NASA’s James Webb Space Telescope discovers coldest ices ever measured, crucial for life.
The James Webb Space Telescope (JWST or Webb) is NASA’s most powerful space observatory yet. It has peered deep into a dense molecular cloud and found a rich variety of pristine interstellar ice, including a range of molecules crucial for life, at temperatures of minus 440 degrees Fahrenheit (minus 263 degrees Celsius). This is the coldest ices ever measured.
The molecular cloud studied is called Chameleon I, located in the constellation of Chameleon, about 500 light-years away from Earth. It is one of the closest star-forming regions, with pockets alive with young stars. The chemical composition of these systems and any building blocks of life they may contain is determined by the ices embedded deep inside the molecular cloud.
Using Webb’s powerful instruments, including its near-infrared camera (NIRCam), astronomers have probed into Chameleon I’s dusty heart and discovered ices at their early stages of evolution. They used light from two background stars to light up the cloud in infrared wavelengths and study the chemical fingerprints that showed up as dips in the resulting spectral data. This data helped the team identify how much of which molecules are present in Chameleon I.
The team spotted an expected assortment of major life-supporting compounds such as water, carbon dioxide, carbon monoxide, methane and ammonia. The observations also revealed signs of carbonyl sulfide ice, which allowed the first measurements of how much sulfur is present in the molecular clouds. The researchers also detected the simplest complex organic molecule, methanol, which is thought to be an unambiguous indicator of complex, early chemical processes.
The fact that the team detected methanol suggests that the stars and planets that would eventually form in this cloud “will inherit molecules in a fairly advanced chemical state”. Methanol can be combined with other simpler ices to form amino acids, which are the building blocks of proteins. It is thought that these compounds can include glycine, one of the simplest amino acids.
Molecular clouds such as Chameleon I begin as diffuse regions of dust and gas. Ices containing important molecules necessary for life form on the surfaces of dust grains, and as the clouds accumulate into clumps of gas and proceed toward star formation, these ices grow in size while remaining layered on the dust grains. Dust grains become crucial catalysts for simple organic elements to evolve into complex molecules that can eventually form the building blocks of life. With Webb’s data, astronomers already know that a bunch of discovered elements in Chameleon I are much less abundant than scientists expected.
The research published in the journal Nature Astronomy has opened a new window on the formation pathways for the simple and complex molecules that are needed to make the building blocks of life. In the coming months, the team plans to use Webb’s data to calculate the sizes of the dust grains and shapes of ices. This will help us to better understand how habitable exoplanets are built.