Studies suggest ancient ocean on Mars and most diverse organics yet, but no proof of life
Two landmark findings in April have intensified the hunt for signs of ancient life on Mars: evidence consistent with a long-vanished ocean in the planet’s northern hemisphere and the most diverse suite of organic molecules ever identified there. Neither result proves life once existed, but together they narrow the search and refine where and how scientists look next.
In a study published April 15 in Nature, California Institute of Technology geologists Abdallah Zaki and Michael Lamb analyzed topographic data from Mars orbiters and found a flat, shelf-like band of terrain that closely resembles a continental shelf on Earth.
The feature, which spans roughly a third of the planet’s surface in the north, traces the boundary between lowlands and higher ground “like a ring that remains around a drained bathtub,” according to a press release announcing the discovery. Because liquid water is considered essential for life, the prospect that a vast ocean existed millions of years ago further strengthens the case that Mars once offered habitable conditions.
A second paper, published April 21 in Nature and led by University of Florida geologist Amy Williams, reported that a rock sample collected and drilled by NASA’s Curiosity rover in 2020 contains the most varied mix of organic compounds detected on Mars to date.
Of 21 carbon-containing molecules identified, seven had never before been observed on the planet. NASA said the results constitute “the most diverse collection of organic molecules ever found on the Red Planet,” while cautioning that scientists cannot determine whether the compounds formed through biological activity or purely geological processes.
Even so, the agency said the discovery renewed confirmation that ancient Mars had the right chemistry to support life. The findings add to a growing body of results from NASA’s rovers. In February, scientists reported that Curiosity had detected organic compounds in a rock sample that, on Earth, are most often produced by living organisms.
And in September 2025, NASA announced that a rock sample collected by the Perseverance rover was found to possibly be preserving evidence of ancient microbial life, known as a biosignature. Curiosity and Perseverance continue to explore different regions of Mars as NASA pursues its Artemis campaign to return humans to the Moon and looks ahead to sending the first astronauts to the red planet.
As part of that push, the agency plans in 2028 to launch the first nuclear-powered spacecraft to Mars in what could be a pivotal test of a technology with major implications for future exploration.