James Webb Space Telescope discovers water around a mysterious comet

The investigation of Comet 238P/Read, which hides in the main asteroid belt, may shed light on the origin of the water that sustains life on Earth.

Water has been discovered orbiting a rare comet that is situated in the main asteroid belt between Jupiter and Mars by the James Webb Space Telescope.

The James Webb Space Telescope (JWST)'s sighting marks yet another scientific milestone since it is the first time that gas—in this case, water vapor—has been seen to surround a comet in the main asteroid belt. This is significant because it demonstrates how ice from the main asteroid belt may have maintained water from the early solar system.

Michael Kelley, an astronomer at the University of Maryland, led this study. "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 the JWST can we say 'yes,' it's definitely water ice that is creating that effect," he said. We can now show that water ice from the early solar system may be retained in the asteroid belt thanks to the JWST's studies of Comet Read.

The finding of water vapor near Comet 238P/Read may greatly support the idea that comets brought water, a necessary component for life, to Earth. But comet research has also revealed a mystery: Comet 238P/Read is devoid of the carbon dioxide that scientists had anticipated seeing.

The team was more surprised by the apparent absence of carbon dioxide than by the detection of water vapor because carbon dioxide has been estimated to make up as much as 10% of the volatile material in comets that is readily cooked off by the sun in the past.

There are two reasons, according to the scientists, why carbon dioxide may be lacking from Comet 238P/Read. One possibility is that the comet once included carbon dioxide, which it has since lost as a result of heat from the sun.

Carbon dioxide vaporizes more readily than water ice and might percolate out over billions of years, according to Kelley. "Being in the asteroid belt for a long time could do it," Kelley said.

The possibility that this main belt comet evolved in a region of the solar system devoid of carbon dioxide is an alternate explanation for the absence of the compound.

Come here frequently? examining comets in the main asteroid belt?

The main asteroid belt is mostly home to stony things like asteroids, as its name indicates. However, it does sometimes host a comet-like object like Comet 238P/Read. These cometary entities may be recognized by the fact that they periodically get brighter while being encircled by a halo of material called a coma. They are also capable of growing a comet-like tail of material.

The coma and tail of a comet are made of solid frozen material, which sublimates into gas as the comet gets closer to the sun and warms up. All comets are thought to originate from either the Oort Cloud, which is thought to exist at the very edge of the solar system, or the Kuiper Belt, which extends past Neptune. These locations would provide the water ice in these bodies with protection from solar radiation, allowing it to be preserved, whereas a location closer to the sun near Mars might not.

Comet 238P/Read was one of three objects that contributed to establishing this family of comets that were discovered closer to Earth. The categorization of "main belt comet" is a very recent one. It wasn't apparent to astronomers if these ice worlds could likewise retain frozen water. This is the first concrete proof they have.

For the powerful space telescope, seeing the comet in such detail is quite an achievement, and it marks the first time that gas has been proven in such a main-belt comet.

"We're not sure how all this water got here," said Stefanie Milam, a research co-author and Webb Deputy Project Scientist for Planetary Science. "Our water-soaked world, teeming with life and unique in the universe as far as we know." We can better comprehend other planetary systems and determine if they may eventually include an Earth-like planet by understanding the history of water distribution in the solar system.

As of right now, the team's goal is to investigate beyond Comet 238P/Read to see if other uncommon comets have comparable components. This may include more observations using the JWST and other telescopes as well as in-situ missions that might actually gather cometary samples.

"With the JWST, we can finally see what's going on with them and draw some conclusions," co-author and Universities for Research in Astronomy (AURA) astronomer Heidi Hammel said of the small, dim asteroid belt objects. Do further main belt comets lack carbon dioxide as well? It will be intriguing to find out in any case.

The team's research is published in the journal Nature