Airborne observatory improves views of solar corona during cloud-covered eclipse

Using unique equipment installed on NASA’s WB-57 aircraft flying above heavy clouds off the coast of Iceland, a Southwest Research Institute-led team successfully observed a total solar eclipse on Wednesday. The high-altitude jet followed the moon’s shadow at 50,000 feet (15,000 meters) to take measurements of the solar corona in nine different wavelengths, ranging from visible to infrared light.

“This eclipse was the perfect opportunity to use the unique imaging capabilities of NASA’s high-flying research observatory,” said Dr. Amir Caspi, a senior program manager at SwRI’s Solar System Science and Exploration Division in Boulder, Colorado. He is principal investigator of the project, which was conducted in collaboration with NASA’s Johnson Space Center in Houston and Langley Research Center in Hampton, Virginia. “The eclipse track was mostly over the Atlantic Ocean, in locations where clouds are common, exemplifying the advantages of the WB-57’s mobile, high-altitude capabilities.”

The team collected high-resolution images of the eclipse with the Scientifically Calibrated In-Flight Imagery team’s Airborne Multispectral Imager, or SAMI, mounted on the nose of the aircraft. Originally developed at Langley to image the Artemis I rocket plume and capsule reentry, SAMI has found additional use for astronomical imaging through a series of eclipse observations. These unique observations allow scientists to view the complex and dynamic features of the sun’s outer atmosphere in ways that aren’t possible or practical by any other means.

The faint light from the corona is usually overpowered by the intense brightness of the sun itself but is readily accessible when the moon blocks the bright solar disk. Observing from high altitude not only overcomes cloud cover but also allows imaging of wavelengths, such as infrared, that are absorbed by Earth’s atmosphere.

In addition to revealing the million-degree corona, eclipses also sometimes reveal prominences, huge loops of hot magnetized plasma that can erupt from the sun’s atmosphere. If the resulting solar particles reach Earth, they could potentially damage satellites, interfere with GPS navigation and knock out power grids, so understanding them better is important to reduce the risks posed by space weather.

“The data are really exciting and include a massive, unexpected prominence on the sun’s east limb, which will provide some very interesting science,” said SwRI’s Dr. William Ashfield, who led the calibration and analysis of observations from the 2024 eclipse and will continue with the new measurements. “Based on lessons learned from using SAMI in 2024, the new observations will allow us to explore this phenomenon in all of SAMI’s passbands. I’m looking forward to digging into the results.”

The team meticulously planned the flight path and observing sequence to ensure the plane would encounter the eclipse on time and complete its observations in the brief window of totality available at high altitude. The pilot and sensor equipment operator executed the plan perfectly, resulting in two minutes and 56 seconds of totality—exactly the duration the mission intended to achieve. The mission produced more than 2 terabytes of high-speed observations at tens of images per second, allowing scientists to track both structure and dynamics within the corona.

“We achieved all of our mission objectives,” Caspi said. “This spectacular success was made possible by the efforts of the entire team, including the WB-57 air and ground crew who executed the mission, the SCIFLI/SAMI team who built and calibrated the instrument, the science team who planned and will analyze the observations, and even the U.S. Navy and government of Iceland, who hosted us and provided extensive logistical support.”

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Alexander Pol

PhD nano-engineering from Delft University. Published researcher and journal reviewer. Brings scientific insight to content standards.

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