Sandy Gas Jets Hypothesized on Mars

圖示版權與提供: Ron Miller (ASU)
Explanation:
     What's causing seasonal dark spots on Mars? Every spring, strange dark spots appear near the Martian poles, and then vanish a few months later. These spots typically span 50 meters across and appear fan shaped. Recent observations made with THEMIS instrument onboard NASA's Mars Odyssey, currently orbiting Mars, found the spots to be as cold as the carbon dioxide (CO2) ice beneath them. Based on this evidence, a new hypothesis has been suggested where the spots are caused by explosive jets of sand-laden CO2. As a pole warms up in the spring, frozen CO2 on the surface thins, perforates, and begins to vent gaseous CO2 held underneath. Within this hypothesis, interspersed dark sand would explain the color of the spots, while the underlying frozen CO2 would explain the coolness of the spots. Pictured above, an artist depicts what it might be like to stand on Mars and witness the venting of these tremendous gas and dust jets.
說明:
      火星上具季節變化的暗斑是怎麼產生的？每年的春季，奇特的暗斑就會出現在火星的極區，然後在數個月後消失。這些暗斑典型的跨度約有50公尺，而且具有扇形的形狀。正在探索火星的火星奧德賽號探測船，最近用搭載的THEMIS相機進行的觀測，發現這些暗斑和它下方的乾冰一樣冷。根據這項證據，一項剛被提出的假說認為，這些暗斑是由飽含砂塵的二氧化碳噴流所造成的。在春季時，極區溫度上升，表面的乾冰變薄、穿孔、並開始噴出下方的二氧化碳氣體。在這個假說的架構內，挾雜的暗色砂粒可以解釋暗斑的顏色，而下方的乾冰可以解釋暗斑所具有的溫度。在上面的圖示裡，畫家描繪站立在火星目睹這種這種強大氣砂噴流的可能景象。
資料來源: Scientific American
                 Department of Physics, NCKU