Bharat SainiLast Updated on February 27, 2017 by Bharat Saini
Sagittarius B2 is a molecular cloud about 100 light years wide near the centre of our galaxy, the Milky Way. The cloud is particularly curious because it contains a relatively high concentration of organic molecules. It’s a galactic chemistry lab of sorts, is one of the stinkiest places in the Milky Way.
Among the noxious fumes are chemicals like ethylene glycol, acetic acid, plenty of ethanol and hydrogen sulfide. Scientists have also detected ethyl formate, which has a fruity, lemony scent.
These chemicals are all vanishingly rare compared with hydrogen molecules.
In clouds like Sagittarius B2 – and also in the cloud that long ago birthed our solar system – icy coatings can condense around tiny grains of dust. When radiation hits the ice-covered grains, it produces free radicals, driving chemical reactions that can build larger molecules.
In the cloud Sagittarius B2 a team of scientists have recently found the first chiral interstellar molecule – a structure, common in biology that can come in different mirror-image versions like our right and left hands. The findings are subsequent to what in 2008, a team led by Arnaud Belloche at the Max Planck Institute in Bonn, Germany, found amino acetonitrile, a close relative of glycine, the simplest amino acid. In 2014, the same group announced the first detection of an interstellar molecule with a branching carbon backbone. That suggests complex amino acids might also be able to grow in space.
Belloche is currently observing the cloud again with the Atacama Large Millimeter Array in Chile and says that they have detected nearly 200 molecules in the interstellar medium and it’s amazing to see how complex the chemistry in space can go. In our solar system, comets seem to have many of the same molecules, even amino acids. So do meteorites. It’s possible that these substances, delivered through crash landings on early Earth, provided some of the ingredients life needed to start. But before that – long before – they may have been grown in the thin, icy rind of irradiated dust grains, drifting in space, bathed in the light of newborn stars.
For more than 40 years, that’s made Sagittarius B2 a sort of Valley of the Kings or Burgess Shale for cosmic chemists: a place to return again and again to make discoveries. In doing so, we might gain some insight into the origin of life.
It’s even possible that clouds like Sagittarius B2 could represent “cradles of life” in the galaxy, chemical factories that churn out some of life’s foundational building blocks. If true, it unfortunately means that life probably didn’t start with a biological equivalent of that “new car” smell.
