The Way The World Searches for Extraterrestrial Life May Be Holding Back Discoveries

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The Way The World Searches for Extraterrestrial Life May Be Holding Back Discoveries

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by Jeffrey Kluger

Editor at Large

Jun 2, 2026 10:56 AM CUT

The search for life in space continues.

The search for life in space continues.Loop Images/Universal Images Group—Getty Images

by Jeffrey Kluger

Editor at Large

Jun 2, 2026 10:56 AM CUT

One of science’s greatest false alarms occurred on Aug. 7, 1996, when NASA announced that scientists had discovered “strong circumstantial evidence that life once existed on Mars.” That evidence was a scattering of tiny tube-like structures that looked for all the world like fossilized bacteria inside a small meteorite from Mars. Television networks interrupted regular broadcasts to cover the news, and President Clinton convened a Rose Garden press conference to comment on it.

The rock, Clinton said, “speaks to us across … billions of years and millions of miles. It speaks of the possibility of life. If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered.”

Alas, it was not confirmed. Further experiments showed that the same tiny formations can be the result of geologic—completely abiotic—processes. With that, exobiologists avoided one of the things they fear the most: the false positive—seeing the existence of life where none exists. But what about the false negative—failing to see, or even rejecting plain evidence that indicates something living might be in the air, the soil, the matrix of a rock?

That’s the question raised by an intriguing new paper in the journal Nature Astronomy, which argues that our life-detection methods are sometimes flawed, our biases are sometimes roadblocks, and we too often fail to turn over a rock—both literally and metaphorically—to see if something’s living underneath it. That could mean that data gathered suggesting life during multi-billion dollar missions sent specifically to hunt for it—in the deserts of Mars, in the oceans of Saturn’s moon Enceladus and Jupiter’s Europa, on the surface of distant exoplanets—could be overlooked or dismissed before getting a fair and robust scientific vetting. We’re visiting other worlds to look for extant life but setting ourselves up for failure when we get there.

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“We should be aware of these false negative results,” said Inge Loes ten Kate, professor of astrobiology and planetary science at Utrecht University and the University of Amsterdam and the lead author of the paper, in a statement that accompanied its release. “It means there are shortcomings in recognizing the existence of life. These shortcomings are not high on the research agenda.”

Read more: Is Colonizing Space the Next Stage of Human Evolution?

One of the biggest causes of false negatives in the search for life, the authors argue, is that the consequences of being wrong do not carry existential risks. In epidemiology, a false negative may allow a lurking virus to range free and take lives; in environmental science it can lead a coastal community to remain unprepared for an approaching typhoon. In exobiology, it leads only to the status quo—living in a world in which life has not yet been discovered anywhere else in the universe.

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“Because false negatives in biology do not present…acute risks,” the authors write, “they receive much less attention. Nevertheless, they are still missed opportunities to detect life.”

One of the most-cited examples of the power of no in exobiological experiments occurred during the missions of the Viking 1 and 2 spacecraft, which landed on Mars on July 20, 1976 and Sept. 3, 1976 respectively. During the course of the missions, the twin spacecraft scooped up samples of Martian soil and treated them with nutrients, water, and heat, to see if the samples would show signs of biology, such as releasing radioactively tagged carbon gasses, or absorbing carbon monoxide and carbon dioxide in the soil. In at least two of the studies such possible signs of Martian metabolism were detected, but again, scientists dismissed the results since abiotic processes could account for the reactions too.

“There has never been a mission that looked further into that,” said Ten Kate in a conversation with TIME. “I would love to see a mission going into that direction again.”

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It’s also possible that our detection methods are imperfect, with gaseous byproducts of biology getting hidden or obscured by background atmospheric gasses. Using a gas chromatograph mass spectrometer, for example, the spectral biosignatures of carbon dioxide and methane may overlap, leading to the gasses being confused with each other and signs of life being dismissed or lost.

“We really [have to] look at an environment from all different viewpoints,” says Ten Kate. “We...