NASA James Webb Space Telescope Solves Water Mystery and Raises More Questions

Tuesday - May 16 2023, 18:49 UTC - 1 year ago

NASA’s James Webb Space Telescope has enabled a long-sought scientific breakthrough in solving the mystery behind Earth’s abundant water. With its efficient detection of gas - specifically water vapor - around a comet in the main asteroid belt, it has been demonstrated that water ice from the early solar system can be preserved in the warmer asteroid belt, inside the orbit of Jupiter. However, the lack of Carbon dioxide present in Comet Read was a surprise, and leads to new possibilities concerning the Comet's origin and other possible explanations.

NASA’s James Webb Space Telescope has enabled another long-sought scientific breakthrough, this time for solar system scientists studying the origins of Earth’s abundant water. Using Webb’s NIRSpec (Near-Infrared Spectrograph) instrument, astronomers have confirmed gas – specifically water vapor – around a comet in the main asteroid belt for the first time, indicating that water ice from the primordial solar system can be preserved in that region. However, the successful detection of water comes with a new puzzle: unlike other comets, Comet 238P/Read had no detectable carbon dioxide.

"Our water-soaked world, teeming with life and unique in the universe as far as we know, is something of a mystery – we’re not sure how all this water got here," said Stefanie Milam, Webb deputy project scientist for planetary science and a co-author on the study reporting the finding. "Understanding the history of water distribution in the solar system will help us to understand other planetary systems, and if they could be on their way to hosting an Earth-like planet," she added.

Comet Read is a main belt comet – an object that resides in the main asteroid belt but which periodically displays a halo, or coma, and tail like a comet. Main belt comets themselves are a fairly new classification, and Comet Read was one of the original three comets used to establish the category. Before that, comets were understood to reside in the Kuiper Belt and Oort Cloud, beyond the orbit of Neptune, where their ices could be preserved farther from the Sun. Frozen material that vaporizes as they approach the Sun is what gives comets their distinctive coma and streaming tail, differentiating them from asteroids. Scientists have long speculated that water ice could be preserved in the warmer asteroid belt, inside the orbit of Jupiter, but definitive proof was elusive – until Webb.

"In the past, we’ve seen objects in the main belt with all the characteristics of comets, but only with this precise spectral data from Webb can we say yes, it’s definitely water ice that is creating that effect," explained astronomer Michael Kelley of the University of Maryland, lead author of the study.

"With Webb’s observations of Comet Read, we can now demonstrate that water ice from the early solar system can be preserved in the asteroid belt," Kelley said.

The missing carbon dioxide was a bigger surprise. Typically, carbon dioxide makes up about 10 percent of the volatile material in a comet that can be easily vaporized by the Sun’s heat. The science team presents two possible explanations for the lack of carbon di oxide around Comet Read – either it was never there and instead has been replaced by other gases like carbon monoxide, or it may have been present but quickly destroyed by sunlight.