Credit: micah tindell/unsplash
There are trillion of charged particles – protons and electrons, the basic bricks of the matter – they dart over the head at any time. These high energy particles, which can travel near the speed of light, generally remain thousands of kilometers away from the earth, trapped there by the shape of the magnetic field of the earth.
Occasionally, however, an event that can push them out of place happens, sending electrons that rain in the terrestrial atmosphere. These high energy particles in the space constitute those that are known as Van Allen’s radiation belts and their discovery was one of the first spatial age. A new study of my research team has discovered that electromagnetic waves generated by lightning can trigger these electronic showers.
A short history lesson
At the beginning of the spatial race in the 1950s, Professor James Van Allen and his research team at the University of Iowa were in charge of building an experiment to fly on the first satellite of the United States, Explorer 1. They designed sensors to study cosmic radiation, which is caused by high energy high -energy particles.
After the launch of Explorer 1, however, they noticed that their instrument was detecting significantly higher radiation levels than expected. Instead of measuring a distant source of radiation beyond our sun system, they seemed to measure a local and extremely intense source.
This measurement led to the discovery of Van Allen’s radiation belts, with two regions in the shape of high energy electron paste and ions that surround the planet.
Scientists believe that the inner radiation belt, which reaches the peak of about 1000 kilometers) from the earth, is composed of high energy electrons and protons and is relatively stable over time.
The external radiation belt, about three times further away, consists of high energy electrons. This belt can be highly dynamic. Its position, density and energy content may vary significantly for now in response to solar activity.
The discovery of these high radiation regions is not only an interesting story about the first days of the space race; It also serves as a reminder that many scientific discoveries took place for a happy accident.
It is a lesson for experimental scientists, including me, to maintain an open mind when analyzing and evaluating the data. If the data does not correspond to our theories or expectations, it may be necessary to revisit these theories.
Our curious observations
While I teach the history of space to space in a spatial policy course at the University of Colorado, Boulder, rarely I connect it to my experience as a scientist who seeks the radiation belts of the earth. Or, at least, I didn’t do it until recently.
In a study conducted by Max Feinland, a university student in my research group, we came across some of our unexpected observations of earth’s radiation belts. Our discoveries have made us rethink our understanding of the inner radiation belt of the earth and the processes that strike it.
Initially, we decided to search for very rapid explosions-underconds-of high energy electrons that enter the atmosphere from the external radiation belt, where they are generally observed.
Many scientists believe that a type of electromagnetic wave known how “choir” can drop these electrons and send them to the atmosphere. They are called World Waves due to their distinct chirping sound when you listen to a radio receiver.
Feinland has developed an algorithm to look for these events in decades of measurements from Sampex satellite. When he showed me a plot with the position of all the events he had detected, we noticed that some of them were not where we expected. Some events mapped on the internal radiation belt rather than on the external belt.
This discovery was curious for two reasons. For one, choir waves are not prevalent in this region, so something else had to shake these electrons.
The other surprise was to find such energetic electrons in the internal radiation belt. The measurements of the Van Allen Mission of NASA probes have aroused a renewed interest in the internal radiation belt. Van Allen’s observations have suggested that high energy electrons are often not present in this inner radiation belt, at least not during the first years of that mission, from 2012 to 2014.
Our observations have now shown that, in fact, there are times when the internal belt contains high energy electrons. How many times this is true and in what conditions are open questions to be explored. These high energy particles can damage space vehicles and damage human beings in space, so researchers must know when and where in space they are present to design better spaces.
Determine the culprit
One of the ways to disturb the electrons in the internal radiation belt and kick them in the Earth’s atmosphere actually begins in the atmosphere itself.
The lightning, the large electromagnetic exhausts that illuminate the sky during thunderstorms, can actually generate electromagnetic waves known as informants generated by lightning.
These waves can therefore travel through the atmosphere in space, where they interact with electrons in the internal radiation belt, just as chorus waves interact with electrons in the external radiation belt.
To check if the lightning was behind our surveys of the internal radiation belt, we looked back to the explosions of electrons and compared them with the temporal data. Some lightning activities seemed related to our electrons events, but it was not largely.
In particular, only the lightning that occurred immediately after the so -called geomagnetic storms led to the explosions of electrons that we have detected.
Geomagnetic storms are ailments in the space of space near the earth often caused by large eruptions on the surface of the sun. This solar activity, if directed towards the earth, can produce what researchers call the space climate. The space climate can cause splendid auror, but it can also stop satellite operations and the electricity grid.
We discovered that a combination of time on Earth and time in the space produces the unique signatures of electrons that we have observed in our study. Solar activity disturbs the radiation belts of the earth and populates the internal belt with very high energy electrons, so the lightning interacts with these electrons and creates the rapid gusts that we have observed.
These results provide a nice reminder of the interconnected nature of the earth and space. They were also a welcome reminder for me of the often non -linear process of scientific discovery.
Lauren Blum is associate professor of atmospheric and spatial physics at the University of Colorado Boulder. Blum receives funding from NASA and NSF.
This article is republished by The conversation Under a Creative Commons license. Read the original article.
