NASA Science Mission Directorate: Heliophysics Division

We live in the extended atmosphere of an active star. While sunlight enables and sustains life, the Sun's variability produces streams of high energy particles and radiation that can harm life or alter its evolution.

Under the protective shield of a magnetic field and atmosphere, the Earth is an island in the Universe where life has developed and flourished. The origins and fate of life on Earth are intimately connected to the way the Earth responds to the Sun's variations.

Understanding the Sun, Heliosphere, and Planetary Environments as a single connected system is the goal of the Science Mission Directorate's Heliophysics Research Program. In addition to solar processes, our domain of study includes the interaction of solar plasma and radiation with Earth, the other planets, and the Galaxy. By analyzing the connections between the Sun, solar wind, planetary space environments, and our place in the Galaxy, we are uncovering the fundamental physical processes that occur throughout the Universe. Understanding the connections between the Sun and its planets will allow us to predict the impacts of solar variability on humans, technological systems, and even the presence of life itself.

We have already discovered ways to peer into the internal workings of the Sun and understand how the Earth's magnetosphere responds to solar activity. Our challenge now is to explore the full system of complex interactions that characterize the relationship of the Sun with the solar system. Understanding these connections is especially critical as we contemplate our destiny in the third millennium. Heliophysics is needed to facilitate the accelerated expansion of human experience beyond the confines of our Earthly home. Recent advances in technology allow us, for the first time, to realistically contemplate voyages beyond the solar system. There are three primary objectives that define the multi-decadal studies needed:

• To understand the changing flow of energy and matter throughout the Sun, Heliosphere, and Planetary Environments. • To explore the fundamental physical processes of space plasma systems. • To define the origins and societal impacts of variability in the Earth-Sun System.

A combination of interrelated elements is used to achieve these objectives. They include complementary missions of various sizes; timely development of enabling and enhancing technologies; and acquisition of knowledge through research, analysis, theory, and modeling.

NASA launched the Magnetospheric Multiscale, or MMS, mission in March 2015 to solve the mystery of how magnetic fields around Earth connect and disconnect, explosively releasing energy via a process known as magnetic reconnection.

Big Questions

• What causes the sun to vary?

We live in the extended atmosphere of a magnetic variable star that drives our solar system and sustains life on Earth. Our Sun varies in every way we can observe it. The Sun gives off light in the infrared, visible, ultraviolet, and at x-ray energies, and it gives off magnetic field, bulk plasma (the solar wind) and energetic particles moving up to nearly the speed of light, and all of these emissions vary.

• How do the Earth and Heliosphere respond?

Our planet is immersed in this seemingly invisible yet exotic and inherently dangerous environment. Above the protective cocoon of Earth’s lower atmosphere is a plasma soup composed of electrified and magnetized matter entwined with penetrating radiation and energetic particles.

• What are the impacts on humanity?

Modern society depends heavily on a variety of technologies that are susceptible to the extremes of space weather — severe disturbances of the upper atmosphere and of the near-Earth space environment that are driven by the magnetic activity of the Sun. Strong electrical currents driven in the Earth’s surface during auroral events can disrupt and damage modern electric power grids and may contribute to the corrosion of oil and gas pipelines.

Focus Areas Earth moves through the heliosphere, the exotic outer atmosphere of a star. The space beyond Earth’s protective atmospheric cocoon is highly variable and far from benign. The Sun, our solar system, and the region of the galaxy just outside present us with a complex, interacting set of physical processes. It is the one part of the cosmos accessible to in situ scientific investigation, our only hands-on astrophysical laboratory.

STEREO - 3D image of the Sun

NASA's Solar TErrestrial RElations Observatory (STEREO) satellites have provided the first three-dimensional images of the sun. For the first time, scientists will be able to see structures in the sun's atmosphere in three dimensions. The new view will greatly aid scientists' ability to understand solar physics and there by improve space weather forecasting.

Building on NASA’s rich history of exploration of Earth’s neighborhood and distant planetary systems, we are poised to provide a predictive understanding of our place in the solar system. We do not live in isolation; we are intimately coupled with the Sun and the space environment through Earth’s climate system, our technological systems, the habitability of planets and solar system bodies we plan to explore, and ultimately the fate of Earth itself. Variability in this environment affects the daily activities that constitute the underpinning of modern society, including communication, navigation, and weather monitoring and prediction. Because the space environment matters to humans and their technological systems both on Earth and in space, it is essential as a space-faring Nation that we develop an understanding of these space plasma processes.

Heliophysics research and exploration focuses on studying the Sun, the heliosphere, and planetary environments as elements of a single, interconnected system, one that contains dynamic space weather and evolves in response to solar, planetary, and interstellar conditions. Such an understanding represents not just a grand intellectual accomplishment for our times —it also provides knowledge and predictive capabilities essential to future utilization and exploration of space.

Heliosphere: Plasmas and their embedded magnetic fields affect the formation, evolution and destiny of planets and planetary systems. The heliosphere shields the solar system from galactic cosmic radiation. Our habitable planet is shielded by its magnetic fi eld, protecting it from solar and cosmic particle radiation and from erosion of the atmosphere by the solar wind. Planets without a shielding magnetic field, such as Mars and Venus, are exposed to those processes and evolve differently. And on Earth, the magnetic field changes strength and configuration during its occasional polarity reversals, altering the shielding of the planet from external radiation sources.

Magnetospheres: Determine changes in the Earth's magnetosphere, ionosphere, and upper atmosphere in order to enable specification, prediction, and mitigation of their effects. Heliophysics seeks to develop an understanding of the response of the near-Earth plasma regions to space weather. This complex, highly coupled system protects Earth from the worst solar disturbances while redistributing energy and mass throughout.

Space Environment: Understand the causes and subsequent evolution of solar activity that affects Earth's space climate and environment. The climate and space environment of Earth are significantly determined by the impact of plasma, particle, and radiative outputs from the Sun. Therefore, it is essential to understand the Sun, determine how predictable solar activity truly is, and develop the capability to forecast solar activity and the evolution of disturbances as they propagate to Earth.