August M
Scientists have identified what appear to be enormous water-carved caves on Mars, revealed through giant skylights in the Hebrus Valles region. The discovery suggests the Red Planet may preserve ideal environments for ancient biosignatures — and could inform future missions designed specifically to enter these caverns.
Researchers analyzing data from multiple Mars missions say they’ve found evidence of karstic caves — enormous underground voids carved when slightly acidic water dissolves rock — in the northern mid-latitudes of Mars.
As reported by Space.com, the team identified eight skylights, each tens to over 100 meters wide, offering glimpses into these hidden structures below.
The skylights are distinct from impact craters: they lack raised rims and ejecta, suggesting they formed when the surface collapsed into empty space beneath it.
Chunyu Ding of Shenzhen University, who co-led the study, told Space.com that exploring these caverns in situ is “an achievable goal” for future missions as technology advances, Space.com notes.
How the caves likely formed
According to Space.com, unlike previously found Martian caves that were created by ancient lava tubes, the Hebrus Valles features sit far from volcanic terrain.
Instead, the area contains long-dried river channels and abundant minerals that point to a wetter, more Earth-like past.
Using data from NASA’s Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter, Ding’s team showed that the region is rich in carbonate rocks such as limestone and sulfate rocks like gypsum.
These sediments were deposited more than 3.5 billion years ago, when lakes and shallow seas pooled across the Martian surface.
As Mars cooled and surface water froze into subsurface ice and brines, later heating events — from distant volcanic activity, impacts or orbital cycles — may have melted some of that ice.
The resulting water could have seeped through fractures, dissolving rock and gradually hollowing out cavern systems.
Why these caves matter for life
Karstic caves would provide natural shielding from harsh surface radiation, extreme temperature swings and dust storms — conditions inhospitable to modern Martian life but ideal for preserving traces of ancient microbes.
The presence of nearby subsurface ice, hinted at by hydrogen detections from Mars Odyssey’s Gamma-Ray Spectrometer, adds to the site’s scientific appeal, Space.com reports.
If life ever emerged on Mars, caves like these may be among the best places to search for chemical markers or preserved organic material.
Sources: Space.com
