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A Science Strategy for Space Physics: Part III A Science Strategy for Space Physics Part III Research Strategy Part III outlines the four common thrusts in the committees' recommended strategy for future U.S. research in space physics, and it summarizes the more specific research efforts recommended to address the five key scientific topics that the CSSP and CSTR believe should be and will be at the forefront of research in space physics during the next decade. Those five topics, discussed in detail in Chapters 1 through 5, are listed in Box 3. Under each topic, the research activities recommended by the committees are entered in the order of their priority (i.e., the highest priorities are listed first). RECOMMENDED RESEARCH ACTIVITIES REPORT MENU NOTICE In generating the prioritized lists of recommended research activities, the MEMBERSHIP CSSP and CSTR considered the following issues: SUMMARY PART I PART II Importance. What is the importance of a particular research activity to CHAPTER 1 answering the questions posed for the related major topic? Is the research effort CHAPTER 2 highly likely to resolve one or more important issues? Does it address a major CHAPTER 3 piece of the puzzle? CHAPTER 4 CHAPTER 5 Timeliness. Is the technology necessary to conduct the activity in PART III APPENDIX hand or on the near horizon, and is the activity ripe for progress if initiated in the coming decade? Is the activity time-critical or a unique opportunity? Does the activity take advantage of the availability of new tools? Breadth. Would the results of the research activity provide fundamental understanding with broad applicability? Would the results be applicable to other aspects of space physics, to space science in general, or to other branches of science? file:///C|/SSB_old_web/strapart3.html (1 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III Practical relevance. Is the research activity highly relevant to the issue of the effects of solar variability on the Earth? Balance. Would implementation of the activity help redress the current imbalance1between "big" and "little" science and between planning, development, and pure science activities in space physics? It is important to use with care and common sense the priorities recommended in this report. In many cases the activities are not really in direct competition; they address different scientific issues, their funding agencies may be different, and the amount of money needed may be very different. A priority rank is not an absolute attribute; it is a function of the question being asked. If one carries out only the highest-priority activity that addresses a particular question, the question will not be answered unambiguously or completely. Lower- priority activities can often be justified over higher-priority ones if they are more affordable in the current environment or if they better meet some other goal such as balance between subdisciplines, research techniques, institutions, or other parameters that were not taken into account in the present study. Often two or more lower-priority items taken together can be as important as a single higher- priority item. Also to be factored in are new or unforeseen developments or results in science and technology. But, other things being equal, the committees believe that the scientific precedence for space physics research is that given in Box 3. RECOMMENDED RESEARCH EMPHASES The recommended research activities listed in Box 3 are elements of the overarching goal of achieving greater understanding of the physical processes that underlie the observable phenomena of space physics. These rather detailed lists of diverse research efforts incorporate four common elements that the CSSP and CSTR consider to be the most important emphases for space physics research in the next decade: 1. Complete currently approved programs. Successful completion of the current programs is the committees' highest-priority objective, given that the committees endorse the previous scientific strategies for which those programs were proposed and approved. Successful completion of the current efforts will provide the foundation to which new elements will be added to make scientific progress. In making successful completion of current undertakings the first priority, the committees emphasize that space physics programs do not end with the launch of a spacecraft or the construction of a new facility. For an effort to be worthwhile, the data must be acquired, carefully analyzed, and interpreted. Each of those steps, followed by theoretical assimilation of the results, is necessary to gain the insights needed to advance the science. Furthermore, giving increased emphasis to data collection and interpretation will also help improve the balance file:///C|/SSB_old_web/strapart3.html (2 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III between large- and small-scale efforts in space physics. It must also be recognized, however, that the high priority given to successful completion of established programs does not imply blanket endorsement of extended missions. Each mission extension must compete on its own merits with other ways in which the same resources could be spent. The committees' specific recommended actions for experiment operation and data analysis and interpretation are as follows: a. Completing the diverse components of the International Solar- Terrestrial Physics program. This includes the full-term support of mission operations and data analysis, with effective coordination of the observational and data-analysis campaigns involving the many spacecraft, both U.S. and foreign, and supporting ground-based observatories. The flight projects should cooperate with the several organizations or programs (GEM, STEP, and the IACG) that have been put in place for that purpose. b. Enhancing data analysis and interpretation efforts for other space missions that have been launched recently or are currently in development. These include Yohkoh, SAMPEX, FAST, ACE, SOHO, Galileo, and Cassini. Adequate support is also required for the successful fulfillment of the objectives of NSF's CEDAR, GEM, and SUNRISE programs. c. Streamlining mission operations to help keep extended missions going as well as minimize operations costs for new missions. d. Carrying out extended missions for the uniquely placed Voyager (to the greatest possible heliocentric distance) and Ulysses (through the solar polar passes at solar maximum). e. Continuing support of those ground- and space-based observations that require improved statistics or the acquisition of data over a range of solar- cycle conditions. At issue are (1) gap-free, space-based observations of the variability of solar luminosity, (2) solar neutrino and helioseismological observations, and (3) monitoring of the composition, dynamics, and temperature of the middle and upper atmospheres to obtain a baseline for future studies of climate changes, together with (4) monitoring and prediction of space "weather" in support of a wide range of research and operational activities. f. Enhancing the effectiveness of some of the longer-duration programs by soliciting new ideas and analysis techniques from guest investigators and by ensuring easy access to archived data resulting from the various programs for use in "small science" research tasks. 2. Exploit existing technologies and opportunities to obtain new results in a cost-effective manner. The technology is already in place to take the next observational steps required to address many of the important questions in space physics. Both spacecraft and instrument technology are available to complement point-by-point in situ measurements of the magnetosphere with file:///C|/SSB_old_web/strapart3.html (3 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III global imaging and to carry out a multi-spacecraft mission capable of establishing a baseline for studies of changes in the middle and upper atmospheres while separating spatial from temporal effects in those regions. Measurement of solar irradiance variations can also be carried out using current instrument designs. Other objectives can be addressed effectively by inclusion of instruments for space physics research on missions of opportunity, such as NASA's planetary missions and Department of Defense spacecraft, or through international collaborations. On suborbital platforms such as rockets and balloons or on the ground at new sites such as in the polar cap, operation of existing types of instruments can allow unique studies of some aspects of magnetosphere- ionosphere-atmosphere coupling. The advent of new networking, telescience, and other collaboration methods allows real-time display of data from widely separated sensors. Exploiting this technology allows experiments and observations to be optimized while reducing costs. 3. Develop the new technology required to advance the frontiers of space physics. We must continue to push the limits of technology in order to achieve other high-priority objectives or to lower the cost of projects that are already technically feasible. The technology required to approach the Sun ever more closely will open one of the most exciting frontiers of space science. New spacecraft using lightweight structures and miniaturized electronics, and balloon technology allowing 8- to 20-day flights around the South Pole, should enable some high-priority space physics measurements to be made inexpensively in the near term. A good start has been made in the development of the new technology required for the study of high-energy radiation and particles from transient solar events with high angular and spectral resolutions and wide spectral coverage. New techniques for fabrication of lightweight optics are becoming available from the former Soviet Union. Advanced instruments for the analysis of the rarest components of the cosmic radiation such as very heavy or very energetic particles must continue to be developed and flight-tested on long- duration balloons that can carry heavier payloads than are possible with current balloons. Small, capable instruments must be developed to enable affordable in situ measurements of the solar corona, the distant heliosphere, and some regions of planetary magnetospheres. Advances are also required in (a) infrared instrumentation and a large-aperture infrared-capable solar telescope, (b) second- generation instruments for magnetospheric imaging with greater sensitivity, energy and composition discrimination, and angular resolution, and (c) instrumentation for exploring the regions between those altitudes reached by balloons and by satellites. As already mentioned, one of the conclusions of this report is that the highest near-term priority for space physics is the successful completion of the ISTP program and thorough correlation and analysis of the diverse sets of data that it will generate. That recommendation is entirely consistent with the current emphasis on the development of space technology that can be transferred to other sectors of the economy. The operations and data analysis phase of ISTP is a good opportunity for the development and use of new technology for experiment operations, automated or remote operations of ground-based scientific facilities, data distribution and archiving, and data visualization and other aids to interpretation. file:///C|/SSB_old_web/strapart3.html (4 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III 4. Support strongly the theory and modeling activities vital to space physics. As emphasized in previous reports,2-5 theory and modeling complement data analysis as vital components of all the subdisciplines of space physics research. In the coming decade, special attention or emphasis should be given to the following: a. Recognizing that synergy between observations, modeling, and theory provides the optimum way of addressing the principal questions in space physics; b. Making numerical simulations of space physics systems more realistic by extending them to three dimensions, longer time durations, and a greater range of scale sizes, and including additional interacting physical and chemical processes; c. Ensuring that space physicists have ready access to state-of-the-art computational facilities, given that modeling relevant processes will require an order-of-magnitude increase in computer throughput; d. Exploiting new insights gained from theory, especially the theory of nonlinear processes. Such work has already been started, with the development of new ways of looking at nonlinearities. Some problems, such as understanding the solar dynamo, require totally new theoretical insights, as opposed to extended modeling or simulations. It is possible that such insights might result from plasma-physics experiments performed in terrestrial laboratories; and e. Revisiting earlier efforts to predict solar activity, such as coronal mass ejections and flares, using simulations combined with solar observations. Although the four areas of emphasis summarized above are in priority order, it is absolutely essential that progress be made in all four. The space physics community must reap the benefits of what has already been built and paid for. Space physicists must take advantage of existing capabilities to make new types of measurements in a cost-effective way. Researchers must also develop and use the technology required for future progress. Finally, space physicists must continuously digest the new data, decide what those data mean, and keep fine-tuning and reviewing the scientific questions that drive the research. file:///C|/SSB_old_web/strapart3.html (5 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III Box 3 Prioritized Listing of Research Activities in Five Topics Identified as Key Areas for Study in the Next Decade Mechanisms of Solar Variability Use helioseismology to study the structure and dynamics of the solar surface and interior over a full solar cycle. Assure continuity of total and spectral irradiance measurements, supported by spatially resolved spectrophotometry, to investigate correlations between solar magnetic activity and solar output variations. Measure high-energy radiation and particles from flares and coronal mass ejections with good angular resolution, good spectral resolution, and wide spectral coverage to determine what drives each of these phenomena and how they contribute to the solar output at high energies. Observe surface magnetic fields, velocities, and thermodynamic properties with enough spatial resolution (<150 km, with an ultimate goal of <100 km) to study small-scale structures such as flux tubes. Make global-perspective measurements of the solar surface magnetic and velocity fields and solar oscillations to measure the three-dimensional structure and long-term evolution of active regions and to detect weak but coherent global oscillations. Measure active regions with angular resolution of ~1 arc sec and temporal resolution of ~10 min for a duration of ~10 days without nighttime gaps to determine their magnetohydrodynamic history of emergence, development, and decay. The Physics of the Solar Wind and the Heliosphere Continue to obtain and synthesize the data from the present constellation of heliospheric spacecraft (Voyager, Ulysses, Wind, and ACE) and from the interplanetary cruise phases of planetary missions in order to characterize the global and solar-cycle-dependent properties of the heliosphere and its interaction with the interstellar medium. Carry out in situ observations of the solar corona to explore and characterize the region of acceleration of the solar wind plasma and the physical processes responsible for that acceleration. Obtain new types of data required to reveal the mechanisms responsible for the transport of energy from the solar surface into the chromosphere and corona to understand how these are heated. Carry out stereo imaging of the solar corona to reveal the three- dimensional structure of coronal features without the ambiguity caused by integration along the line of sight. Develop and use techniques for the remote sensing of the coronal file:///C|/SSB_old_web/strapart3.html (6 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III magnetic field in order to improve knowledge of the acceleration of the solar wind and of the initiation of coronal mass ejections. Make in situ measurements of the outer heliospheric boundaries and the interstellar medium with instruments specifically designed for those purposes. The Structure and Dynamics of Magnetospheres and Their Coupling to Adjacent Regions Reap the full scientific potential of the International Solar-Terrestrial Physics program and its coordinated programs to advance understanding of the transport of mass, momentum, and energy throughout the solar wind, and the magnetosphere and ionosphere systems. Simultaneously image the plasma and energetic particle populations in the aurora, plasmasphere, ring current, and inner plasma sheet to study the global structure and large-scale interactions of magnetospheric and ionospheric regions during different levels of solar and geomagnetic activity. Maintain the full complement of particle and field instruments on current and future planetary missions to gain increased understanding of the formation and dynamics of diverse magnetospheres and ionospheres. Further develop and exploit ground-based facilities that image the ionospheric manifestations of solar wind/magnetosphere coupling processes to complement the magnetospheric imaging initiative aimed at studying the global properties of the magnetosphere. Explore Mercury's magnetosphere to understand the role of an ionosphere in coupling between the solar wind and planetary magnetospheres. Target localized regions that require greater understanding of the small- scale physical processes occurring there with high-resolution, multispacecraft measurements that take advantage of new smaller, lighter, more capable instruments and more sophisticated data-compression schemes. The Middle and Upper Atmospheres and Their Coupling to Regions Above and Below Exploit the exciting new capabilities of UARS, FAST, and CEDAR to provide the foundation for future advances in our understanding of the middle and upper atmospheres. Investigate the reaction of the middle and upper atmospheres to upward propagating waves and energy inputs from space so that the sources of important features such as the quasi-biennial and semiannual oscillations and the causes of mesosphere/lower-thermosphere structure and variability can be understood. Study the long-term variations in the middle and upper atmospheres using a combination of consistent long-term satellite and ground-based measurements together with three-dimensional radiative-chemical-dynamical modeling to understand natural and anthropogenic changes in these regions. file:///C|/SSB_old_web/strapart3.html (7 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III Develop methods to observe the time-dependent electrodynamics operating on microscales to global scales, both in the upper atmosphere- ionosphere-magnetosphere coupling regions so that feedback processes can be characterized, and in the regions above thunderstorms so that the effects of electrified clouds on the "global circuit" and on middle atmosphere chemistry and energetics can be characterized. Take advantage of opportunities to include carefully chosen, appropriate instruments on planetary orbiter missions to make measurements critical to understanding planetary aeronomy and its relation to terrestrial aeronomic processes. Plasma Processes That Accelerate Very Energetic Particles and Control Their Propagation Complete the observations from the current and planned network of interplanetary spacecraft to study particle acceleration, fractionation, and transport. Extend direct composition measurements to 1015 eV to probe the limits of acceleration and trapping mechanisms. Measure abundances of radioactive isotopes above 1 GeV/nucleon to search for evidence of an extended galactic magnetosphere and wind. Measure the spectra of positrons (10 MeV to 100 GeV) and antiprotons (100 MeV to 100 GeV) to determine where those particles are created and how they are accelerated. Measure isotope abundances for nuclei heavier than nickel and elemental abundances through the actinides to probe the plasma regions where the nuclei are synthesized and to measure the time scales involved. REFERENCES 1. Board on Atmospheric Sciences and Climate and the Space Studies Board, National Research Council, A Space Physics Paradox: Why Has Increased Funding Been Accompanied by Decreased Effectiveness in the Conduct of Space Physics Research?, National Academy Press, Washington, D.C., 1994. 2. Space Studies Board and the Board on Atmospheric Sciences and Climate, National Research Council, Assessment of Programs in Solar and Space Physics—1991, National Academy Press, Washington, D.C., 1991. 3. Space Science Board, National Research Council, Solar-System file:///C|/SSB_old_web/strapart3.html (8 of 10) [6/18/2004 2:20:46 PM]

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A Science Strategy for Space Physics: Part III Space Physics in the 1980's: A Research Strategy, National Academy of Sciences, Washington, D.C., 1980. 4. Space Science Board, National Research Council, The Role of Theory in Space Science, National Academy Press, Washington, D.C., 1983. 5. Space Science Board, National Research Council, An Implementation Plan for Priorities in Solar-System Space Physics, National Academy Press, Washington, D.C., 1985. Last update 2/18/00 at 11:28 am Site managed by Anne Simmons, Space Studies Board file:///C|/SSB_old_web/strapart3.html (9 of 10) [6/18/2004 2:20:46 PM]