After using Venus’ gravity as a slingshot toward the Sun for the seventh time, NASA’s Parker Solar Probe is ready to make history again.

December 24, fium fium fium. On Christmas Eve, the Parker solar probe will fly closer to the Sun than ever before. At 6.1 million kilometers from the solar surface, the small 50 kg spacecraft will enter the star’s atmosphere. Not for a long time, but long enough for its heat shield to reach temperatures of 1,371 ºC.

All this while the probe once again breaks its own speed record: 692,000 kilometers per hour, the fastest a man-made object has ever traveled; and still, 0.064% of the speed of light.

So that. NASA wants to find the place where the solar wind is born, an invisible but incessant flow of matter and energy that emanates from the Sun and affects the entire solar system, triggering, among other phenomena, the polar auroras. To do this, the Parker probe has to enter the corona of the Sun.

The Parker mission collects data to understand how energy is transferred, why the corona is hotter than the photosphere, how the solar wind accelerates, and the origin of high-energy solar particles. This information will help better understand the Sun’s impact on Earth and improve predictions of space weather that affects satellites and electrical systems.

It is not easy to get to the Sun. For starters, it has a huge gravitational field, so the power of a heavy rocket like the Delta IV Heavy had to be combined with multiple gravitational assists from Venus to get the ship close. It is its speed that prevents it from falling into the Sun.

The other big challenge is the temperature. The Sun’s corona is millions of degrees away, so NASA had to invest a lot of money in materials. All wiring is electronic, made from niobium and reinforced with sapphire crystal.

The Faraday cup, the instrument that measures the fluxes of ions and electrons in the solar wind, is made of titanium-zirconium-molybdenum, a material with a melting point of 2,349 ºC. The probe does not heat up to these temperatures thanks to its 11 cm thick carbon fiber reinforced carbon heat shield.

A posthumous gift. The Parker Solar Probe is named after Eugene N. Parker, the astrophysicist who predicted the existence of the solar wind in the 1950s; an idea ridiculed by the scientific community until, in 1962, NASA’s Mariner 2 probe managed to detect it.

Parker witnessed the launch of the probe in 2018, when he was 91 years old, and although he died in 2022, the measurements made by the solar probe on Christmas Eve will in some way be his Christmas gift to the world.

Image | POT

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