Finding extraterrestrial life
No life outside Earth has ever been confirmed; the best candidates are Mars, icy ocean moons and the atmospheres of exoplanets.
Open in the interactive tree →Life elsewhere would show whether biology is a cosmic rule or a fluke. Methods include biosignature gases in exoplanet atmospheres, samples from Mars and icy moons, and radio or laser technosignatures (SETI).
As of October 2026
The NASA Exoplanet Archive lists 6,375 confirmed exoplanets in early October 2026 (6,000 was passed on 17 September 2025). Claims of life have not held up: dimethyl sulfide on K2-18 b is disputed, and Perseverance's 'Sapphire Canyon' rock from Cheyava Falls (Nature, 10 September 2025) shows possible biosignature minerals that non-biological chemistry can also explain. Sample return is stuck: Congress's FY2026 budget (January 2026) did not fund the NASA-ESA Mars Sample Return, leaving China's Tianwen-3 (launch window December 2028 to January 2029, return 2031). Europa Clipper reaches Jupiter in April 2030 and ESA's JUICE in July 2031; the Habitable Worlds Observatory is aimed at the 2040s, with Congress giving US$150 million for FY2026 and the FY2027 request at US$5 million.
What is missing
- Mars samples in Earth laboratories; Perseverance's cache has no ride home
- A space telescope able to image Earth-like planets directly (contrast about 10^-10), i.e. the Habitable Worlds Observatory
- Agreed criteria for what counts as proof, including ruling out false positives
- Missions that sample ocean worlds such as Europa and Enceladus
- Stable funding over decades
Becomes possible once solved
- Proof that life arose more than once
- A second example of biology to compare with Earth's
- Guidance on where to search next and how to protect other worlds
- A major shift in science and culture
Open steps
- Vetting exoplanet candidates High AI leverageSeparate real planets from instrument artefacts in survey data fast enough to choose targets for atmosphere follow-up.
- Reading exoplanet atmospheres Medium AI leverageRetrieve gas abundances from noisy spectra and state how sure a detection really is, so disputed claims such as K2-18 b can be tested.
- Biotic versus abiotic chemistry Medium AI leverageBuild and validate tests that tell life-made chemistry from non-biological chemistry, using meteorites, ancient rocks and lab mixtures.
- Technosignature searches Medium AI leverageSearch radio and optical archives for artificial signals and rule out interference, with reproducible follow-up.
- Life detection on ocean worlds Low AI leverageDesign instruments and onboard analysis that can detect trace organics on Europa or Enceladus during short flybys or landings.
Where AI could help
Medium AI leverage. AI speeds candidate vetting and data analysis, but proof needs samples, new telescopes and agreed criteria that only missions can supply.
- Vet exoplanet candidates and atmosphere spectra faster and flag false positives such as instrument artefacts
- Classify chemical mixtures as biotic or abiotic to judge Mars samples and ocean-world flyby data
- Search radio and optical archives for technosignatures with anomaly detection
- Give probes onboard autonomy to pick science targets between rare ground contacts
Shown so far
- In January 2026, NASA's ExoMiner++ neural network flagged about 7,000 TESS planet candidates, which still need telescope follow-up to be confirmed. source
- In September 2023, a machine-learning model on pyrolysis GC-MS data separated biotic from abiotic samples, including ancient and meteorite samples, with about 90% accuracy (PNAS). source
- In January 2023, a deep-learning search of 820 nearby stars for radio technosignatures found eight signals of interest, none of which reappeared when re-observed. source
Prerequisites
- Deep-space probes (Voyager)1977
- Exoplanet discovery1995
- Mars rovers1997Rovers test whether Mars was ever habitable
- Kepler Planet Census2009Kepler showed how common planets in habitable zones are
- Asteroid Sample Return2020–2023Bennu held amino acids and nucleobases: life's raw ingredients exist off Earth
- James Webb Space Telescope2021