulate older theories about these processes and generate new ones as knowledge of solar activity expands.

Flare (10,000,000 K) Extreme Ultraviolet, Gamma Rays, X-Rays

e three-dimensional Sun A

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4. 4. 13 NASA/Marshall Space Flight Center SAMEX Coverage of the Evolution and Dynamics of the Solar Atmosphere

The primary scientific objectives of the SAMEX mission are ...... LARGE-SCALE TEMPORAL CHANGES to observe the formation and configuration of energy-packed, nonpotential magnetic fields in active ...... CHANGES IN THE CHROMOSPHERE regions, to quantify the nonpotential characteristics of these fields (shear, stress, free energy, electric currents, ...SMALL-SCALE AND WEAK FIELD EVOLUTION magnetic forces, instabilities) as they develop and evolve, and to determine what factors lead to the destabilization of the fields with the subsequent eruption of flares. Specific observations are needed to meet these objectives. We must observe, measure, and monitor GROWTH AND CHANGES OF THE CORONA - THE the solar magnetic field from the base, /NHOMOGENEITY OF THE CORONA from the photosphere to the corona. We must derive quantitative ...... CHROMOSPHERE AND TRANSIT/ON measurements with unprecedented REGION EVOLUTION accuracy to obtain the free energy and other characteristics of this field. ....GROWTH OF LARGE-SCALE ACTIVE REGION Furthermore, we must measure the field over the extent of an entire active region, with the best possible spatial and temporal resolution. Solar scientists, astrophysi- cists, and plasma physicists all will benefit from these detailed ...... DETAILED TEMPORAL CHANGES observations by SAMEX. The Sun is a laboratory in which we can study at close range the high-energy ...... X-RA Y EMISSION OF THE CORONA processes that occur in other stars. Specifically, SAMEX will give us a look ...... DYNAMICS OF THE CHROMOSPHERE at the interactions of magnetic fields and plasmas that create flares and MAGNETIC RECONFIGURATION, TEMPORAL AND other explosive events. To understand SPAT/AL RESOLUTION ON A LARGE these phenomena, we must first AND SMALL SCALE AT HIGH MAGNETIC SENSITIVITY understand the evolution through which their energy is built up, stored, and released.

...... GLOBAL DYNAMICS, CORONAL HOLES, VELOCITY FIELDS ...... SUBMERGENCE OF MAGNETIC FIELD 14 SAMEX Instruments: State-of-the-Art Solar Ob

To fulfill these science weather, day-night cycles, and poor • A significant reduction in the errors objectives and observational seeing. Even a low-Earth orbit will in calculating electric currents, requirements, the SAMEX instruments provide long periods of uninterrupted magnetic free energy, Lorentz forces, were carefully chosen to form a viewing. Furthermore, the magnetic and magnetic gradients. configuration of three coaligned sensitivity required of the vector • More accurate model calculations. instruments capable of cotemporal magnetograph can be achieved only • First-time observations of the observations of the solar field from from space. The trio of instruments transverse field in emerging and photosphere to corona. The cannot be separated; they must be submerging flux and in flux instruments make observations at flown together and coaligned. cancellation. different wavelengths; they reflect the • Detection of changes in the best technology available for the VECTOR MAGNETOGRAPH magnetic field as a result of flares. observations planned. The solar vector magnetograph Achieving this level of Quantitative measurements of will measure all three components of instrument sensitivity has required the three components of the vector the surface magnetic field and the several unique design concepts: field can be made reliably and with line-of-sight velocities of the • A rotating polarizer and quarter- high spatial resolution only in the lower photospheric gases. wave plate for the primary elements of atmosphere, but the field morphology The vector magnetograph is the polarimeter. can be traced in the higher the essential core SAMEX instrument, • Specially designed coatings for atmosphere from spectroheliog rams for it provides the necessary mirrors and lenses to minimize that highlight the filamentary structure quantitative measurements of the instrumental polarization. of the chromosphere and corona. vector magnetic field. It has been "A spectral range from 5243 to Thus, the optimum complement of especially designed to achieve the 5254 A that minimizes the instruments for SAMEX includes a most important objective of the requirements on the optics but allows vector magnetograph that will mission - to measure the magnetic flux tube diagnostics. accurately measure the vector field as accurately as possible. • A large-array (2048 x 2048) solid- magnetic field in the photosphere, a Present systems are limited to state detector with multiport readout. hydrogen-alpha telescope to image measuring the transverse (to the Limitations of present the chromospheric field and coronal line-of-sight) component with technology and the realities of making prominences, and an XUV imaging accuracies on the order of 150G. This space-based observations from a telescope to outline the loop structure accuracy level is inadequate to free-flying satellite impose certain of the coronal field. observe the characteristics of restrictions on the interrelated All three instruments are nonpotential magnetic fields that are parameters of field of view, spatial required to provide the coaligned, essential for studying solar activity. resolution, magnetic sensitivity, and cotemporal data needed to detail the The SAMEX magnetograph will yield temporal resolution. The final 3-D structure of the field, to register magnetic field measurements with a parameters selected for the SAMEX the locations of flare onset, and to sensitivity of approximately 30 G, a magnetograph were derived from an define the 3-D changes wrought by dramatic improvement over present extensive trade-off study, and they flares. These observations must be systems; this is a factor of 25 in represent an optimum compromise made from space, because XUV polarimetric accuracy. for carrying out the primary scientific radiation does not penetrate the Among the results anticipated objectives. atmosphere and because it is through use of the SAMEX vector The 0.5 arcsec spatial impossible to achieve from the ground magnetograph are the following: resolution will allow scientists to see a the long-term, high spatial resolution • More accurate measurements of solar region as small as 360 kilometers observations that are necessary to the azimuth of the transverse (222 miles) wide and thus will resolve understand how the field evolves component and, thus, more accurate most features in active regions. The toward flare conditions. Too many measurements of the degree of spatially unresolved fields can be times, Earth-based observations are magnetic shear as evidenced by this analyzed using flux tube diagnostics terminated at critical times because of azimuth. because of the special spectral lines

15 -Va t/ons

ncluded in the selected spectral ange. Instrument Vector H XUV The time resolution (:55 Characteristics Magnetograph Telescope Telescope ninutes) is consistent with the spatial Atmospheric region Photosphere Chromosphere Corona esolution and sufficient to observe Telescope type nost of the dynamic phenomena Cassegrain Cassegrain Wolter 1* elated to solar activity, especially the Telescope aperture 30 cm 30 cm 35 cm )rocess of field evolution building up Spatial resolution o flare onset, and is consistent with (arc sec) 0.5 0.5 0.5 he spatial resolution. Field of view The field of view will completely (arc min) 4.3x8.5 4.3x8.5 4.3x8.5 :over all but a few extremely large Spectral resolution active regions. This coverage is 1 MA 20 m 1 —20A ?ssential for model calculations to Spectral bandpass 120 mA 250 mA Variable )rovide the proper boundary Spectral range 5243-5254 A 6563 ± 4 A 3-400A :onditions for the models, for Temporal resolution 5 minutes 1 second 1 second )bserving associated activities, and * or Normal incidence Newtonian r submergence studies.

Instrument Specifications: SAMEX Vector Magnetograph MAGING TELESCOPES Spatial Resolution The XUV imaging telescope o.s arcsec vill observe the high-temperature Field of View 4.3 x 8.5 arcmin )lasma structures in the transition Polarization Sensitivity 10 4 egion and corona, showing the Magnetic Sensitivity ocation and magnitude of solar Line-of-Sight Field 1 Gin 40seconds activity. This instrument will utilize Transverse Field —30 G in 4 minutes ecent advances in optical design to Spectral Parameters attain excellent spatial resolution and Position Accuracy arge fields of view. The hydrogen- 1 MA Full Width at Half Maximum alpha telescope will observe the 120 mA Range ;tructure and dynamics of the plasma 5243-52544 n the chromosphere with high Doppler Velocity Resolution 60 msec1 emporal and spatial resolution. Temporal Resolution The requirements on these two Vector Magnetogram 5 minutes ;ystems are set by the specifications Dopplergram lOseconds )f the vector magnetograph and the cientific objective to map the nagnetic field from the photosphere Detector System o the corona cospatially and (common to all 3 instruments) ;imultaneously. Thus, they have the • 2048 x 2048 CCD array with 27 Iim pixels, or quadrant structure of ame field of view, spatial resolution, four 1024 x 1024 arrays and temporal registration - a ecessity demonstrated by the limited • half array for imaging, half for storage/readout pace observations of the past two • 1 msec image-to-storage shift time (eliminates need for shutter) Jecades. • serial readout ports (reduces readout time below exposure time) • pixel binning capabilities

16 a.

a. Hr image Solar Optical Observing Network b. X-ray image American Science & Engineering c. Magnetogram image NASA/Marshall Space Flight Center

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17 The significant advantage of the SAMEX mission lies in the coordination of these three instruments for simultaneous observations. SAMEX will be able to see solar active regions in detail, providing images and spectral data on the birthplaces of solar flares. Furthermore, SAMEX will monitor the precursors of flare eruptions (such as intensified magnetic shear, filament activation, or early signs of enhanced X-ray emission) as well as the presence of coronal holes. SAMEX will also detect coronal loops, enabling analysts to determine the magnetic field configuration of the outer solar atmosphere and its effect on the solar wind that will have an impact on the geomagnetic environment. The SAMEX instruments will form the first complement of experiments ever flown on a mission specifically designed to study the buildup and release of energy in solar flares. For that reason alone, the instruments are being designed with the best technology. Meeting the specifications for sensitivity, field of view, spectral coverage, spatial resolution and temporal resolution, they will achieve the scientific objectives of the SAMEX mission. We expect many exciting discoveries about our star, the Sun.

18 Shared Benefits: A Broad Community of Users

NOAAiSpace Environment Services Center NORAD (USAF) University of Colorado Global Weather Central High Altitude (USAF) Observatory (NCAR) Ai

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University of California Berkeley Lockheed Palo Alto Research Laborato Stanford University Wilcox Solar Observatory - NASA/Ames Research Center Big Bear Solar - Observatory San Fernando Observatory Owens Valley Radio Observatory / Mt. Wilson .iia. Observatory doom California Institute niversit y of California 'a.. of Technology San Diego / / \ NASNJet Propulsion University of Arizona \ Laboratory Kitt Peak National NJol Observatory Very Large\ Array Space C University of Hawaii (NOAO/NSO) (NRAO) Los Alamos Hollonan AFB National Laboratory Observatory IN Mees Solar (USAF/SOON) -Observatory ALASKA- Air Force / Geophysics Laboratory Sacramento Peak Palehua Observatory Observatory (NSO) (USAF/SOON) ui.. HAWAII Monson

University of Alaska 19 SAMEX is logically the next spacecraft for research in solar activity. It is the product of careful Herzberg Institute deliberation and planning within the of Astrophysics solar physics community to determine Bather Service Ottawa River the best means of answering the most (USAF) Solar Observatory important questions about the Sun's University of Chicago activity. The scientific community has dh laid a firm foundation in solar research with almost three decades' worth of rocket-borne and orbital instruments. // Results from sounding rockets, the manned Skylab Apollo Telescope Harvard College Observatory Mount, the small Orbiting Solar Observatories, the Solar Maximum sonian Astrophysical Observatory Mission spacecraft, and Spacelab 2 have shown us a Sun that is dynamic, Air Force physics Laboratory changeable, explosive, and mysterious. Designed with the )lumbia University advantages of today's technology Hopkins University and the knowledge gleaned from past ASNGoddard research, SAM EX is the best research ace Flight Center tool yet devised to answer the many iersity of Maryland perplexing questions that still cloud rtional Science our understanding of the Sun. Foundation SAMEX fits into the broad A Headquarters international strategy for concentrated Universities solar physics research into the next ace Research century. This observatory Associates complements other proposed Pentagon spacecraft and augments all ground- Javal Research based observatories. Through a data I I IL ._I I..#I IL!! Laboratory analysis facility and network, scientists University of Alabama at universities and research centers Huntsville ., around the world will have access to ihIH. SAMEX data for a comprehensive understanding of the Sun. SAMEX is a crucial link in the chain of solar PUERTO RICO research. SAMEX data also will be * important to astrophysicists studying magnetized plasmas elsewhere in the Ramey Observatory (USAF/SOON) universe.

LEGEND: • Universities Observatories @ Space • DOD Solar observatories and KIC research centers NASA. Marshall Space Flight Center

While the research results of SAMEX will be impressive, the rewards of a SAMEX mission will k gong extend beyond the scientific d - -zgs:. 0 saw was seen community. The effects of solar 55551•5• SISal amossnams radiation on military and civilian 1u1u 5_ -, .' I 11155 8204499AAW systems in space are severe: 1555551an communications blackouts, 55555,11UI5U 5 RIasasla III RI ZZ 55551 5 5 55555 '. navigation errors, and garbled signals no asIi5IIII 55 m aasa are just afew of the hazards to routine 55 555 samsi-sa M 4'11 i;55555 Ownussom mass 5554555*555 and emergency operations of aircraft, • - a spacecraft, and ground systems. names Isa Managers and operators of such systems would benefit tremendously from knowing when solar events will I occur. The information from SAMEX A Role "X*VaAA8S an observations of flare and pre-flare Uft I phenomena will lead to the development of improved prediction techniques, enabling us to protect expensive and sophisticated systems U.. I I from the effects of solar radiation. U I Among the beneficiaries of SAMEX will be the many subscribers a to the Space Environment Services was Center, operated jointly by the National Oceanic and Atmospheric Administration (NOAA) and the Air Force. The Center distributes alerts, If forecasts, indices, and reports based on real-time data from worldwide sources. These services help individuals and organizations reduce losses caused by sporadic solar activity. Sharing the benefits will be the military; satellite and aviation industries whose operations are affected by vagaries in the space environment; electric power, telephone, and pipeline utilities; geophysical exploration enterprises affected by geomagnetic variations; and scientists with sensitive research instruments in space, in the atmosphere, or on the ground. Personnel in manned spacecraft and high altitude aircraft will benefit from improved information about the status of their environment. 21

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22 A Current Need: Planning for the 21st Century

1985 1990 MAXIMUM SOLAR ACTIVITY 91 'LA ES 22 SOMTAR-A

MINIMUM SOLAR ACTIVITY

Research missions during the solar cycles, 1985-2010 NASA Marshall Space Flight Center

23

1995 2000 2005 2010

SOH AD BITING SOLAF LABOFRATO A PIN HDLE TATION OCCULTER

SAMEX will complement both These programs will coordinate solar the approved and proposed studies observations by balloons, ground of solar activity planned for the 1990's. observatories, and spacecraft. With the flight of missions such as the Coordinated observing campaigns Orbiting Solar Laboratory (OSL) to and data analysis are essential to observe fine-scale solar structure in improved understanding and the visible spectrum, the Japanese prediction of solar activity. Solar-A spacecraft to study high- SAMEX will also provide the energy solar flare phenomena, and scientific foundation for forecasting the European Space Agency's Solar flares and other phenomena that and Heliospheric Observatory produce effects upon the near-Earth (SOHO) to study coronal dynamics, environment. However, there is a gap the solar interior, and interplanetary of approximately 20 years between fields and particles, the next few the acquisition of scientific data and decades could bring unprecedented the development of an operational advances in our knowledge of the Sun system. SAMEX should fly soon, so and its interactions with the that the next generation of solar interplanetary environment. monitors can support the forecasting SAMEX could be an important needs of the new century's military component of the Max 91 and and civilian systems. FLARES 22 programs of worldwide The technology for a SAMEX research planned for the next solar mission is ready, and the timing is maximum period from 1991 to 1995. excellent: SAMEX is needed now.

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