Scientists have developed a simple test in the search for alien life, they claim.
The breakthrough helps the search for the “holy grail” of astrobiology: a reliable test that will determine whether there is or was life on other planets.
The discovery uses artificial intelligence to determine with 90 per cent accuracy whether a sample is biological or not.
And it could be used on existing samples, researchers say. That might mean, for instance, that we already have gathered the samples that could tell us whether there is life on Mars.
Scientists hope that their test could be used on samples already collected by the Mars Curiosity rover’s Sample Analysis at Mars (SAM) instrument. The rover has an instrument on board to analyse those samples, and that data could be used in the test.
The findings could also help tell us more about our own planet, revealing the history of mysterious and ancient rocks found on Earth.
“The search for extraterrestrial life remains one of the most tantalizing endeavors in modern science,” said lead author Jim Cleaves of the Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC.
“The implications of this new research are many, but there are three big takeaways: First, at some deep level, biochemistry differs from abiotic organic chemistry; second, we can look at Mars and ancient Earth samples to tell if they were once alive; and third, it is likely this new method could distinguish alternative biospheres from those of Earth, with significant implications for future astrobiology missions.”
The technique does not look for specific molecules or compounds that could be indicative of life, as much previous work has done. Instead, it looks for small differences in the molecular patterns of samples using different kinds of analysis.
It was built by giving an artificial intelligent system data about 134 known samples, with information about whether they are biotic or abiotic. To test it, it was then given new samples – including those from living things, remnants of ancient life and other abiotic samples that did not point to life, such as pure chemicals – and identified them with 90 per cent accuracy.
The system also started predicting another kind of sample type, dividing the biotic ones into “living” and “fossils”. That means it could tell the difference between a freshly harvested leaf and something else that died long ago, for instance.
Scientists hope that with time it could eventually be able to distinguish other hints in the data, such as signs of photosynthesis or cells that have a nucleus.
Previous research has struggled because organic molecules tend t degrade over time. But the new method works even when the samples have decayed and changed significantly, the researchers behind it said.
“This routine analytical method has the potential to revolutionize the search for extraterrestrial life and deepen our understanding of both the origin and chemistry of the earliest life on Earth,” said Robert Hazen, of the Carnegie Institution for Science, one of the leaders of the research. “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 findings could also help solve mysteries on life. Many ancient rocks on Earth are at the middle of argument over whether they hold the oldest fossil microbes in life, while others say they do not have any life – and researchers are already feeding data about those rocks from Australia, Canada and elsewhere into the tool.
“We’re applying our methods right now to address these long-standing questions about the biogenicity of the organic material in these rocks,” Hazen says.
A paper describing the work, ‘A robust, agnostic biosignature based on machine learning’, is published in the Proceedings of the National Academy of Sciences.