Scientists Are Hunting Extraterrestrial Life Right Now, Here's Where the Search Actually Stands

Jupiter's moon Europa holds roughly twice the volume of all Earth's oceans beneath a shell of ice that may be 15 to 25 kilometres thick. The water has been in contact with a rocky seafloor for billions of years. On Earth, that combination, liquid water, rock, chemical gradients, is where life began. NASA's Europa Clipper spacecraft launched in October 2024 and will reach Jupiter's system around 2030. It carries a mass spectrometer, an ice-penetrating radar, and a magnetometer to map the ocean's depth and salinity. It will not land. It will fly past Europa more than 50 times, each pass skimming as low as 25 kilometres above the surface, sampling the plumes of water vapour that vent through cracks in the ice. If those plumes carry organic molecules, phosphorus, or chemical signatures of metabolic activity, Clipper will read them.

Enceladus, Saturn's small moon, already delivered a result that changed the conversation. The Cassini spacecraft, before it was deliberately crashed into Saturn in 2017, flew through Enceladus's geysers and detected molecular hydrogen, silica nanoparticles, and complex organic compounds. Molecular hydrogen in that context signals active hydrothermal vents on the seafloor, the same environment that sustains chemosynthetic ecosystems kilometres below the surface of Earth's oceans, with no sunlight at all.

NASA's Perseverance rover has been collecting rock cores in Jezero Crater since 2021. Jezero was once a lake fed by a river delta. Perseverance has found organic molecules, carbon-bearing compounds, in several samples. Organics are not life. They form through chemistry that has nothing to do with biology. But they are the raw material, and finding them in an ancient lakebed is the right kind of result. The rover has cached 23 sealed tubes of Martian rock on the surface. A joint NASA-ESA mission is planned to retrieve those tubes and bring them to Earth laboratories, where scientists can run analyses far more sophisticated than anything a rover can carry. That sample return mission has faced budget pressure, but the tubes are waiting.

The European Space Agency's ExoMars Rosalind Franklin rover, long delayed, is designed to drill two metres below the Martian surface, deeper than any previous Mars mission. Radiation destroys organic molecules at the surface, but two metres down, material could have been shielded for hundreds of millions of years. The rover carries a instrument called MOMA, the Mars Organic Molecule Analyser, built to detect the specific molecular chirality that distinguishes biological compounds from abiotic ones. Life on Earth produces molecules with a consistent handedness, left-handed amino acids, right-handed sugars. Random chemistry produces equal mixtures. If MOMA finds a bias, it is a signal worth taking seriously.

The James Webb Space Telescope has done something no previous instrument could: it can read the atmospheric chemistry of planets orbiting other stars. When a planet passes in front of its star, starlight filters through the planet's atmosphere. Different molecules absorb different wavelengths. Webb reads those absorption lines and identifies what the atmosphere contains.

In 2023, Webb detected carbon dioxide and sulphur dioxide in the atmosphere of K2-18b, a planet about 8.6 times Earth's mass orbiting a red dwarf star 120 light-years away. It also reported a tentative detection of dimethyl sulphide, a compound that, on Earth, is produced almost exclusively by marine phytoplankton. The researchers were careful: the signal was at the edge of statistical significance, and the team explicitly called for confirmation. Abiotic pathways for dimethyl sulphide production in planetary atmospheres are not fully ruled out. But K2-18b is now one of the most watched exoplanets in astrobiology. Webb will return to it.

The broader point is that Webb has given scientists a tool to screen dozens of exoplanets for biosignatures without leaving Earth. The list of candidates in or near the habitable zones of their stars runs into the hundreds. ISRO's own planned contributions to space science, including future Earth-observation and deep-space missions, may eventually feed data into the global astrobiology picture, though India's current flagship in solar science, Aditya-L1, is focused on the Sun rather than exoplanet atmospheres.

The Search for Extraterrestrial Intelligence has spent decades scanning radio frequencies for signals that could not be explained by natural astrophysical processes. The Breakthrough Listen initiative, funded since 2015 with 100 million dollars over ten years, is the most systematic effort yet. It uses the Green Bank Telescope in West Virginia and the Parkes telescope in Australia to survey the million stars closest to Earth, the entire galactic plane, and the 100 nearest galaxies. It has produced no confirmed detection. What it has produced is a methodology: machine learning models trained to distinguish human radio frequency interference from candidate signals of unknown origin. In 2019, Breakthrough Listen published a candidate signal from the direction of Proxima Centauri, the closest star to the Sun at 4.24 light-years. The signal, designated BLC1, was eventually attributed to interference from human technology. The process of ruling it out took months of careful analysis, and that process is now the template for evaluating future candidates.

The search has also moved beyond radio. Optical SETI looks for laser pulses. Technosignature research asks what industrial civilisations leave behind in planetary atmospheres, the same atmospheric chemistry methods Webb uses for biosignatures, applied to signs of technology rather than biology.

Sara Seager, an astrophysicist at MIT and one of the leading figures in exoplanet research, has said she believes signs of life on another world will be found within her lifetime. She is in her fifties. The caveat she always adds is that the first detection will likely be ambiguous, a statistical signal in an atmospheric spectrum, not a radio message or a photograph. The ambiguity will be real and the debate will take years to resolve.

Nathalie Cabrol, an astrobiologist at the SETI Institute who studies extreme environments on Earth as analogues for Mars, puts the Mars question differently: she thinks the more important question is not whether life exists on Mars now, but whether it ever did, and whether we will recognise it if we find it. Life that evolved independently on Mars might use chemistry different enough from Earth life that our instruments, designed around Earth biology, could miss it entirely.

The honest answer to how close is: close enough that specific missions with specific instruments are pointed at specific targets, and the scientists running those missions are not speaking in decades-long timescales anymore. Europa Clipper data will start arriving before 2031. Webb is observing now. Perseverance's samples are waiting for retrieval. The search has a schedule.