Mars has 'footprints'? Nasa rover spots strange pits unlike anything seen before

Nasa's Curiosity rover has found a strange pattern of tiny pits on Mars that initially look like footprints, but scientists say they were not made by anything walking across the Red Planet.The unusual formations were photographed as Curiosity explored Mount Sharp, a mountain rising about 5,500 metres above the Martian surface. The pits are roughly 1 centimetre wide and appear as shallow depressions across the exposed bedrock.Scientists say small holes and dents are not unusual on Mars. However, these newly observed formations stand out because of their unusual shape and because researchers could not identify the objects that may have created them.Tiny pits create a new Martian mysteryMichelle Minitti, deputy principal investigator for Nasa's Mars Hand Lens Imager programme, told the BBC the formations were unlike features previously seen by the rover."After Curiosity's 14 years on the surface, Mars continues to surprise. Both of our workspaces this week contained features unlike quite anything we have seen in the past - broad, shallow pits (like the one in the image above) dotted across the bedrock."Pits are not uncommon - when resistant nodules or pebbles weather out of their host rock, they leave behind a void"But the pits of this week were much broader and shallower than past features and were not accompanied by obvious objects that were once in the pits."The pits are therefore not evidence of an animal or other object physically stepping on the surface. Researchers believe geological processes are responsible, although they are still trying to determine exactly how the formations developed.Minitti described the discovery as a new puzzle in understanding the geological history of this part of Mount Sharp."They were a welcome new puzzle into the processes that have affected this particular section of rocks in the stratigraphy of Mount Sharp."Curiosity keeps probing the Red PlanetCuriosity also examined the rock around the pits, finding layers with different textures and structures. Its instruments detected resistant layers that differ from the surrounding bedrock and may have formed because of differences in their chemical composition.The discovery adds to a long list of unusual geological features studied by Curiosity since it landed on Mars in 2012.The rover has now spent more than 5,000 days exploring the planet and has sent more than 700,000 images back to Earth. Its latest observations are helping scientists piece together how the rocks and surface of Mount Sharp formed and changed over time.So while the tiny formations may look like footprints at first glance, there is no evidence that anything actually walked across them. For scientists, however, that makes the discovery no less interesting because the pits offer another clue to the geological forces that have shaped Mars.