Are we looking for Martian life in all the wrong places?
A new study suggests that we may be searching in the wrong place for signs of life on Mars, when we examine rocks excavated by meteor impacts for organic compounds. The research could allow space agencies to select landing sites for future missions that are more likely to yield samples containing the markers of ancient, or even present-day life.
When NASA searches for life on Mars,the search focuses on trying todetect tiny organic compounds, whichare most likely to be discovered encased in Martian rock. However,compounds that may have existed in rocks located on the surface ofMars would have been degraded by radiation from the Sun.
Consequently,rocks that had been buried deep beneath the surface, and recently (atleast in geological terms) brought to the surface by powerful meteorstrikes, are considered prime targets for rovers such as Curiosity asthey trundle along looking for signs of life.
The new study, undertaken by scientistsfrom Imperial College London and the University of Edinburgh, aimedto test whether biological compounds encased in Martian rock couldsurvive the extreme conditions created in the aftermath of a meteorstrike.
Theteam placed various organic compounds contained in an analogue ofMartian rock inside a piston cylinder device, and subjected them tothe temperature and pressure that would be exerted on the sample, ifit were to be ejected by the impact of a 10-m (33-ft) meteorimpact.
Following chemical analysis of thesamples, it was discovered that a meteor strike of this magnitudewould destroy certain types of organic compounds, but that otherswould survive. Traces of long chain hydrocarbon dominated-matter,which comprises algal and microbial life, were degraded to the extentthat they were undetectable. However, organic compounds known as aromatic hydrocarbons, which are found in plant life, survived the testsrelatively unscathed.
The knowledge that meteor impacts havethe capacity to erase the hallmarks of life that may once have beencontained in excavated rocks could aide space agencies when selectingthe landing sites for future missions to the Red Planet. Further research may identify certain families of impact sites best suited to discovering clues to life on Mars, and which ones to avoid.
Moving forward, the team intends totest a wider range of impact intensities in order to determine theextent to which the size of the meteor, the angle at which it struck,and the depth at which the sample is buried has an effect on anorganic compound's ability to survive an impact.
Source: Imperial College London