The Mission


NASA's Solar Probe Plus mission will revolutionize our understanding of the sun.

The MissionScience Objectives

NASA's Solar Probe Plus mission will revolutionize our understanding of the sun. Solar Probe Plus will provide new data on solar activity and make critical contributions to our ability to forecast major space-weather events that impact life on Earth.

  • Measurements from within the region where all the action happens
  • On the final three orbits, Solar Probe Plus will fly to within 9 solar radii of the sun's "surface" 9 solar radii is 9 times the radius of the sun, or about 3.9 million miles. That is about seven times closer than the current record-holder for a close solar pass, the Helios spacecraft.
  • At closest approach, Solar Probe Plus will be hurtling around the sun at approximately 450,000 miles per hour! That's fast enough to get from Philadelphia to Washington, D.C., in one second.
  • At closest approach to the sun, while the front of Solar Probe Plus' solar shield faces temperatures approaching 1,400° Celsius, the spacecraft's payload will be near room temperature.

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.

Solar Probe Plus has three detailed science objectives:

The MissionLaunch

Launching in 2018, Solar Probe Plus will provide new data on solar activity and make critical contributions to our ability to forecast major space-weather events that impact life on Earth.

Credit: ULA

Dates: Jul 31 – Aug 19, 2018 (20 days)
Max. Launch C3: 154 km2/s2
Launch Vehicle: Delta IV-Heavy with Upper Stage

Launch Window: July 31 – August 19, 2018

The MissionJourney to the Sun

Solar Probe Plus will swoop to within 4 million miles of the sun's surface, facing heat and radiation like no spacecraft before it. To get there, it takes an innovative route.

Trajectory Design

Solar Probe Plus will use seven Venus flybys over nearly seven years to gradually shrink its orbit around the sun, coming as close as 3.7 million miles (5.9 million kilometers) to the sun, well within the orbit of Mercury and about eight times closer than any spacecraft has come before.

Solar Probe Plus is a true mission of exploration; for example, the spacecraft will go 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. Still, as with any great mission of discovery, Solar Probe Plus is likely to generate more questions than it answers.

  • 24 Orbits
  • 7 Venus gravity assist flybys

Final Solar Orbits

At closest approach, Solar Probe Plus will be hurtling around the sun at approximately 450,000 miles per hour! That's fast enough to get from Philadelphia to Washington, D.C., in one second.

  • Closest approach: 3.83 million miles
  • Speed ~450,000 miles per hour (~125 miles per second)
  • Orbit period: 88 days

The MissionTimeline

It has been 50+ years since the Solar Probe Concept was introduced. . . We are on our way!

Solar Probe Plus will be a historic mission, flying into the sun's atmosphere (or corona) for the first time. Coming closer to the sun than any previous spacecraft, Solar Probe Plus will employ a combination of in situ measurements and imaging to achieve the mission's primary scientific goal: to understand how the sun's corona is heated and how the solar wind is accelerated. Solar Probe Plus will revolutionize our knowledge of the origin and evolution of the solar wind.

Mission duration: 6 yrs, 11 months

NASA Logo Solar Probe Plus Logo

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