Division of Space Technology, Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, Luleå, Sweden.
Institut für Kartographie, Technische Universität Dresden, Dresden, Germany.
Sci Rep. 2019 Feb 14;9(1):2040. doi: 10.1038/s41598-019-39599-z.
Several interpretations of recurring slope lineae (RSL) have related RSL to the potential presence of transient liquid water on Mars. Such probable signs of liquid water have implications for Mars exploration in terms of rover safety, planetary protection during rover operations, and the current habitability of the planet. Mawrth Vallis has always been a prime target to be considered for Mars rover missions due to its rich mineralogy. Most recently, Mawrth Vallis was one of the two final candidates selected by the European Space Agency as a landing site for the ExoMars 2020 mission. Therefore, all surface features and landforms in Mawrth Vallis that may be of special interest in terms of scientific goals, rover safety, and operations must be scrutinised to better assess it for future Mars missions. Here, we report on the initial detection of RSL candidates in two craters of Mawrth Vallis. The new sightings were made outside of established RSL regions and further prompt the inclusion of a new geographical region within the RSL candidate group. Our inferences on the RSL candidates are based on several morphological and geophysical evidences and analogies: (i) the dimensions of the RSL candidates are consistent with confirmed mid-latitude RSL; (ii) albedo and thermal inertia values are comparable to those of other mid-latitude RSL sites; and (iii) features are found in a summer season image and on the steep and warmest slopes. These results denote the plausible presence of transient liquid brines close to the previously proposed landing ellipse of the ExoMars rover, rendering this site particularly relevant to the search of life. Further investigations of Mawrth Vallis carried out at higher spatial and temporal resolutions are needed to identify more of such features at local scales to maximize the scientific return from the future Mars rovers, to prevent probable biological contamination during rover operations, to evade damage to rover components as brines can be highly corrosive, and to quantify the ability of the regolith at mid-latitudes to capture atmospheric water which is relevant for in-situ-resource utilization.
几种对反复出现的坡线（RSL）的解释都将 RSL 与火星上可能存在的瞬态液态水联系起来。液态水的这些可能迹象对火星探测具有重要意义，包括漫游车的安全、漫游车操作期间的行星保护，以及行星当前的宜居性。由于其丰富的矿物学，Mawrth Vallis 一直是火星漫游车任务的首选目标。最近，Mawrth Vallis 是欧洲航天局选择的两个最终候选着陆点之一，作为 ExoMars 2020 任务的着陆点。因此，Mawrth Vallis 中所有可能在科学目标、漫游车安全和操作方面具有特殊意义的地表特征和地貌都必须进行仔细检查，以便为未来的火星任务更好地评估它们。在这里，我们报告了在 Mawrth Vallis 的两个陨石坑中首次发现 RSL 候选者。新的观测结果是在已建立的 RSL 区域之外进行的，这进一步促使将一个新的地理区域纳入 RSL 候选者群体。我们对 RSL 候选者的推断是基于几个形态和地球物理证据和类比：（i）RSL 候选者的尺寸与已确认的中纬度 RSL 一致；（ii）反照率和热惯性值与其他中纬度 RSL 地点相当；（iii）特征出现在夏季图像以及最陡峭和最温暖的斜坡上。这些结果表示，在靠近 ExoMars 漫游车先前提出的着陆椭圆的地方，可能存在瞬态液态盐水，这使得该地点特别与生命搜索相关。需要在更高的空间和时间分辨率下对 Mawrth Vallis 进行进一步调查，以在局部尺度上识别更多此类特征，从而最大限度地提高未来火星漫游车的科学回报，防止漫游车操作期间可能的生物污染，避免漫游车部件损坏，因为盐水可能具有高度腐蚀性，并量化中纬度地区的风化层捕获大气水的能力，这对于原位资源利用很重要。
