April 12 :
During the solar eclipse that crossed North America on April 8, 2024, three Black Brant IX sounding rockets were launched by the National Aeronautics and Space Administration (NASA) to study "the disturbances in the ionosphere created when the Moon eclipses the Sun." This unique mission was called Atmospheric Perturbations around Eclipse Path (APEP).
Space and Atmospheric Instrumentation Lab director and professor of engineering physics at Embry-Riddle Aeronautical University in Daytona Beach, Florida, Dr. Aroh Barjatya, oversaw the project.
The Wallops Flight Facility in Virginia was the site of the APEP mission. "These intervals are important to collect data on how the Sun’s sudden disappearance affects the ionosphere, creating disturbances that have the potential to interfere with our communications," the NASA statement said, adding that the sounding rockets were launched "at three different times: 45 minutes before, during, and 45 minutes after the peak local eclipse" in Virginia.
An atmospheric layer between 90 and 500 kilometres (55 to 310 miles) above the surface of the Earth is called the ionosphere. As the signals travel through the area, they are reflected and refracted by radio waves, which in turn affects satellite communications, according to Barjatya's statement. For a world that is becoming more and more reliant on communication, it is essential to have a firm grasp of the ionosphere and create models to aid in the prediction of disturbances.
These rockets were fired and recovered from New Mexico's White Sands Test Facility during the annular solar eclipse that occurred in October 2023. For the most recent APEP mission, they were later modified with new instruments. According to the announcement, the rockets will measure the electric and magnetic fields nearby, the density of charged and neutral particles, and their estimated peak altitude of 260 miles (420 km).
According to Barjatya, "Each rocket will eject four secondary instruments the size of a two-liter soda bottle that also measure the same data points," which equals the results of fifteen rockets, even though only three were launched. This was disclosed before the mission began.
Not only did many teams around the US launch these rockets, but they also used a variety of techniques to collect data on the ionosphere. A group of Embry-Riddle students, for example, sent a string of balloons into the sky at great altitude.
"We have to make hay while the Sun shines... or, I suppose for eclipse science, while it doesn't." Barjatya added, "In all seriousness though, this data set will reveal the widespread effects that eclipses have on the ionosphere at the smallest spatial scales." This was in response to the fact that the next total solar eclipse over the contiguous United States won't happen until 2044 and the next annular eclipse won't happen until 2046.
The sun's rays vanish abruptly during a solar eclipse, only to resurface in a little patch of sky. The ionospheric temperature and density are impacted by this abrupt shift, causing waves to propagate through the atmosphere.
"The eclipse is like a motorboat abruptly ripping through the water if you think of the ionosphere as a pond with some gentle ripples on it," Barjatya remarked. "As it swiftly returns to the water, it briefly raises the water level, and it leaves a wake just beneath and behind it."
According to Barjatya, "All satellite communications go through the ionosphere before they reach Earth." He used the 2017 North American total solar eclipse as an example, saying that detectors observed atmospheric changes hundreds of miles outside the eclipse's path. Understanding and modelling all ionosphere disruptions is crucial as our reliance on space-based assets grows.
