Parker Solar Probe

Why fly to the Sun

The Sun's outer atmosphere, the corona, is millions of degrees hotter than its visible surface, and nobody fully knows why. The corona also launches the solar wind, a stream of charged particles that fills the solar system and can disturb satellites and power grids on Earth. Parker Solar Probe was built to answer these questions by going there.

Surviving the heat

Parker's front-facing heat shield is 11.4 cm of carbon foam sandwiched between carbon composite sheets, with a white coating to reflect sunlight. On the sunny side it reaches about 1,400 degrees Celsius, while the instruments behind it stay near room temperature. Venus flybys gradually shrank its orbit.

Record breaker

In 2021 Parker became the first spacecraft to fly through the corona. On December 24, 2024, it passed about 6.1 million km from the Sun's surface, at around 692,000 km/h, the fastest any human-made object has travelled. It has discovered magnetic zigzags in the solar wind called switchbacks and traced them to the Sun's surface.

Parker works alongside ESA's Solar Orbiter, launched in 2020, which watches the Sun from a little farther away and photographs its poles. Comparing data from both spacecraft lets scientists trace solar wind streams from their source on the Sun to the space around the planets.

A tribute to a scientist

The probe is named after Eugene Parker, who predicted the solar wind in 1958. It was the first NASA spacecraft named after a living person, and Parker watched its launch in 2018. He died in 2022, after seeing his spacecraft confirm ideas he had proposed decades earlier.

Why it is so fast

Getting close to the Sun is surprisingly hard. Earth, and everything launched from it, already moves sideways around the Sun at about 30 km per second, and a spacecraft must cancel most of that motion to fall inward. Parker uses repeated Venus flybys to slow its orbital motion, which lets it fall closer each time. As it drops toward the Sun it speeds up enormously, like a skater pulling in their arms.

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