NASA's Webb Telescope Discovers Water In A Rare Comet And Scientists Are Stunned

hero nasa webb comet 238p
Scientists took NASA's Webb telescope on a treasure hunt in the asteroid belt, and ended up finding as many questions as answers. Solar system scientists identified water vapor on Comet Read, an important clue in solving how water came about on Earth, but it was missing another key component: carbon dioxide.

NASA's James Webb Space Telescope (JWST) has been providing scientists and astronomers with astounding images and breakthroughs into the mysteries of our solar system since its launch into deep space. However, with new answers often come new questions. Such was the case when solar system scientists delved deeper into Comet 238P/Read with JWST.

Comet Read is located in the main asteroid belt, but every once in a while emits a halo, or coma. It was one of the original three, in fact, to be used to establish the category of main belt comets.

nasa webb comet 238p nircam image
Comet 238P/Read image captured by JWST's NIRCam.

Before being reclassified, the comets were presumed to reside in the Kuiper Belt and Oort Cloud, located beyond the orbit of Neptune. This vast distance from the Sun allowed them to maintain their ice. As comets approach the Sun, they give off a distinctive coma and streaming tail, allowing scientists and astronomers to differentiate them from asteroids. Until now, scientists could only speculate that water ice could be preserved in the asteroid belt within the orbit of Jupiter, according to a recent NASA blog post.

"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 Michael Kelley of the University of Maryland, and lead author of the study published in the journal Nature. He added, "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."

comet 238P read emission spectrum
Comet 238P/Read Emission Spectrum.

While the new discovery delighted scientists, it also brought about another question of why it was missing carbon dioxide. Scientists have proposed two possible reasons for the missing carbon dioxide. One is that Comet Read had carbon dioxide when it was formed, but lost it due to the warmer temperatures over time. The second thought being Comet Read may have formed in a "particularly warm pocket of the solar system, where no carbon dioxide was available."

"Being in the asteroid belt for a long time could do it - carbon dioxide vaporizes more easily than water ice and could percolate out over billions of years," Kelley remarked.

Heidi Hammel of the Association of Universities for Research in Astronomy (AURA), and lead for Webb's Guaranteed Time Observations, hopes they can eventually answer the question, "Do other main belt comets also lack carbon dioxide?" She added, "Either way, it will be exciting to find out."

The new find is just the beginning. Scientists will now take all the data collected from Comet Read and see how it compares to other main belt comets. Objects in the asteroid belt are very small and faint, but with Webb, scientists can finally see what is happening with them and come to some conclusions.
Tags:  space, NASA, Comet, asteroid, jwst, webb