Advanced science.  Applied technology.



Go to Heliophysics


Ninety-nine percent of the observable universe is in the plasma state, which is often referred to as the “fourth state of matter.” Plasmas are collections of electrically charged particles — ions and electrons — whose behavior is controlled by electric and magnetic fields and which can generate and carry powerful electrical currents. All solar system bodies — the planets, their moons, asteroids, comets — are immersed in a magnetized plasma, either the solar wind or the plasma confined within a planetary magnetosphere (the region of space dominated by a planet’s magnetic field). Heliophysics seeks to characterize and understand the physical processes operating in these various plasma environments. We study the dynamical connections that link the Sun, the solar wind, and the magnetized plasma environments of the planets and moons of our solar system. We develop the technology and knowledge to detect and predict space weather — extreme conditions in space that affect people and technology.


  • Measuring the space plasma environment throughout the solar system  
  • Inventing, designing, building, and testing the next generation of space instrumentation (space plasma and energetic particle instruments, energetic neutral atom cameras, mass spectrometers, ultraviolet imagers)
  • Conducting experiments in state-of-the-art laboratories
  • Analyzing past and current mission data to uncover the fundamental processes controlling the space environment


  • The structure and dynamics of the solar wind and the interstellar boundary  
  • Magnetic reconnection and solar-wind-magnetosphere interactions  
  • Magnetospheric and plasma physics at Earth, Mercury, Jupiter, Saturn, and Pluto  
  • Plasma-atmosphere interactions at Mars, Venus, Titan, comet Churyumov-Gerasimenko, Enceladus, and the Galilean satellites  
  • Fundamental plasma physics research throughout the heliosphere and beyond
  • Statistical mechanics of space charged particle systems out of thermal equilibrium


  • Magnetospheric Multiscale (MMS)
  • Van Allen Probes
  • Imager for Magnetopause to Aurora Global Exploration (IMAGE)
  • Interstellar Boundary Explorer (IBEX)
  • Solar Orbiter 
  • Solar Probe Plus 
  • Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS)
  • Ulysses 
  • Advanced Composition Explorer (ACE)
  • CubeSats (e.g., CUSP, CERES) and rockets (e.g., GREECE, Big Dog)
  • In addition to dedicated heliophysics missions, a number of planetary missions also carry heliophysics experiments: Juno, New Horizons, Cassini, Rosetta, Mars Express, Venus Express