The James Webb Space Telescope has detected water vapor around a rare comet in the asteroid belt between Mars and Jupiter.
A simulation of comet 238P/Read shows the sublimation process – the ice vaporizing as it approaches the Sun. Photo: NASA/ESA
This new discovery marks a significant scientific breakthrough for the James Webb Space Telescope, representing the first time that gas, in this case, water vapor, has been found around the comet 238P/Read, as reported by Space on May 16. This finding is crucial because it indicates that water in the early solar system may have been preserved in the form of ice within the main asteroid belt.
“Previously, we’ve seen objects in the main belt with characteristics of comets, but with this precise spectroscopic data from JWST, we can now be sure that it’s water ice creating that effect,” said astronomer Michael Kelley at the University of Maryland, the lead researcher. The new study has been published in the journal Nature.
The discovery of water vapor around 238P/Read, a comet located in the main asteroid belt of the solar system, helps reinforce the hypothesis that water, a crucial component for life, was transported from space to Earth by comets. However, the new research also brings forth another mystery: 238P/Read lacks CO2, as predicted by astronomers.
The absence of CO2 around the comet 238P/Read has surprised scientists because previous calculations suggested that this compound accounted for up to 10% of the volatile matter within comets. They propose two possible reasons for the lack of CO2. First, the comet may have contained CO2 during its formation but lost it due to solar heating. Second, 238P/Read may have formed in a region of the solar system without this compound.
The main asteroid belt of the solar system primarily consists of rocky objects like asteroids. However, on occasion, there are objects like the comet 238P/Read. The head and tail of a comet are formed from solid ice material, which directly transforms into gas as the comet approaches the Sun and heats up.
“Our water-rich world – teeming with life and unique in the human understanding of the universe – still holds many mysteries. We are not sure how this amount of water came to be here. Investigating the history of water distribution in the solar system will help us understand other planetary systems and assess whether they might contain a planet like Earth,” said Stefanie Milam, a co-author of the study.
Next, the research team aims to observe 238P/Read to determine whether similarly rare comets share the same composition. To achieve this, they may conduct more detailed observations using the James Webb Telescope and other telescopes while relying on sample-return missions from comets in the main asteroid belt.