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A Mastcam image from the Mars Curiosity rover captures what looks like a doorway into a rock ledge. It was formed when layered rock cracked and eroded away.  Courtesy NASA Mars Curiosity Rover team.
A Mastcam image from the Mars Curiosity rover captures what looks like a doorway into a rock ledge. It was formed when layered rock cracked and eroded away. Courtesy NASA Mars Curiosity Rover team.

The planet Mars has a lot of intriguing geological features, but a doorway in the side of some sedimentary rock on the flank of Mount Sharp (Aeolis Mons) isn’t one of them. In fact, no such doorway on Mars (supposedly created by aliens) exists. But, there is a break in the rock that really, really does look like one. The fact that it isn’t a real doorway hasn’t stopped a lot of speculation over its appearance in an image snapped by the MastCam on the Curiosity rover on Sol 3466 (May 7, 2022). The plain truth is that the odd-looking feature is really a fracture in ancient layers of sand that have hardened into rock over millions of years. A combination of light, shadow and viewing angle makes it look like a door. But, it’s not.


A closeup of the purported doorway on Mars shows the structure of the rock, cracks inside the broken area, and sand deposits nearby. Cutaway from the Mastcam image by C.C. Petersen.

It’s not the first time an odd “something” on Mars, or other places in the solar system (including Earth), has caught people’s attention. People are familiar with the “Face on Mars” furor over a purported alien face on the planet. It turned out to be nothing more than an eroded mesa in the Cydonia region. But, that didn’t stop a small cottage industry of writers and speakers from pushing the idea that ancient aliens built it as a signal to us (or something). Subsequent missions that imaged the surface showed that there are no faces on Mars. And, there aren’t any statues or spoons, or other spooky objects either. In every case, the objects that people thought they saw turned out to be ordinary rocks or rock formations.

Science Doorway on Mars

A composite image of Mount Sharp in Gale Crater, created by NASA’s Curiosity Rover in 2015. The rover is currently atop a region called Greenheugh Pediment on the mountain, which is where it snapped the image of the “doorway on Mars” that has excited people’s imaginations. Credit: NASA/JPL-Caltech/MSSS

There are a lot of really cool features on Mars: rock formations, river beds, volcanoes, and craters. They provide more than enough exciting science, so we really don’t need mysterious “visions” that stem from overactive imaginations and the very human tendency to see shapes or make pictures out of random or ambiguous visual scenes. (The technical term for that tendency is pareidolia.) We’ve covered that term before, in stories about the Moon and other interesting objects in space.

In a way, the purported “mysterious door” rock feature on Mars gives us a chance to do a quick review here about what the Curiosity rover has helped scientists discover. Currently, it’s exploring the central mountain in Gale Crater. There are some pretty familiar-looking scenes there and that familiarity does provide us with a doorway to understanding ancient and current Mars, and how it got the way it is.

Recognizing Familiar Things on a Distant World

We see a LOT of sandstones and other sedimentary rocks on Mars, particularly in the area Curiosity is exploring. They look familiar to us because there are similar rocks here on Earth. Understanding how they formed here opens a door to an understanding of how they formed on Mars. Similar processes were involved in both cases: deposition and erosion by water and wind. By observing such materials here at home, and how they behave, we can get a good feel for
Did you miss our previous article…
https://www.mansbrand.com/astronomers-find-a-star-that-contains-65-different-elements/

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