One of the many unanswered questions about the origin of life on Earth is: where did organic molecules – those containing carbon, from which life as we know it is derived – come from? Given the conditions needed to create complex organic compounds, it was assumed that they were made on Earth. But chemical analysis of meteorites suggested that such chemistry could happen beyond Earth, too.
Life-supporting material, it seems, can be manufactured in sterile interstellar space, rather than needing the more cosy environment of a planet. The suggestion is that this interstellar medium harbours complex organic molecules – perhaps in abundance. New results just published in the journal Science by Arnaud Belloche of the Max Planck Institute for Radioastronomy and his colleagues add a piece of evidence to support this.
To find this evidence, Belloche observed the biggest star factory of our Galaxy using the newly-built Atacama Large Millimeter Array (ALMA) situated in the inhospitable Atacama plateau of Chile. This telescope collects microwave light coming from space and splits it into a multitude of colours using a spectrometer. Just like a household radio tunes radio stations, ALMA can scan a range of microwave channels.
Molecules at much lower temperatures than Earth – perhaps hundreds of degrees below room temperature – naturally emit light at energies corresponding to the radio waves and microwaves. Just like a slinky spring would oscillate vigorously if you shake it at just the right frequency, molecules bend, oscillate and rotate at very specific energies. The more complicated the molecule, the more diversified is the microwave light that it sends back. The exact mixture of light produced depends on factors such as the temperature and the density of the molecules. Analysing a microwave spectrum is therefore not a simple feat as it requires to disentangle a mess over hundreds of channels.
