Watery streaks on Mars might be sand flows

• Autores: Leah Crane
• Localización: New scientist, ISSN 0262-4079, Nº. 3118, 2017, pág. 16
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • The mysterious dark flows on Mars may not be water after all. Instead, they could be rivulets of sand, set in motion by sunlight on the Martian surface. Frederic Schmidt at the University of Paris-South and his colleagues have an idea that needs no liquids: sand avalanches caused by sunlight and shadow. When sunlight hits the sand, it heats up the top layer while leaving deeper layers cool. This temperature gradient changes the pressure of tiny gas pockets around the sand particles shifting the gas upward. This in turn jostles grains of sand and soil, causing them to slip dawn the Martian slopes. The effect should be most pronounced in afternoon shadows cast by boulders or outcrops. In this situation, the contrast between the cooling surface and the still-warm layers just below creates a pressure gradient as well, shifting the gas and sand even more.