Signs of life from under Mars’ surface may not survive in rocks excavated by some meteorite impacts, suggest scientists, adding that life may be present deep underground.
Researchers analysing samples from Mars’ surface have not yet conclusively detected organic compounds that are indigenous to Mars and which would be indicators of past or present life.
Scientists now suggest that a good place to find these organic compounds would be deep underground — from rocks that have been blasted to the surface by meteor impacts.
This is because such rocks have been sheltered from the Sun’s harmful radiation and from chemical processes on the surface that would degrade organic remains.
“We’ve literally only scratched the surface of Mars in our search for life, but so far the results have been inconclusive,” said Professor Mark Sephton, co-author of the research from Imperial College, London.
Rocks excavated through meteorite impacts provide scientists with another unique opportunity to explore for signs of life, without having to resort to complicated drilling missions.
“Our study is showing us is that we may need to be nuanced in our approach to the rocks we choose to analyse,” Sephton added.
The team from Imperial College London and University of Edinburgh has replicated meteorite blasts in the lab.
The aim was to see if organic compounds encased in rock could survive the extreme conditions associated with them being blasted to the surface of Mars by meteorites.
The study, published today in Scientific Reports, suggests that rocks excavated through meteorite impacts may incorrectly suggest a lifeless early Mars even if indicators of life were originally present.
Meteorites often contain organic matter not created by life, which have some similarities in their organic chemistry to land plants. The team infer that they also should also be resistant to blast impacts.
The study could help future missions to Mars determine the best locations and types of blast excavated rocks to examine to find signs of life.
"The study is helping us to see that when organic matter is observed on Mars, no matter where, it must be considered whether the sample could have been affected by the pressures associated with blast impacts,” noted Dr Wren Montgomery from the department of earth science and engineering.
The next steps will see the team investigating a broader range of pressures and temperatures.
This could help future Mars missions further refine the types and locations of rocks that they can analyse for signs of past or present life.