A key objective of the Perseverance rover mission is to acquire samples of Martian rocks for future return to Earth. Eventual laboratory analyses of these samples would address key questions about the evolution of the Martian climate, interior, and habitability. Many such investigations would benefit greatly from samples of Martian bedrock that are oriented in absolute Martian geographic coordinates. However, the Mars 2020 mission was designed without a requirement for orienting the samples. Here we describe a methodology that we developed for orienting rover drill cores in the Martian geographic frame and its application to Perseverance's first 20 rock samples. To orient the cores, three angles were measured: the azimuth and hade of the core pointing vector (i.e., vector oriented along the core axis) and the core roll (i.e., the solid body angle of rotation around the pointing vector). We estimated the core pointing vector from the attitude of the rover's Coring Drill during drilling. To orient the core roll, we used oriented images of asymmetric markings on the bedrock surface acquired with the rover's Wide Angle Topographic Sensor for Operations and eNgineering (WATSON) camera. For most samples, these markings were in the form of natural features on the outcrop, while for four samples they were artificial ablation pits produced by the rover's SuperCam laser. These cores are the first geographically-oriented (<2.7° 3σ total uncertainty) bedrock samples from another planetary body. This will enable a diversity of paleomagnetic, sedimentological, igneous, tectonic, and astrobiological studies on the returned samples.

中文翻译：

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毅力号火星车在火星上钻取的定向基岩样本

毅力号火星车任务的一个关键目标是获取火星岩石样本，以便将来返回地球。最终对这些样本的实验室分析将解决有关火星气候、内部结构和宜居性演变的关键问题。许多此类调查将大大受益于以绝对火星地理坐标为导向的火星基岩样本。然而，2020 年火星任务的设计并未要求对样本进行定向。在这里，我们描述了一种用于在火星地理框架中定向流动钻芯的方法，及其在毅力号前 20 个岩石样本中的应用。为了对芯进行定向，测量了三个角度：芯指向矢量（即，沿着芯轴定向的矢量）的方位角和角度以及芯滚动（即，围绕指向矢量旋转的固体角度）。我们根据流动站取芯钻机在钻探过程中的姿态估计了岩芯指向矢量。为了定向核心卷，我们使用了基岩表面上的不对称标记的定向图像，这些图像是通过流动站的操作和工程广角地形传感器（WATSON）相机获取的。对于大多数样本来说，这些标记都是露头上自然特征的形式，而对于四个样本来说，它们是由流动站的 SuperCam 激光器产生的人工烧蚀坑。这些岩心是来自另一个行星体的第一个地理导向（<2.7° 3 σ总不确定性）基岩样本。这将使对返回的样本进行各种古地磁学、沉积学、火成岩、构造和天体生物学研究成为可能。