Earth is enshrouded in what later became known as the Van Allen belts, toroidal bands of extraordinarily high-energy, high-intensity radiation.3
The scope of studies in solar and space physics has since expanded to encompass the study of Earth’s space environment, the solar wind and its interactions with other planets, and the Sun’s role in creating and controlling the electrically charged plasma that fills the heliosphere. Progress in the field has critical impacts on society because we are increasingly dependent on a growing array of technologically advanced, but vulnerable, electronic devices in space. Because the Sun’s output is highly variable in location, intensity, and time, Earth’s near-space environment is a profoundly dynamic one and hosts numerous phenomena that present hazards to spacecraft, humans in space, and ground-based infrastructure on Earth (see Box 1.1, “Severe Space Weather Events—Understanding Societal and Economic Impacts”).
Beyond understanding our local environment, space physics strives to understand how particles are accelerated to very high energies and how such particles subsequently move in magnetic fields around distant planets, distant stars, and—by extension—distant galaxies. Space physics provides the fundamental knowledge to prescribe how energy is transported and converted to form the remarkable tapestry of cosmic objects that have been observed. Studying the Earth system and its parent star provides the cosmic laboratory and the prototype that form the basis for understanding the environs of virtually all other planets, stars, and entire cosmic systems.
The programs, initiatives, and investments in the field that are outlined in this report are designed to make fundamental advances in current scientific knowledge of the governing processes of the space environment—from the interior of the Sun, to the atmosphere of Earth, to the local interstellar medium. These advances also enable predictive capabilities to be improved to the point that highly reliable forecasts can be made regarding the state of the space environment, particularly the disruptive space weather disturbances that threaten society and the economy, and their important technical infrastructure. The wealth of scientific insights that this recommended program will enable will also provide direct benefits to other scientific fields, including astrophysics, planetary science, and laboratory plasma physics. Many of the proposed activities will involve international collaboration and cooperation, thereby leveraging U.S. investments while simultaneously sustaining a U.S. leadership role in this science. Quite importantly, action on this decadal survey’s recommendations will attract into the field the new talent that is required to ensure the continued vitality of solar and space physics.
In this report, the Committee on a Decadal Strategy for Solar and Space Physics (Heliophysics) provides specific recommendations to its sponsors, NASA and the National Science Foundation (NSF), but its guidance is relevant to other federal departments and agencies, especially the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DOD), the U.S. Geological Survey, and the Federal Emergency Management Agency. In developing its recommendations, the committee considered programs that vary widely in scale, ranging from what NASA’s Heliophysics Division denotes as a flagship-class mission—one costing over $1 billion—to NSF grants programs that are smaller by some four orders of magnitude. In addition, the survey committee gave considerable attention to the cadence at which recommended programmatic elements should be repeated. For example, large spaceflight missions at NASA may be so complex and place such high demands on the community that they can be implemented only once or twice per decade. By contrast, smaller missions in the Explorer-class of spacecraft, or NSF ground-based facilities, can be developed and brought to scientific fruition on timescales of 3 to 5 years.
3 Explorer II failed to reach orbit; data from Explorer III and Explorer I together provided the information that is credited with the discovery of the radiation belts.