Water Where None Was Expected
One of science's most durable questions — where did Mars's ancient water go? — may have a startling new answer. Scientists analyzing seismic data from NASA's InSight lander have identified what appears to be a substantial reservoir of liquid water locked in fractured rock deep beneath the Martian surface, at depths of 10 to 20 kilometers. If confirmed, the discovery would represent the largest known water reservoir on Mars and would fundamentally alter scientific thinking about the planet's potential for harboring microbial life, either in its past or potentially its present.
Mars's surface is bone-dry today — a frigid desert where any liquid water exposed to the thin atmosphere would instantly freeze or evaporate. But planetary scientists have long suspected that water that once filled Martian lakes, rivers, and perhaps even a northern ocean did not simply disappear into space. The new findings suggest that at least some of that water seeped downward and now persists as liquid at depths where the geothermal heat of the planet's interior keeps temperatures above freezing despite Mars's cold surface.
How the Discovery Was Made
The evidence comes from seismic waves recorded by InSight's sensitive seismometer during marsquakes — the Martian equivalent of earthquakes. When seismic waves travel through different types of rock and fluid, they change speed in characteristic ways. The pattern detected in InSight's data — a specific attenuation signature in certain wave types — is consistent with seismic waves passing through a layer of water-saturated fractured rock rather than dry igneous or sedimentary material.
The analysis used techniques originally developed for studying Earth's crust and refined for the challenging signal environment of Mars, where InSight's data quality degraded over time as dust accumulated on its solar panels. The researchers report high confidence in the detection but acknowledge that the indirect nature of seismic inference means the finding will require corroboration from future missions before it can be considered confirmed.
The depth of the reservoir — 10 to 20 kilometers — puts it well beyond the reach of any current Mars drilling capability. The deepest drilling ever attempted on Earth, Russia's Kola Superdeep Borehole, reached 12 kilometers after more than 20 years of effort. Reaching the hypothesized Martian water would require technology that does not currently exist in any planned Mars mission portfolio.
Implications for Martian Life
The astrobiological implications are significant. Life as we know it requires liquid water, and the presence of a liquid water reservoir — even at extreme depth — keeps Mars in the conversation as a potentially habitable world. On Earth, microbial life has been found thriving in deep crustal environments: in hot springs, in rock formations kilometers underground, and in conditions of extreme temperature and pressure that would be lethal to most surface life. Mars's deep water, if real, would occupy a similarly extreme environment.
The discovery also has implications for Mars colonization planning, though the practical challenges of accessing water at 15-kilometer depth make it a theoretical resource rather than a practical one for any near-term human mission scenario.
What Comes Next
The InSight mission ceased operations in December 2022 when its solar panels became too dust-covered to power the lander, but left behind a dataset that scientists are still mining for discoveries. Future Mars missions with seismometers — which ESA's ExoMars Surface Platform has planned — will extend and refine the seismic survey of Mars's interior. And deep-penetrating radar systems analogous to the MARSIS radar that detected a briny lake beneath Mars's southern polar ice cap may eventually provide more definitive confirmation. For now, the finding stands as one of the most consequential Mars discoveries in years — a credible new possibility that recasts the story of what happened to Mars's water.
This article is based on reporting by Live Science. Read the original article.
