JWST detected water in the asteroid belt for the first time
And a new mystery…
Water is not exclusive to Earth. It is abundant in the solar system and we have spotted it on planets and moons, and comets are full of it. As they approach the Sun and receive its heat, the ice turns into gas and disappears into the vacuum of space.
So while water in the form of ice has already been detected in the Main Belt of asteroids which lies between Mars and Jupiter, its water vapor has not been detected until today, being a mystery. The James Webb Space Telescope is now coming to solve this mystery .
JWST detected gaseous water ejected from comet 238P/Read, revealing that the water it contained dates back to the formation of the Solar System. The discovery also confirms that objects from the Main Belt asteroid may have helped bring water to Earth while the Solar System was still young.
Since the discovery of comets in the Main Belt, we have collected a fair amount of evidence that their activity comes from sublimation, but until now it has all been indirect. The new JWST results are the first direct evidence of sublimation in the form of water gasification by a Main Belt comet.
Most objects in the Main Belt are asteroids, which are inert pieces of rock. But comets are defined by their activity, which is primarily influenced by their icy composition. They usually move around the Sun in large elliptical orbits and as they approach the Sun, the ice inside them sublimates creating a cloudy atmosphere around them and long tails. We haven’t detected many Main Belt comets because we thought they were too close to the Sun and scientists weren’t sure if they had enough icy material to produce sublimation.
Using JWST’s infrared spectrograph, researchers captured the blurry image of Comet Read, revealing that it’s not just sublimating gases, it’s sublimating water. However, the discovery also created another mystery. Typically, comets also have 10-20% carbon dioxide from their volatile compounds, but Read did not detect this.
This can have two possible explanations. One is that the comet had carbon dioxide but lost all of it, since it sublimes more easily than water in the form of ice. The other explanation is that the part of the solar system where Comet Read formed was too hot for carbon dioxide to exist, so it never did.
The presence of water in the Main Belt is important because objects from this belt have been suggested as the possible source of Earth’s water in the early Solar System, and today’s Main Belt comets may offer an opportunity to confirm this hypothesis. We will only know this if they actually contain water in the form of ice. Confirmation of sublimation by at least one Main Belt comet confirms that learning the source of Earth’s water from comets in this belt is a viable possibility.
The research was published in Nature .
