Solar Probe Plus will employ a combination of in-place and remote measurements to achieve the mission's primary scientific goals: determine the structure and dynamics of the magnetic fields at the sources of solar wind; trace the flow of energy that heats the corona and accelerates the solar wind; determine what mechanisms accelerate and transport energetic particles; and explore dusty plasma near the Sun and its influence on solar wind and energetic particle formation. Details are spelled out in a Solar Probe Science and Technology Definition Team study.
In September 2010, NASA selected five investigations for Solar Probe Plus:
Solar Wind Electrons Alphas and Protons Investigation, which will specifically count the most abundant particles in the solar wind — electrons, protons and helium ions — and measure their properties. The investigation also is designed to catch some of the particles in a special cup (known as a Faraday cup) for direct analysis. Principal Investigator: Justin C. Kasper, Smithsonian Astrophysical Observatory, Cambridge, Mass.
The Wide-field Imager, a telescope that will make 3-D images of the sun's corona, or atmosphere. The experiment actually will see the solar wind and provide 3-D images of clouds and shocks as they approach and pass the spacecraft. This investigation complements instruments on the spacecraft providing direct measurements by imaging the plasma the other instruments sample. Principal Investigator: Russell Howard, Naval Research Laboratory, Washington
The Fields Experiment, which will make direct measurements of electric and magnetic fields, radio emissions, and shock waves that course through the Sun's atmospheric plasma. The experiment also serves as a giant dust detector, registering voltage signatures when specks of space dust hit the spacecraft's antenna. Principal Investigator: Stuart Bale, University of California Space Sciences Laboratory, Berkeley, Calif.
The Integrated Science Investigation of the Sun, which consists of two instruments that will take an inventory of elements in the Sun's atmosphere using a mass spectrometer to weigh and sort ions in the vicinity of the spacecraft. Principal Investigator: David McComas, Southwest Research Institute, San Antonio.
Heliospheric Origins with Solar Probe Plus Principal Investigator Marco Velli, of NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the mission's observatory scientist, responsible for serving as a senior scientist on the science working group. He will provide an independent assessment of scientific performance and act as a community advocate for the mission.
Instruments will be retracted inside the umbra (shadow) of the Thermal Protection System to limit solar exposure.