(ORDO NEWS) — When winter comes to Mars, the surface turns into a truly otherworldly world, said NASA‘s Jet Propulsion Laboratory. Winter on Mars is also cold – at the poles the temperature can drop to -123°C.
However, snow drifts should not be expected. No region of Mars receives more than a few meters of snow. And most of it falls into extremely flat areas.
However, the planet offers unique winter phenomena that scientists have been able to study thanks to Mars explorer robots.
There are two types of Martian snow: water ice with carbon dioxide and dry ice.
Because the Martian air is so thin and the temperature is so cold, water ice snow sublimates and turns into gas before it hits the ground. Dry ice reaches the ground.
Snow occurs only at the poles, under cloud cover and at night. Cameras on orbiting spacecraft can’t see through clouds, and ground-based Martian missions can’t survive the extreme cold.
As a result, not a single image of falling snow was ever made. But scientists know that this happens thanks to several special scientific instruments.
The Mars Reconnaissance Orbiter captures light at wavelengths invisible to the human eye. This ability allowed scientists to detect snow falling to the ground from carbon dioxide.
And in 2008, the Phoenix lander, 1600 kilometers from the north pole of Mars, used a laser instrument to detect snow from water ice falling to the surface.
Because of the way water molecules bind together when they freeze, snowflakes on Earth have six sides.
The same principle applies to all crystals: the shape of a crystal is determined by how the atoms are arranged.
In the case of carbon dioxide, the molecules in dry ice always form a cube when frozen. Moreover, each snowflake is less than the width of a human hair.
Perhaps the most fabulous event comes at the end of winter, when all the accumulated ice begins to “melt” and sublimate into the atmosphere. In this case, the ice acquires bizarre and beautiful forms.
This “thaw” also causes geysers to erupt: the translucent ice allows sunlight to heat the gas below it, and that gas eventually erupts, sending a fan of dust to the surface.
They are studied to understand where the Martian winds blow.
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