James Webb Space Telescope confirms water vapor on asteroid belt comet

By Greg Hahne
Published: Monday, May 15, 2023 - 3:21pm

IMAGE: NASA, ESA, CSA, Mike Kelley (UMD) IMAGE PROCESSING: Henry Hsieh (PSI), Alyssa Pagan (STScI)
This image of Comet 238P/Read was captured by the NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope on September 8, 2022. It displays the hazy halo, called the coma, and tail that are characteristic of comets.

Researchers have confirmed the presence of water vapor around a rare comet in the asteroid belt between the planets Mars and Jupiter. 

The discovery from the James Webb Space Telescope shows water ice from the early solar system can be preserved in the region.

Comet 238P/Read is unlike most other comets in that it doesn’t originate from beyond the orbit of the farthest planet in our solar system, Neptune.

This illustration of Comet 238P/Read shows the main belt comet sublimating—its water ice vaporizing as its orbit approaches the Sun.

While scientists were able to speculate that water ice could be preserved in the asteroid belt, these measurements are the first definitive proof.

No Carbon Dioxide was detected, which is unusual for comets. It could have been lost due to the relatively warmer temperatures in the asteroid belt as opposed to the Kuiper Belt. 

Another explanation could be that Comet Read formed in a warmer part of the solar system where no CO2 was available. 

The researchers say the discovery will help them understand how water is dispersed in solar system formation, and if other systems could host Earth-like planets.

The University of Arizona helped build The Near-Infrared Camera on James Webb Space Telescope, which detected the vapor. The study was published in the journal Nature.

This graphic presentation of spectral data highlights a key similarity and difference between observations of Comet 238P/Read by the NIRSpec (Near-Infrared Spectrograph) instrument on NASA’s James Webb Space Telescope in 2022.