No life beyond Earth has been confirmed yet. Where scientists are looking, which signs would count as evidence, and the closest calls so far.
By The Orbital Record editorial teamPublished Last reviewed
As of October 2026, no life beyond Earth has been confirmed. Astrobiology is the science of life’s origin, evolution and distribution in the universe, and its best targets are Mars, Europa, Enceladus and the atmospheres of exoplanets. Telescopes and missions now operating or planned could detect convincing signs of life within decades.
This guide is evidence first. It covers what would count as evidence, where the search is happening, the closest calls so far, and the big questions such as the Fermi paradox.
We have exactly one confirmed example of life: Earth’s. That is the central fact of astrobiology, and it cuts both ways.
Why many scientists expect life to be common. The raw materials are everywhere. Water, organic molecules and energy sources are found across the solar system and in planet-forming disks. More than 6,000 exoplanets are confirmed, and many rocky ones orbit in habitable zones (exoplanets guide). Life also appeared on Earth relatively soon after the planet cooled. And in 1953 Stanley Miller showed that sparks in a mix of simple gases produce amino acids, the building blocks of proteins (the Miller-Urey experiment).
Why some do not. Making ingredients is not making a cell. We do not know how life began on Earth, so we cannot say how likely it is to begin elsewhere. Complex, intelligent life may require a long chain of unlikely steps. A single example cannot tell us whether life is common or a fluke.
The way out of that deadlock is to find a second, independent origin of life. That is what the rest of this guide is about.
Astrobiology is the study of life in a cosmic context: how it began, how it evolves, where it could exist beyond Earth and how to detect it. It draws on astronomy, microbiology, chemistry, geology, oceanography and planetary science. NASA runs a dedicated Astrobiology Program, and life detection now shapes mission design from Mars rovers to space telescopes.
Astrobiology also studies life at the limits on Earth. In September 2026 researchers reported a “fire amoeba” that divides at 63 degrees Celsius, a new record for complex cells with a nucleus (fire amoeba sets a heat record). Each such extreme widens the range of places worth searching.
A biosignature is something that could point to life: a gas, a mineral pattern, a molecule or a structure. The hard part is that almost every candidate can also be made without life. Main kinds:
False positives are the trap. In 1996 a team announced possible fossil microbes in the Martian meteorite ALH84001 (McKay et al. 1996), and the US president made a public statement. Later studies favored non-biological explanations. To avoid a repeat, NASA scientists proposed in 2021 a seven-step Confidence of Life Detection (CoLD) scale, from a first possible signal to independently confirmed evidence of life. No claim so far has climbed beyond the early steps.
Mars was warmer and wetter more than 3 billion years ago, with rivers and lakes. NASA’s Perseverance rover is exploring Jezero Crater, an ancient lake bed. In July 2024 it examined a rock nicknamed “Cheyava Falls” with millimeter-scale “leopard spots” of the minerals vivianite and greigite next to organic carbon. On Earth such patterns often form through microbial chemistry. In September 2025 NASA called the features a “potential biosignature,” meaning they might have a biological origin but need more study, and the rover sealed a core of the rock, the “Sapphire Canyon” sample (Hurowitz et al. 2025). Only laboratories on Earth could settle it.
The evidence keeps building. In April 2026 Curiosity’s team reported 21 carbon-bearing molecules in one sample, seven never before seen on Mars (Curiosity’s most diverse organic molecules), and in September 2026 Perseverance showed rocks on Jezero’s rim were altered by water at least three times (Perseverance and Jezero’s water episodes).
Jupiter’s moon Europa hides a global salty ocean under its ice shell, probably with more water than all of Earth’s oceans combined. NASA’s Europa Clipper launched on October 14, 2024, and will reach Jupiter in April 2030 to make dozens of close flybys. ESA’s Juice, launched in April 2023, will study Europa, Ganymede and Callisto in the 2030s. Neither can detect life directly; both will test whether the ocean is habitable. What keeps such oceans liquid so far from the Sun is tidal heating, the flexing of a moon by its giant planet’s gravity. Its most extreme example is Jupiter’s volcanic moon Io, where in 2026 the Juno spacecraft took the first temperature readings below the surface and found heat rising far faster than sunlight can explain (Juno at Io).
Saturn’s small moon Enceladus sprays its ocean into space through cracks near its south pole, and NASA’s Cassini spacecraft flew through the plumes. It found water with salts, organic molecules and molecular hydrogen, a sign of hydrothermal activity and a potential food source for microbes (Waite et al. 2017). In 2023 phosphates turned up in ice grains from the ocean, at concentrations far above Earth’s seas (Postberg et al. 2023). All six key elements for life as we know it have now been found or inferred there.
Saturn’s largest moon, Titan, has a thick nitrogen atmosphere, lakes of liquid methane and ethane, and rich organic chemistry, with a water ocean deep below. NASA’s Dragonfly, a nuclear-powered rotorcraft, is due to launch in July 2028 and arrive in 2034 to fly between sites and study prebiotic chemistry.
Beyond the solar system, the only practical way to search for life is through light: the chemistry of an exoplanet’s atmosphere. The key idea is the habitable zone, the range of distances from a star where liquid water could exist on a planet’s surface, defined in its modern form by James Kasting and colleagues in 1993 (habitable zones).
Most nearby habitable-zone planets orbit red dwarfs, which flare violently and may strip away atmospheres. JWST has found that several rocky planets around such stars lack thick atmospheres, while the more promising ones are still being observed. Our ranked list of the most Earth-like exoplanets explains each candidate.
The most publicized test case is K2-18b, a sub-Neptune 124 light-years away. In 2023 JWST found methane and carbon dioxide in its atmosphere (Madhusudhan et al. 2023), and in April 2025 the same team reported a possible signal of DMS at about 3 sigma. Independent reanalyses have found the signal is not statistically significant, and the claim is unconfirmed. The dated story is in K2-18b and the search for life.
If life and intelligence are common, why do we see no sign of anyone else? That is the Fermi paradox, named after physicist Enrico Fermi, who asked “where is everybody?” over lunch at Los Alamos in 1950. Proposed answers range from life being rare, to civilizations not lasting, to us simply not having searched enough. We weigh them in the Fermi paradox explained.
The Drake equation, written by Frank Drake for a 1961 meeting at Green Bank, West Virginia, breaks the question “how many civilizations could we detect?” into seven factors multiplied together:
Sixty-five years later, the first three are measured or reasonably constrained. Exoplanet surveys showed that most stars have planets, which settled factor 2. The last four remain guesses that span many orders of magnitude, which is why published estimates range from less than one to millions.
The search for extraterrestrial intelligence (SETI) began with a two-page paper. In 1959 Giuseppe Cocconi and Philip Morrison argued that radio telescopes could detect signals from nearby stars and suggested listening near 1,420 megahertz, the natural frequency of hydrogen (Cocconi and Morrison 1959). In 1960 Frank Drake ran the first search, Project Ozma, pointing a Green Bank antenna at two Sun-like stars.
The most famous candidate, the “Wow!” signal recorded by Ohio State University’s Big Ear telescope on August 15, 1977, was strong and narrow, but it was never seen again and cannot be called evidence. Today the largest search is Breakthrough Listen, started in 2015, which uses radio and optical telescopes on several continents. No confirmed technosignature has been found, including in targeted searches of interstellar visitors such as the comet 3I/ATLAS.
No one can promise a date, but the coming decades bring real, scheduled tests:
Whatever the answer, the search is producing a census of where life could exist, and that is a first in human history.
For a careful explanation of the Fermi paradox and the case for and against alien life, our video library includes Kurzgesagt’s “The Fermi Paradox: Where Are All The Aliens?”
Nobody knows yet. As of October 2026, no life beyond Earth has been confirmed. Scientists have found promising places, such as ancient lake beds on Mars and the hidden oceans of Europa and Enceladus, and some intriguing chemical hints, but no observation so far has ruled out non-biological explanations.
We do not know. The Milky Way alone holds hundreds of billions of stars, most with planets, and the chemistry of life appears to be common. That makes many scientists expect life elsewhere, but with only one known example of life, its true frequency cannot yet be estimated from data.
Unknown. Europa almost certainly has a salty liquid water ocean beneath its ice, with more water than all of Earth's oceans, which makes it one of the most promising places to look. NASA's Europa Clipper, launched in October 2024, will arrive at Jupiter in 2030 to study whether it could support life.
No. In September 2025 NASA announced that a rock sampled by the Perseverance rover holds a potential biosignature: mineral spots that on Earth often form with help from microbes. NASA stresses they could also form without life, and the sample would need to be studied in laboratories on Earth to decide.
There is no date, but the next two decades bring real tests: Europa Clipper at Jupiter from 2030, the Dragonfly lander at Titan in 2034, ESO's Extremely Large Telescope from the early 2030s, and NASA's proposed Habitable Worlds Observatory in the 2040s, designed to search Earth-like exoplanets for signs of life.
A biosignature is any substance, pattern or structure that could be evidence of past or present life, such as certain gases in an atmosphere, minerals shaped by microbes or complex organic molecules. Because many can also form without life, scientists treat a biosignature as a candidate until every non-biological explanation is ruled out.
Astrobiology is the science of the origin, evolution, distribution and future of life in the universe. It combines astronomy, biology, chemistry, geology and planetary science to ask how life began on Earth, where else it could exist, and how we would recognize it if we found it.
The Drake equation, written by astronomer Frank Drake in 1961, estimates the number of detectable civilizations in the Milky Way by multiplying seven factors, from the rate of star formation to how long civilizations remain detectable. The first factors are now measured; the last ones remain educated guesses.
Miller, Science, 117, 528-529, 1953
Showed in 1953 that sparks in methane, ammonia, hydrogen and water vapor make amino acids. Stanley Miller's flask experiment founded prebiotic chemistry.
Cocconi and Morrison, Nature, 184, 844-846, 1959
Proposed in 1959 that radio telescopes listen for alien signals near 1,420 MHz, hydrogen's natural frequency. Cocconi and Morrison's paper founded SETI.
Kasting et al., Icarus, 101, 108-128, 1993
Calculated in 1993 where a planet can keep liquid surface water. James Kasting's climate model put the Sun's habitable zone at 0.95 to 1.37 AU.
McKay et al., Science, 273, 924-930, 1996
Proposed in 1996 that Mars meteorite ALH84001 held possible fossils of life. David McKay's claim was never confirmed; later work favored abiotic origins.
Waite et al., Science, 356, 155-159, 2017
Found in 2017 molecular hydrogen in the plume of Saturn's moon Enceladus. Hunter Waite's Cassini team traced it to hydrothermal reactions in its ocean.
Madhusudhan et al., The Astrophysical Journal Letters, 956, L13, 2023
Detected in 2023 methane and carbon dioxide on K2-18 b with JWST. Madhusudhan's team proposed an ocean world; its tentative DMS hint is disputed.
Postberg et al., Nature, 618, 489-493, 2023
Detected in 2023 phosphates from the ocean of Saturn's moon Enceladus, at least 100 times Earth's levels. Frank Postberg's team used Cassini ice grains.
Hurowitz et al., Nature, 645, 332-340, 2025
Found in 2025 a potential biosignature in Cheyava Falls, a Mars rock with leopard spots. Joel Hurowitz's Perseverance team says Earth labs must decide.
Introduces the Fermi paradox: with so many stars and planets, why have we seen no sign of aliens, and what might that mean for us? A short animated primer on the search for life. Kurzgesagt - In a Nutshell
Becky Smethurst assesses the claim that JWST found dimethyl sulfide, a possible marker of life, in the atmosphere of K2-18b, and how strong that evidence really is. A useful lesson in weighing biosignature claims. Dr. Becky
Explains how NASA's Europa Clipper will study whether Jupiter's moon Europa could host life despite its intense radiation, with planetary scientist Robert Pappalardo. An engaging introduction to ocean worlds. Veritasium
Becky Smethurst's September 2025 news roundup on the Perseverance rock samples offering the strongest evidence yet for possible past life on Mars, plus JWST on TRAPPIST-1e and interstellar comet 3I/ATLAS. Dr. Becky
Covers evidence that the ocean under Enceladus's ice is more active than thought, including the largest plume yet seen in JWST images, and what it means for the chances of life there. Accessible and detailed. Astrum