So when an international team of scientists last year claimed to have detected phosphine in the atmosphere of Venus, it raised the tantalising prospect of the first evidence of life on another planet — albeit the primitive, single-celled variety. But not everyone was convinced, with some scientists questioning whether the phosphine in Venus’s atmosphere was really produced by biological activity, or whether phosphine was detected at all.
Now an international team, led by UNSW Sydney scientists, has made a key contribution to this and any future searches for life on other planets by demonstrating how an initial detection of a potential biosignature must be followed by searches for related molecules. “To identify life on a planet, we need spectral data,” she says.
As UNSW School of Chemistry’s Dr Laura McKemmish explains, when scientists look for evidence of life on other planets, they don’t need to go into space, they can simply point a telescope at the planet in question. “With the right spectral data, light from a planet can tell you what molecules are in the planet’s atmosphere.”
LOOK AND LEARN In a paper published today in the journal Frontiers in Astronomy and Space Sciences, they described how the team used computer algorithms to produce a database of approximate infrared spectral barcodes for 958 molecular species containing phosphorus.
“Phosphine is a very promising biosignature because it is only produced in tiny concentrations by natural processes. However, if we can’t trace how it is produced or consumed, we can’t answer the question of whether it is unusual chemistry or little green men who are producing phosphine on a planet,” says Dr McKemmish. Phosphorus is an essential element for life, yet up until now, she says, astronomers could only look for one polyatomic phosphorus-containing molecule, phosphine.
Dr McKemmish continues: “At the start, we looked for which phosphorus-bearing molecules — what we called P-molecules — are most important in atmospheres but it turns out very little is known. So we decided to look at a large number of P-molecules that could be found in the gas-phase which would otherwise go undetected by telescopes sensitive to infrared light.” To provide insight, Dr McKemmish brought together a large interdisciplinary team to understand how phosphorus behaves chemically, biologically and geologically and ask how this can be investigated remotely through atmospheric molecules alone. “What was great about this study is that it brought together scientists from disparate fields — chemistry, biology, geology — to address these fundamental questions around the search for life elsewhere that one field alone could not answer,” says astrobiologist and co-author on the study, Associate Professor Brendan Burns.
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