For all the fuss it caused, it is only about a foot high.
The “door” was imaged by NASA’s Curiosity rover on May 7 on the slopes of Mount Sharp, the central massif within Gale crater, where it landed in 2012. Described on one website as a “pharaonic tomb door” because of its resemblance to some ancient Egyptian remains, it is, in fact, only about one foot high.
It is hard to spot on the panoramic image mosaic of the hillside above, but it leaps out at the eye if you see the individual frame where it occurs, as seen below. It does look like a doorway until you realize how small it is. And if you boost the contrast in the dark parts of the image, the picture just about reveals a solid rock face at the back of the shadowed interior. So as a gateway into the hollow hills of Mars, it doesn’t lead very far.
Nobody with even a little geological experience is likely to mistake the feature as a “door.” A geologist would note the thin and slightly sloping repeated layers of sandstone making up the whole of the rock face and would immediately expect that they were looking at the eroded remains of hardened sand dunes. These once covered the stream and lake sediments that Curiosity examined earlier in its gradual climb up through the layers of sedimentary rock making up Mount Sharp.
