Phobos and Deimos occupy unique positions both scientifically and programmatically on the road to the exploration of the solar system. Japan Aerospace Exploration Agency (JAXA) plans a Phobos sample return mission (MMX: Martian Moons eXploration). The MMX spacecraft is scheduled to be launched in 2024, orbit both Phobos and Deimos (multiple flybys), and retrieve and return >10 g of Phobos regolith back to Earth in 2029. The Phobos regolith represents a mixture of endogenous Phobos building blocks and exogenous materials that contain solar system projectiles (e.g., interplanetary dust particles and coarser materials) and ejecta from Mars and Deimos. Under the condition that the representativeness of the sampling site(s) is guaranteed by remote sensing observations in the geologic context of Phobos, laboratory analysis (e.g., mineralogy, bulk composition, O-Cr-Ti isotopic systematics, and radiometric dating) of the returned sample will provide crucial information about the moon’s origin: capture of an asteroid or in-situ formation by a giant impact. If Phobos proves to be a captured object, isotopic compositions of volatile elements (e.g., D/H, 13 C/ 12 C, 15 N/ 14 N) in inorganic and organic materials will shed light on both organic-mineral-water/ice interactions in a primitive rocky body originally formed in the outer solar system and the delivery process of water and organics into the inner rocky planets.

中文翻译：

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火卫一样本返回对了解火星-月球系统的重要性

在探索太阳系的道路上，火卫一和火卫二在科学和程序上都占据着独特的位置。日本宇宙航空研究开发机构（JAXA）计划进行火卫一样本返回任务（MMX：火星卫星探测）。MMX 航天器计划于 2024 年发射，围绕火卫一和火卫二（多次飞越）轨道运行，并在 2029 年取回超过 10 克火卫一风化层并将其送回地球。火卫一风化层代表了内源性火卫一积木和外源性火卫一的混合物包含太阳系抛射物（例如，行星际尘埃粒子和较粗的材料）和来自火星和火卫二的喷射物的材料。在火卫一地质背景下的遥感观测保证采样点的代表性的条件下，实验室分析（例如矿物学、返回样本的整体成分、O-Cr-Ti 同位素系统学和放射性测年）将提供有关月球起源的重要信息：通过巨大的撞击捕获小行星或原位形成。如果火卫一被证明是一个捕获的物体，无机和有机材料中挥发性元素（例如，D/H、13 C/ 12 C、15 N/ 14 N）的同位素组成将揭示有机矿物水/冰最初形成于外太阳系的原始岩石体中的相互作用以及水和有机物向内岩石行星的输送过程。