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The First Mission to the Nearest Star

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.

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Solar Probe Fact Sheet

Solar Probe Fact Sheet

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  • Solar Probe Plus will orbit the Sun 24 times, gradually “walking in” toward the Sun with each pass. The closest points of each orbit come well within orbit of Mercury the closest planet to the Sun.
  • On the final three orbits, Solar Probe Plus will fly to within 8.5 solar radii of the Sun’s “surface” 8.5 solar radii is 8.5 times the radius of the Sun, or about 3.7 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.
  • Solar Probe Plus will pass Venus less than two months after launch and will be collecting science data at its first solar pass just one month later.
  • At closest approach to the Sun, while the front of Solar Probe Plus’ solar shield faces temperatures approaching 2,500° Fahrenheit (or about 1,400° Celsius), the spacecraft’s payload will be near room temperature.

Solar Probe Plus Timeline

LAUNCH
JULY 30, 2018

VENUS FLYBY #1
SEPTEMBER 27, 2018

VENUS FLYBY #2
DECEMBER 21, 2019

VENUS FLYBY #3
JULY 5, 2020

VENUS FLYBY #4
FEBRUARY 15, 2021

VENUS FLYBY #5
OCTOBER 10, 2021

VENUS FLYBY #6
AUGUST 15, 2023

VENUS FLYBY #7
OCTOBER 31, 2024

FIRST CLOSE APPROACH
DECEMBER 19, 2024

CREDIT: JHU/APL

Learn more about Solar Probe Plus