2017年06月12日:火星上的不寻常坑洞-（An Unusual Hole in Mars）

上的不寻常坑洞-（An Unusual Hole in Mars）" title="2017年06月12日:火星上的不寻常坑洞-（An Unusual Hole in Mars）">
2017年06月12日:火星上的不寻常坑洞-（An Unusual Hole in Mars）--原图下载

上的不寻常坑洞">
Image Credit: NASA, MRO, HiRISE,JPL, U. Arizona
说明: 这个不寻常的坑洞是怎么产生的？ 事实上，在这片酷似瑞士奶酪的景观里，到处都是圆洞；不过，除了其中一个之外，其他的在淡色的二氧化碳乾冰蒸发后，都露出了下方满是尘土的火星表面。这个位在影像右上角的极不寻常坑洞，宽度大约100公尺，而且看似贯穿到了下层。然而，为何会有这个坑洞存在与及为何它周围环绕着圆形的撞击坑，至今仍然众说纷纭。不过，最为大家接受的说法指称它是源自陨石撞击。像这类的坑洞之所以特别有趣，是因为它们可能是深入下层大型地下坑洞的入口。而这种自然形成的坑道，与严酷的火星表面有相当程度的隔绝，因此它们是保有火星生命的可能地点。也因此，这种坑洞会是未来太空船、探测器甚至载人行星际探测船的主要探索标的。

原文：

Image Credit: NASA, MRO, HiRISE,JPL, U. Arizona
Explanation: What created this unusual hole in Mars?Actually, there are numerous holes pictured in this Swiss cheese-like landscape, with all-but-one of them showing a dusty, dark, Martian terrain beneath evaporating, light, carbon-dioxide ice. The most unusual hole is on the upper right, spans about 100-meters, and seems to punch through to a lower level.Why this hole exists and why it is surrounded by a circular crater remains a topic of speculation, although a leading hypothesis is that it was created by a meteor impact. Holes such as this are of particular interest because they might be portals to lower levels that extend into expansive underground caves.If so, these naturally-occurring tunnels are relatively protected from the harsh surface of Mars, making them relatively good candidates to contain Martian life.These pits are therefore prime targets for possible future spacecraft, robots, and even human interplanetary explorers.