Before the Space Age, scientists such as Kristian Birkeland, Carl Strmer, Nicholas Christofilos, and Enrico Medi studied the potential of trapped charged particles in a vacuum. Since space was considered a vacuum, these experiments gave NASA some idea of what they would be facing with their unmanned and manned flights.
In early 1958, under the supervision of James Van Allen at the University of Iowa, Explorer 1 and Explorer 3 verified the presence of the Van Allen Radiation Belt, held in place by Earth’s magnetosphere.
The trapped radiation was discovered for the first time by the spacecraft Explorer 4, Pioneer 3, and Luna 1.
Specifically, the phrase Van Allen belts is used in reference to the radiation belts that encircle the planet Earth; however, comparable radiation bands have been identified around other planets as well.
Long-term radiation belts are not supported by the Sun since it does not have a stable, worldwide dipole field.
The Earth’s atmosphere restricts the particle distribution of the belts to areas above 200–1,000 km (124–620 miles), and the belts do not extend beyond 8 Earth radii (RE) in length.
Though they contain deadly and disruptive radiation, the belts do serve a useful purpose in deflecting solar winds and gamma rays around the Earth, protecting us from overexposure to these corrosive visitors.
In terms of volume, the belts are restricted to an area that stretches about 65°[6] on each side of the celestial equator. So envision it as a sort of figure 8, or elongated doughnut, with the Earth smack dab in the middle.
The inner Van Allen Belt is almost entirely composed of highly charged protons.
Within the inner Van Allen Belt, the height ranges normally from 1,000 km (620 mi) to 12,000 km (7,500 mi) above the surface of the Earth.
Certain circumstances, such as during periods of increased solar activity or in geographical locations such as the South Atlantic Anomaly, might result in the inner boundary lowering to around 200 km[12] above the Earth’s surface.
The South Atlantic Anomaly is the point where the inner Van Allen Radiation Belt comes nearest to the Earth’s atmosphere. It can be problematic to spacecraft launched in the area (roughly from off the coast of Brazil to the Ivory coast in Africa) because in some cases it comes as close as 120 miles to the Earth’s surface. Due to the high radiation inside the belt, satellites may malfunction when passing through it, and computers aboard manned spacecraft have crashed when going through the Anomaly. So the area is avoided as much as possible by NASA and other spacecraft.
In the lower belts and at lower altitudes, it is hypothesized that proton energies greater than 50 MeV are produced by neutron beta decay caused by collisions with nuclei in the upper atmosphere caused by cosmic ray impacts.
When there is a shift in the magnetic field, as occurs during geomagnetic storms, it is assumed that proton diffusion is the source of the lower energy protons.
RBSPICE (Radiation Belt Storm Probes Ion Composition Experiment) aboard the Van Allen Probes discovered a pattern in the radiation belts that resembled “zebra stripes” in March 2014, according to the reports published in scientific and astronomy journals.
Initially suggested in 2014, the hypothesis said that the planet’s rotation created an oscillating, weak electric field that permeated the whole inner radiation belt owing to the tilt in the Earth’s magnetic field axis. This idea has now been proven incorrect.
A 2016 research, on the other hand, came to the conclusion that the zebra stripes were caused by ionospheric winds imprinting on radiation bands in the outer belt.
The outer Van Allen Belt is composed mainly of highly charged electrons.
By removing the charged particles from the Van Allen belts, it might be possible to create new orbits for satellites and make astronaut flight more safe.
HVOLTE, also known as the High Voltage Orbiting Long Tether, is a proposal suggested by Russian physicist Vladimir Vladimirovich Danilov and improved by Robert P. Hoyt and Robert L. Forward for draining and eliminating radiation fields from the Van Allen radiation belts[39] that encircle the Earth.
The beaming of very-low-frequency (VLF) radio waves from the ground into the Van Allen belts is another suggestion for emptying the Van Allen belts.
It has also been suggested to drain radiation belts surrounding other planets, for example, before studying Europa, which orbits inside Jupiter’s radiation belt. But there is a developing holistic feeling among astrophysicists that such large scale meddling is not in the best interests of either the solar system or of the human race. It’s seen as destruction of the environment in some circles.
According to the most recent available information, it is still unclear if the removal of these radiation bands would have any harmful unintended repercussions. But their cost alone would be prohibitive, and would require the financial cooperation of the all the technologically advanced nations of the world. Weakened by the pandemic and war, it’s likely the Van Allen Radiation Belts will be safe from the depredation of scientists for some time to come!
