Signs of extraterrestrial life may have been ignored by researchers for decades, say a team of astrobiologists, warning of the potential pitfalls of false negatives in the search for ET.
In a recent paper in Nature Astronomy, researchers at Utrecht University argue that poorly designed tests for life elsewhere in the cosmos are a great waste of science funding.
Astrobiology is a specialized field dedicated to discovering the origins of life and detecting life on other planets, yet it remains ambiguous in its conclusions.
False Extraterrestrial Signals
“We should be aware of these false-negative results,” says lead author Inge Loes ten Kate, professor in astrobiology at Utrecht University and the University of Amsterdam. “It means there are shortcomings in recognizing the existence of life. These shortcomings are not yet high on the research agenda.”
The researchers argue that while false positives are well considered in the astrobiology field, potential false negatives, in which existing extraterrestrial life may not appear present, are largely overlooked, to the detriment of the field.
The researchers identified three primary reasons why the search for extraterrestrial life may lead to false negatives. The first is that ancient life on distant worlds may not have been preserved, leaving no remnants left to uncover, even if something once lived. The second two are related; the signals of life on some world may be extremely faint, and our current level of technology may not be advanced enough to detect them.
“There are several life-detection instrument concepts in development for Mars and even for icy moons that so far have not yet been selected for a mission that I would love to see fly,” Professor ten Kate told The Debrief. “Even though we will always run the risk that those instruments will not find life, whether it is there or not.”
Targeting the Extraterrestrial
“We therefore advocate for the development of a targeted research strategy that systematically addresses these risks, in which we must combine laboratory experiments with modeling research and fieldwork,” ten Kate explained. “Space missions and instruments are designed to detect potential signs of life, but the risk of overlooking something is not taken into account.”
“The search for signs of life should go hand in hand with better-defined questions and testable hypotheses to justify specific measurement or observation targets,” ten Kate continued.
The researchers favor using artificial intelligence tools to recognize patterns in extraterritorial data, which might identify elements missed by the human eye, and then apply them to future observations. They also note that failing to identify evidence of life may lead to long-term mistakes, such as dismissing objectives and instruments too hastily. They compare this to a person looking at a rock from above, unaware that bugs live beneath it, and, down the line, resource extraction could destroy the rock and the bugs with it.
Possibilities for Life Elsewhere
The Utrecht researchers say that much work remains to be done theorizing what sort of life may exist in the cosmos, what types of environments that life could persist in, and what external signals it should produce. A recent example the team is interested in is an unusual oxidation noted in a Martian rock last year, which bore intriguing similarities to finds on Earth, the only planet known to harbor life.
“On Earth, we only see such differing oxidation as a result of the presence of life,” ten Kate said. “But does that necessarily mean that we are dealing with life in an extraterrestrial context?”
The team says that to better understand this promising Martian discovery, astrobiologists will have to refine their understanding of geochemistry in an extraterrestrial environment before sending a crewed mission to investigate the Red Planet.
If there were life, and it were hidden, ten Kate argues, “there would be a high likelihood of the crew unknowingly killing that Martian life.”
“Although this hypothetical Martian life might ‘only’ be unicellular, like bacteria, in my opinion, we do not have the right to kill it, not even accidentally,” ten Kate concluded. “This is, of course, an ethical dilemma, and I know not everybody would agree.”
The paper, “False Negatives in the Search for Extraterrestrial Life,” appeared in Nature Astronomy on May 21, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.