Alien life detection: researchers in Japan have built a method that can tell apart the two mirror-image forms of amino acids one molecule at a time. Because life prefers one form, the technique could one day lead to compact instruments for hunting biosignatures in space.
The challenge of finding life beyond Earth
Searching for signs of life in our solar system and further afield means looking for biosignatures, chemical traces that point to biology. The difficulty is building instruments that are both sensitive and small enough to fly on a space mission. A team at the University of Osaka now reports an electrical approach that could help close that gap.
Mirror-image molecules as a clue
Amino acids, the building blocks of proteins, come in two mirror-image versions, called L- and D-forms. They share the same chemical formula, yet living things almost exclusively use the L-form (while sugars in life appear in the D-form). Non-living chemistry, by contrast, produces both forms in roughly equal amounts. So a strong imbalance between L and D is a potential fingerprint of life, which makes amino acids a favorite target in astrobiology.
Traditional methods measure large groups of molecules at once and come with practical difficulties. An electrical alternative has been proposed as simpler, less sensitive to vibration and free of chemical reagents.
Counting molecules through a nanoscale gap
The Osaka team let molecules pass through a gap between two gold nanowires. Each passing molecule produces a characteristic electrical tunneling current, and the waveform differs between the L- and D-forms, so individual molecules can be counted. Combined with artificial intelligence, the method told the two forms apart with over 80% accuracy. Lead author Takahito Oshiro says this is the first time amino acid chirality has been distinguished at the single-molecule level.
Tested on a meteorite and desert soil
Real samples are messy mixtures, so the researchers tried the method on extracts from the Murchison meteorite and on soil from Chile’s Atacama Desert, a Mars-like environment. According to senior author Masateru Taniguchi, the technique captured the main features of the amino acid composition just as traditional methods did.
What this could mean
The hope is that this work leads to compact, electrically based instruments that could detect extraterrestrial life. The 80% accuracy and the lab setting show that this is still an early step, but it is a promising one: a small chip-like sensor is far easier to send to Mars or an icy moon than a room-sized laboratory.
This article draws on the press release “Electrical technique could help identify signs of life in space” from the University of Osaka, published on Phys.org, which describes a study in Nature Communications (2026).
https://phys.org/news/2026-10-electrical-technique-life-space.html
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