The James Webb Space Telescope’s newest discovery is a story of two detections.
Solar system scientists took NASA’s James Webb Space Telescope on a treasure hunt in the asteroid belt, and what they didn’t discover turned out to be as vital as what they did. If a spectrum of doable chemical compounds serves as a map of what to look for, X marked the spot of water vapor on Comet Read – a long-sought clue in the bigger thriller of how Earth’s liquid water, and consequently life, first got here to be. However, carbon dioxide was lacking from the map, although it’s present in all different comets. So in addition to persevering with to pursue the historical past of historical water in the photo voltaic system, scientists have an surprising new quest on their arms, and will probably be searching for solutions in our cosmic yard.
NASA’s Webb Finds Water, and a New Mystery, in Rare Main Belt Comet
NASA’s James Webb Space Telescope has enabled one other long-sought scientific breakthrough, this time for photo voltaic system scientists finding out the origins of Earth’s abundant water. Using Webb’s NIRSpec (Near-Infrared Spectrograph) instrument, astronomers have confirmed fuel – particularly water vapor – round a comet in the principle asteroid belt for the primary time, indicating that water ice from the primordial photo voltaic system may be preserved in that area. However, the profitable detection of water comes with a brand new puzzle: in contrast to different comets, Comet 238P/Read had no detectable carbon dioxide.
“Our water-soaked world, teeming with life and unique in the universe as far as we know, is something of a mystery – we’re not sure how all this water got here,” stated Stefanie Milam, Webb deputy mission scientist for planetary science and a co-author on the research reporting the discovering. “Understanding the history of water distribution in the solar system will help us to understand other planetary systems, and if they could be on their way to hosting an Earth-like planet,” she added.
Comet Read is a major belt comet – an object that resides in the principle asteroid belt however which periodically shows a halo, or coma, and tail like a comet. Main belt comets themselves are a reasonably new classification, and Comet Read was one of many authentic three comets used to establish the category. Before that, comets had been understood to reside in the Kuiper Belt and Oort Cloud, past the orbit of Neptune, the place their ices may very well be preserved farther from the Sun. Frozen materials that vaporizes as they method the Sun is what offers comets their distinctive coma and streaming tail, differentiating them from asteroids. Scientists have lengthy speculated that water ice may very well be preserved in the hotter asteroid belt, contained in the orbit of Jupiter, however definitive proof was elusive – till Webb.
“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,” defined astronomer Michael Kelley of the University of Maryland, lead creator of the research.
“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,” Kelley stated.
The lacking carbon dioxide was a much bigger shock. Typically, carbon dioxide makes up about 10 % of the risky materials in a comet that may be simply vaporized by the Sun’s warmth. The science staff presents two doable explanations for the dearth of carbon dioxide. One risk is that Comet Read had carbon dioxide when it fashioned however has misplaced that due to heat temperatures.
“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 stated. Alternatively, he stated, Comet Read could have fashioned in a very warm pocket of the photo voltaic system, the place no carbon dioxide was obtainable.
The subsequent step is taking the analysis past Comet Read to see how different major belt comets evaluate, says astronomer Heidi Hammel of the Association of Universities for Research in Astronomy (AURA), lead for Webb’s Guaranteed Time Observations for photo voltaic system objects and co-author of the research. “These objects in the asteroid belt are small and faint, and with Webb we can finally see what is going on with them and draw some conclusions. Do other main belt comets also lack carbon dioxide? Either way, it will be exciting to find out,” Hammel stated.
Co-author Milam imagines the chances of bringing the analysis even nearer to house. “Now that Webb has confirmed there is water preserved as close as the asteroid belt, it would be fascinating to follow up on this discovery with a sample collection mission, and learn what else the main belt comets can tell us.”
The research is revealed in the journal Nature.
Reference: “Spectroscopic identification of water emission from a main-belt comet” by Michael S. P. Kelley, Henry H. Hsieh, Dennis Bodewits, Mohammad Saki, Geronimo L. Villanueva, Stefanie N. Milam and Heidi B. Hammel, 15 May 2023, Nature.