What if alien life is out there, but we're just really bad at spotting it? That's the premise of a new paper in Nature Astronomy, where researchers argue that the search for extraterrestrial life is plagued by 'false negatives' - cases where life exists but we fail to detect it. Lead author Inge Loes ten Kate, a professor of astrobiology at Utrecht University and the University of Amsterdam, warns: 'We are currently investing a great deal of money in missions that might need to be designed differently.'

The problem, the researchers say, is that we're so worried about false positives (thinking we found aliens when we didn't) that we've neglected the opposite risk. False negatives can happen when traces of life don't survive, signals are too faint, or our tech just can't pick them up. Ten Kate argues this deserves more attention: 'We advocate for the development of a targeted research strategy that systematically addresses these risks.'

The team suggests AI could help, since machine learning might spot patterns humans miss. 'Because then you might well uncover things that we would never be able to see on our own,' Ten Kate notes. Missing life could have consequences beyond scientific embarrassment: policymakers might approve mining on other worlds, inadvertently destroying alien organisms. 'There is a danger that policymakers will approve the premature exploitation of raw materials on planets, with the risk of irreversibly destroying unnoticed life,' she says.

One challenge is that we tend to look for life as we know it. 'But how do you investigate things you can't find?' Ten Kate asks. 'We tend to look for things we already know.' The researchers point to iron-bearing minerals on Mars that show oxidation unlike anything nearby - on Earth, such oxidation is a sign of life. But whether it indicates Martian microbes remains unknown. 'We simply do not yet understand what is going on here,' Ten Kate says. 'But if we do not investigate this further, it could indeed result in a false negative.'

The takeaway? Before we send a rover or a mining crew anywhere, we'd better study the landing zone thoroughly. 'So make sure you've studied the situation in the landing zone meticulously in advance,' Ten Kate advises.