The ‘doorway’ seen on Mars is not for aliens. Here’s how it really formed.


No, this is NOT a doorway for Martians.”This is a very curious image,” British geologist Neil Hodgson, who has studied the geology of Mars, told Live Science. “But in short – it looks like natural erosion to me.”

The Mars Curiosity rover’s Mast camera snapped this intriguing image of the Red Planet, showing a “doorway” structure, on May 7, 2022, or Sol 3466 in Martian days. (Image credit: NASA/JPL-Caltech/MSSS)

Curiosity snapped the image with its Mast camera (“Mastcam” for short) on May 7, and it was released by NASA(opens in new tab) later in the week. No, this is NOT a doorway for Martians. Although the internet erupted on Thursday after a photograph from NASA’s Curiosity rover appeared to show an “alien door,” experts are pretty sure it’s just a natural feature of the Martian landscape.Several clues make it clear that the subject of the image is not an actual door: For a start, it’s less than 3 feet (1 meters) high, planetary geologist Nicholas Mangold of the University of Nantes in France told Live Science in an email.

Or this may show the Martians were small, he quipped.

Other tongue-in-cheek suggestions from the internet included the idea that it is the space tomb of Jesus; a crib for E.T.; or a save-point for a video game, the Vice website reported.

But the real answer is that it’s none of those things. Instead, what looks like a door is in fact a shallow opening in the rock that’s almost certainly caused by natural forces, say the experts.Hodgson, a vice president at the British geoscience firm Searcher(opens in new tab), thinks the “door” is caused by erosion.

Rocky layers called strata can be seen on the rock, dipping on the left and higher at the right. “These are silt beds, with harder sandy beds that stand out,” he told Live Science in an email.

“They were deposited perhaps 4 billion years ago under sedimentary conditions, possibly in a river (I’d need to see more of the outcrop to be sure) or a wind-blown dune.” Mars erodes
So if the door isn’t a door, what is it?Martian winds have eroded the strata since they’ve become exposed on the surface, and the images even show traces of them inside the “door,” he said.

Several natural vertical fractures are also visible in the image, among them fractures caused by the way rocks weather on Mars; and the small cave or “door” seems to have formed where the vertical fractures intersect with the strata, he said.It seems “a large boulder has fallen out under its weight” to create the door-shaped cave, he said. “Gravity isn’t as strong on Mars, but it is plenty strong enough to do this.” The culprit is the rock lying on the surface just to the right of the “door,” which appears to have a smooth vertical edge – possibly because it fell out relatively recently and hasn’t been exposed for long to the Martian winds: It’s “all very natural, and similar to outcrops you can see in many arid places on Earth,” he said.

No Marsquakes
Mangold, who studies geological data from the Curiosity and Perseverance rovers, agrees that the Martian “door” has been created naturally by the structure of the rock.