First Discovery of Water Molecules on Asteroid

Scientists have detected water molecules on the surface of two asteroids for the first time ever, using data from the now-retired SOFIA airborne observatory. This discovery sheds new light on how water may have been delivered to Earth and other planets in the solar system.

How SOFIA detected water on asteroids

SOFIA, or the Stratospheric Observatory for Infrared Astronomy, was a modified Boeing 747SP aircraft that carried a 2.7-meter (8.9-foot) telescope. It operated from 2010 to 2022, flying at altitudes of up to 45,000 feet (13,700 meters) and observing the infrared universe.

One of the instruments on board SOFIA was the Faint Object InfraRed Camera (FORCAST), which could measure the infrared emission from celestial objects. Infrared light is invisible to the human eye, but it can reveal the temperature, composition and structure of objects in space.

Using FORCAST, researchers observed four silicate-rich asteroids and found that two of them, named Iris and Massalia, exhibited a specific wavelength of light that indicated the presence of water molecules at their surface. The study was published in The Planetary Science Journal on February 14, 2024.

What water molecules on asteroids mean for astrobiology

Water is essential for life as we know it, but its origin and distribution in the solar system are still poorly understood. Asteroids are remnants of the planetary formation process, so studying their composition can reveal clues about the history and evolution of our cosmic neighborhood.

The water molecules on Iris and Massalia could be trapped in silicate glass, adsorbed on silicate surfaces, or bound to minerals, similar to how water is found on the moon’s sunlit surface. The abundance of water on these asteroids was comparable to that on the moon, according to the study.

This is the first time that water molecules have been detected on an asteroid in space, as previous detections were made on asteroid samples returned to Earth by spacecraft missions. The finding suggests that water can persist for long periods of time on asteroids in the inner solar system, despite the intense heat from the sun.

The discovery has implications for astrobiology, as it implies that water may have been more widely available in the early solar system than previously thought. This could have influenced the delivery of water to Earth and other planets, as well as the emergence and evolution of life.

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