A mysterious hole on Mars has sparked speculations that it could be a gateway to ancient alien life. 

The crater-like opening, about 150 feet across, sits on the edge of an ancient volcano, and scientists have suggested it could be protecting lifeforms from the Red  Planet's radiation and harsh conditions.

While researchers are unsure how deep the pit goes, they said it is likely an underground lava tube that formed during a volcanic explosion - and the deep tunnel could serve as a shelter for astronauts set to put boots on the Martian world.

The University of Arizona re-posted a photo of the Mars hole for its 'Picture of the Day' this month, spurring additional conversation about how it will influence future scientific missions.

Although scientists captured the image with the HiRISE camera in 2022, they are still working to uncover how or why these holes exist.

Researchers have theorized that the holes are 'skylights' where the ground above the lava tubes caved in, according to Brandon Johnson a geophysicist at Purdue University who studies impact craters throughout the solar system.

Lava tubes are underground passageways, similar to a long cave, which formed during a volcanic explosion.

As the lava flows downhill, its surface cools and hardens into a dark crust which works as an insulator for the lava flowing beneath its surface.

This allows the lava to stay hotter and flow further, leaving an empty tunnel in its wake.

'There's more than one of these [pits] on Mars that we've seen,' Johnson told Business Insider. 

'But they're really interesting because they're places where astronauts might be able to go and be safe from radiation.'

Mars's thin atmosphere and lack of a global magnetic field like Earth - which extends into space and interacts with the solar wind to block radiation emitted from the sun - creates dangerous radiation levels.

Radiation poses a major challenge for astronauts who would be exposed to the high-energy cosmic rays that could cause long-term health problems like cataracts, heart disease, cancer, genetic damage and death.

However, these holes could lead to lava tubes large enough for astronauts to survive the elements, if humans make it to Mars.

'On the Earth, these lava tubes can be large enough to walk around in, but they can also be small or the voids can be discrete or discontinuous,' Ross Beyer, a planetary scientist with the SETI Institute, told Business Insider. 

'So these pits we see could open into larger caves, or they could just be isolated pits,' Beyer continued, adding: 'There's no way to know what's in them until we explore them in more detail.'

There is no known timeframe for when a mission might bring humans to the planet, but scientists have suggested other options to find out more about the pits.

'There are missions proposed to essentially have a robot go on a line and drop down into one of these skylights and be able to explore what's inside of them,' Johnson said while noting that there is no such mission in the works yet.

The pits don't guarantee that there is life on Mars, but Johnson added: 'This is a good place to look.'