08年五大天文新发现 Top 5 Amazing Astronomy Discoveries in 2008
发布: 2008-12-28 11:41 | 作者: webmaster | 来源: 本站原创 | 查看: 260次
2. 火星可能存在生命
凤凰号火星探测器拍摄的全景照片
2008年的火星受到“明星”般的待遇。5月，宇航局的“凤凰”号火星登陆器正式驾临这颗红色星球；“机遇”号和“勇气”号火星探测漫游者仍在其地表跋涉；“火星侦察轨道器”探测器已对火星近40%的区域进行拍摄。所有类似任务的一个重要目标就是寻找火星过去或现在存在液态水这个生命摇篮的迹象。这也就是为什么“凤凰”号在火星北极附近发现水冰之后成为世界各大媒体关注的焦点。
2008年初，“勇气”号在古瑟夫陨坑发现了硅沉积物。科学家表示，这说明热水曾一度通过热液喷口穿过火星土壤。在地球上，这些热液喷口可能曾是生命的港湾。如果火星确曾有生命存在过的话，硅沉积物能够保存古代生命体的化石。在“火星侦察轨道器”的帮助下，科学家发现火星表面存在碳酸盐的证据。由于碳酸盐无法在酸性恶劣环境中存在，这一矿物质的发现说明，在还是一个湿润世界的时候，火星上曾出现过微生物。
2. Martian life?
The red planet has gotten celebrity treatment this past year, with the touchdown of NASA's Phoenix Mars Lander in May, the continuing presence of the Mars Exploration Rover twins (Spirit and Opportunity) and NASA's Mars Reconnaissance Orbiter (which has imaged nearly 40 percent of the planet).
A major goal of such missions has been to find signs of past or present liquid water, the main ingredient for life. That's why Phoenix snagged a star-studded headline when the lander collected water ice near Mars' north pole this year.
Earlier in the year, Spirit found deposits of silica in Gusev Crater, suggesting, scientists said, that hot water once flowed through the Martian soil in hydrothermal vents. As on Earth, these hydrothermal vents may have once harbored life. The discovered silica could preserve fossils of such ancient life if it did indeed exist there.
And just in from MRO — evidence of carbonates on the Martian surface. Since carbonates can't survive in acidic, harsh conditions, the mineral finding suggests any microbes crawling around when Mars was wet could've enjoyed a cushy existence.
