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Project Hail Mary meets reality: 45 planets could harbor alien life

Date:

March 25, 2026

Source:

Royal Astronomical Society

Summary:

Astronomers have narrowed down the cosmic search for life, identifying fewer than 50 rocky planets among thousands of known exoplanets that may have the right conditions to support life. Using new data from ESA’s Gaia mission and NASA archives, researchers pinpointed worlds in the “habitable zone,” where temperatures could allow liquid water to exist. Some of the most intriguing targets include nearby systems like TRAPPIST-1 and Proxima Centauri, offering tantalizing possibilities just dozens of light-years away.

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An artist’s impression of what the TRAPPIST-1 planetary system may look like, showing (from left to right) TRAPPIST-1 a, b, c, d, e, f, g, and h, based on available data about the planets' diameters, masses, and distances from the host star. Of these, TRAPPIST-1 d, e, f, and g are thought to be the most Earth-like planets. Credit: NASA/JPL-Caltech

Astronomers searching for extraterrestrial life have now identified the most promising places to look. Out of more than 6,000 known exoplanets, researchers have narrowed the list to just under 50 rocky worlds that may be capable of supporting life.

The findings, published in Monthly Notices of the Royal Astronomical Society, echo the kind of mission imagined in the Hollywood film Project Hail Mary. In that story, Ryan Gosling's character travels to a distant star system in search of a way to save Earth, encountering alien life along the way, including a being named Rocky and fictional microorganisms like Astrophage and Taumoeba.

Habitable Zone Planets and Liquid Water Potential

Professor Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, led the research alongside a team of undergraduate students. They analyzed new data from the European Space Agency's Gaia mission and the NASA Exoplanet Archive to identify planets located in the "habitable zone."

This region around a star is not too hot and not too cold, making it more likely that liquid water could exist on a planet's surface. Since water is essential for life as we know it, planets in this zone are considered the best candidates.

The study, titled 'Probing the limits of habitability: a catalogue of rocky exoplanets in the habitable zone', also highlights planets that receive levels of stellar energy similar to Earth.

"As Project Hail Mary so beautifully illustrates, life might be much more versatile than we currently imagine, so figuring out which of the 6,000 known exoplanets would be most likely to host extraterrestrials such as Astrophage and Taumoeba -- or Rocky -- could prove critical, and not just to Ryan Gosling," Professor Kaltenegger said.

"Our paper reveals where you should travel to find life if we ever built a 'Hail Mary' spacecraft."

45 Rocky Worlds Identified as Top Targets

The team identified 45 rocky planets within the habitable zone that could potentially support life. They also highlighted an additional 24 planets within a more restrictive 3D habitable zone, based on tighter assumptions about how much heat a planet can tolerate before becoming uninhabitable.

Among these are well-known exoplanets such as Proxima Centauri b, TRAPPIST-1f, and Kepler 186f, along with lesser-known candidates like TOI-715 b.

Some of the most intriguing targets include the TRAPPIST-1 system planets d, e, f, and g, located about 40 light-years from Earth, as well as LHS 1140 b, which lies 48 light-years away. Whether these worlds can sustain liquid water depends partly on their ability to maintain an atmosphere.

Earth-Like Energy and Promising Nearby Worlds

Several planets receive levels of starlight similar to what Earth gets from the Sun. These include the transiting planets TRAPPIST-1 e, TOI-715 b, Kepler-1652 b, Kepler-442 b, and Kepler-1544 b, along with planets such as Proxima Centauri b, GJ 1061 d, GJ 1002 b, and Wolf 1069 b, which are detected through the motion they induce in their host stars.

Researchers also selected planets located near the inner and outer edges of the habitable zone to better understand where the limits of habitability lie. While the concept of the habitable zone has been studied since the 1970s, new observations could refine or even reshape current theories, Professor Kaltenegger explained.

Testing the Limits of Planetary Habitability

Some exoplanets follow highly elliptical orbits, meaning the amount of heat they receive from their star changes significantly over time. Studying these worlds could reveal whether a planet must remain continuously within the habitable zone or if it can move in and out while still maintaining conditions suitable for life.

Planets such as K2-239 d, TOI-700e, and K2-3d, along with Wolf 1061c and GJ 1061c, can help scientists study the inner boundary of habitabi