Two UA scientists part of historic mission to 'touch the sun'

A red-hot voyage to the sun is going to bring us closer to our star than ever before, and two University of Arizona faculty members are helping with the first-of-its kind space project.

NASA’s Parker Solar Probe will be the first spacecraft to “touch the sun,” hurtling through the sizzling solar atmosphere and coming within just 3.8 million miles of the sun’s surface. The probe is expected to launch from Cape Canaveral, Florida, early Saturday Tucson time.

Joe Giacalone, professor at the UA’s Lunar and Planetary Laboratory, is a co-investigator on the Integrated Science Investigation of the Sun, which will detect and observe movement of high energy particles in the sun’s atmosphere.

Giacalone will provide “theoretical and numerical analysis support to aid the interpretation of the observations,” he said.

Kristopher Klein, an LPL assistant professor, is a team member on the Solar Wind Electrons Alphas and Protons investigation, a suite of instruments that will measure the solar wind.

“The University of Arizona and LPL has a long history of involvement in space exploration,” Giacalone said. “Secondly, we have a long history of studying the sun.”

Just some examples include Tucson as the former headquarters of the National Solar Observatory and the McMath Pierce telescope on Kitt Peak. Roger Angel and his team at the Steward Observatory Solar Lab are also looking for ways to harness energy of the sun for energy.

The instruments Giacalone and Klein are involved with will work in concert with two more instrument teams to investigate solar mysteries.

For example, scientists are unsure why the corona, the sun’s outermost atmosphere, is hundreds of times hotter than the sun’s surface. Scientists are also curious as to what drives the solar wind — the steady, supersonic stream of charged particles blasting off the corona and into space in all directions. The probe is named for astrophysicist Eugene Parker, who first proposed the concept of solar winds.

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While granting us life, the sun also has the power to disrupt spacecraft in orbit, and communications and electronics on Earth.

Scientists expect the $1.5 billion, seven-year mission to shed light not only on our own dynamic sun, but the billions of other yellow dwarf stars — and other types of stars — out there in the Milky Way and beyond.

Getting up close to our star is important. At the distance of earth — 93 million miles — “a lot of the action has already happened,” Giacalone said. At such distances, “you get the integration of a bunch of different processes.” But at the probe’s closest, scientists can isolate those processes and tease out never-before-seen details of the sun’s corona.

“There are missions that are studying the solar wind, but we’re going to get to the birthplace,” said Nicola Fox, project scientist at Johns Hopkins University.

The Parker Solar Probe will be able to withstand temperatures of 2,500 degrees thanks to a revolutionary 4½-inch-thick reflective heat shield. Almost everything on the spacecraft will be sheltered behind the shield at a comfortable room temperature.

The spacecraft will use Venus for seven gravity assists on its journey around the sun.

With the first solar orbit, the Parker probe will come within 15.5 million miles of the sun and beat out NASA’s former Helios 2 spacecraft that got within 27 million miles of the sun in 1976.

In all, the spacecraft will make 24 elongated laps around the sun, much closer than the orbit of Mercury, which orbits about 36 million miles from the sun.

The Parker probe’s final three orbits — in 2024 and 2025 — will be the closest. The spacecraft eventually will run out of fuel and, no longer able to keep its heat shield pointed toward the sun, will burn and break apart.