Traveling to the Sun: Why Won’t Parker Solar Probe Melt?

This summer, NASA’s Parker Solar Probe will launch to travel closer to the Sun, deeper into the solar atmosphere, than any mission before it. If Earth was at one end of a yard-stick and the Sun on the other, Parker Solar Probe will make it to within four inches of the solar surface.

Inside that part of the solar atmosphere, a region known as the corona, Parker Solar Probe will provide unprecedented observations of what drives the wide range of particles, energy and heat that course through the region — flinging particles outward into the solar system and far past Neptune.

Inside the corona, it’s also, of course, unimaginably hot. The spacecraft will travel through material with temperatures greater than a million degrees Fahrenheit while being bombarded with intense sun light.

So, why won’t it melt?

Parker Solar Probe has been designed to withstand the extreme conditions and temperature fluctuations for the mission. The key lies in its custom heat shield and an autonomous system that helps protect the mission from the Sun’s intense light emission, but does allow the coronal material to “touch” the spacecraft.

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Credits: NASA/Johns Hopkins APL/Ed Whitman

Parker Solar Probe’s heat shield is made of two panels of superheated carbon-carbon composite sandwiching a lightweight 4.5-inch-thick carbon foam core.

To reflect as much of the Sun’s energy away from the spacecraft as possible, the Sun-facing side of the heat shield is also sprayed with a specially formulated white coating.

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Credits: NASA/Glenn Benson

In the Astrotech processing facility in Titusville, Florida, near NASA's Kennedy Space Center, on Tuesday, June 5, 2018, technicians and engineers perform light bar testing on NASA's Parker Solar Probe. The spacecraft will launch on a United Launch Alliance Delta IV Heavy rocket from Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida.

The mission will perform the closest-ever observations of a star when it travels through the Sun's atmosphere, called the corona. The probe will rely on measurements and imaging to revolutionize our understanding of the corona and the Sun-Earth connection

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Betsy Congdon of Johns Hopkins Applied Physics Lab is the Lead Thermal Engineer on the heat shield that NASA's Parker Solar Probe will use to protect itself against the Sun.

The shield is so robust, Congdon can use a blowtorch on one side and the other side remains cool enough to touch.

NASA's Parker Solar Probe is heading to the Sun. Why won't the spacecraft melt?

Thermal Protection System Engineer Betsy Congdon (Johns Hopkins APL) outlines why Parker can take the heat.