Scientists warn alien life searches could miss real evidence
A Nature Astronomy paper says missions need to study how biosignatures can be hidden, erased or misread before ruling out life beyond Earth.
By Tom Brennan · Health & Medicine Correspondent
3 min read
A new paper in Nature Astronomy argues that missions searching for extraterrestrial life could fail even when life is present. The risk matters because missed evidence could steer scientists away from promising worlds and allow future activity to damage environments that have not been properly checked, according to researchers led by Inge Loes ten Kate of Utrecht University and the University of Amsterdam.
The paper focuses on “false negatives” in astrobiology: cases in which life exists, or once existed, but observations do not reveal it. Utrecht University said scientists have often worried about false positives, where a signal appears biological but later proves to have a nonliving cause; ten Kate’s team says the reverse problem deserves more attention.
The researchers say several factors can hide signs of life. Biological traces may break down over time, signals may be too weak for instruments to detect, or current technology may be unsuited to the chemistry or setting where evidence exists.
Ten Kate said, according to Utrecht University, that shortcomings in recognizing life are not yet a major priority in research planning. The team argues that space missions should be designed with explicit tests for how biosignatures might be missed, using laboratory work, computer modelling and field studies on Earth.
The authors say mission planners should connect instruments and observation targets to clear questions about what life could look like in a given environment. They also say researchers should study landing zones carefully before sending spacecraft, because a poorly chosen or poorly understood site could lead to incomplete results.
Artificial intelligence could help, the paper says. Utrecht University said pattern-finding systems may detect relationships in data that people would not easily identify, although the researchers present AI as one tool rather than a substitute for mission design and scientific testing.
The paper lays out two major consequences of a false negative. Scientists could downgrade targets that are actually worth studying or withhold support for instruments capable of detecting unfamiliar forms of life, the researchers say. In a second scenario, policymakers could approve resource extraction on another world before scientists have ruled out the presence of life, risking irreversible damage, according to ten Kate’s team.
The researchers also point to chemistry as a major source of uncertainty. A planet could host active life while its atmospheric gases are removed, hidden or altered by other processes, making biological activity harder to see from afar.
The team says the hardest cases involve life that does not resemble organisms known on Earth. Ten Kate argues that scientists tend to search for familiar signals, so they need a clearer understanding of which forms of life are possible in specific environments and what traces those organisms might leave.
As an example of uncertainty, Utrecht University cited iron-bearing minerals found on Mars last year with oxidation patterns different from nearby material. Ten Kate said similar oxidation differences on Earth are seen only in connection with life, but the researchers do not claim the Martian minerals prove biology or represent a known missed detection.
Instead, the authors say the minerals show why more geochemical work is needed. Better knowledge of chemical reactions in alien settings, they argue, can help scientists reduce the chance of dismissing real evidence of life.
This story draws on original reporting from ScienceDaily.