To unlock the mysteries of the corona, but also to protect a society that is increasingly dependent on technology from the threats of space weather, SPP will use seven Venus flybys over nearly seven years to gradually shrink its orbit around the Sun. The spacecraft will come as close as 3.9 million miles (6.2 million kilometers) to the Sun, well within the orbit of Mercury and more than seven times closer than any spacecraft has come before.
Flying into the Sun’s atmosphere (or corona) for the first time, SPP will employ a combination of in situ measurements and imaging to revolutionize our understanding of the corona and expand our knowledge of the origin and evolution of the solar wind.
SPP will perform its scientific investigations in a hazardous region of intense heat and solar radiation. The spacecraft will fly close enough to the Sun to watch the solar wind speed up from subsonic to supersonic, and it will fly though the birthplace of the highest-energy solar particles.
To perform these unprecedented investigations, the spacecraft and instruments will be protected from the Sun’s heat by a 4.5-inch-thick (11.43 cm) carbon-composite shield, which will need to withstand temperatures outside the spacecraft that reach nearly 2,500 degrees Fahrenheit (1,377 degrees Celsius).
The compact, solar-powered probe will house solar arrays that will retract and extend as the spacecraft swings toward or away from the sun during several loops around the inner solar system, making sure the panels stay at proper temperatures and power levels. At its closest passes the spacecraft must survive solar intensity of about 475 times what spacecraft experience while orbiting Earth.
In order to unlock the mysteries of the corona, but also to protect a society that is increasingly dependent on technology from the threats of space weather, we will send Solar Probe Plus to touch the sun.
The primary science goals for the mission are to trace the flow of energy and understand the heating of the solar corona and to explore what accelerates the solar wind. Solar Probe Plus provides a statistical survey of the outer corona.
This investigation will make direct measurements of electric and magnetic fields and waves, Poynting flux, absolute plasma density and electron temperature, spacecraft floating potential and density fluctuations, and radio emissions.
FIELDS PI: Prof. Stuart Bale; University of California, Berkeley
This investigation makes observations of energetic electrons, protons and heavy ions that are accelerated to high energies (10s of keV to 100 MeV) in the sun's atmosphere and inner heliosphere, and correlates them with solar wind and coronal structures.
IS☉IS PI: Dr. David McComas; Princeton University
These telescopes will take images of the solar corona and inner heliosphere. The experiment will also provide images of the solar wind, shocks and other structures as they approach and pass the spacecraft. This investigation complements the other instruments on the spacecraft providing direct measurements by imaging the plasma the other instruments sample.
WISPR PI: Dr. Russell Howard; Naval Research Laboratory
This investigation will count the most abundant particles in the solar wind -- electrons, protons and helium ions -- and measure their properties such as velocity, density, and temperature.
SWEAP PI: Prof. Justin Kasper; University of Michigan/ Smithsonian Astrophysics Observatory
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