Why will NASA launch three probes during the solar eclipse on October 14?

It’s an anticipated event for Americans who love the sky: on October 14, Earth moonmoon And the sunsun They will be perfectly aligned. This alignment will temporarily eclipse the Sun and it will find itself hidden behind the Moon. This phenomenon is called an annular solar eclipse, which is different from a total solar eclipse. during Solar eclipseSolar eclipse In total, the Moon completely hides the solar disk, so that the latter is replaced by a very dark lunar silhouette, revealing only… Solar crownSolar crown.

On the other hand, during an annular solar eclipse, the apparent size of the Moon in the sky is slightly smaller than that of the Sun: observers looking at the sky see a very bright ring appearing around the disk during the peak of the eclipse. .lunar ring, also called “lunar ring.” firefire The annular solar eclipse on October 14 will only be visible from the American continent, where… brightnessbrightness Our Sun’s appearance will decrease until it reaches 10% of its usual brightness.

Effects on the ionosphere, an atmospheric layer controlled by sunlight

The ionosphere of a planet corresponds to its part AtmosphereAtmosphere where is the GasGas Ionized, meaning that the atoms are MoleculesMolecules One or more losses or wins ElectronsElectronsThus, charged particles become ionsions). On the ground,IonosphereIonosphere It occupies a large part of the atmosphere and is located at an altitude of approximately 60 to 1000 km.

Ultraviolet radiation from the Sun is the origin of the ionosphere: the latter They interact with atmospheric moleculeswhich sometimes allows them to be separated (for example, ultraviolet light can separate a dioxygen molecule into two atoms ofOxygenOxygen), but also to ionize it. UV light can actually strip an electron from a molecule or atom, producing a soup consisting of ions (which are missing an electron) and free electrons in equal amounts. Through these processes, the gases in the ionosphere act as an absorbing filter, helping to limit the amount of ultraviolet radiation that reaches the Earth’s surface. during the day, Solar radiationSolar radiation Constants allow these particles to remain separate; But when night falls, much of it reassembles into neutral molecules or atoms, before separating again at dawn.

Dynamics still poorly understood during a solar eclipse

During a solar eclipse, sunlight disappears and reappears almost instantly on a small portion of the Earth’s surface. In a very short time, the temperature and density of the ionosphere decreases and then rises again, producing types of waves that move through the material, like a body of water in which a boat is moving. waveswaves (or waves) in its wake.

To study these phenomena, NASANASA She planned to launch her program Atmospheric disturbances around the path of the eclipse (Aviv)It was implemented in partnership with researchers fromEmbry-Riddle Aeronautical University, in Florida. A little anecdote The abbreviation “Aviv” refers to the Egyptian god Apophis (Aviv in Egyptian), a god represented in the form of a serpent who, according to mythology, was pursuing the sun god Ra to the point of making him almost completely disappear, leading to his reappearance. Solar eclipse.

Therefore, the US Space Agency plans to launch three probes into the ionosphere, the first 35 minutes before the peak of the eclipse, the second during the peak of the eclipse, and the last 35 minutes after it. They will travel through our atmosphere at altitudes between 70 and 325 kilometers to deploy four scientific instruments that will measure differences in… Electric fieldsElectric fields The magnetic forces of the ionosphere, as well as changes in temperature and density. During their paths (ascension and descent), these sensors will be able to accurately measure changes occurring at different altitudes. The two probes will be recovered at the end of the mission to be launched again during the next total solar eclipse on April 8, 2024.

The effect of the ionosphere on communications satellites

At the same time, it will complete many important ground observations. Researchers from the Haystack Observatory, led by Massachusetts Institute of Technology MIT will use its instruments to measure ionospheric perturbations slightly beyond the eclipse’s path. A team of students fromEmbry-Riddle Aeronautical University Probe balloons will be deployed at high altitudes to measure weather changes as the eclipse passes.

All these measurements will help create an accurate model of ionospheric dynamics. Understanding them is increasingly essential because all of our satellite communications pass through the ionosphere before reaching Earth. It therefore seems necessary to fully understand the behavior of the ionosphere and to be able to predict the disturbances that may occur there.