When reports of strange landscape features spotted on the Martian landscape come in, they usually come from the same old YouTube-based armchair sleuths. Now that Google Mars lets anyone with an internet connection pore over the Martian surface for rocks that look like ancient buildings, rocks that look like alien spacecraft, or rocks that look like weird rocks. This week, however, NASA’s own Jet Propulsion Laboratories have published images taken near Mars’ South Pole which show a strange, perfectly round depression in the Martian surface.
The image was taken by the Mars Reconnaissance Orbiter (MRO) which is currently enjoying a nice, sunny view of Mars’ South Pole. The dark, round depression stands out starkly against the white, Swiss-cheese-like terrain of the melting carbon dioxide ice surrounding it. While much of the inside of the hole is in shadow, what appears to be a bit of the same ice can be seen inside. Based on the resolution of the MRO’s High Resolution Imaging Science Experiment, or HiRISE camera, the unexplained pit is hundreds of meters across. According to a NASA press release, researchers currently think the feature might simply be an odd impact crater or perhaps caused by underground erosion. Still, the possibility remains that we're seeing something else entirely. We might have sent a couple of remote control robots to the Martian surface, but the Red Planet is still largely a mystery.
A few months ago, another strange circular feature was seen in the same area and likewise baffled the NASA astronomers and scientists analyzing MRO data. As the cameras and sensors aboard Mars orbiters improve, it’s natural that we’ll begin to discover new and strange-looking landscape features unlike anything seen on Earth. While proof of an ancient Martian civilization still eludes us, neat circular holes are still better than nothing.