The University of Iowa hitched a ride on a NASA mission that will virtually touch the sun.

Faculty and a graduate student in the UI Department of Physics and Astronomy are participating in the historic, nearly seven-year mission highlighted by a spacecraft’s closest-ever approach to a star. The mission, called the Parker Solar Probe, launched Aug. 11. At its nearest, the probe will be a mere 3.8 million miles from the sun’s surface, more than seven times closer than any spacecraft has come before.

“It’s going to be incredibly hot,” says Jasper Halekas, associate professor in physics and astronomy at Iowa and a co-investigator for one of the instruments aboard the spacecraft. “We’re talking about temperatures that will be more than 2,500 degrees Fahrenheit.”

Scientists are excited because they expect to learn a lot about the solar wind, a super-heated stream of energetic particles constantly generated by the sun. Disturbances in the solar wind, which zips along at 1 million miles per hour, rattle Earth’s magnetic field and pump energy into the Van Allen radiation belts (named after famed UI physicist James Van Allen).

Scientists call such disturbances to the environment around Earth “space weather.”

Understanding space weather is important because major jolts of solar wind—such as from a solar flare emanating from the sun’s surface—can affect the operation of satellites and telecommunications on Earth. Mission scientists hope that learning more about the origin and evolution of the solar wind will yield more accurate predictions of space weather—just like advances in technology, such as Doppler radar, have led to more accurate terrestrial weather forecasting .

“It’s a fundamental discovery mission,” Halekas says. “We’re going somewhere we’ve never been. We’ve got some ideas what the solar atmosphere looks like, but we don’t know for sure. The best part is we may get some surprises, and that will be really neat if it happens.”

The UI is involved with the Solar Wind Electrons, Alphas, and Protons (SWEAP) instrument, outfitted with four sensors and one of four suites of instruments on the probe. Mostly tucked behind a cutting-edge heat shield, SWEAP will sample the solar wind to gather information on protons, alpha particles and electrons—the three main components of the solar wind. Halekas is a co-investigator on the instrument.

At the UI, Halekas and graduate student Daniel McGinnis have created software that will allow SWEAP investigators to separate particle counts in the solar wind from interference by the spacecraft as it hurtles through the sun’s atmosphere at 430,000 mph.

McGinnis, a fifth-year graduate student from Sioux Falls, South Dakota, says the work has been challenging, in part because there are contingencies that can’t be fully planned for in an environment that has never been observed.

“The extreme near-sun environment will likely charge the spacecraft in unusual ways. That charge, along with the magnetic fields produced by some of the other equipment onboard, will bend the trajectories of electrons and ions on their way into our instruments,” McGinnis says. “I have been working on estimating how big of an effect this will have on our measurements and how we can correct for it.”

Greg Howes, associate professor in physics and astronomy, who is a co-investigator on the Parker Solar Probe instrument, which will measure the electromagnetic fields around the sun. Collecting this data is important, Howes says, because scientists are unsure why the solar corona, or the sun’s expansive atmosphere, is about 1.8 million degrees Fahrenheit, whereas the sun’s surface is far cooler, checking in at roughly 11,000 degrees Fahrenheit.

The answer lies in better understanding how individual particles are heated and how the heat is supplied and transferred to them.

“How fields and particles interact is the most fundamental aspect we want to understand,” Howes says. “Then we can build up to the bigger picture to understand more fully the sun’s dynamics.”

“I'm reminded that this is actually for a spacecraft that is going be launched through outer space into the sun’s atmosphere to measure its electrons, and my heart races,” says McGinnis, whose main research interest is the physics of the solar wind. “It’s an honor to be a small part of the legacy of space physics and solar system exploration at the University of Iowa.”