Using data from NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), scientists at the Southwest Research Institute have discovered, for the first time, water molecules on the surface of an asteroid. Scientists examined four silicate-rich asteroids using the FORCAST instrument to isolate mid-infrared spectral signatures indicating the presence of molecular water on two of them. Credit: NASA/Carla Thomas/Southwest Research Institute
Using data from the Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint project of NASA and the German Space Agency at DLR, scientists at the Southwest Research Institute have discovered, for the first time, molecules of water on the surface of an asteroid. Scientists examined four silicate-rich asteroids using the FORCAST instrument to isolate mid-infrared spectral signatures indicating the presence of molecular water on two of them.
“Asteroids are leftovers from the planetary formation process, so their composition varies depending on where they formed in the solar nebula,” said SwRI’s Dr. Anicia Arredondo, lead author of a paper in The Journal of Planetary Science about the discovery. “The distribution of water on asteroids is particularly interesting because it can shed light on how water was transported to Earth.”
Anhydrous or dry silicate asteroids form near the sun while icy materials coalesce further away. Understanding the locations of asteroids and their compositions tells us how materials in the solar nebula have been distributed and evolved since their formation. The distribution of water in our solar system will provide insight into the distribution of water in other solar systems and, because water is necessary for all life on Earth, determine where to look for potential life, both in our solar system and beyond.
“We detected a feature unambiguously attributed to molecular water on the asteroids Iris and Massalia,” Arredondo said. “We based our research on the team’s success in finding molecular water on the sunlit surface of the Moon. We thought we could use SOFIA to find this spectral signature on other bodies.”
SOFIA detected water molecules in one of the largest craters in the Moon’s southern hemisphere. Previous observations of the Moon and asteroids had detected some form of hydrogen, but could not distinguish water from its close chemical relative, hydroxyl. Scientists detected roughly the equivalent of a 12-ounce bottle of water trapped in a cubic meter of soil spread across the lunar surface, chemically bound to minerals.
“Based on the band intensity of the spectral features, the abundance of water on the asteroid is consistent with that of the sunlit moon,” Arredondo said. “Similarly, on asteroids, water can also be bound to minerals, adsorbed onto silicate, and trapped or dissolved in silicate impact glass.”
Data from two fainter asteroids, Parthenope and Melpomene, were too noisy to draw a definitive conclusion. The FORCAST instrument is apparently not sensitive enough to detect the spectral feature of water if it is present. However, with these findings, the team is calling on NASA’s James Webb Space Telescope, the first infrared space telescope, to use its precise optics and superior signal-to-noise ratio to study more targets.
“We made initial measurements on two other asteroids with Webb during the second cycle,” Arredondo said. “We have another proposal for the next cycle to look at 30 more targets. These studies will improve our understanding of the distribution of water in the solar system.”
More information:
Anicia Arredondo et al, Detection of molecular H2O on nominally anhydrous asteroids, The Journal of Planetary Science (2024). DOI: 10.3847/PSJ/ad18b8
Provided by Southwest Research Institute
Quote: Scientists identify water molecules on asteroids for the first time (February 12, 2024) retrieved February 13, 2024 from
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