Credit: Micah Tindell/UNSPLASH
There are trillions of charged particles – protons and electronsThe Basic Building Blocks of Matter – What Around Above Your Head at Any Given Time. These high-energy particles, which can travel at close to the speed of light, typically remain thosands of kilometers away from earth, trapped there by the shape of Earth's Magnetic filed.
Occasional, thought, an event happen that can jostle them out of place, sending electrons Raining Down Into Earth's AtmosphereThese high-energy particles in space make up what are known as the Van allen radiation beltsAnd their discovery was one of the first of the space age. A new study From my research team has found that electromagnetic waves generated by lightning can trigger these showers.
A brief history lesson
At the start of the space race in the 1950s, Professor James van allen And his research team at the university of iowa was tasked with building an expert to fly on the united states' very first satellite, Explorer 1They designed sensors to study cosmic radiationWhich is caused by high-energy particles originating from the sun, the milky way galaxy, or beyond.
After Explorer 1 launched, Thought, they noticed that their instrument was detecting significant higher levels of radiation Than expected. Rather than measuring a distant source of radiation beyond our solar system, they appear
This measurement LED to The discovery of The van allen radiation belts, two doughnut-shaped regions of high-energy electrons and ieons encircling the planet.
Scientists believe that inner radiation belt, peaking about 621 mills (1000 kilometers) from Earth, is composed of Electrons and high-energy protons and is related stables.
The outer radiation belt, About Three Times Farthr Away, is made up of high-energy electrons. This belt can be highly dynamicIts location, density and energy content may vary significant by the hour in response to solar activity.
The discovery of these high-radiation regions is not only an interesting story about the early days of the space race; It also serves as a reminder that many scientific discoveries have come about by happy accident.
It is a lesson for experimental scientists, MySelf Includedto keep an open mind when analyzing and evaluating data. If the data does not match our theories or expectations, those theories may need to be revisited.
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Our curious observations
While I Teach The History of the space race in a space policy course at the University of Colorado, Boundo, I Rarely Connect it to my own experience as a scientist resure Or, at least, I didn'T until recently.
In a study by max feinland, an undergraduate student in my research group, we stumbled upon some of our own Unexpected observations of Earth's radiation belts. Our findings have made usthink our undersrstanding of Earth's Inner radiation belt and the processes affecting it.
Originally, we set out to look for very rapid-sub-second- Bursts of high-energy electrons Entering the atmosphere from the outer radiation belt, where they are typically observed.
Many Scientists Believe That a type of electromagnetic wave known as “chorus” can know these electrons out of position and send them toward the atmosphere. Thei're called chorus waves due to their distinct chirping sound When listened to on a radio receiver.
Feinland developed an algorithm to search for these events in decades of measurements from the Sampex satelliteWhen he showed me a plot with the location of all the events he'd detected, we noticed a number of thatm we we do not where we are expected. Some events mapped to the inner radiation belt rather than the outer belt.
This finding was curious for two reasons. For one, chorus waves are prevalent in this region, so someshing else had to be shaking these electrons loose.
The other surprise was founding electrons this energetic in the inner radiation belt at all. Measurements from Nasa's van allen probes mission Prompted renewed interest in the inner radiation belt. Observations from the van allen probes suggested that high-energy electrons are often not present In this inner radiation belt, at least not during the first few years of that mission, from 2012 to 2014.
Our observations now showed that, in fact, there are times that the inner belt contains high-energy electrons. How often this is true and under what conditions remain open questions to explore. These high-energy particles can damage spacecraft and harm humans in space, so researchers need to know where and where in space they are present to better design spacecraft.
Determining The Culprit
One of the ways to disturb electrons in the inner radiation belt and kick them into earth's atmosphere actually begins in the atmosphere its.
Lightning, the large electromagnetic discharges That light up the sky during thundrstorms, can actually generate electromagnetic waves knowledge as Lightning-generated whistles,
These waves can then travel through the atmosphere out into space, where they Interact with Electrons in the inner radiation belt – much as chorus waves interact with electrons in the outer radiation belt.
To test whicher lightning was behind our inner radiation belt detections, we looked back at the electron bursts and compared them with thundersstorm dataSome lightning activity see correlated with our electron events, but much of it was not.
Specifically, only lightning that occurred right after so-called geomagnetic stories resulted in the bursts of Electrons we detected.
Geomagnetic Storms Are disturbances in the near-ear-space environment often caused by large erutions on the sun's surface. This Solar Activity, If Directed Toward Earth, Can Produce What Researchers Term Space WeatherSpace weather can result in stunning aurraras, but it can also disrupt satellite and power grid operations.
We discovered that a combination of weather on earth and weather in space produces the unique electron signatures we observe in our study. The Solar Activity Disturbs Earth's radiation belts and populates the inner belt with very high-energy electrons, then the lightning interactions with these ElectRs and Creates the Rapid Bursi.
These results provide a nice reminder of the interconnected nature of ear and space. They were also a welcome reminder to me of the often nonlinear process of scientific discovery.
Lauren Blum Is an assistant professor of atmospheric and space physics at the University of Colorado BounderBlum receives funding from nasa and the nsf.
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