Recent findings from a 2021 study, led by a scientist from the University of Alaska Fairbanks, have started to clarify the intricate particle-level mechanisms behind the spectacular auroras that flicker across the sky.
The Kinetic-scale Energy and momentum Transport experiment, or KiNET-X, was launched from NASA’s Wallops Flight Facility in Virginia on May 16, 2021, as the last few minutes of a nine-day launch period came to a close.
Professor Peter Delamere from UAF published his analysis of the experiment’s findings on November 19 in Physics of Plasmas.
“The stunning auroras are highly complex phenomena,” Delamere remarked. “There are numerous processes happening simultaneously, both in the aurora and in Earth’s surrounding space environment that contribute to what we see.”
“Figuring out the cause-and-effect relationships in this system is extremely challenging because we can’t precisely pinpoint the events in space that lead to the light displays we observe in the auroras,” he explained. “KiNET-X has proven to be a tremendously fruitful experiment that will help uncover more of the secrets behind auroras.”
One of NASA’s largest sounding rockets ascended over the Atlantic Ocean into the ionosphere and released two canisters filled with barium thermite. These canisters were detonated—one at approximately 249 miles above Earth and the other 90 seconds later, during descent, at around 186 miles close to Bermuda. The resulting clouds were observed from the ground in Bermuda and by a NASA research plane.
The experiment’s objective was to mimic, on a small scale, an environment where the low energy of solar wind transforms into the high energy that creates the quickly moving and glimmering displays known as discrete auroras. Through KiNET-X, Delamere and his fellow researchers are making strides in understanding the process of electron acceleration.
“We successfully generated energized electrons,” Delamere noted. “While we didn’t produce enough to create an aurora, the fundamental physics related to electron energization were certainly present in the experiment.”
The primary goal of the experiment was to generate an Alfvén wave, a specific type of wave that occurs in magnetized plasmas, such as those discovered in the sun’s outer layer, Earth’s magnetosphere, and other areas in the solar system. Plasmas—composed mainly of charged particles—can also be produced in laboratory settings, such as in KiNET-X.
Alfvén waves emerge when disturbances in plasma affect the magnetic field. Such plasma disturbances could arise from various sources, including sudden injections of particles from solar flares or the interaction between two plasmas with differing densities.
KiNET-X successfully produced an Alfvén wave by introducing barium into the upper atmosphere, disturbing the surrounding plasma.
Sunlight then transformed the barium into an ionized plasma. The interaction between the two plasma clouds resulted in the creation of the Alfvén wave.
This Alfvén wave generated electric field lines that aligned with the planet’s magnetic field lines. As theorized, this electric field significantly boosted the acceleration of electrons along the magnetic field lines.
“It demonstrated that the barium plasma cloud interacted with the surrounding plasma, transferring energy and momentum for a brief period,” Delamere explained.
This transfer appeared as a narrow beam of accelerated barium electrons moving toward Earth along the magnetic field line, visible only in the magnetic field line data from the experiment.
“This is similar to an auroral beam of electrons,” Delamere commented.
He referred to it as the experiment’s “golden data point.”
Analyzing this beam, visible in various shades of green, blue, and yellow pixels in Delamere’s imagery, can aid scientists in understanding the processes that lead to the mesmerizing northern lights.
The findings thus far point to a successful project, capable of providing even more insights when considered alongside earlier experiments.
“It’s a matter of piecing together the complete picture using all available data and numerical simulations,” Delamere said.
Three doctoral students from UAF’s Geophysical Institute also took part in the project. Matthew Blandin assisted with optical operations at Wallops Flight Facility, Kylee Branning operated cameras on a NASA Gulfstream III aircraft from Langley Research Center in Virginia, and Nathan Barnes contributed to computer modeling in Fairbanks.
The experiment also involved researchers and equipment from institutions such as Dartmouth College, the University of New Hampshire, and Clemson University.
