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Solar and Space Physics: A Science for a Technological Society
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SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
with more than 100 times the sensitivity of earlier studies, for microflares and nanoflares that may heat
the corona. IMAP high-resolution composition and charge-state measurements will trace 1-AU impulsive
events while remote-sensing and near-Sun observations provide spatial and temporal structures of solar
and interplanetary acceleration regions.
• Determine the origin and variability of suprathermal electrons, protons, and heavy ions on timescales
of minutes to hours. Discovering suprathermal-ion production mechanisms is one key to understanding
particle acceleration. Pioneering observations by Ulysses, ACE, Wind, and STEREO revealed the importance
of suprathermal ions and raised questions about their origin, but these studies had limited time resolution and statistical accuracy. SPP and Solar Orbiter will measure the evolution of ion and electron halo
solar wind and suprathermal tails close to the Sun, providing improved opportunities to isolate solar and
interplanetary contributions and to test theoretical models. Comprehensive measurements of suprathermalion composition, spectra, and intensity fluctuations by IMAP will relate energetic-particle populations to
interplanetary structures and physical processes.
• Develop advanced methods for forecasting and nowcasting of solar eruptive events and space
weather. Combining SPP and Solar Orbiter in situ observations with 1-AU imaging and in situ data will
provide ground truth for SEP-acceleration models and thereby improve SEP forecasts (motivation M2). The
data may also reveal how monitoring critical near-Sun conditions (for example, active-region, shock, and
suprathermal-seed properties) can aid forecasting. Multipoint measurements of SEP radial and longitudinal
distributions will clarify current environmental-model uncertainties.
It is critical that forecasters develop predictive capabilities for space weather events while maintaining
comprehensive measurements for nowcasting solar wind and energetic-particle inputs into geospace (motivation M2). IMAP, like ACE before it, will be a keystone of the Heliophysics Systems Observatory (HSO)
by providing comprehensive solar wind data; diagnostics of suprathermal-ion and electron sources; solar
wind and energetic-particle inputs into geospace; and evolving interplanetary magnetic-field properties.
IMAP will also provide unprecedented measurements of suprathermal-tail variability and determine how
seed populations are related to higher-energy particles accelerated by shocks, waves, and disturbances.
FASR would provide many new observations important with respect to space weather, including observations of coronal magnetic fields in active regions and their evolution before, during, and after flares and
CMEs; “real-time” observations of coronal-shock locations and properties; measurements of the spectral
evolution of electron energy-distribution functions; and radio flux-density spectra in communication bands.
10.4.4 Discover How the Sun Interacts with the Local Galactic Medium and Protects Earth
The coming decade offers unique opportunities for additional breakthroughs in understanding how the
heliosphere and local galactic medium interact. Those opportunities address associated SHP actions 4a-c:
• Determine the spatial-temporal evolution of heliospheric boundaries and their interactions. Solarcycle changes in the solar wind dynamic pressure affect the structure of heliospheric boundaries. In the next
few years, Voyager and IBEX observations will determine how the global heliosphere responds to increased
solar activity. Complementary solar wind, pickup-ion, and anomalous and galactic cosmic-ray observations
by ACE, Wind, and STEREO will provide context for evolving solar conditions and measure the cosmic-ray
response to global-heliosphere changes. IMAP, with its unprecedented roughly 80 times greater sensitivity
and duty cycle in ENA maps (and 10 times higher angular resolution), will deliver definitive measurements
of the fine structure and detailed evolution of the global heliosphere. By combining those breakthrough
Solar and Space Physics: A Science for a Technological Society
288
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
with more than 100 times the sensitivity of earlier studies, for microflares and nanoflares that may heat
the corona. IMAP high-resolution composition and charge-state measurements will trace 1-AU impulsive
events while remote-sensing and near-Sun observations provide spatial and temporal structures of solar
and interplanetary acceleration regions.
• Determine the origin and variability of suprathermal electrons, protons, and heavy ions on timescales
of minutes to hours. Discovering suprathermal-ion production mechanisms is one key to understanding
particle acceleration. Pioneering observations by Ulysses, ACE, Wind, and STEREO revealed the importance
of suprathermal ions and raised questions about their origin, but these studies had limited time resolution and statistical accuracy. SPP and Solar Orbiter will measure the evolution of ion and electron halo
solar wind and suprathermal tails close to the Sun, providing improved opportunities to isolate solar and
interplanetary contributions and to test theoretical models. Comprehensive measurements of suprathermalion composition, spectra, and intensity fluctuations by IMAP will relate energetic-particle populations to
interplanetary structures and physical processes.
• Develop advanced methods for forecasting and nowcasting of solar eruptive events and space
weather. Combining SPP and Solar Orbiter in situ observations with 1-AU imaging and in situ data will
provide ground truth for SEP-acceleration models and thereby improve SEP forecasts (motivation M2). The
data may also reveal how monitoring critical near-Sun conditions (for example, active-region, shock, and
suprathermal-seed properties) can aid forecasting. Multipoint measurements of SEP radial and longitudinal
distributions will clarify current environmental-model uncertainties.
It is critical that forecasters develop predictive capabilities for space weather events while maintaining
comprehensive measurements for nowcasting solar wind and energetic-particle inputs into geospace (motivation M2). IMAP, like ACE before it, will be a keystone of the Heliophysics Systems Observatory (HSO)
by providing comprehensive solar wind data; diagnostics of suprathermal-ion and electron sources; solar
wind and energetic-particle inputs into geospace; and evolving interplanetary magnetic-field properties.
IMAP will also provide unprecedented measurements of suprathermal-tail variability and determine how
seed populations are related to higher-energy particles accelerated by shocks, waves, and disturbances.
FASR would provide many new observations important with respect to space weather, including observations of coronal magnetic fields in active regions and their evolution before, during, and after flares and
CMEs; “real-time” observations of coronal-shock locations and properties; measurements of the spectral
evolution of electron energy-distribution functions; and radio flux-density spectra in communication bands.
10.4.4 Discover How the Sun Interacts with the Local Galactic Medium and Protects Earth
The coming decade offers unique opportunities for additional breakthroughs in understanding how the
heliosphere and local galactic medium interact. Those opportunities address associated SHP actions 4a-c:
• Determine the spatial-temporal evolution of heliospheric boundaries and their interactions. Solarcycle changes in the solar wind dynamic pressure affect the structure of heliospheric boundaries. In the next
few years, Voyager and IBEX observations will determine how the global heliosphere responds to increased
solar activity. Complementary solar wind, pickup-ion, and anomalous and galactic cosmic-ray observations
by ACE, Wind, and STEREO will provide context for evolving solar conditions and measure the cosmic-ray
response to global-heliosphere changes. IMAP, with its unprecedented roughly 80 times greater sensitivity
and duty cycle in ENA maps (and 10 times higher angular resolution), will deliver definitive measurements
of the fine structure and detailed evolution of the global heliosphere. By combining those breakthrough