Japan Is Launching a Probe to Collect the First-Ever Samples From a Martian Moon
Japan Is Launching a Probe to Collect the First-Ever Samples From a Martian Moon
日本即将发射探测器，旨在采集火星卫星的首批样本
A Mars probe from the Japan Aerospace Exploration Agency (JAXA) may answer some longstanding questions about the Red Planet and its moons. The mission—dubbed MMX for “Martian Moons eXploration”—aims to collect at least 10 grams of samples from Phobos, one of two moons orbiting the planet, and if successful, these will be the first rocks from a Martian moon ever brought to Earth.
日本宇宙航空研究开发机构（JAXA）的一项火星探测任务，或许能解答关于这颗红色星球及其卫星的一些长期未解之谜。该任务被称为“火星卫星探测”（Martian Moons eXploration，简称 MMX），目标是从火星的两颗卫星之一——火卫一（Phobos）上采集至少 10 克样本。如果成功，这将是人类首次将火星卫星的岩石带回地球。
They won’t arrive quickly, however. The MMX probe will take approximately one year to reach Mars. It will then collect samples during three years of operations while orbiting the red planet before taking another year to return to Earth. If all goes well, scientists expect to receive the moon rocks in 2031.
然而，这些样本不会很快送达。MMX 探测器大约需要一年时间才能抵达火星。随后，它将在环绕火星运行期间进行为期三年的探测与采样工作，再花费一年时间返回地球。如果一切顺利，科学家们预计将在 2031 年收到这些月球岩石。
One of the most interesting questions the probe can answer is how Mars’ moons, Phobos and Deimos, formed. There are two main possibilities. One is that the moons condensed from material ejected during a massive collision with Mars. The other hypothesis is that the moons were asteroids from the outer solar system that were captured by Mars’ gravity.
该探测器能解答的最有趣的问题之一，就是火星的两颗卫星——火卫一（Phobos）和火卫二（Deimos）是如何形成的。目前主要有两种可能性：一种是卫星由火星遭受巨大撞击后喷射出的物质凝聚而成；另一种假说则认为，这两颗卫星是来自太阳系外围的小行星，被火星引力捕获而成。
The moons are dark in color, and their light-reflecting properties closely resemble those of asteroids rich in water and carbon. Their orbits, however—which are nearly circular along Mars’ equatorial plane in the same direction as the planet’s rotation—are better explained by the giant impact hypothesis. Comparing samples from Mars’ moons to those previously collected from the Martian surface could help settle this debate.
这两颗卫星颜色较暗，其光反射特性与富含水和碳的小行星非常相似。然而，它们的轨道几乎呈圆形，且沿着火星赤道平面与火星自转方向一致，这用“大碰撞假说”来解释更为合理。将火星卫星的样本与此前从火星表面采集的样本进行对比，或许有助于平息这场争论。
To get the Martian moon rocks and transport them back to Earth, however, means overcoming some significant technical challenges in space flight and communication. At launch, the spacecraft will have a mass of 4,480 kilograms (9,900 pounds). More than half of this weight will be fuel, divided into three reserves: one for the outbound leg, one for exploration, and one for the return leg. Once in the vicinity of Mars, MMX will jettison the outbound module after its propellant is exhausted; following the flyby of Deimos, the exploration module will also be jettisoned.
然而，要获取火星卫星岩石并将其运回地球，意味着必须克服航天飞行和通信方面的重大技术挑战。发射时，探测器的质量将达到 4480 公斤（9900 磅）。其中超过一半的重量是燃料，分为三个储备部分：一部分用于去程，一部分用于探测，另一部分用于返程。一旦进入火星附近，MMX 将在去程模块燃料耗尽后将其抛弃；在飞越火卫二后，探测模块也将被抛弃。
The probe, designed by Mitsubishi Electric, will then land on the surface of Phobos, a delicate procedure given the moon’s size, with an approximate radius of just 11 kilometers. (In comparison, Earth’s moon has a radius of more than 1,700 kilometers.) Descent methods used on Earth’s moon rely on its specific gravity, which is about 300 times as strong as that of Phobos. However, Phobos’ gravity is approximately 50 times greater than that of the asteroid Ryugu, where JAXA has previously landed probes. Landing on Ryugu involved prolonged hovering, a typical method for landing on smaller celestial objects, but this is not feasible for MMX as it would consume too much fuel given Phobos’ greater pull.
该探测器由三菱电机设计，随后将着陆在火卫一表面。考虑到火卫一半径仅约 11 公里，这是一个极其精细的操作过程。（相比之下，地球的月球半径超过 1700 公里。）在月球上使用的着陆方法依赖于其特定的重力，而月球重力约为火卫一的 300 倍。不过，火卫一的重力大约是 JAXA 此前曾着陆过的小行星“龙宫”（Ryugu）的 50 倍。在“龙宫”上着陆时采用了长时间悬停的方法，这是在较小天体上着陆的典型方式，但这对 MMX 来说不可行，因为考虑到火卫一较大的引力，这种方法会消耗过多的燃料。
To overcome this challenge, the probe is equipped with high-precision autonomous navigation, which it will need, given that there will be a delay of up to 20 minutes for radio signals to travel between Earth and MMX. The probe must therefore autonomously decide on and execute the descent, landing, and later takeoff sequences.
为了克服这一挑战，探测器配备了高精度自主导航系统。鉴于地球与 MMX 之间的无线电信号传输延迟长达 20 分钟，这是必不可少的。因此，探测器必须自主决定并执行下降、着陆以及随后的起飞程序。
During the descent, the probe will compare the terrain to data on the topography of Phobos’ craters, using this information to adjust its position toward the target landing site. Once it’s reached an altitude under 300 meters, the probe will also detect whether parts of the surface have changed in elevation, labeling significant discrepancies as hazardous areas. This mechanism allows the probe, if necessary, to change the landing site or abort the landing and temporarily ascend.
在下降过程中，探测器会将地形与火卫一陨石坑的地形数据进行比对，利用这些信息调整位置，向目标着陆点靠拢。一旦高度降至 300 米以下，探测器还会探测表面部分区域的海拔是否发生变化，并将显著的差异标记为危险区域。这一机制使得探测器在必要时可以更换着陆点，或者中止着陆并暂时上升。
Just ahead of the main spacecraft’s landing, the IDEFIX rover—jointly developed by the French and German space agencies—will be deployed onto the surface of Phobos to conduct approximately 100 days of independent exploration. This preliminary survey by the rover will serve as a scout to ensure a safer landing.
在主探测器着陆前夕，由法国和德国航天机构联合开发的 IDEFIX 漫游车将被部署到火卫一表面，进行约 100 天的独立探测。漫游车的这项初步勘测将充当“侦察兵”，以确保主探测器能更安全地着陆。
Once on the surface, a robotic arm will drill cylindrical tubes into the surface to collect samples. The probe is also equipped with a device first developed by NASA that uses a stream of nitrogen gas to collect fine particles from the very top layer of dust. Whether or not Phobos originated from an impact with the planet, experts believe Martian sand can be obtained from the lunar surface. Over time, meteorite impacts have blasted materials off Mars, coating its moons. Scientists expect about 0.1 percent of the samples collected will be debris from Mars itself.
一旦着陆，机械臂将钻入表面采集圆柱状样本。探测器还配备了一种由 NASA 最初开发的装置，利用氮气流从最表层的尘埃中收集微小颗粒。无论火卫一是否起源于火星撞击，专家们都认为可以从其表面获得火星沙尘。长期以来，陨石撞击将物质从火星表面轰击出来，覆盖在卫星上。科学家预计，采集到的样本中约有 0.1% 将是来自火星本身的碎片。
Costing about $345 million US, this mission marks Japan’s first Mars probe launch in 28 years. Beyond the scientific insights it’s expected to provide, from an engineering perspective, the mission aims to test new technologies that could aid future sampling and round-trip travel to Mars.
该任务耗资约 3.45 亿美元，是日本 28 年来首次发射火星探测器。除了预期提供的科学见解外，从工程角度来看，该任务还旨在测试有助于未来火星采样和往返旅行的新技术。
MMX is scheduled to launch from the Tanegashima Space Center on October 20, 2026.
MMX 计划于 2026 年 10 月 20 日从种子岛宇宙中心发射。
This story originally appeared on WIRED Japan and has been translated from Japanese.
本文最初发表于《连线》（WIRED）日本版，由日语翻译而来。