当地球处于北半球冬季时，火星南半球正接近春末，轨道卫星看到的暗色“花朵”——在21世纪初首次发现——表明局部环境在某些时段比火星表面其他时间更适居。

在南半球冬季，高纬度冷到足以让大气中的二氧化碳冻结成不透明的干冰冰盖，厚度约1米；但随着春季到来，尘埃从内部加热使其变得半透明，阳光促使底部升华，气体压力在冰下累积，直到变薄的冰层破裂并以小喷流喷出、携带并沉积暗色尘埃。

由此形成的放射状星爆沉积以及相关的蛛网状（“蜘蛛”）侵蚀地貌，刻画出一种可重复的季节性机制：受压的二氧化碳气体在冰下流动、喷逸，并在这些区域雕刻地表。

While Earth is in northern-hemisphere winter, Mars’s southern hemisphere is nearing the end of spring, and dark “blooms” seen by orbiting satellites—first identified in the early 2000s—indicate local conditions that can be more habitable than Mars’s surface at other times.

In southern winter, high latitudes become cold enough for atmospheric carbon dioxide to freeze into an opaque dry-ice cap about 1 metre thick; but as spring arrives, dust warms it from within, makes it translucent, and sunlight drives basal sublimation that builds gas pressure until the thinning layer ruptures in small jets that carry and deposit dark dust.

The resulting radial starburst deposits and related araneiform (“spider”) erosional features trace a repeatable seasonal mechanism: pressurised carbon-dioxide gas flows beneath ice, vents, and sculpts the surface across these regions.

Source: The spiders on the icecaps of Mars

Subtitle: Astrobiologists think they could point to more habitable areas on the red planet

Dateline: 12月 30, 2025 05:49 上午