- 3529 - ELECTRON RAIN - new college satellites are measuring. College students working with scientists have discovered a new source of super-fast, energetic electrons raining down on Earth, a phenomenon that contributes to the colorful aurora borealis but also poses hazards to satellites, spacecraft and astronauts.
------- 3529 - ELECTRON RAIN - new college satellites are measuring
- These researchers observed unexpected, rapid "electron precipitation" from low-Earth orbit using the “ELFIN” mission, a pair of tiny satellites built and operated on the UCLA campus by students.
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- Electrons in a Van Allen radiation belt encounter “whistler waves” and are sent raining toward the north pole. THEMIS satellites are near the radiation belt, while UCLA’s ELFIN hovers above Earth.
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- By combining the ELFIN data with more distant observations from the THEMIS spacecraft, the scientists determined that the sudden downpour was caused by “whistler waves“, a type of electromagnetic wave that ripples through plasma in space and affects electrons in the Earth's magnetosphere, causing them to "spill over" into the atmosphere.
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- Whistler waves are responsible for far more electron rain than current theories and space weather models had predicted.
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- "ELFIN is the first satellite to measure these super-fast electrons“. This mission is yielding new insights due to its unique vantage point in the chain of events that produces them.
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- Central to that chain of events is the near-Earth space environment, which is filled with charged particles orbiting in giant rings around the planet, called Van Allen radiation belts. Electrons in these belts travel in Slinky-like spirals that literally bounce between the Earth's north and south poles.
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- Under certain conditions, whistler waves are generated within the radiation belts, energizing and speeding up the electrons. This effectively stretches out the electrons' travel path so much that they fall out of the belts and precipitate into the atmosphere, creating the electron rain.
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- One can imagine the Van Allen belts as a large reservoir filled with water -- or, in this case, electrons. As the reservoir fills, water periodically spirals down into a relief drain to keep the basin from overflowing. But when large waves occur in the reservoir, the sloshing water spills over the edge, faster and in greater volume than the relief drainage. ELFIN, which is downstream of both flows, is able to properly measure the contributions from each.
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- The low-altitude electron rain measurements by ELFIN, combined with the THEMIS observations of whistler waves in space and sophisticated computer modeling, allowed the team to understand in detail the process by which the waves cause rapid torrents of electrons to flow into the atmosphere.
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- The findings are particularly important because current theories and space weather models, while accounting for other sources of electrons entering the atmosphere, do not predict this extra whistler wave-induced electron flow, which can affect Earth's atmospheric chemistry, pose risks to spacecraft and damage low-orbiting satellites.
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- The research further showed that this type of 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.
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- Although space is commonly thought to be separate from our upper atmosphere, the two are inextricably linked. Understanding how they're linked can benefit satellites and astronauts passing through the region, which are increasingly important for commerce, telecommunications and space tourism.
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- Since its inception in 2013, more than 300 UCLA students have worked on ELFIN (Electron Losses and Fields investigation). The two microsatellites, each about the size of a loaf of bread and weighing roughly 8 pounds, were launched into orbit in 2018, and since then have been observing the activity of energetic electrons and helping scientists to better understand the effect of magnetic storms in near-Earth space.
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April 1, 2022 ELECTRON RAIN - new college satellites are measuring 3529
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