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The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics (2003)

Chapter:2. Integrated Research Strategy for Solar and Space Physics

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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
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2
Integrated Research Strategy for Solar and Space Physics

In developing a research strategy for solar and space physics for the coming decade, the committee was guided by several considerations. First, solar and space physics will achieve the greatest gains in understanding through coordinated investigations of its objects of study as interacting parts of complex systems. Second, to address the scientific challenges presented in Chapter 1, a combination of observational programs and complementary theory and modeling initiatives is needed, with the observational programs including both ground- and space-based elements. (The committee noted that many such efforts are already important components of planned or proposed agency programs.) Third, the vulnerability of society’s technological infrastructure to space weather necessitates a mix of basic, targeted basic, and applied research initiatives that will lead both to advances in fundamental scientific knowledge and to progress in the application of that knowledge to the mitigation of space weather effects on technology and society. The research strategy that the committee has developed is thus an integrated one, a strategy that provides for the coordinated investigation of solar system plasmas as complex, coupled systems and that seeks to maximize the synergy between observational and theoretical initiatives and between basic research and targeted research programs. A final, critical consideration was cost realism. Accordingly, the committee exercised great care to ensure that its recommended research strategy is consistent with the anticipated budgets of the various federal agencies.

The programs and initiatives that constitute the committee’s recommended strategy for solar and space physics research during the decade 2003-2013 are described in the sections that follow. The discussion is organized in terms of the scientific challenges set forth in the preceding chapter and emphasizes the complementarity of the various recommended initiatives. The section “Roadmap to Understanding” describes the criteria that the committee used and the decision-making process that it followed in

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

establishing priorities among the programs and initiatives recommended by the disciplinary study panels. Cost estimates are presented in tabular form, and costs and phasing for all recommended programs are illustrated graphically in three waterfall charts.

THE SUN’S DYNAMIC INTERIOR AND CORONA

Helioseismological studies of the solar interior have attained a high degree of sophistication through the ground- and space-based measurements of Doppler shifts by GONG and SOHO, from which images of the magnetic fields and flow systems below the solar surface are deduced. Similarly, imaging and spectral data from the solar corona and transition region provided by the SOHO and TRACE satellites have demonstrated the central role of the magnetic field in controlling coronal dynamics. However, the mechanisms by which the solar magnetic field is generated, including its reversals and temporal cycles, are still not completely understood. Solar B, a mission now in development by Japan’s Institute of Space and Astronautical Science (ISAS) and in which NASA is a participant, will measure how magnetic fields emerge onto the solar surface and reveal the details of the interaction between convective flows and magnetic fields. Also under development now is STEREO, which will measure the three-dimensional development and propagation of coronal mass ejections (CMEs) through the inner heliosphere.

The next important scientific steps in solar physics are the following: (1) to refine and sharpen the probing of the solar interior; (2) to treat the outer layers of the Sun and its atmosphere as a single system; (3) to develop the science of coronal mapping for measurement of the structure and strength of the coronal magnetic field; and (4) to make precise spectral measurements of the solar atmosphere over a broad range to map velocity distributions and to determine what spectral bands have the strongest effects at Earth and how they vary over the solar cycle. Three new programs, working in concert, will take these steps: the Solar Dynamics Observatory (SDO), the Advanced Technology Solar Telescope (ATST), and the Frequency-Agile Solar Radiotelescope (FASR).

SDO, which is part of the approved NASA Living With a Star program and is now in development, will explore the Sun from its center to the subsurface layers of the convection zone to the outer solar atmosphere, probing the subsurface origin of active regions with acoustic imaging of the convection zone and tracking their development in space and time. By virtue of the high data rate available from its geosynchronous orbit, SDO

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

will make full-disk, high-resolution (in both space and time) maps of the Doppler velocities and magnetic fields of the Sun, making possible the exploration of the complete life cycle of active regions. SDO will also carry an ultraviolet (UV) spectrograph in order to understand the link between solar activity and solar spectral radiance.

The ground-based ATST, which is currently undergoing a design study funded by the NSF, will be a 4-meter facility that employs adaptive optics to study the solar magnetic field, from the photosphere up through the corona. In the lower atmosphere the telescope will achieve a flux density sensitivity of a few gauss or smaller. It will provide observations of the solar atmosphere at a high temporal cadence and with better than 0.1-arcsecond resolution, which is sufficient to resolve the pressure scale height and the photon mean free path in the solar atmosphere. ATST will thus enable critical tests of models of solar plasma processes.

An important ground-based element of the NSF-supported program recommended in this report is FASR (see Figure 2.1), which, like ATST, is now in a design study phase.1 FASR represents a significant advance beyond existing solar radio instruments yet is well within the reach of emerging technologies. A wide range of solar features from within a few hundred kilometers of the visible surface of the Sun to high up in the solar corona can be studied in detail with the unique diagnostics available in the radio regime. FASR capabilities will include measuring the properties of both thermal and nonthermal electrons accelerated in solar flares, measuring coronal magnetic field strengths in active regions, and mapping kinetic electron temperatures throughout the chromosphere and corona.

Two of the major mysteries in solar physics are the fact that the Sun’s corona is several hundred times hotter than the underlying photosphere and the fact that the coronal gases are accelerated to supersonic velocities within a few solar radii of the surface to form the solar wind. Resolving these mysteries—understanding how the corona is heated and how the solar wind originates and evolves in the inner heliosphere—has been identified by the Panel on the Sun and Heliospheric Physics as its top science priority for the coming decade. To answer these questions requires measurements from a spacecraft that passes as close to the solar surface as possible. A Solar Probe mission will make in situ measurements of the plasma, energetic particles, magnetic field, and waves inward of ~0.3 AU to an altitude of 3 solar radii above the Sun’s surface. This region is one of the last unexplored frontiers in the solar system. Such measurements will locate the source and trace the flow of energy that heats the corona; determine the acceleration processes and find the source regions of the fast and

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

FIGURE 2.1 Artist’s conception showing a portion of the Frequency-Agile Solar Radiotelescope’s ~100-dish antenna array. FASR, which is the committee’s highest-priority small initiative for solar physics, will produce high-resolution images of the Sun’s atmosphere from the chromosphere up into the mid-corona. Courtesy of D.E. Gary (New Jersey Institute of Technology).

slow solar wind; identify the acceleration mechanisms and locate the source regions of solar energetic particles; and determine how the solar wind evolves with distance in the inner heliosphere. In addition, if suitable remote-sensing instruments are included, a Solar Probe mission can complement the in situ measurements with valuable close-up views of the Sun.2 Because of the profound importance of the scientific questions that a Solar Probe will address, the committee recommends that this mission be implemented as soon as possible.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

THE HELIOSPHERE AND ITS COMPONENTS

The heliosphere begins in the outer solar corona and ends at its interface with the interstellar medium (see Chapter 1). As such, it encompasses the entire solar system and is the domain of solar plasmas, magnetic fields, and energetic particles as well as interstellar dust, neutral atoms, and pickup ions. The plasma continuously flowing from the Sun in fast and slow solar winds is highly dynamic and turbulent, and the embedded CMEs and interplanetary shocks cause the impulsive transfer of solar energy to the magnetospheres (whether intrinsic or induced) of planets and small bodies. The heliosphere contains the connective tissue of the Sun-Earth connection; however, little is known about its source or its destiny. The new frontiers of heliospheric research lie at its inner boundary in the solar corona and its outer boundary with the interstellar medium. A Solar Probe mission will investigate the innermost boundary of the heliosphere. Moving outward from the Sun, ESA’s Solar Orbiter mission will periodically corotate with the Sun in an elliptical orbit with perihelion of 45 solar radii. With its payload of imaging and in situ instruments, some of which will be contributed by the United States, Solar Orbiter will be poised to reveal the magnetic structure and evolution of the corona and the resulting effects on plasmas, fields, and energetic particles in the inner heliosphere. Participation in this mission will provide the United States with a highly leveraged means of investigating the structure and evolution of the inner heliosphere for the first time.

STEREO will perform stereoscopic imaging and two-point, in situ measurement of CMEs in the inner heliosphere. The next important step in understanding the heliospheric propagation of CMEs will be accomplished with a Multispacecraft Heliospheric Mission (MHM).3 MHM will consist of four or more spacecraft separated in solar longitude and radius with at least one orbital perihelion at or within ~0.5 AU. Orbiting in and near the ecliptic plane, these spacecraft will make in situ measurements of plasmas, fields, waves, and energetic particles in the inner heliosphere, providing two-dimensional slices through propagating CMEs and the ambient solar wind.

The boundary between the solar wind and the local interstellar medium (LISM) is one of the last unexplored regions of the heliosphere. Very little is currently known about this boundary or the nature of the LISM that lies beyond it. The outer boundary of the heliosphere will eventually be sampled directly by an Interstellar Probe mission. Advances in propulsion technology are expected to make such a mission feasible during the decade 2010-2020. Although it cannot yet be included in the program recommended by

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

the committee, an Interstellar Probe is a high-priority future mission for which the required technology investments should begin as soon as possible. In the meantime, certain aspects of the heliospheric boundary and the LISM can be studied by a combination of remote sensing and in situ sampling techniques. This investigation could be accomplished by an Interstellar Sampler mission traveling to distances of several AU to measure the neutral atoms of the LISM that penetrate well into the heliosphere and to obtain energetic neutral atom images and extreme ultraviolet images of the heliospheric boundary. Such a mission is gauged to be feasible within the resources of the Explorer program and so is not prioritized separately in this report.

SPACE ENVIRONMENTS OF EARTH AND OTHER SOLAR SYSTEM BODIES

Earth’s magnetosphere and ionosphere formed the historical starting point for space physics research and remain an important focus for study because they constitute the human space environment and because they provide important prototypes for understanding the magnetospheres and ionospheres of other planets and small solar system bodies. In addition, the basic physical phenomena of space plasmas, which can be studied directly in Earth’s magnetosphere, occur in remote and therefore inaccessible locations in the universe.

Having been the focus of numerous space- and ground-based investigations over the past four decades, the study of geospace has reached a level of maturity that brings the shortcomings of understanding into sharp focus. What specific physical processes transfer energy from the solar wind to geospace? What is the nature of the global response of Earth’s magnetosphere and ionosphere to the variable solar-wind input? These are the most basic and important questions that can be asked about geospace, but they have not received satisfactory answers. However, the maturity of the field now allows the interrogation of large databases, the development of sophisticated models, and the construction of new, definitive experiments both for Earth’s space environment and for that of other solar system bodies.

Magnetic fields are continually being created by the solar dynamo but are also continually being annihilated by both small- and large-scale magnetic reconnection in the corona. Reconnection converts magnetic energy to particle kinetic energy and heat, and the results are heating of the corona and explosive outbursts of solar flares. Similarly at Earth, magnetic fields are continually being created by the internal dynamo and being annihilated

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

by reconnection with solar wind magnetic field lines at the dayside magnetopause and reconnection of open field lines within the geomagnetic tail. As at the Sun, these processes result in the energization of charged particles. NASA’s Solar Terrestrial Probe (STP) mission Magnetospheric Multiscale (MMS) is designed to probe the reconnection process at the magnetopause and in the tail with a cluster of four spacecraft. MMS will benefit greatly from the groundbreaking research on magnetospheric and solar wind plasma dynamics that is being done with the European Cluster 2 mission. With its ability to adjust orbits and spacecraft separations, the MMS cluster will probe the boundary regions where reconnection is occurring and test directly theories of reconnection from the magnetohydrodynamic scale (thousands of kilometers) down to the ion and electron kinetic scales (kilometers).

Earth’s ionosphere-thermosphere system is the site of complex electrodynamic processes that redistribute and dissipate energy delivered from the magnetosphere in the form of imposed electric fields and precipitating charged particles. Previous studies have revealed much about the composition and chemistry of this region and about its structure, energetics, and dynamics. However, a quantitative understanding has proved elusive because of the inability to distinguish between temporal and spatial variations, to resolve the variety of spatial and temporal scales on which key processes occur, and to establish the cross-scale relationships among small-, intermediate-, and large-scale phenomena. Geospace Electrodynamic Connections (GEC) (see Figure 2.2) is a multispacecraft STP mission that has been specifically designed to overcome these difficulties and to provide new physical insight into the coupling among the ionosphere, thermosphere, and magnetosphere.

Sounding rockets are an important part of NASA’s Suborbital Program and have been a mainstay for the investigation of important small-scale physical processes in the ionosphere-thermosphere, for a wide range of magnetospheric studies, and for the development of new instruments for space physics. While the flight time of these rockets is small, their slow velocity through specific regions of space (nearly an order of magnitude less than that of orbiting vehicles) and their ability to sustain very high telemetry rates from multiple payloads launched from a single vehicle make them extremely useful for studying the fine structure of dynamic phenomena like the aurora. Moreover, some important regions of space are too low in altitude to be sampled by satellites (i.e., the mesosphere below 120 km), so sounding rockets are the only platforms from which direct in situ measurements can be carried out in these regions.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

FIGURE 2.2 The Geospace Electrodynamic Connections (GEC) mission is a multispacecraft Solar Terrestrial Probe mission designed to study the multiple spatial and temporal scales on which the ionosphere-thermosphere system receives electromagnetic energy from the magnetosphere and redistributes and dissipates it through ion-neutral interactions. During the 2-year mission, the spacecraft will perform several “deep dipping” excursions that will allow them to make in situ measurements down to altitudes as low as 130 kilometers. Courtesy of NASA Goddard Space Flight Center.

The Advanced Modular Incoherent Scatter Radar (AMISR) is a planned NSF program that will bring the observing power of a modern multi-instrument, ground-based observatory to a variety of geophysical locations chosen to optimize the benefit of the observations to specific scientific inquiry (Figure 2.3). In addition to its incoherent scatter radar, AMISR will host a variety of ground-based diagnostics that together will address key science questions about atmosphere-ionosphere-magnetosphere (AIM) interactions

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

FIGURE 2.3 The Advanced Modular Incoherent Scatter Radar (AMISR) is the committee’s top-ranked small initiative for ground-based geospace research. It combines a powerful state-of-the-art incoherent scatter radar with supporting optical and radio instrumentation in a transportable format. This flexibility enables the AMISR to study a wide range of ionospheric phenomena at polar, auroral, equatorial, and mid-latitudes and to act in close conjunction with other ground-based, suborbital, and satellite investigations of the geospace environment. This artist’s conception depicts the fast-steering, multibeam RAO probing the dynamic auroral environment at high latitudes. Courtesy of J. Kelly and C.J. Heinselman (SRI International).

that can only be tackled with a detailed knowledge of evolving time and altitude variations in a specific region.

A Small Instrument Distributed Ground-Based Network4 will combine state-of-the-art instrumentation with real-time communications technology to provide both broad coverage and fine-scale spatial and temporal resolution of upper atmospheric processes crucial to understanding the coupled AIM system. Placing a complement of instruments, including Global Posi-

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

tioning System receivers and magnetometers, at educational institutions will provide a rich, hands-on environment for students, while instrument clusters at remote locations will contribute important global coverage. This flexible NSF initiative will provide the simultaneous real-time measurements needed for assimilation into physics-based models and to address the space weather processes and effects in the upper atmosphere. These detailed, distributed measurements will complement the capabilities at the larger ground-based facilities that host the incoherent scatter radars.

Global magnetospheric imaging, currently available from the IMAGE mission, needs to be developed further, specifically with stereo imaging, which will be implemented for 1- to 30-keV neutral atoms with the Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) mission (launch dates in 2003 and 2004). Stereo imaging is essential because magnetospheric plasmas are optically thin. The Stereo Magnetospheric Imager (SMI), a proposed STP mission,5 will obtain EUV images of the plasmasphere and neutral atom images of the plasma sheet and ring current from two widely spaced spacecraft, thereby greatly improving the accuracy with which global ion images can be produced. In addition, SMI will provide an auroral imaging capability, which has become a standard tool for assessing the global activity of the magnetosphere.

A large database of spacecraft magnetic field measurements has made it possible to construct good models of the average configuration of Earth’s magnetosphere for different levels of magnetic activity. However, the actual instantaneous configuration of the magnetosphere is not expected ever to resemble any of its average states. What is needed is a dynamic image of the magnetic fields and plasmas within the magnetosphere. Measurements by a large constellation of spacecraft carrying magnetometers and simple plasma instruments can yield dynamic “images” of large portions of the magnetosphere. Magnetospheric Constellation (MagCon) is an STP mission that is designed to investigate the dynamics and structure of Earth’s near magnetotail by means of a constellation of 50 to 100 spacecraft.

The Explorer program has long provided the opportunity for targeted investigations, which can complement the larger initiatives recommended by the committee. However, the committee is concerned that the overall rate at which solar and space physics missions are undertaken is still rather low. A revitalized University-Class Explorer (UNEX) program would address this problem while allowing innovative small investigations to be conducted. However, the very existence of a UNEX program depends critically on low-cost access to space, which is discussed in Chapter 7.

Jupiter has a giant magnetosphere that has gross similarities with Earth’s

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

FIGURE 2.4 Electrical currents aligned with Jupiter’s strong magnetic field couple the moons Io, Ganymede, and Europa with Jupiter’s high-latitude ionosphere. Bright auroral emissions observed at the footpoints of the magnetic flux tubes linking the moons to the ionosphere (inset) are the signature of this coupling, the physics of which is only partially understood. (The letters superposed on the auroral image in the inset identify the emission features associated with the footpoints of Io, Ganymede, and Europa.) A probe to study the still unexplored polar regions of Jupiter’s magnetosphere will answer basic questions about the nature of electrodynamic coupling between the Jovian atmosphere and magnetosphere and about auroral acceleration in a magnetospheric environment much different from Earth’s. Hubble Space Telescope image courtesy of J.T. Clarke (Boston University) and NASA/Space Telescope Science Institute. Artist’s rendering of the Jovian inner magnetosphere courtesy of J.R. Spencer (Lowell Observatory). Reprinted by permission from Nature 415:997-999 and cover, copyright 2002, Macmillan Publishers Ltd.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

magnetosphere (bow shock, magnetopause, magnetotail), but Jupiter’s strong magnetic field and Io’s abundant plasma source produce dramatic differences. Jupiter’s high rotation rate and the strong volcanic mass loading from Io create an intense outward centrifugal force that pulls plasma and magnetic flux outward from the inner magnetosphere and stretches the magnetic field into a disk-like configuration. Previous flyby missions and the Galileo orbiter have explored only the equatorial region of the Jovian magnetosphere. To understand how the magnetospheric plasma couples with the low-altitude auroral regions, measurements in a polar orbit are needed. From an elliptical polar orbit, a Jupiter Polar Mission (JPM) will determine the relative contributions of planetary rotation and the solar wind to the energy budget of the Jovian magnetosphere (see Figure 2.4). It will determine how the plasma circulates in the magnetosphere and assess the role of Io’s volcanism in providing the mass that drives this circulation process. JPM will identify the charged particles responsible for the Jovian aurora and determine how these particles become energized, and it will identify the electrodynamic processes that couple the Jovian moons to the planet’s high-latitude ionosphere.

THE ROLE OF THEORY AND MODELING IN MISSIONS AND FUNDAMENTAL SPACE PLASMA PHYSICS

Over the past decade and more, theory and modeling have played an increasingly important role both in defining satellite missions and other programs and in interpreting data through the development of new physical models. The enhanced role of theory and modeling is a consequence of the development of powerful computational tools that have facilitated the exploration of the dynamics of complex nonlinear plasma systems at both large magnetohydrodynamic spatial scales and kinetic microscales. Before the advent of these tools it was not possible to study these dynamical processes through analytic techniques alone.

In the coming decade, the deployment of clusters of satellites and large arrays of ground-based instruments will provide a wealth of data over a very broad range of spatial scales. Theory and computational models will play a central role, hand in hand with data analysis, in integrating these data into first-principles models of plasma behavior. Examples of the catalyzing influence of theory and computation on the interpretation of data from observational assets are many. A case in point is recent research in the area of magnetic reconnection, where new theoretical developments have

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

spurred the successful search for signatures of kinetic reconnection in satellite data.

Theory and modeling activities have further importance in the application of the results from solar and space physics to allied fields such as astrophysics and fusion energy sciences. The heliosphere is the space physicist’s laboratory wherein a wide variety of plasma processes, parameters, and boundary conditions are encountered (cf. Chapter 4). Many of these phenomena can be sampled directly and the results applied to systems where direct measurements are either very difficult or altogether infeasible. The identification of the critical dimensionless parameters controlling plasma dynamics through analysis combined with state-of-the-art computation is central to the successful extrapolation to differing environments, where absolute parameters may be very different from those that apply to solar-system plasmas.

NASA’s Sun-Earth Connection Theory program has been very successful in focusing critical-mass theory and modeling efforts on specific topics in space physics. The NSF has long encouraged and supported theoretical and modeling investigators through its grants program. Theoretical work provides the community with state-of-the-art computational models that are developed and utilized with support from all the funding agencies. This theoretical understanding is used extensively for interpreting individual measurements as well as for developing physics-based data assimilation procedures for diverse but coupled parameters.

In view of the strongly coupled nature of the Sun-heliosphere system and the complementary objectives of the solar and space physics programs of the different federal agencies, two interagency initiatives are being proposed by the committee. One of these—the Virtual Sun—will incorporate a systems-oriented approach to theory, modeling, and simulation that will ultimately provide continuous models from the solar interior to the outer heliosphere.6 The Virtual Sun will be developed in a modular fashion by focused attacks on various physical components of the heliosphere and on cross-cutting physical problems. The solar dynamo and three-dimensional reconnection are areas ripe for near-term concentration because they complement the planned ground- and space-based measurement programs.

The Coupling Complexity research initiative7 will address multiprocess coupling, nonlinearity, and multiscale and multiregional feedback in space physics. The program advocates both the development of coupled global models and the synergistic investigation of well-chosen, distinct theoretical problems. For major advances to be made in understanding coupling complexity in space physics, sophisticated computational tools, fundamental

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

theoretical analysis, and state-of-the-art data analysis must all be integrated under a single umbrella program. Again, this initiative is motivated by the anticipated ground- and space-based measurements that will provide spatially distributed data that must be incorporated into a single understanding of the physical processes at work in different volumes of geospace.

SPACE WEATHER

Earth’s space environment is subject to severe episodic changes that are correlated with specific heliospheric disturbances. Like terrestrial weather, severe space weather can have disruptive and even destructive effects that must be mitigated. Effective mitigation requires characterization of the geospace environment in both its quiescent and disturbed states, an understanding of the physical processes that are involved in disturbed conditions (e.g., the acceleration of radiation belt electrons during magnetic storms), and, ultimately, the ability to forecast space weather events accurately. As in the case of terrestrial meteorology, global measurements and large-scale numerical modeling are required. The geospace environment poses a particularly challenging problem because the magnetosphere is a vast, three-dimensional structure whose distant components can be coupled quickly and directly by plasma phenomena such as field-aligned currrents.

While focusing specifically on those regions and phenomena that most directly affect the technological infrastructure of modern society, space weather research aims at a basic physical understanding of the geospace environment. Despite its practical orientation and benefits, space weather research is thus to be understood as targeted basic research rather than applied research in the traditional sense. The multiagency National Space Weather Program (NSWP) has developed a sound framework for rapid progress in this area. This program, with NSF as the lead agency, has provided better understanding of the role of magnetosphere-ionosphere coupling processes in producing radio-wave scintillations, large magnetic-field changes, and other space weather effects observable on the ground. The NSWP has been successful by providing support for focused activities that harness scientific understanding of the geospace environment to provide better specifications and predictions. The recent implementation of NASA’s Living With a Star (LWS) program has added a spaceflight segment and additional modeling activity to the national space weather effort.

The Solar Dynamics Observatory, the first LWS mission, will provide nearly continuous observations of the Sun from geosynchronous orbit, gathering data on solar variability and monitoring the occurrence of geoeffective

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

solar activity. In addition, SDO will monitor EUV irradiance, allowing the fundamental sources of ionization and heating in the ionosphere and thermosphere to be specified. The STEREO mission will provide a unique perspective from which to observe CMEs that are directed toward Earth, while a mission at L1 (which could be provided by a NOAA contribution, as recommended in Chapter 5, or possibly by Triana) will provide critical measurements of the solar wind plasma and the interplanetary magnetic field once the operational lifetime of the Advanced Composition Explorer is over. Global images of the magnetosphere from SMI will allow the response of the magnetosphere to solar inputs to be related to ionospheric and thermospheric responses described by data from ground-based facilities such as AMISR and from the GEC mission.

Despite the wide variety of data that can be used to specify and predict space weather, critical gaps in understanding have been identified. Some of the strongest effects of severe magnetospheric storms are produced by radiation belt particles, which often appear spontaneously and without precursors. The important energization and transport processes for these particles are not understood, primarily because with single satellites, changes in the particle distribution functions and electric and magnetic fields in the inner magnetosphere are measured at satellite orbital periods rather than at particle drift periods. Multiple spacecraft are needed to describe more fully the inner magnetospheric particle and field environment on appropriate time scales. Similarly, multipoint measurements are also needed in the ionosphere, where global changes occur on time scales that are short compared with the orbital periods and on spatial scales that are smaller than the longitudinal orbit spacing of even low-altitude satellites. To address these needs, the LWS Geospace Network will contain both a radiation-belt component and an ionosphere-thermosphere component, with each component consisting of two spacecraft.

Ionospheric effects at equatorial, auroral, and middle latitudes constitute a second major category of space weather effects that must be better characterized and understood. Electric fields and particles couple the lower atmosphere and ionosphere to the disturbed magnetosphere above, and large-scale changes in total electron content and ionospheric scintillations can adversely affect communications and navigation systems. Focused research on the processes involved will be provided by AMISR and other high-resolution ground- and space-based facilities, while the Small Instrument Distributed Ground-Based Network will provide the real-time data and the spatial/temporal resolution needed to address and model these effects in the large-scale upper atmosphere system.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

To provide more advanced warning of solar wind disturbances as well as to warn of approaching corotating streams that could be missed by a single Sun-aligned probe, the committee recommends a Solar Wind Sentinels (SWS) mission8 as part of the future LWS program. Three spacecraft equipped with 100-m solar sails will surround the Earth-Sun line at 0.98 AU with separations in the 0.1-AU range. In addition to providing advanced warning, these spacecraft will provide measurements of the spatial and temporal structure of heliospheric phenomena such as CMEs, interplanetary shocks, and solar-wind streams as they propagate toward Earth. The MHM will also provide information on spatial gradients that may affect the geo-effectiveness of solar eruptions.

The continuing growth in the number of solar and space physics data sets and the need to use multiple data sets in characterizing and predicting the geospace environment require that the accessibility of the data and modeling tools be assured. The Solar and Space Physics Information System proposed by the Panel on Theory, Modeling, and Data Exploration is designed to fill this need. This system will assign the tasks of data validation, access, and delivery to experienced scientists and provide access to the latest interpretive models for all interested scientists. By originating this effort inside the science community that is generating the information, attention will be given to timely delivery of data products together with uncertainty estimates.

ROADMAP TO UNDERSTANDING

The committee was charged with recommending “a systems approach to theoretical, ground-based, and space-based research that encompasses the flight programs and focused campaigns of NASA, the ground-based and base research programs of NSF, and the complementary operational programs of other agencies such as NOAA, DOD, and DOE.” To accomplish this task, the approaches put forward by the four technical study panels were integrated, and those projects with the highest scientific impact and, in some cases, the greatest potential societal benefit were considered further (the programs with the greatest potential societal benefit are generally those related to the LWS program or the NSWP). This selected group of planned and proposed activities makes up the vigorous and essential research program that is briefly described in the earlier sections of this chapter. However, decisions had to be made about what the optimum affordable sequence of science activities (all of them highly meritorious) is, about which programs need to be operational simultaneously, and about which pro-

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

grams have the highest priority in case budgetary limitations or other unforeseen circumstances limit the overall effort. The committee embarked on this decision process by first looking at the total cost of each individual program (or, in the case of level-of-effort activities such as the NASA Suborbital Program, the accumulated cost over the next decade) to categorize the activity as large (>$400 million), moderate ($250 million to $400 million), or small (<$250 million). By this measure, some relatively large NSF investments, such as AMISR and FASR, were grouped together with the small NASA programs.

The first consideration in developing a recommended program was to map the scientific challenges (Chapter 1) to the objectives and capabilities of the planned and proposed program elements. Table 2.1 shows the mapping between the science challenges and the various missions and facilities selected by the committee.

The underlying vitality of the solar and space physics discipline depends heavily on the robustness of NASA’s Supporting Research and Technology (SR&T) program and of NSF’s base science program and the CEDAR, GEM, and SHINE initiatives, as well as of the NSF-led NSWP. In addition, the development of a systems-level understanding of the geospace environment requires that a high priority be assigned to establishing an initiative to address the complex coupling processes between the different regions. Thus a separate “Vitality” category was identified, and its programs were prioritized in a manner similar to that for the programs in the large, moderate, and small categories. Under the rubric Vitality, the committee considered a number of existing and new activities that stabilize and enhance the connective fabric of the solar and space physics program. In addition to the aforementioned NSF base program, the NSWP, and NASA’s SR&T program, NASA’s Sun-Earth Connection Theory program and Guest Investigator program have been particularly important. Further support for these programs as well as support for new programs—the Coupling Complexity Research initiative, the Virtual Sun, the Solar and Space Physics Information System, and the LWS Data Analysis, Theory, and Modeling program—was also carefully considered.

Within the four main categories, the science impact of each program on the overall solar and space physics discipline was considered along with the program’s potential societal benefits. The programs were ranked by a consensus of the members of the committee following extensive discussions over the course of two prioritization meetings attended by all committee members. The overall rankings are shown in Table 2.2, which also gives brief descriptions of the various programs and missions.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

TABLE 2.1 Mapping of Missions and Facilities to Scientific Challenges

Scientific Challenges

Missions and Facilities

The Dynamic Solar Interior and Corona

The Heliosphere and Its Components

Earth and Planetary Space Environments

Fundamental Space Plasma Physics

Space Weather

Large

Solar Probe

X

X

 

X

 

Moderate

Magnetospheric Multiscale

 

 

X

X

 

Geospace Network

 

 

X

 

X

Jupiter Polar Mission

 

 

X

X

 

Multispacecraft Heliospheric Mission

 

X

 

X

 

Geospace Electrodynamic Connections

 

 

X

X

X

Suborbital Program

X

 

X

X

 

Magnetospheric Constellation

 

 

X

X

X

Solar Wind Sentinels

 

X

 

 

X

Stereo Magnetospheric Imager

 

 

X

 

X

Small

Frequency-Agile Solar Radiotelescope

X

 

 

X

X

Advanced Modular Incoherent Scatter Radar

 

 

X

 

X

L1 Monitor

 

 

 

 

X

Solar Orbiter

X

X

 

 

 

Small Instrument Distributed Ground-Based Network

 

 

X

 

X

University-Class Explorers

X

 

X

X

X

Planned/approved initiatives

Solar Dynamics Observatory

X

 

 

 

X

Advanced Technology Solar Telescope

X

 

 

X

X

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

Recommendation: The committee recommends the approval and funding of the prioritized programs listed in Table 2.2.

While all the programs in Table 2.2 are exceptionally meritorious, small discriminators emerged in the ranking process. The maturity of the study phase of the Magnetospheric Multiscale mission and its attack on the fundamental problems of magnetic reconnection are highly valued. So, too, are the fundamental science questions related to ionospheric variability and particle acceleration in the inner magnetosphere that will be addressed by the LWS Geospace Network missions. Together, these programs will significantly improve the nation’s ability to specify and predict the response of the geospace environment to solar activity. Similarly, the ability to image the Sun with rapid temporal and spatial resolution using the Frequency-Agile Solar Radiotelescope, an important science opportunity in its own right, greatly complements the science program associated with the Solar Dynamics Observatory. Finally, the AMISR will allow many fundamental parameters to be measured in regions important to understanding the response of the ionosphere and atmosphere to external energy inputs driven by the Sun. In addition to their importance for ground-based basic research in solar and space physics, the committee also notes that FASR and AMISR will contribute importantly to the national space weather effort—FASR by providing real-time and near-real-time solar data and AMISR through improved understanding of disturbances of the upper atmosphere and ionosphere associated with space weather events.

Beyond these programs are others with great scientific merit and societal benefit that are directly related to an improved specification of how the geospace system responds to changes in inputs from the Sun and solar wind. An important element of this endeavor is the maintenance of an L1 solar-wind monitor, which the committee recommends be implemented by NOAA (cf. Chapter 5).

The rankings set forth in Table 2.2 were combined with available cost estimates and considerations of technical readiness to arrive at a phasing of programs that could be conducted in the next decade and remain within a reasonable budget. Table 2.3 shows the costing and readiness factors that the committee used to construct the implementation schedule for the NASA initiatives shown in Figure 2.5. In each case the costs include Phases B through D only. MMS and Geospace Network take their place as the important first steps in the committee’s recommended program. These and the other flight programs are superposed on enhancements to the SR&T program and the Suborbital Program that reflect the high scientific produc-

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

TABLE 2.2 Priority Order of the Recommended Programs in Solar and Space Physics

Type of Program

Rank

Program

Description

Large

1

Solar Probe

Spacecraft to study the heating and acceleration of the solar wind through in situ measurements and some remote-sensing observations during one or more passes through the innermost region of the heliosphere (from ~0.3 AU to as close as 3 solar radii above the Sun’s surface).

Moderate

1

Magnetospheric Multiscale

Four-spacecraft cluster to investigate magnetic reconnection, particle acceleration, and turbulence in magnetospheric boundary regions.

2

Geospace Network

Two radiation-belt-mapping spacecraft and two ionospheric mapping spacecraft to determine the global response of geospace to solar storms.

3

Jupiter Polar Mission

Polar-orbiting spacecraft to image the aurora, determine the electrodynamic properties of the Io flux tube, and identify magnetosphere-ionosphere coupling processes.

4

Multispacecraft Heliospheric Mission

Four or more spacecraft with large separations in the ecliptic plane to determine the spatial structure and temporal evolution of coronal mass ejections (CMEs) and other solar-wind disturbances in the inner heliosphere.

5

Geospace Electrodynamic Connections

Three to four spacecraft with propulsion for low-altitude excursions to investigate the coupling among the magnetosphere, the ionosphere, and the upper atmosphere.

6

Suborbital Program

Sounding rockets, balloons, and aircraft to perform targeted studies of solar and space physics phenomena with advanced instrumentation.

7

Magnetospheric Constellation

Fifty to a hundred nanosatellites to create dynamic images of magnetic fields and charged particles in the near magnetic tail of Earth.

8

Solar Wind Sentinels

Three spacecraft with solar sails positioned at 0.98 AU to provide earlier warning than L1 monitors and to measure the spatial and temporal structure of CMEs, shocks, and solar-wind streams.

9

Magnetospheric Imager

Stereo Two spacecraft providing stereo imaging of the plasmasphere, ring current, and radiation belts, along with multispectral imaging of the aurora.

Small

1

Frequency-Agile Solar Radiotelescope

Wide-frequency-range (0.3-30 GHz) radiotelescope for imaging of solar features from a few hundred kilometers above the visible surface to high in the corona.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

Type of Program

Rank

Program

Description

2

Advanced Modular Incoherent Scatter Radar

Movable incoherent scatter radar with supporting optical and other ground-based instruments for continuous measurements of magnetosphere-ionosphere interactions.

3

L1 Monitor

Continuation of solar-wind and interplanetary magnetic field monitoring for support of Earth-orbiting space physics missions. Recommended for implementation by NOAA.

4

Solar Orbiter

U.S. instrument contributions to European Space Agency spacecraft that periodically corotates with the Sun at 45 solar radii to investigate the magnetic structure and evolution of the solar corona.

5

Small Instrument Distributed Ground-Based Network

NSF program to provide global-scale ionospheric and upper atmospheric measurements for input to global physics-based models.

6

University-Class Explorer

Revitalization of University-Class Explorer program for more frequent access to space for focused research projects.

Vitality

1

NASA Supporting Research and Technology

NASA research and analysis program.

2

National Space Weather Program

Multiagency program led by the NSF to support focused activities that will improve scientific understanding of geospace in order to provide better specifications and predictions.

3

Coupling Complexity

NASA/NSF theory and modeling program to address multiprocess coupling, nonlinearity, and multiscale and multiregional feedback.

4

Solar and Space Physics Information System

Multiagency program for integration of multiple data sets and models in a system accessible by the entire solar and space physics community.

5

Guest Investigator Program

NASA program for broadening the participation of solar and space physicists in space missions.

6

Sun-Earth Connection Theory and LWS Data Analysis, Theory, and Modeling Programs

NASA programs to provide long-term support to critical-mass groups involved in specific areas of basic and targeted basic research.

7

Virtual Sun

Multiagency program to provide a systems-oriented approach to theory, modeling, and simulation that will ultimately provide continuous models from the solar interior to the outer heliosphere.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

TABLE 2.3 Cost Estimates for Phases B Through D and Technical Concern Levels for the Recommended Flight Missions and Ground-Based Facilities (million dollars)

Program

Cost (FY 2002)

Technical Concern

Solar Probe

650

Moderate-high

Geospace Electrodynamic Connections

300

Low

Geospace Network

400

Low

Jupiter Polar Mission

350

Moderate

Magnetospheric Constellation

325

High

Magnetospheric Multiscale

350

Low

Multi-Heliospheric Probes

300

Moderate

Solar Wind Sentinels

300

Moderate

Stereo Magnetospheric Imager

300

Low

Suborbital Program

30/yr (2002)-60/yr (2012)

Low

Frequency-Agile Solar Radiotelescope

60

Low

L1 Monitor

100

Low

Relocatable Atmospheric Observatory

65

Low

Small Instrument Distributed Ground-Based Network

5/yr

Low

Solar Orbiter

100

Moderate

University-Class Explorer

35/yr

Moderate

NOTE: Cost estimates were obtained directly from agency estimates whenever possible. Large, medium, and small programs are grouped separately in alphabetical order.

tivity of these efforts and the need to ensure that the overall science under-pinning the major missions does not fall short of its full potential. Because the committee believes that it is imperative to understand the three-dimensional development of energetic solar events such as CMEs as they propagate from the inner heliosphere to 1 AU and beyond, it has included a Multispacecraft Heliospheric Mission in its recommended program. The committee is aware that the different ways in which a mission of this type might be implemented present different technology challenges. For example, an inner heliospheric mission might best be implemented using solar sails. However, in view of the importance of the understanding to be gained through multipoint measurements in the inner heliosphere, the committee recommends the early implementation of an MHM that is consistent with existing technology.

The committee emphasizes the scientific importance of investigating the complex space environments of other planets. Such investigations serve

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

FIGURE 2.5 Recommended phasing of the highest-priority NASA missions, assuming an early implementation of a Solar Probe mission. Solar Probe was the Survey Committee’s highest priority in the large mission category, and the committee recommends its implementation as soon as possible. However, the projected cost of Solar Probe is too high to fit within plausible budget and mission profiles for NASA’s Sun-Earth Connection (SEC) Division. Thus, as shown in this figure, an early start for Solar Probe would require funding above the currently estimated SEC budget of $650 million per year for fiscal years 2006 and beyond. Note that mission operations and data analysis (MO&DA) costs for all missions are included in the MO&DA budget wedge.

as rigorous tests of the ideas developed from the study of Earth’s own environment while extending the knowledge base to other solar-system bodies. The committee therefore strongly recommends a Jupiter Polar Mission, which will study energy transfer in a magnetosphere that is the largest object in the solar system and that, unlike Earth’s, is powered principally by planetary rotation.

A Solar Probe is the only large mission considered by the committee for which the technical readiness is appropriate for implementation in the decade 2003-2013. The scientific merit of a Solar Probe mission (which was the top priority of the Panel on the Sun and Heliospheric Physics) is out-

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

FIGURE 2.6 Recommended phasing of the highest-priority NASA missions if budget augmentation for Solar Probe is not obtained. MO&DA costs for all missions are included in the MO&DA budget wedge.

standing, and the committee recommends its implementation as soon as possible. However, the projected cost of such a mission is too high to fit within either the LWS program or the STP program. Thus, for this important program, separate funding would be required, as is illustrated in Figure 2.5, in which the Solar Probe budget profile extends above the projected Sun-Earth Connection (SEC) baseline budget projection.

In the event that funding augmentation for a Solar Probe mission cannot be secured, the recommended program can still be implemented but with Solar Probe having to start later, which would not be desirable or in keeping with its high scientific priority. Such an alternative sequencing is illustrated in Figure 2.6, which is based on a conservative estimate of the SEC budget.

A summary of the expected NSF funding profile and the recommended phasing of major NSF initiatives is shown in Figure 2.7. An important aspect of the recommended program is the additional funding for facilities

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

FIGURE 2.7 Recommended phasing of major new and enhanced NSF initiatives. The budget wedge for new facilities science refers to support for guest investigator and related programs that will maximize the science return of new ground facilities to the scientific community. Funding for new facilities science is budgeted at approximately 10 percent of the aggregate cost for new NSF facilities.

science (“guest investigator”), which will allow the scientific community to reap the scientific results that the investment in new ground-based observatories will make possible. The new facilities science is budgeted at ~10 percent of the aggregate cost of the new NSF facilities. The cost estimate for the NSF Upper Atmosphere base program includes costs for the CEDAR, GEM, and SHINE research initiatives, which coordinate community research activity and encourage strong student participation, as well as for individual research support in the areas of aeronomy, magnetospheric physics, and solar-terrestrial relations. NSF projections are that this baseline will double within 5 years; the committee has included this projection, doubling funding for the Upper Atmosphere base, the NSWP, and new facilities every 5 years.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

TABLE 2.4 Deferred High-Priority Flight Missions (Listed Alphabetically)

Mission

Reason for Deferral

Large

Interstellar Probe

Advanced propulsion technology needed

Moderate

Auroral Cluster

Lower priority than moderate missions shown in Table 2.2

Dayside Boundary Constellation

Next step after Magnetospheric Constellation

Geospace System Response Imagers

Advanced solar sail technology needed

Io Electrodynamics

Next step after Jupiter Polar Mission

Mars Aeronomy Probe

Not supported by existing SEC mission lines

Reconnection and Microscale Probe

Lower priority than moderate missions shown in Table 2.2

Venus Aeronomy Probe

Not supported by existing SEC mission lines

The budgets for the highly rated AMISR and FASR projects begin immediately (some funds are already being spent for AMISR), and the ongoing ATST budget is shown on the reasonable assumption that it will continue through to completion. Funding for the new program involving small arrays begins gradually and accelerates as the AMISR buildout is completed.

DEFERRED HIGH-PRIORITY FLIGHT MISSIONS

Several large and moderate missions suggested by the panels were given high priority by the committee but were not included in the recommended program because of the overall budget constraint, mission sequencing requirements, or technical readiness issues. These missions are listed alphabetically in Table 2.4.

SUMMARY

The committee based the foregoing national strategy for the next decade of solar and space physics research on a systems approach to understanding the physics of the coupled solar-heliospheric environment. The work of the study panels was essential to the committee’s deliberations and conclusions, as were all of the public outreach activities that were undertaken. The existence of ongoing NSF programs and facilities in solar and space physics, of two complementary mission lines in the NASA Sun-Earth Connection Division—Solar Terrestrial Probes (STP, basic research) and Living With a Star (LWS, targeted basic research)—and of applications and operations activities in NOAA and the DOD facilitated the development of an integrated research strategy.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

As a key first element of its systems-oriented strategy, the committee endorsed three approved NASA missions, Solar-B (STP), STEREO (STP), and the Solar Dynamics Observatory (LWS). Together with ongoing NSF-supported solar physics programs and facilities as well as the start of the Advanced Technology Solar Telescope (ATST), these missions constitute a synergistic approach to the study of the inner heliosphere. This approach will involve coordinated observations of the solar interior and atmosphere and of the formation, release, evolution, and propagation of CMEs toward Earth. Later in the decade covered by the study, an overlapping of the Solar Dynamics Observatory (LWS), the ATST, and the Magnetospheric Multiscale mission (STP), together with the start of the Frequency-Agile Solar Radiotelescope, will form the intellectual basis for a comprehensive investigation of magnetic reconnection in the dense plasma of the solar atmosphere and the tenuous plasmas of geospace.

The committee’s ranking of the Geospace Electrodynamic Connections (STP) and Geospace Network (LWS) missions acknowledges the importance of studying Earth’s ionosphere and inner magnetosphere as a coupled system. Together with a ramping up of the launch opportunities in the Suborbital Program and the implementation of both the AMISR and the Small Instrument Distributed Ground-Based Network, these missions will provide a unique opportunity to study the local electrodynamics of the ionosphere down to altitudes where energy is transferred between the magnetosphere and the atmosphere, while simultaneously investigating the global dynamics of the ionosphere and radiation belts. The implementation of the L1 Monitor (NOAA) and of the Vitality programs will be essential to the success of this systems approach to basic research and targeted basic research. Later on in the committee’s recommended program, concurrent operations of a Multispacecraft Heliospheric Mission (LWS), Stereo Magnetospheric Imager (STP), and MagCon (STP) will provide opportunities for a coordinated approach to understanding the large-scale dynamics of the inner heliosphere and Earth’s magnetosphere (again with strong contributions from the ongoing and new NSF initiatives).

To understand the genesis of the heliospheric system it is necessary to determine the mechanisms by which the solar corona is heated and the solar wind is accelerated and to understand how the solar wind evolves in the innermost heliosphere. These objectives will be addressed by a Solar Probe mission. Because of the importance of these objectives for the overall understanding of the solar-heliosphere system, as well as of other stellar systems, a Solar Probe mission should be implemented as soon as possible within the coming decade. Solar Probe measurements will be comple-

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×

mented by correlative observations from such initiatives as Solar Orbiter, the Solar Dynamics Observatory, the Advanced Technology Solar Telescope, and the Frequency-Agile Solar Radiotelescope.

Similarly, because comparative magnetospheric studies are so important for advancing understanding of basic magnetospheric processes, the committee has assigned high priority to a space physics mission to study high-latitude electrodynamic coupling at Jupiter. Such a mission will provide both a means of testing and refining theoretical concepts developed largely in studies of the terrestrial magnetosphere and a means of studying in situ the electromagnetic redistribution of angular momentum in a rapidly rotating system, with results relevant to such astrophysical questions as the formation of protostars.

NOTES

1.  

While both FASR and ATST are now in the design phase, ATST is the more mature of the two programs. (The FASR design study began only recently, after the Panel on the Sun and Heliospheric Physics had finalized its recommendations.) The committee and the panel therefore regarded ATST as an “approved initiative” and considered FASR to be a “new initiative” that was to be evaluated and ranked with other new initiatives. The committee considers both ATST and SDO to be essential elements of a baseline program on which the recommended new initiatives will build. It recommends continued funding for technology development in support of ATST (cf. Chapter 3 of this report).

2.  

As explained in note 1 in the Executive Summary, the Solar Probe mission recommended by the Panel on the Sun and Heliospheric Physics emphasizes in situ measurement of the solar wind and corona near the Sun. The panel does not consider remote sensing a top priority on a first mission to the near-Sun region, although it does allow as a possible secondary objective remote sensing of the photospheric magnetic field in the polar regions. While accepting the panel’s assessment of the critical importance of the in situ measurements for understanding coronal heating and solar wind acceleration, the committee does not wish to rule out the possibility that some additional remote-sensing capabilities, beyond the remote-sensing experiment to measure the polar photospheric magnetic field envisioned by the panel, can be accommodated on a Solar Probe within the cost cap set by the committee.

3.  

For more details on MHM, see the report of the Panel on the Sun and Heliospheric Physics in the companion volume to this report (2003, in press).

4.  

Cf. the report of the Panel on Atmosphere-Ionosphere-Magnetosphere Interactions in the companion volume to this report (2003, in press).

5.  

Described in the Sun-Earth Connection Roadmap: Strategic Planning for the Years 2000-2020, NASA Office of Space Science, 1997.

6.  

Cf. the report of the Panel on the Sun and Heliospheric Physics in the companion volume to this report ((2003, in press).

7.  

Cf. the report by the Panel on Theory, Modeling, and Data Exploration in the companion volume to this report ((2003, in press).

8.  

Described in the Sun-Earth Connection Roadmap: Strategic Planning for the Years 2000-2020, NASA Office of Space Science, 1997.

Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
×
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
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Suggested Citation:"2. Integrated Research Strategy for Solar and Space Physics." National Research Council. 2003. The Sun to the Earth -- and Beyond: A Decadal Research Strategy in Solar and Space Physics. Washington, DC: The National Academies Press. doi: 10.17226/10477.
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The sun is the source of energy for life on earth and is the strongest modulator of the human physical environment. In fact, the Sun’s influence extends throughout the solar system, both through photons, which provide heat, light, and ionization, and through the continuous outflow of a magnetized, supersonic ionized gas known as the solar wind.

While the accomplishments of the past decade have answered important questions about the physics of the Sun, the interplanetary medium, and the space environments of Earth and other solar system bodies, they have also highlighted other questions, some of which are long-standing and fundamental. The Sun to the Earth—and Beyond organizes these questions in terms of five challenges that are expected to be the focus of scientific investigations in solar and space physics during the coming decade and beyond.

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