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Solar and Space Physics: A Science for a Technological Society
40
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
• Solar and heliospheric physics (SHP)—which covers the physics of the outer regions of the Sun and
the solar wind and its expansion through interplanetary space;
• Solar wind-magnetosphere interactions (SWMI)—which deals with the interaction of the solar wind
with magnetized bodies (principally Earth and other planets) and the resulting dynamics of their magnetospheres and the associated coupling to the underlying ionosphere or planetary surface; and
• Atmosphere-ionosphere-magnetosphere interactions (AIMI)—which concerns the dynamics of planetary ionospheres owing to solar, magnetospheric, and atmospheric drivers and coupling.
The work of the three decadal survey panels representing these areas provided the basis for distillation of
the key science challenges discussed in this chapter.
A DECADE OF HELIOPHYSICS DISCOVERY
The decade 2003-2012 was a time of significant progress in all areas of solar and space physics. Dramatic advances were made in establishing the relationships among solar activity, resulting interplanetary
disturbances, the response of Earth’s space environment, and the dynamics of the outer boundaries of
our solar system with interstellar space. The links between the solar dynamo, convection, active regions,
flares, coronal mass ejections (CMEs), and disturbances in the interplanetary medium are now identified.
Researchers have identified candidate mechanisms that accelerate ions and electrons to relativistic energies in the inner heliosphere. They know the interplanetary conditions that drive geomagnetic activity
and storms and have identified the dominant dynamic characteristics of the coupled magnetosphereionosphere-thermosphere system. Finally, they have now begun to explore the outermost reaches of the
Sun’s influence at the boundary between the heliosphere and interstellar space.
These developments occurred in coordination with advances in physics-based numerical simulations
that provide the foundation for understanding phenomena in terms of underlying physical processes, yielding insights into the basic physics of the systems and attaining a measure of predictive capability. Researchers are now poised to answer questions concerning universal physical processes, advance understanding
of the complex coupling and nonlinear dynamics of the heliosphere, and apply this understanding for
mitigation of harmful impacts to Earth’s technological infrastructures. To show how the recommendations
of this report follow from the flow of scientific discovery, a selection of the most salient discoveries and
advances are presented below. 1
The Sun and Heliosphere
The Solar Dynamo and Activity
Over the past decade, the solar dynamo, which is the source of the Sun’s magnetic field and the resultant dissipation that drives solar activity, continued as a high-priority focus of research. The results of this
work also have important implications for understanding stellar dynamos. Solar activity reached normal
levels in cycle 23, but the minimum between cycles 23 and 24 in 2008-2009 reached low levels not seen
1 For a more complete discussion of ongoing missions and their contributions, see, for example, NASA, “Senior Review 2010 of the
Mission Operations and Data Analysis Program for the Heliophysics Operating Missions,” July 5, 2010, available at http://science.
nasa.gov/media/medialibrary/2010/07/22/SeniorReview2010-MODAProgramPublic_V3.pdf. Also see, NASA, “Heliophysics: State of
the Discipline,” in Heliophysics: The Solar and Space Physics of a New Era: Recommended Roadmap for Science and Technology
2009-2030, 2009 Heliophysics Roadmap Team Report to the NASA Advisory Council Heliophysics Subcommittee, May 2009, available at http://sec.gsfc.nasa.gov/2009_Roadmap.pdf.
Solar and Space Physics: A Science for a Technological Society
40
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
• Solar and heliospheric physics (SHP)—which covers the physics of the outer regions of the Sun and
the solar wind and its expansion through interplanetary space;
• Solar wind-magnetosphere interactions (SWMI)—which deals with the interaction of the solar wind
with magnetized bodies (principally Earth and other planets) and the resulting dynamics of their magnetospheres and the associated coupling to the underlying ionosphere or planetary surface; and
• Atmosphere-ionosphere-magnetosphere interactions (AIMI)—which concerns the dynamics of planetary ionospheres owing to solar, magnetospheric, and atmospheric drivers and coupling.
The work of the three decadal survey panels representing these areas provided the basis for distillation of
the key science challenges discussed in this chapter.
A DECADE OF HELIOPHYSICS DISCOVERY
The decade 2003-2012 was a time of significant progress in all areas of solar and space physics. Dramatic advances were made in establishing the relationships among solar activity, resulting interplanetary
disturbances, the response of Earth’s space environment, and the dynamics of the outer boundaries of
our solar system with interstellar space. The links between the solar dynamo, convection, active regions,
flares, coronal mass ejections (CMEs), and disturbances in the interplanetary medium are now identified.
Researchers have identified candidate mechanisms that accelerate ions and electrons to relativistic energies in the inner heliosphere. They know the interplanetary conditions that drive geomagnetic activity
and storms and have identified the dominant dynamic characteristics of the coupled magnetosphereionosphere-thermosphere system. Finally, they have now begun to explore the outermost reaches of the
Sun’s influence at the boundary between the heliosphere and interstellar space.
These developments occurred in coordination with advances in physics-based numerical simulations
that provide the foundation for understanding phenomena in terms of underlying physical processes, yielding insights into the basic physics of the systems and attaining a measure of predictive capability. Researchers are now poised to answer questions concerning universal physical processes, advance understanding
of the complex coupling and nonlinear dynamics of the heliosphere, and apply this understanding for
mitigation of harmful impacts to Earth’s technological infrastructures. To show how the recommendations
of this report follow from the flow of scientific discovery, a selection of the most salient discoveries and
advances are presented below. 1
The Sun and Heliosphere
The Solar Dynamo and Activity
Over the past decade, the solar dynamo, which is the source of the Sun’s magnetic field and the resultant dissipation that drives solar activity, continued as a high-priority focus of research. The results of this
work also have important implications for understanding stellar dynamos. Solar activity reached normal
levels in cycle 23, but the minimum between cycles 23 and 24 in 2008-2009 reached low levels not seen
1 For a more complete discussion of ongoing missions and their contributions, see, for example, NASA, “Senior Review 2010 of the
Mission Operations and Data Analysis Program for the Heliophysics Operating Missions,” July 5, 2010, available at http://science.
nasa.gov/media/medialibrary/2010/07/22/SeniorReview2010-MODAProgramPublic_V3.pdf. Also see, NASA, “Heliophysics: State of
the Discipline,” in Heliophysics: The Solar and Space Physics of a New Era: Recommended Roadmap for Science and Technology
2009-2030, 2009 Heliophysics Roadmap Team Report to the NASA Advisory Council Heliophysics Subcommittee, May 2009, available at http://sec.gsfc.nasa.gov/2009_Roadmap.pdf.