The Danger of Fast Electron Source in Space

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Electrons in a Van Allen radiation belt (blue) encounter whistler waves (purple) and rain toward the north pole (red). The THEMIS satellites are seen near the radiation belt, while Ucla's ELFIN is hovering over Earth. Credit: Zhang, et al., Nature Communications, 2022

UCLA scientists have discovered a new source of superfast, energetic electrons raining down on Earth, a phenomenon that contributes to the colorful aurora borealis but also poses a danger to satellites, spacecraft and astronauts. Using the ELFIN mission, a pair of small satellites built and operated by undergraduate and graduate students led by a small group of instructors on the UCLA campus, researchers observed unexpected, rapid "electron rains" from low Earth orbit. Before the Danger of Fast Electron Source in Space, let us remind you of two separate issues. These are "Elfin Mission" and "Aurora Borealis".

What is Elfin Mission?

Scientists from the University of California Los Angles (UCLA) observed this rain, known as "electron precipitation," from low Earth orbit using the Electron Losses and Fields Investigation, or ELFIN (Electron Losses and Fields Investigation) mission.

Elfin's Dr. The first high-impact results publication, published by Xiaojia Zhang in Nature Communications, also took place.

“Using a NASA-funded CubeSat, scientists have uncovered a new source of superfast, energetic electrons raining down on our planet, which may have implications for space infrastructure and atmospheric modeling.

ELFIN is a pair of small, cube-shaped moons known as CubeSats. It was built and operated by UCLA undergraduate and graduate students under the guidance of a small team of staff mentors.”

Since its founding in 2013, more than 300 UCLA students have worked on ELFIN (Electron Loss and Fields research), funded by NASA and the National Science Foundation.

The two microsatellites, each about the size of a loaf of bread and weighing about 8 pounds, were launched into orbit in 2018 and have been observing the activity of energetic electrons ever since, helping scientists better understand the impact of magnetic storms. In space near Earth. The satellites are operated from the UCLA Mission Operations Center on campus.

What is Aurora Borealis?

Also known as aurora polaris or aurora polaris, it is a natural display of light in the Earth's sky, seen predominantly in high latitude regions (around the North Pole and Antarctica). Auroras create dynamic patterns of bright lights that appear as curtains, rays, spirals, or dynamic flickers that cover the entire sky.

Auroras are the result of effects on the magnetosphere caused by the solar wind. These effects change the trajectories of charged particles in the magnetospheric plasma. These particles, mainly electrons and protons, precipitate into the upper atmosphere (thermosphere/exosphere).

The resulting ionization and excitation of atmospheric components emit light of varying color and complexity. The shape of the aurora, which occurs within bands around both polar regions, also depends on the amount of acceleration given to the precipitating particles.

If we go back to our article;

By combining the ELFIN data with observations from NASA's THEMIS spacecraft farther away, scientists have found that the sudden downpour is a type of electromagnetic wave that ripples out of plasma in space, affecting electrons in Earth's magnetosphere and causing them to "dump" into the atmosphere. Whistler Waves They determined that it was caused by

Their findings, published March 25 in the journal Nature Communications, show that whistler waves are responsible for far more electron rain than current theories and models of space weather predict.

"ELFIN is the first satellite to measure these superfast electrons," said Xiaojia Zhang, lead author and researcher in UCLA's Department of Earth, planetary and space sciences. “The Mission provides new insights because of its unique perspective on the chain of events that produced them.”

At the center of this chain of events is the near-Earth space environment filled with charged particles swirling in giant rings around the planet called the Van Allen radiation belts. Electrons in these bands move in Slender-like spirals, literally bouncing between Earth's north and south poles. Under certain conditions, whistler waves are produced within the radiation belts that energize and accelerate electrons. This lengthens the electrons' path of motion so effectively that they fall through regions called belts or bands and precipitate in the atmosphere, creating a shower of electrons.


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Electron rain that can cause the aurora borealis and affect orbiting moons and atmospheric chemistry. Credit: NASA, Emmanuel Masongsong/UCLA

Vassilis Angelopolous, professor of space physics at UCLA and principal investigator of ELFIN, said you can imagine the Van Allen Belts as a large reservoir filled with water, or in this case electrons.

When the reservoir is full, the water is periodically wrapped in a drain to prevent the basin from overflowing. But when large waves occur in the reservoir, the flowing water pours out faster from the edge and in a larger volume than the drain. Downstream of both streams, ELFIN can accurately measure the contributions of each.

Elfin's measurements of low-altitude electron showers, combined with THEMIS observations of whistler waves in space and sophisticated computer modeling, allowed the team to understand in detail the process that causes the waves' rapid streams of electrons to flow into the atmosphere.

The findings are particularly important because they may affect existing theories and models of space weather. Because these models do not predict the electron flow from this extra whistler wave that could affect the Earth's atmospheric chemistry, pose a risk to the spacecraft, and damage low-orbit satellites.

The researchers also showed that such radiation belt electron loss to the atmosphere can increase significantly during geomagnetic storms, disturbances caused by enhanced solar activity that can affect near-Earth space and Earth's magnetic environment.

“Although space is often thought of as separate from our upper atmosphere, the two are inextricably linked,” Angelopoulos said. “Understanding how they are connected could benefit satellites and astronauts passing through the region, which is increasingly important to commerce, telecommunications and space tourism.”

"It's very rewarding that we increase our knowledge of space science using data from hardware we build ourselves," said Colin Wilkins, co-author of the current study, instrument leader at Elfin and a space physics doctoral student in the Department of Earth, planetary and space sciences.

Source: Physorg

Günceleme: 30/03/2022 17:30

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