Banner image: Artist's rendering of Parker Solar Probe orbiting the sun. (Credit:听NASA/Johns Hopkins APL/Steve Gribben)
Over the past year, NASA鈥檚 came closer to the sun than any other object designed and developed by humans鈥攁nd CU Boulder scientists have been along for the ride.
The spacecraft has whirled around the star three times since its launch in August 2018. In the process, it flew within 15 million miles of the sun鈥檚 surface. This close brush allowed scientists to observe the chaotic behavior of the star鈥檚 corona, or the highest part of its atmosphere, in previously impossible-to-see detail.听
Now, researchers on the mission have released the first set of results from the probe鈥檚 red-hot path through space. The findings could help scientists better understand how the sun ejects waves of energetic and potentially dangerous particles that can shut down satellites orbiting Earth and even disrupt power grids on the ground.
Space plasma physicist David Malaspina is part of a team of CU Boulder scientists who contributed to those early insights. The group designed a signal processing electronics board that is integral to the , one of four suites of instruments onboard the Parker Solar Probe.听
One year into its seven-year journey, the听Parker Solar Probe is already challenging what physicists thought they knew about humanity鈥檚 favorite star.
鈥淭here are 24 orbits in total before we get to the spacecraft鈥檚 closest approach,鈥� said Malaspina, an assistant professor in the Department of Astrophysical and Planetary Sciences and affiliated with the (LASP). 鈥淲e have a long way to go, but already we鈥檙e finding incredibly interesting things and brand-new physics.鈥�
Oceans and lakes
NASA and the Johns Hopkins University Applied Physics Laboratory manage the Parker Solar Probe mission, and the University of California, Berkeley听leads the FIELDS experiment.
The spacecraft itself is a feat of engineering鈥攃apable of hitting speeds of more than 400,000 miles per hour and packing a one-of-a-kind heat shield that will help it survive the extremes of space. Researchers like Malaspina are hoping that the Parker Solar Probe will help them answer several burning questions about the sun鈥檚 corona that were previously beyond their reach.
For starters, how does this roiling, gas-filled region of space get so toasty, hitting temperatures of nearly 1 million degrees Fahrenheit?
鈥淗ow this is happening is basically unknown, especially in this region where the solar probe is traveling,鈥� said Alexandros Chasapis, a research scientist at LASP who has worked on the mission. 鈥淲e just didn鈥檛 have any data.鈥�
Even with those unknowns, Parker Solar Probe researchers were still surprised by what they saw during their first few passes around the sun.
Scientists have long known that the sun鈥檚 corona is a turbulent place where electric and magnetic fields, the focus of the FIELDS experiment, twist and snap like rubber bands. The closer the spacecraft got to the corona, the more the team realized that those turbulent regions weren鈥檛 the whole story.
鈥淚mmediately adjacent to those regions are places that are extremely quiet, like being on a calm lake,鈥� Malaspina said. 鈥淭he spacecraft crossed from calm lake to raging storm to calm lake. It kept alternating.鈥�
The FIELDS team . 听
New frontiers
Parker Solar Probe's current location and trajectory. (Credit: NASA/Johns Hopkins APL)
The researchers still aren鈥檛 sure what the consequences of that patchwork structure might be for the solar wind emitted by the sun鈥攖hey theorized that the most dangerous outbursts from the sun might actually come from its calmest spots.
But Malaspina said that the electric and magnetic field sensors that make up the FIELDS experiment could give scientists a closer look at that structure.听
In a second paper published recently in The Astrophysical Journal, he and his colleagues explored a closely related phenomenon: plasma waves, or ripples in the boiling-hot clouds of ions that emanate from the sun.
鈥淣ear Earth, you rarely see these plasma waves at all,鈥� Malaspina said. 鈥淏ut once you get in toward the sun, you see more and more of them. They fill up a large volume of space.鈥�
Using FIELDS observations, the team found that a certain type of plasma wave seemed to emerge directly from the solar wind鈥檚 calm lakes. These waves, Malaspina said, are likely stirred up by electrons spinning around the sun鈥檚 magnetic field lines, a bit like a child going down a twisting slide.听
鈥淭heir trajectory winds up looking kind of like a helix,鈥� Malaspina said. 鈥淭he electrons spiral up the field line and can grow these types of waves.鈥�
He added that the observed plasma waves could allow scientists to make indirect measurements of physics occurring deep within the corona鈥攂eyond the range of the Parker Solar Probe鈥檚 instruments.
The CU Boulder team is also just excited to be a part of a mission that is already rewriting space science textbooks. In many cases, researchers at LASP have been the first people to see data collected by the FIELDS experiment, a role that Chasapis called a 鈥減rivilege and a responsibility.鈥�
鈥淚t鈥檚 really fun to get to play with the data,鈥� he said.
Malaspina, who has spent his career studying the sun鈥檚 physics, is eager to learn more about how the star connects to life on Earth.
鈥淓nergy from sun is an integral part of our natural world, just as much as air or water or the ground below our feet,鈥� he said. 鈥淟earning about solar processes is vital to understanding how humans can thrive on Earth or anywhere else in the solar system鈥�
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