Centre for Research in Earth and Space Science, Department of Earth and Space Science and Engineering, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.
Applied Physics Laboratory, Johns Hopkins University, Baltimore, Maryland, USA.
Nature. 2017 Jan 12;541(7636):188-190. doi: 10.1038/nature20779. Epub 2017 Jan 4.
Penitentes are snow and ice features formed by erosion that, on Earth, are characterized by bowl-shaped depressions several tens of centimetres across, whose edges grade into spires up to several metres tall. Penitentes have been suggested as an explanation for anomalous radar data on Europa, but until now no penitentes have been identified conclusively on planetary bodies other than Earth. Regular ridges with spacings of 3,000 to 5,000 metres and depths of about 500 metres with morphologies that resemble penitentes have been observed by the New Horizons spacecraft in the Tartarus Dorsa region of Pluto (220°-250° E, 0°-20° N). Here we report simulations, based upon a recent model representing conditions on Pluto, in which deepening penitentes reproduce both the tri-modal (north-south, east-west and northeast-southwest) orientation and the spacing of the ridges of this bladed terrain. At present, these penitentes deepen by approximately one centimetre per orbital cycle and grow only during periods of relatively high atmospheric pressure, suggesting a formation timescale of several tens of millions of years, consistent with crater ages. This timescale implies that the penitentes formed from initial topographic variations of no more than a few tens of metres, consistent with Pluto's youngest terrains.
冰棱是由侵蚀作用形成的冰雪特征，在地球上，其特征是直径几十厘米的碗状凹陷，边缘逐渐变成高达数米的尖顶。冰棱被认为是欧罗巴异常雷达数据的一种解释，但到目前为止，除地球外，在其他行星体上还没有明确识别出冰棱。新视野号飞船在冥王星的塔图鲁斯多萨地区（220°-250°E，0°-20°N）观测到了具有冰棱形态的、间距为 3000 至 5000 米、深度约 500 米的规则脊。在这里，我们报告了基于最近一个代表冥王星条件的模型的模拟结果，其中加深的冰棱再现了脊的三模态（南北向、东西向和东北-西南向）取向和间距。目前，这些冰棱每轨道周期大约加深一厘米，并且只在相对较高的大气压力期间生长，这表明形成时间尺度为数千万年，与陨石坑的年龄一致。这个时间尺度意味着冰棱是由最初的地形变化形成的，不超过几十米，与冥王星的最年轻地形一致。
