In mid-summer NASA’s “Curiosity” rover sent the lens of its NavCam camera up and made some amazing pictures of clouds, very rare for the Red Planet. NASA notes that clouds like cirrus clouds on Earth are a sight in the distant past of Mars.
Eight photographs of thin clouds lines in the Martian sky were made on July 17 about five degrees south of the Martian equator. Then the rover lowered the camera and made eight more pictures, in which clouds consisting of ice crystals move along the southern horizon. In the foreground of these photographs, several hills are clearly visible. A little later on the same day, the probe repeated a series of images, and no clouds were observed on them, which indicates the fleetingness of this natural phenomenon on the Red Planet.
NASA also notes that the pictures for the first time in the history of the Martian observations made it possible to clearly see the clouds in the atmosphere of the planet. To emphasize the dynamics of the change from frame to frame, Harissa Campbell, a member of the scientific team of the mission “Kyuriosity” from York University in Toronto, processed the images, reducing noise.
In turn, her colleague John Moores explained that the clouds on Mars are most likely formed from frozen water crystals that condense on dust particles in cold areas of the atmosphere. On Earth such clouds, called pinnate, form at high altitude. However, in the case of Mars, it is not possible to establish the height of the formation of these clouds: there is no special equipment on the rover.
Scientists also note that although today such clouds are a rarity for Mars, billions of years ago the situation could be different. Then the climate on the planet was probably warm enough and water could flow on the surface of Mars for an extended period of time.
Last year researchers from the Karl Sagan Institute suggested that it was the cirrus clouds of 3.2 billion years ago that could provide the necessary protection for liquid water. In this case, computer simulation showed that under certain circumstances clouds in the early Martian atmosphere could remain about four to five times longer than on Earth.