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Solar Probe Plus is an exciting mission of exploration and discovery, a journey to the Sun itself. By flying into the Sun's outer atmosphere - called the corona - Solar Probe plus will gather data on the processes that heat the corona and accelerate the solar wind - solving two fundamental mysteries that have been top-priority science goals for many decades. This mission will transform our understanding of the Sun and its sister Sun-like stars and enabling further exploration through our own solar system.

Solar Probe Plus will study the streams of charged particles the Sun hurls into space from a vantage point where the processes that heat the corona and produce solar wind actually occur. At closest approach Solar Probe will zip past the Sun at 125 miles per second, protected by a carbon-composite heat shield that must withstand up to 2,600 degrees Fahrenheit and survive blasts of radiation and energized dust at levels not experienced by any previous spacecraft.

Solar Probe Plus' science objectives fall under two main themes:

  • Coronal heating and solar wind acceleration
  • Production, evolution and transport of solar energetic particles

To address these objectives, Solar Probe Plus will travel closer to the Sun than any other spacecraft and explore the innermost region of our solar system. With the data it transmits back to Earth, solar and space physicists will answer questions that cannot be answered by any other means and will attain a deep understanding of phenomena and processes in this fascinating and critical region. And as with any great voyage into uncharted realms, The journey of Solar Probe Plus to the Sun holds the promise of many more
unanticipated discoveries—new mysteries to challenge humankind’s ever expanding knowledge of our home in the universe.


Solar Probe Plus will explore one of the last regions of the inner solar system to be visited by a spacecraft, the Sun’s outer atmosphere where it extends into space. From as close as 3.7 million miles above the Sun’s surface, Solar Probe Plus will repeatedly sample the near-Sun environment, revolutionizing our knowledge and understanding of coronal heating and of the origin and evolution of the solar wind. The data will also help us answer critical heliophysics questions that have puzzled scientists for decades. By making direct, in-situ measurements of the region where some of the most hazardous solar energetic particles are energized, Solar Probe Plus will make a fundamental contribution to our ability to characterize and forecast the radiation environment in which future space explorers will work and live.


Solar Probe Plus has four scientific priorities:

  • Determine the structure and dynamics of the magnetic fields at the sources of both fast and slow solar wind
  • Trace the flow of energy that heats the corona and accelerates the solar wind
  • Determine what mechanisms accelerate and transport energetic particles
  • Explore dusty plasma phenomena near the Sun and its influence on the solar wind and energetic particle formation

The Solar Probe Plus science objectives will be addressed through a combination of in situ and remote-sensing observations made from an orbit slightly above the ecliptic plane - the "line" on which most planets orbit the Sun - and at progressively closer distances to the Sun. The spacecraft will reach its closest distance - just 8.5 times the radius of the Sun - roughly 6½ years after launch.


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NASA Curator: Ayris A. Narock

NASA Official: Adam Szabo
Last Updated: 11/04/2010

Heliophysics Science Division, Code 670
NASA's Goddard Space Flight Center, Greenbelt, Maryland 20771, USA