Scientists develop method of identifying life on other planets

Scientists have developed a way of identifying life on other planets.

They say the new method, which uses artificial intelligence (AI), can determine with 90% accuracy if a sample is biological or non-biological.

According to the researchers, the simple and reliable test could revolutionise the search for life on other planets.

Lead researcher Professor Robert Hazen, of the Carnegie Institution’s Geophysical Laboratory and George Mason University in the US, said: “This is a significant advance in our abilities to recognise biochemical signs of life on other worlds.

“It opens the way to using smart sensors on unmanned spaceships to search for signs of life”.

Dr Hazen added: “This routine analytical method has the potential to revolutionise the search for extra-terrestrial life and deepen our understanding of both the origin and chemistry of the earliest life on Earth.

“It opens the way to using smart sensors on robotic spacecraft, landers and rovers to search for signs of life before the samples return to Earth.”

The scientists say that most immediately, the new test could reveal the history of mysterious, ancient rocks on Earth, and possibly that of samples already collected by the Mars Curiosity rover’s Sample Analysis at Mars (SAM) instrument.

Lead author Jim Cleaves of the Earth and Planets Laboratory, Carnegie Institution for Science in Washington, DC, said: “We’ll need to tweak our method to match SAM’s protocols, but it’s possible that we already have data in hand to determine if there are molecules on Mars from an organic Martian biosphere.

“The search for extra-terrestrial life remains one of the most tantalising endeavours in modern science.”

The method does not rely simply on identifying a specific molecule or group of compounds in a sample.

Instead, the researchers demonstrated that AI can differentiate between living and non-living samples, by detecting subtle differences within a sample’s molecular patterns.

The scientists used Nasa flight-tested methods to analyse 134 varied carbon-rich samples from living cells, age-degraded samples, geologically processed fossil fuels, carbon-rich meteorites, and laboratory-made organic compounds and mixtures.

Fifty-nine of these were of biological origin (biotic), such as a grain of rice, a human hair, crude oil, and 75 were of non-biological origin (abiotic), such as lab-made compounds like amino acids, or samples from carbon-rich meteorites.

Using a suite of machine-learning (AI) methods, the researchers created a model that can predict the abiotic or biotic nature of the sample with around 90% accuracy.

Surprisingly, in spite of significant decay and alteration, the new method detected signs of biology preserved in some instances over hundreds of millions of years.

Dr Hazen said: “These results mean that we may be able to find a lifeform from another planet, another biosphere, even if it is very different from the life we know on Earth.

“And, if we do find signs of life elsewhere, we can tell if life on Earth and other planets derived from a common or different origin.”

He added: “Put another way, the method should be able to detect alien biochemistries, as well as Earth life.

“That is a big deal because it’s relatively easy to spot the molecular biomarkers of Earth life, but we cannot assume that alien life will use DNA, amino acids, etc.

“Our method looks for patterns in molecular distributions that arise from life’s demand for ‘functional’ molecules.”

The findings are published in the Proceedings of the National Academy of Sciences.