Life on Venus, Other Planets May Be Proven With New Insight on Molecules

To determine if life existed on other planets, we must spot more molecules in the planet's atmosphere than previously detected to discard biological-chemical processes.

Searching for life on other planets has gotten a big boost after scientists from the University of New South Wales (UNSW) in Sydney, Australia disclosed in a study (Computational Infrared Spectroscopy of 958 Phosphorus-Bearing Molecules) that spectral signatures of about 1000 atmospheric molecules that could have been involved in the creation or consumption of phosphine.

These scientists have long believed that phosphine, a compound that consists of one phosphorous atom encircled by three nitrogen atoms, may indicate proof of life when discovered in atmospheres of small rocky planets like the Earth, wherein the biological activity of bacteria produces it.

Heightened Prospect of Finding Life on Venus

When scientists in 2020 claimed they had found phosphine in the atmosphere of Venus, it heightened the prospect of discovering the first proof of life, a primitive, single-celled organism, on another planet.

But not all was sure about the claim as other scientists questioned if phosphine in Venus's atmosphere really did originate from biological activity or if the researchers actually found phosphine.

ALSO READ: Life on Venus Debunked: Planet Does Not Contain Traces of Phosphine Gas

Now, UNSW Sydney scientists made an important contribution to present or future searches of life on other planets, showing how an initial discovery of potential biosignature must be followed by searches for related molecules.

In a paper released on April 8, published in the Frontiers in Astronomy and Space Sciences journal, the researchers described how they used computer algorithms to create a database of infrared spectral barcodes for 958 molecular species that have phosphorous.

The scientists pointed out that they need not go to space to find life on other planets. They just need to train a telescope to a target planet.

Spectral Data Needed to Find Life on Other Planets

"To identify life on a planet, we need spectral data," said Dr. Laura McKemmish of the UNSW School of Chemistry who was quoted on the university website. "With the right spectral data, light from a planet can tell you what molecules are in the planet's atmosphere."

Phosphorous is the basic element for life, but even up to the present, astronomers could only search for one polyatomic phosphorous-containing molecule-phosphine.

Dr. McKimmish stated in the study that while phosphine is a very promising biosignature since it is only made in small concentrations by natural processes, they could not determine how it was created or consumed.

"(W)e can't answer the question of whether it is unusual chemistry or little green men who are producing phosphine on a planet," she said.

The study would thus gather a wide-reaching interdisciplinary group to find out how phosphorous behaves biologically, geologically, and chemically, and how these can be probed remotely through atmospheric molecules.

Scientists Probe Behavior of P-Molecules

They determined what phosphorous-carrying molecules, or what is termed as P-molecules, are most important in atmospheres, but the researchers said very little is known. Because of this, the team decided to investigate a number of P-molecules that are found in the gas phase that telescopes sensitive to infrared light could not detect.

New molecular species' barcode data are created one molecule at a time, which takes years to complete. But the UNSW Sydney research team utilized what McKimmish calls "high-throughput computational quantum chemistry" to foresee the spectra of 958 molecules in just two weeks.

While the new dataset may not yet have the accuracy to allow new detections, it can help in preventing misassignments by underscoring the potential for various molecular species that have similar spectral barcodes.

New Knowledge Can Help in Future Searches of Exoplanet Life

As the debate continues on the existence of phosphine in the atmosphere of Venus and possible signs of life on the planet, these recent additions to what we already know in what can be spotted using telescopes will be significant in finding possible signs of life on exoplanets, or planets outside our solar system.

"Our paper provides a novel scientific approach to following up the detection of potential biosignatures and has relevance to the study of astrochemistry within and outside the Solar System," said McKemmish.

"Further studies will rapidly improve the accuracy of the data and expand the range of molecules considered, paving the way for its use in future detections and identifications of molecules."