Sure, it’s been sweltering in Iowa this week, but University of Iowa researchers are doing groundbreaking studies on an environment that’s beyond scorching — using data from a spacecraft that’s orbiting the sun.
U-I physics and astronomy professor Jasper Halekas is the lead author of a report on the sun’s electric field and the solar wind that flows outward from our star. Halekas compares that flow to an earthly waterway.
“Let’s say we’re sitting here in Iowa City watching the Iowa River go by. It’s hard to know when that river might flood unless we know what’s going on upstream, say, at the Coralville Dam,” Halekas says. “So, we really need to make measurements up close, where the source of this solar wind — or in my analogy, the river — is to know what’s going to happen when that solar wind gets to Earth.”
Fluctuations in that solar wind, like a solar flare, can disrupt our power grid, our satellites, and much of our communications on Earth — everything from cell phone calls to GPS navigation to TV and radio broadcasts. The Parker Solar Probe has made eight orbits of the sun so far, and each orbit takes about three months to complete. Remember, the sun is huge.
“Every couple of orbits we fly by Venus and dump a little bit of our momentum there and that allows us to get in still closer to the sun,” Halekas says. “By the end of the mission, we hope to get about two times closer to the sun than we are now — and where we are now is already far closer than anything man-made has ever gone.” The spacecraft has gotten within nine million miles of the sun, which may not sound all that close, but temperatures on the side facing the sun are peaking around 1,000 degrees. It’s a robotic explorer like no other in history, and no, it won’t melt.
“The front end of our spacecraft has this big carbon-carbon heat shield and then there’s a bunch of plumbing that hangs off of the back of it that acts to shunt heat away from that heat shield and keep it from getting back to the rest of the spacecraft,” Halekas says, “and the rest of the spacecraft kinda’ hangs back in the shadow.”
The research they’re doing is historic, he says, as these are the first definitive measurements anyone’s ever been able to make of the sun’s electric field. “I’ve been involved in this mission since it was just a sketch on a napkin, so it’s been extraordinarily rewarding to see it built and tested and launched and now we’re charting new territory closer to the sun than anything man-made has ever gone,” Halekas says, “so, yes, it’s very exciting for me.”
Launched in 2018, the NASA-funded mission is scheduled to run through at least 2025 as the spacecraft should be able to make about 20 orbits around the sun, drawing ever closer, at a speed that should top off around 430-thousand miles an hour. It’s the first NASA spacecraft named after someone who’s still alive, 94-year-old Eugene Parker, an astrophysicist and professor emeritus at the University of Chicago, who first did key research in solar physics in the 1950s.