The University of Michigan in Ann Arbor is leading a $62.6-million NASA mission in an attempt to provide better information on how the sun’s radiation affects the space environment that spacecraft and astronauts travel through.
Coronal mass ejections, which are the most violent solar weather, can flood space with high-energy particle radiation.
The Sun Radio Interferometer Space Experiment, or SunRISE, consists of miniature satellites called cubesats that form a virtual telescope in space to detect and study the radio waves that precede major solar events. The waves can’t be detected on Earth because of the region of its upper atmosphere known as the ionosphere.
SunRISE is expected to launch in 2023 and will offer a never-before-seen glimpse of what goes on in the area above the sun’s surface, the solar corona.
“We can see a solar flare start, and a coronal mass ejection start lifting off from the sun, but we don’t know if it is going to produce high-energy particle radiation, and we don’t know if that high energy particle radiation is going to reach Earth,” says Justin Kasper, professor of climate and space sciences and engineering at U-M who leads the mission. “One reason why is we can’t see the particles being accelerated. We just see them when they arrive at the spacecraft, which isn’t much of a warning.”
U-M will run the science operations center that converts the signals collected from the cubesats into images. The images are expected to reveal which part of a coronal mass ejection is responsible for accelerating radiation particles outward.
Flying in a formation about six miles across, six cubesats will form the first imaging low frequency radio interferometer in space. The satellite constellation will orbit Earth 22,000 miles from the surface.
“The cubesats will give us an entirely new view of how particles are accelerated near the sun and how they travel into interplanetary space,” Kasper says. “The jury is still out on what accelerates the particles and where that acceleration occurs. It turns out the various theories about particle acceleration correspond to different parts of coronal mass ejections, so if we can see which part of the CME is glowing in radio, we figure out which acceleration model is right.”
Not all coronal mass ejections release high-energy particle radiation. During the peak period of the solar cycle, though, major ones happen every couple of months. At their worst, they can include as much plasma and radiation as there is water in the Great Lakes, accelerating from rest to about 3 million miles per hours in minutes. Both plasma and radiation are threatening to the electrical grid on Earth as well as objects in space.
Experts have some ability to forecast when the magnetized plasm will hit Earth, since it takes hours or days to get there. However, radiation travels at near-light speed, so there’s no way to predict when it will arrive.
“Knowing which part of a coronal mass ejection is responsible for producing the particle radiation will help us understand how the acceleration happens,” Kasper says. “It could also result in a unique warning system for whether an event will both produce radiation and release that radiation towards Earth or spacefaring astronauts.”
Most of the project funding will go toward payload and launch, while $5 million will go to U-M for its team and operating costs. NASA’s Jet Propulsion Laboratory will manage the mission. Space Dynamics Laboratory, a nonprofit research corporation, is the other major partner that will build the spacecraft. U-M and NASA’s lab have partnered with MAXAR, a communications satellite company, to launch and place the cubesats in their orbits.
The concept of using a radio telescope in space is not new, but previous concepts for gathering this kind of data have been cost prohibitive.
SunRISE is one of NASA’s Missions of Opportunity, enabled through its Explorers Program.