Scientists have discovered a mysterious hole on the surface of Mars, and they have no idea what lies inside it.

This pit, located in the Arsia Mons region — one of Mars’ giant volcanoes — could potentially be a skylight leading to a vast network of lava tubes.

Lava tubes are natural caverns formed by flowing lava. Here on Earth, they provide shelter for many life forms, and on Mars, they could offer human explorers much-needed protection from the harsh Martian environment.

So, is this hole the key to unlocking a potential Martian habitat?

A mysterious Martian pit — but leading to where?

There’s no shortage of environmental hazards out to kill any astronaut bold enough to dare set foot on Mars. With Mars having only 0.7% of Earth’s sea-level pressure, humans would have to don a full pressure suit or live inside a specialized chamber. Without these precautions, oxygen wouldn’t circulate in the bloodstream, with potentially fatal consequences.

Radiation, however, remains the primary concern. Although Mars is farther from the Sun than Earth, the absence of a magnetic field and its thin atmosphere mean it’s exposed to much higher radiation levels than Earth. The Mars Odyssey probe has shown radiation levels on Mars are at least 2.5 times higher than what astronauts face on the International Space Station. Furthermore, besides regular exposure to cosmic rays and solar wind, it receives occasional, lethal radiation blasts due to solar flares.

Any attempt to colonize the Red Planet will require measures to ensure radiation exposure is kept to a minimum. Some of the proposed ideas thus far involve habitats built directly into the ground or even above-ground habitats using inflatable modules encased in ceramics.

However, a promising alternative lies in Mars’ natural landscape. The planet is scattered with deep pits, caves, and lava tube structures that can act as a shield against radiation.

Collapsed sections of these tubes, called skylights, could provide access to these subterranean refuges. This is what scientists believe this newly identified pit could be. It was recently imaged by the High-Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter (MRO).

The Nature of Martian Pits

The newly examined pit measures only a few meters across and resides in the Tharsis region — a vast volcanic plain, thousands of kilometers across and elevated about 10 km above the planet’s mean elevation. This area was once very volcanically active, so scientists’ best guess is that the pit is a skylight to a lava tube.

However, that’s not the only option. In another image, you can see an illuminated sidewall, indicating it might just be a cylindrical pit. This raises the possibility that the hole may simply be a pit crater, similar to those found in Hawaii.

These craters form when cracks in volcanic rock widen and collapse, offering no access to underground chambers. In Hawaii, pit craters range from 6 to 186 meters deep and 8 to 1140 meters wide. The Arsia Mons pit is about 178 meters deep, Universe Today reports.

Lessons from the Moon

So, the big question now is: does this hole on Mars lead to a larger underground cavern? We don’t have a straight answer yet. But with time, scientists might be able to study and understand Martian pits as well as they do those on the Moon.

We understand lunar lava pits and tubes much better than those on Mars. Some lunar tubes are thermally stable and have boulder-covered floors. There are even plans for robots to explore these lunar caves, potentially housing astronauts in inflatable habitats.

Mars, with its weaker gravity, should support even larger lava tubes. This would provide extremely valuable shelter on a very unforgiving planet. Perhaps this is not all that different from how the first human explorers made bases in caves as they traveled across uncharted territory, colonizing the world.

However, unlike the Moon, we lack conclusive evidence of their existence on Mars. This intriguing pit on Arsia Mons is part of an ongoing search for Martian lava tubes. Future robotic missions designed to explore these potential underground worlds will be crucial in unlocking the secrets they hold.