Water, a common substance on Earth and crucial to life, has long been considered a rare commodity in the inner Solar System. However, recent discoveries are challenging this notion. For the first time, researchers have found evidence of water on the surface of asteroids, specifically on the dry silicate asteroids Iris, Parthenope, Melpomene, and Massalia, all located in the main Asteroid Belt.
Using data from the retired Stratospheric Observatory for Infrared Astronomy (SOFIA), researchers from various institutions across the United States detected a spectral feature attributed to molecular water on the surfaces of Iris and Massalia. This discovery challenges previous observations that couldn’t distinguish between water and its chemical relative, hydroxyl.
Dr. Anicia Arredondo, the lead author of the study from the Southwest Research Institute, explained, “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.”
The estimated amount of water on these asteroids is about a soda can’s worth for each cubic meter of asteroid soil, similar to the value based on observations of the Moon from SOFIA. This finding suggests that water on asteroids can be bound to minerals, adsorbed to silicate, or trapped or dissolved in silicate impact glass.
Finding water on asteroids is important for clarifying how water got to Earth as well as for learning more about the composition of these objects. “Asteroids are remnants of the planetary formation process, so their compositions vary depending on where they formed in the solar nebula,” Dr. Arredondo clarified. The distribution of water on asteroids is particularly interesting because it may provide insight into how water was brought to Earth.
The creative use of SOFIA data allowed for the completion of this study, which yielded important new information on the composition and history of asteroids as well as their likely significance in the transfer of volatile substances like water to Earth.
