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Solar and Space Physics: A Science for a Technological Society
300
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
develop key physical knowledge of the interstellar interactions that influence our home system in its current state, the history and destiny of our solar system, and the habitability of exoplanetary star systems.
Outer heliospheric science is an exciting, rapidly developing field because of groundbreaking all-sky
images of the heliospheric boundaries based on energetic neutral atoms (ENAs) from the IBEX mission and
Cassini-INCA in concert with dual in situ heliosheath observations from the Voyagers and IBEX measurements of interstellar neutral H, He, O, and Ne flow.
The surprising ENA “ribbon” (§10.3.4) demonstrates the importance of the interstellar magnetic field in
the interaction of the heliosphere with our galactic neighborhood. The physical processes that form ENA
spectra and the ribbon are hotly debated because of complex interactions between solar wind, pickup
ions (PUIs), and suprathermal particles. The big picture provided by IBEX, complemented by Voyager
observations, shows that the asymmetry of the heliosphere (§10.3.4) is shaped by the surrounding galactic
magnetic field and that the physical processes that control the interaction exist on relatively small spatial
and temporal scales (months). IMAP provides the next “quantum leap” forward in understanding the heliosphere through substantial improvements in spatial, temporal, and energy resolution 12 and much broader
energy coverage than that of IBEX.
Observations from many spacecraft in the HSO contribute dramatically to understanding of SEP events,
of the importance of suprathermal ions for efficient energization (§10.3.3), of the sources and evolution
of solar wind (§10.3.2), of solar wind and SEP inputs into geospace, and of the evolution of the solarheliospheric magnetic field (§10.3.1). Those observable phenomena are controlled by myriad complex and
poorly understood physical effects that act on distinct particle populations (Figure 10.20). IMAP combines
highly sensitive PUI and suprathermal-ion sensors to provide the species, spectral coverage, and temporal
resolution to associate emerging suprathermal tails with interplanetary structures and physical processes
(SHP action 3c).
IMAP orbits the inner Lagrangian point (L1) with comprehensive and highly sophisticated instruments
to make the key observations that answer these fundamental questions:
• What is the spatiotemporal evolution of heliospheric boundary interactions?
• What is the nature of the heliopause and the interaction of the solar and interstellar magnetic fields?
• What are the composition and physical properties of the surrounding interstellar medium?
• How are particles injected into acceleration, and what mechanisms energize them throughout the
heliosphere and heliosheath?
• What are the time-varying physical inputs at L1 into the Earth system?
The mission’s heliospheric focus highlights the importance of making IMAP ENA maps and maps of ACR
and CGR particles concurrently with in situ Voyager measurements of the heliospheric boundary region
(motivation M3). IMAP enables understanding of particle acceleration through unprecedented collection
power and time-resolved measurements of suprathermal ions that originate in the solar wind, interstellar
medium, and inner heliosphere; enables environmental monitoring that is critical for effective background
evaluation and removal from ENA maps and interpretation of PUI distributions; enables comprehensive
interplanetary monitoring in support of geospace interaction studies; and enables space weather observations at the ideal location, L1 (SHP action 3d and motivation M2).
Answering the fundamental IMAP questions requires:
• High-resolution mapping and time evolution of heliospheric boundaries;
12 D.J. McComas et al., Interstellar Mapping Probe (IMAP) Mission Concept: Illuminating the Dark Boundaries at the Edge of Our
Solar System, white paper submitted to the Decadal Strategy for Solar and Space Physics (Heliophysics), Paper 188.
Solar and Space Physics: A Science for a Technological Society
300
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
develop key physical knowledge of the interstellar interactions that influence our home system in its current state, the history and destiny of our solar system, and the habitability of exoplanetary star systems.
Outer heliospheric science is an exciting, rapidly developing field because of groundbreaking all-sky
images of the heliospheric boundaries based on energetic neutral atoms (ENAs) from the IBEX mission and
Cassini-INCA in concert with dual in situ heliosheath observations from the Voyagers and IBEX measurements of interstellar neutral H, He, O, and Ne flow.
The surprising ENA “ribbon” (§10.3.4) demonstrates the importance of the interstellar magnetic field in
the interaction of the heliosphere with our galactic neighborhood. The physical processes that form ENA
spectra and the ribbon are hotly debated because of complex interactions between solar wind, pickup
ions (PUIs), and suprathermal particles. The big picture provided by IBEX, complemented by Voyager
observations, shows that the asymmetry of the heliosphere (§10.3.4) is shaped by the surrounding galactic
magnetic field and that the physical processes that control the interaction exist on relatively small spatial
and temporal scales (months). IMAP provides the next “quantum leap” forward in understanding the heliosphere through substantial improvements in spatial, temporal, and energy resolution 12 and much broader
energy coverage than that of IBEX.
Observations from many spacecraft in the HSO contribute dramatically to understanding of SEP events,
of the importance of suprathermal ions for efficient energization (§10.3.3), of the sources and evolution
of solar wind (§10.3.2), of solar wind and SEP inputs into geospace, and of the evolution of the solarheliospheric magnetic field (§10.3.1). Those observable phenomena are controlled by myriad complex and
poorly understood physical effects that act on distinct particle populations (Figure 10.20). IMAP combines
highly sensitive PUI and suprathermal-ion sensors to provide the species, spectral coverage, and temporal
resolution to associate emerging suprathermal tails with interplanetary structures and physical processes
(SHP action 3c).
IMAP orbits the inner Lagrangian point (L1) with comprehensive and highly sophisticated instruments
to make the key observations that answer these fundamental questions:
• What is the spatiotemporal evolution of heliospheric boundary interactions?
• What is the nature of the heliopause and the interaction of the solar and interstellar magnetic fields?
• What are the composition and physical properties of the surrounding interstellar medium?
• How are particles injected into acceleration, and what mechanisms energize them throughout the
heliosphere and heliosheath?
• What are the time-varying physical inputs at L1 into the Earth system?
The mission’s heliospheric focus highlights the importance of making IMAP ENA maps and maps of ACR
and CGR particles concurrently with in situ Voyager measurements of the heliospheric boundary region
(motivation M3). IMAP enables understanding of particle acceleration through unprecedented collection
power and time-resolved measurements of suprathermal ions that originate in the solar wind, interstellar
medium, and inner heliosphere; enables environmental monitoring that is critical for effective background
evaluation and removal from ENA maps and interpretation of PUI distributions; enables comprehensive
interplanetary monitoring in support of geospace interaction studies; and enables space weather observations at the ideal location, L1 (SHP action 3d and motivation M2).
Answering the fundamental IMAP questions requires:
• High-resolution mapping and time evolution of heliospheric boundaries;
12 D.J. McComas et al., Interstellar Mapping Probe (IMAP) Mission Concept: Illuminating the Dark Boundaries at the Edge of Our
Solar System, white paper submitted to the Decadal Strategy for Solar and Space Physics (Heliophysics), Paper 188.