IOWA CITY — Imagine trying to study a waterfall by observing its current a mile downstream. That’s essentially what scientists have been doing with our solar system’s sun — and for good reason — as it can reach more than 27 million degrees Fahrenheit.
But that vantage point will change this weekend.
About 2:30 a.m. Saturday at Cape Canaveral Air Force Station in Florida, NASA will launch the world’s first mission to the sun’s atmosphere. The historic Parker Solar Probe is expected to “revolutionize our understanding of the sun,” where changing winds, bursts, and other events reverberate through the solar system and effect Earth, along with other planets.
And University of Iowa physicist Jasper Halekas will be tuning in … maybe.
“I haven’t honestly decided whether I have the fortitude to get up at 2:30 a.m. and watch the webcast or not,” Halekas, one of the project’s about 100 scientists, said Friday. “We’ll see how lively I feel tonight.”
As co-investigator on the mission, Halekas traveled to Florida last week for the launch, which experienced some delays that pushed it past Halekas’ stay. He’s back in Iowa City and, beyond this weekend’s launch, will be tracking this one-of-a-kind probe on its seven-year journey.
“The mission is going to fly closer to the sun than any human-made object has ever gone before,” he said.
We’re talking within 3.8 million miles of the sun’s surface, which sounds like a lot until you consider it’s 25 times closer than Earth, which sits 93 million miles away, and 10 times closer than Mercury, which is 36 million miles from the sun.
Before Parker, the record-holder for closest solar pass was the Helios 2 spacecraft, which went within 27 million miles in 1976. This will be seven times closer.
“The prime scientific goal of the mission is to try and understand what we call the solar wind,” Halekas said of the flow that involves ionized hydrogen, helium, and electrons.
“It constantly flows out from the sun at about a million miles an hour and flows throughout our solar system,” he said. “This solar wind is something that we’ve measured around Earth, of course, but we don’t really understand where it comes from, and how it gets accelerated up to this huge speed, and what its origin is at the sun.”
Beyond the intrigue of humanity’s closest-ever observations of a star and pure scientific curiosity about how our universe works, Halekas said, the probe’s findings could inform some aspects of everyday life on Earth.
For example, he said, when stronger gusts of solar wind penetrate the “bubble” that is Earth’s magnetic field, orbiting spacecraft, satellites used for communication, even electrical grids on the ground can be affected.
“To the extent that we can understand why the solar wind works the way that it does, we hope that that will allow us to predict these kinds of events better than we can today,” Halekas said.
Although its mission is a long one, the probe will achieve some milestones early on, completing one of several planned flybys of Venus within two months of launch. Hurtling toward the sun at about 430,000 mph — enough to get from Philadelphia to Washington, D.C., in one second — it will achieve its first solar encounter a month later.
And it will be “really, really, really hot,” according to Halekas. At its closest pass, the Parker Solar Probe will experience temperatures as high as 2,500 degrees Fahrenheit.
“Needless to say, the critical systems of the space craft, most of the science experiments, cannot survive that temperature,” he said.
The spacecraft’s front will be protected by a heat shield.
“That heat shield is really a magical piece of equipment,” he said.
It, metaphorically speaking, gets us “up to the base of the waterfall.”
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