This discovery will help scientists understand how water reached Earth.
In a major discovery, water molecules have been found on the surface of two asteroids for the first time, revealing new clues about the distribution of water in our solar system. The discovery is based on the analysis of data gathered by Stratospheric Observatory for Infrared Astronomy (SOFIA), now-retired telescope operated by NASA and German Aerospace Centre. The asteroids studied are Iris and Malissa and the research has been published in The Planetary Science Journal.
"We detected a feature that is unambiguously attributed to molecular water on the asteroids," Anicia Arredondo, study lead author and asteroid researcher at the Southwest Research Institute, said in a press release. She also shared a post on X about the discovery.
Both Iris and Malissa are rich in silicates. The water molecules were found trapped in the silicate glass formed by impacts, or chemically bonded to other minerals on the asteroid, according to astronomy.com.
This discovery will help scientists understand how water reached Earth. SOFIA, the instrument used in the research, previously detected water in the Moon's southern part.
Ms Arredondo and her team looked at four asteroids - that also included Parthenope and Melpomene. Three of these asteroids showed absorption at a wavelength of 3 micrometres, but Iris and Massalia also showed absorption at 6 micrometres, a signature only attributable to water.
This is the first time that water molecules have been found on the surface of an asteroid in space. "We based our research on the success of the team that found molecular water on the sunlit surface of the moon. We thought we could use SOFIA to find this spectral signature on other bodies," Ms Arredondo said in the statement.
Iris (with a diametre of 199 km) and Massalia (with a diametre of 135 km) have similar orbits, travelling an average distance of 2.39 astronomical units (AU), or Sun-Earth distances, from the Sun, as per space.com.