Two weeks ago, the Curiosity rover spotted an object on the surface of Mars that bore a striking resemblance to a femur (aka. athigh bone). This sighting caused a bit of a media stir and fueled speculation – mainly by conspiracy and UFO theorists – that proof of life on Mars had finally been found. This claim was quickly picked up by media outlets and began to spread like a bad strain of flu.

Alas, NASA has since announced that the finding, much like the Martian “donut” and “rat”, was just another piece of oddly-shaped rock. Mission scientists believe that here too, the rock was sculpted into its unusual shape by wind or water erosion. NASA announced all this when they released Curiosity’s “thigh bone” photo with a science explanation on Thursday (Aug. 21). In the caption, they said that:

No bones about it! Seen by Mars rover Curiosity using its MastCam, this Mars rock may look like a femur thigh bone. Mission science team members think its shape is likely sculpted by erosion, either wind or water.

If life ever existed on Mars, scientists expect that it would be small simple life forms called microbes. Mars likely never had enough oxygen in its atmosphere and elsewhere to support more complex organisms. Thus, large fossils are not likely.

In short, the long-sought after signs of life that NASA is searching for have yet to be found. The Curiosity rover has found evidence that Mars was once a habitable place in the ancient past, mainly by determining with certainty that it once held water and a viable atmosphere. However, to date, there is no evidence that creatures large enough to leave a bone behind ever existed on the planet.

There is a long tradition of seeing shapes in Mars rocks that don’t reflect reality. The phenomenon in which the human brain perceives faces, animals or other shapes that aren’t really there is known as pareidolia; and when it comes to Mars, there is a long and fertile history of this taking place. In fact, in 1877 when astronomer Giovanni Schiaparelli looked up at Mars when it was in opposition, he spotted a network of lines that ran along the planet.

Later astronomers confirmed these sightings and erroneously thought them to be canals, an observation which was quickly seized upon by the popular imagination and spawned an entire mythos of there being a civilization on Mars. This civilization, made up of little green men known as Martians, is the entire basis of alien mythology which would go on to inspire 20th century works as The War of the Worlds and The Martian Chronicles.

And for those old enough to recall, the “Martian face”, which was captured by the Viking Orbiter in 1976, is a more modern example. As you can see from the picture below (lower right hand), the low-resolution photos of the Cydonian mesa led many people to see a human face in it. This led to much speculation and more than a few crackpot theories about a civilization on Mars.

However, high-res photos taken in 2001 by the Mars Global Surveyor probe (center) put these claims largely to rest by showing that the “face” was just an optical illusion. However, many of these same theorists moved on to claim that pyramid-like formations in that same region (Cydonia) so closely resembled those of Giza that there had to be a common explanation – i.e. aliens built the pyramids.

And in all cases, the golden rule seems to apply: never let little a thing like the facts or plausibility get in the way of a good story! As the rover continues on its long mission to find evidence of life on Mars, I am sure there will be plenty more pictures being seized upon by oddball theorists who are looking to peddle their oddball theories. Some of them are sure to be entertaining, so stay tuned!

Sources: cbc.ca, space.com