Webb telescope hunts life’s icy chemical origins

The new super space telescope James Webb has ventured into the freezer.

It’s been probing some of the darkest, coldest regions in space for clues about the chemistry that goes into making planets, and perhaps even life.

This newly released image shows a segment of the Chameleon I molecular cloud, some 630 light years from Earth.

It’s here, at temperatures down to about -260C, that Webb is detecting types of ice grains not previously observed.

Eventually, such clouds will collapse to form stars and, around them, planets. And the chemistry being spied by Webb will be incorporated.

You can see this in action at top-left of the image.

The orange “hourglass” feature is a protostar – a star in the mode of formation, pulling material from the cloud on to itself.

The orange stars underneath are more mature and bright enough that they generate the distinctive six spikes that have now become familiar in Webb pictures and are artefacts of the telescope’s segmented mirror design.

But to detect the ices, Webb is ignoring all of these stars to the side and looking to stars behind the blue wispy Chameleon I.

As the light from these objects shines through the cloud, some of it is absorbed by the ices to betray their composition.

“It’s sort of like a shadow puppet,” explained Dr Melissa McClure from Leiden University, Netherlands.

“You have some kind of shape that makes the shadow. The ices make an absorption at particular wavelengths of light and you add all those up into a spectrum to see what chemical species you have,” she told BBC News.

This is work done principally on Webb by its near-infrared and mid-infrared spectrometers (NIRSpec and MIRI), and to a degree by its near-infrared camera (NIRCam) which produced the beautiful image at the top of the page.

Webb graphic

In addition to simple ices such as water, carbon dioxide, carbon monoxide, ammonia, and methane, Webb sees several other compounds, including carbonyl sulphide and the more complex organic (carbon-containing) ice methanol. And there are hints too of chemical species with multiple carbon atoms, such as acetone, ethanol, and acetaldehyde.

It is much easier for astronomers to see these targets in space when they’re gases. Webb is breaking new ground by seeing them in the solid state, as ices.

It will aid scientists as they try to understand where the chemistry for life came from and how it built the sophistication it now displays on our planet.

“Even though we detected more ice than ever previously reported, the amount of ‘light elements’ (carbon, hydrogen, oxygen, nitrogen, and sulphur) present within them is still less than we expect,” explained Dr Helen Fraser, from the Open University, UK.

“For astronomers that is exciting, because it means there is something we don’t yet fully understand about interstellar chemistry – and that challenges us not just to keep observing, but also to experiment in the laboratory.”

Image caption,

Shadow puppets: Webb analysed the light shining through the cloud from two stars

Close in to a newly forming star, the icy dust grains like those in Chameleon I would mostly evaporate, but further out they could survive and clump together to make comets.

“These comets would then have a large chemical inventory in them and they would likely bombard planets, certainly early in their history,” said Prof Martin McCoustra from Heriot-Watt University, UK.

“In the case of Earth, the belief today is that the load delivered by comets was part of that organic soup from which life evolved,” he told BBC News.

The telescope is a joint endeavour of the US, European and Canadian space agencies.

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