At the beginning of the century, NASA’s Mars Reconnaissance Orbiter discovered strange formations on the surface of the Red Planet, which scientists called “spiders” because of their specific shape. Many years later, their origin was explained. Results are published by Scientific Reports.
“Spiders” on Mars – unusual branching systems and fractal depressions – are found only in the southern polar region of the planet and have no analogs in the solar system.
After their discovery several years ago, scientists immediately put forward a version of the origin of these formations, but it has only now been confirmed. Researchers have obtained the first physical evidence to support the most popular model for the formation of such structures, known as the Kieffer hypothesis. According to this idea, spider forms are formed by direct sublimation of frozen carbon dioxide.
Giant forms up to 1 km in size are unlike anything on Earth. However, scientists have been able to successfully recreate a smaller version of such formations in the laboratory. To do this, they used a plate of carbon dioxide (dry ice) ice. Scientists also recreated the Martian atmosphere. When cold ice touched a much warmer layer of Martian sediment, part of it instantly turned from a solid to a gas in the process of sublimation. As a result, spider-web cracks formed, from which the gas was pushed through the ice.
The study represents the first set of empirical evidence for a surface process believed to be altering the polar landscape on Mars, lead author Lauren McKeown, a planetary scientist at the Open University in England, said in a statement.