NASA Readies Satellite to Scan Earth's Highest Clouds

Noctilucent clouds over northern Europe. CREDIT: Pekka Parvianien.

A NASA spacecraft aimed at probing the mysteries of Earth's highest clouds is gearing up for launch.

The space agency's Aeronomy of Ice in the Mesosphere (AIM) satellite is counting down towards an April 25 space shot to begin the first-ever mission dedicated to tracking Earth's odd noctilucent - or 'night shining' - clouds.

First observed in 1885, the clouds - also known as polar mesospheric clouds (PMC) - are made of ice crystals hovering some 50 miles (80 kilometers) above Earth. They are only visible at night when they reflect sunlight after the Sun has dipped below the planet's horizon.

In recent years, the previously rare clouds have been found to shine brighter, occur more frequently and appear at lower latitudes than ever before, leading some scientists to speculate that their behavior may be related to global climate changes, such as global warming, said Vicki Elsbernd, NASA's AIM mission program executive at the agency's Washington, D.C. headquarters, during a Wednesday briefing.

Built for NASA by Orbital Sciences and overseen by researchers at Hampton University in Hampton, Virginia, the $140 million AIM spacecraft is slated to rocket spaceward at 4:26:49 p.m. EDT (2026:49 GMT) on April 25 atop an air-launched Pegasus XL rocket. About the size of a small piano, the 430-pound (195-kilogram) spacecraft will depart from California's Vandenberg Air Force Base on a two-year mission.

"Other satellite missions have made measurements of these clouds, but they weren't optimized and it was not their intent in the beginning," AIM principal investigator Jim Russell, of Hampton University, told reporters Wednesday. "They provided information, but not enough to really address the fundamental question of why [the clouds] form and how they vary."

Because similar cloud formations are seen high above the surface of Mars, researchers hope to better understand their implications for life on Earth and future missions to the red planet, Elsbernd added.

"We're very excited about the AIM launch," Elsbernd said. "We expect that the new discoveries from AIM, along with our other great observatory missions, will literally rewrite the textbooks in our understanding of Sun and its effects on the Earth's atmosphere and on the solar system."

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