Scientists have identified a series of deep caves on Mars that may have formed through the slow action of water, suggesting the planet once supported conditions favorable to life. These formations, located in the Hebrus Valles region of Mars, could represent the first known caves on the planet carved by water erosion.
Unlike surface features shaped by volcanic activity or impact events, these pits appear to have developed over time through a collapse process caused by underground voids. Researchers say that if Mars ever hosted life, these caves might have offered a protective environment, shielding organisms from radiation, temperature swings, and frequent dust storms.
The findings, led by Chunyu Ding of Shenzhen University, are detailed in the latest issue of The Astrophysical Journal Letters. The study examined eight large depressions using data collected from past NASA missions. These structures — often called “skylights” — are believed to be entrances to underground chambers similar in form to caves on Earth created by the erosion of soft rock by water.
Water, not lava, may be behind martian cave systems
While many Martian caves discovered previously are linked to lava tubes — channels formed by flowing magma — this study offers a new theory. Researchers believe that ancient water, possibly rich in minerals such as carbonate and sulfate, slowly dissolved parts of the Martian crust, forming hollow chambers beneath the surface.
Over time, the ceilings of these hollow spaces likely collapsed, leaving behind steep-walled, circular pits. These structures differ from impact craters, which often feature raised rims and scattered debris. The absence of such features points to a natural sinkhole formation, similar to those found in karst landscapes on Earth.
To support their findings, the team used thermal data and high-resolution images from NASA’s Mars Global Surveyor. They then built three-dimensional models of the pits, revealing signs consistent with caves created by erosion rather than those shaped by volcanic activity or planetary shifts.
The structures are not only geologically significant — they could also play a key role in future exploration. Because they are shielded from harsh surface conditions, scientists believe they may be among the best places to look for evidence of past microbial life.
Mars caves could provide shelter for future missions
Beyond the search for ancient life, these caves may also serve as natural shelters for future astronauts. The underground environments offer protection from Mars’ harsh radiation and freezing temperatures, making them practical considerations for human missions.
Lead researcher Ding described these skylights as a “new type of cave system,” distinct from anything previously seen on Mars. Their likely connection to water activity makes them promising targets for robotic or human missions in the years ahead.
As scientists refine their understanding of Mars’ past, discoveries like these offer both scientific insights and practical opportunities. With clearly defined sites now on the map, future missions could concentrate efforts on exploring these potential life-harboring formations more closely.