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Solar and Space Physics: A Science for a Technological Society
REPORT OF THE PANEL ON SOLAR AND HELIOSPHERIC PHYSICS
263
explosions of the solar magnetic field and matter known as coronal mass ejections/eruptive flares. Those
events also produce the most destructive space weather at Earth, with damaging consequences ranging
from communication and GPS blackouts to the loss of high-orbiting satellites and power transformers on
the ground.
In recent years, scientists have made substantial progress in understanding the Sun’s magnetic explosions. Researchers know where on the Sun they are likely to occur but are far from understanding when
and how large the explosions will be and, in particular, how so much of their energy produces particle
radiation. It should be emphasized that the processes of magnetic energy storage and release are commonly
observed in all laboratory and cosmic plasmas; therefore, understanding them in the Sun and heliosphere
will be a fundamental advance for all physics. Thus, the SHP panel’s third major science goal, SHP3, is to
determine how magnetic energy is stored and explosively released.
As stated above, the heliopause is where the Sun’s extended atmosphere ends and the galactic medium
begins. That interface where two regions collide is generally rich in unexplored and unique physics. For
example, the dominant energy form in the region is due not to the solar wind plasma or magnetic field
but rather to interstellar neutrals that stream freely into the heliosphere and charge exchange with the
solar wind ions. The magnetic structure of the region is also unique in that the field is wound into such a
tight spiral due to solar rotation that it is almost cylindrical rather than radial. It should also be noted that
the structure of the outer heliosphere has important effects close to home: it determines the penetration
of high-energy galactic cosmic rays into near-Earth space. In situ measurements by the Voyager spacecraft
and new methods to globally image the outer boundary of the heliosphere are spurring a revolution in
understanding of this region. During the next decade, the Voyager spacecraft should pass the heliopause
and enter interstellar space. Extending their presence robotically, humans will have left their home in space
for the first time and entered the universe—a truly historic event. The coming decade will be critical for
gaining an understanding not only of how our space environment is created and driven, but also of how
it ends. That is the SHP panel’s final major science goal for the decade, SHP4, to discover how the Sun
interacts with the local galactic medium and protects Earth.
Associated with each of the SHP panel’s four science goals are several SHP actions that, if carried
out, promise substantial progress in achieving the goals. Box 10.1 summarizes the SHP panel’s four major
science goals and 14 associated actions.
10.2 SOLAR AND HELIOSPHERIC PHYSICS IMPERATIVES
To achieve the four major science goals listed in Box 10.1, the SHP panel developed a strategy that
consists of a set of imperatives for the federal agencies involved in solar and heliospheric research. The
imperatives—actions that are essential for future progress—are listed briefly below according to the relevant
agency (or agencies) and discussed in detail below in this chapter.
10.2.1 Prioritized Imperatives for NASA
1. Complete the development and launch of the Interface Region Imaging Spectrograph (IRIS) and
Solar Probe Plus (SPP) missions, and deliver U.S. contributions to the European Space Agency–National
Aeronautics and Space Administration (ESA–NASA) Solar Orbiter mission. The measurements from those
missions are central to the SHP panel’s strategy for addressing SHP science goals 1, 2, and 3 in the next
decade (§10.5.3.1).
2. Augment the heliophysics Explorer budget to expand launch opportunities and add new costeffective mid-size launch vehicles (§10.5.3.2).
Solar and Space Physics: A Science for a Technological Society
REPORT OF THE PANEL ON SOLAR AND HELIOSPHERIC PHYSICS
263
explosions of the solar magnetic field and matter known as coronal mass ejections/eruptive flares. Those
events also produce the most destructive space weather at Earth, with damaging consequences ranging
from communication and GPS blackouts to the loss of high-orbiting satellites and power transformers on
the ground.
In recent years, scientists have made substantial progress in understanding the Sun’s magnetic explosions. Researchers know where on the Sun they are likely to occur but are far from understanding when
and how large the explosions will be and, in particular, how so much of their energy produces particle
radiation. It should be emphasized that the processes of magnetic energy storage and release are commonly
observed in all laboratory and cosmic plasmas; therefore, understanding them in the Sun and heliosphere
will be a fundamental advance for all physics. Thus, the SHP panel’s third major science goal, SHP3, is to
determine how magnetic energy is stored and explosively released.
As stated above, the heliopause is where the Sun’s extended atmosphere ends and the galactic medium
begins. That interface where two regions collide is generally rich in unexplored and unique physics. For
example, the dominant energy form in the region is due not to the solar wind plasma or magnetic field
but rather to interstellar neutrals that stream freely into the heliosphere and charge exchange with the
solar wind ions. The magnetic structure of the region is also unique in that the field is wound into such a
tight spiral due to solar rotation that it is almost cylindrical rather than radial. It should also be noted that
the structure of the outer heliosphere has important effects close to home: it determines the penetration
of high-energy galactic cosmic rays into near-Earth space. In situ measurements by the Voyager spacecraft
and new methods to globally image the outer boundary of the heliosphere are spurring a revolution in
understanding of this region. During the next decade, the Voyager spacecraft should pass the heliopause
and enter interstellar space. Extending their presence robotically, humans will have left their home in space
for the first time and entered the universe—a truly historic event. The coming decade will be critical for
gaining an understanding not only of how our space environment is created and driven, but also of how
it ends. That is the SHP panel’s final major science goal for the decade, SHP4, to discover how the Sun
interacts with the local galactic medium and protects Earth.
Associated with each of the SHP panel’s four science goals are several SHP actions that, if carried
out, promise substantial progress in achieving the goals. Box 10.1 summarizes the SHP panel’s four major
science goals and 14 associated actions.
10.2 SOLAR AND HELIOSPHERIC PHYSICS IMPERATIVES
To achieve the four major science goals listed in Box 10.1, the SHP panel developed a strategy that
consists of a set of imperatives for the federal agencies involved in solar and heliospheric research. The
imperatives—actions that are essential for future progress—are listed briefly below according to the relevant
agency (or agencies) and discussed in detail below in this chapter.
10.2.1 Prioritized Imperatives for NASA
1. Complete the development and launch of the Interface Region Imaging Spectrograph (IRIS) and
Solar Probe Plus (SPP) missions, and deliver U.S. contributions to the European Space Agency–National
Aeronautics and Space Administration (ESA–NASA) Solar Orbiter mission. The measurements from those
missions are central to the SHP panel’s strategy for addressing SHP science goals 1, 2, and 3 in the next
decade (§10.5.3.1).
2. Augment the heliophysics Explorer budget to expand launch opportunities and add new costeffective mid-size launch vehicles (§10.5.3.2).