华盛顿，10月28日——火星是一个尘土飞扬的地方。日常的风、被称为尘卷风的旋风，以及在局部、区域和全球范围内肆虐的更大规模沙尘暴，都在使尘埃四处流动。尘埃是任何人类火星任务都必须应对的一个因素，而来自美国宇航局一辆火星车的新数据正在揭示它可能构成多大的挑战。
WASHINGTON, Oct 28 - Mars is a dusty place. Dust is circulated by everyday winds, whirlwinds called dust devils and larger dust storms raging at local, regional and global scales. Dust is a factor that must be addressed in any human mission to Mars, and new data from a NASA rover is revealing just how much of a challenge it may present.
美国宇航局的“毅力”号火星车自2021年着陆以来，一直在火星北半球一个名为杰泽罗陨石坑的区域及其周边运行，它探测到了迄今在地球这颗行星邻居上发现的最细微的尘埃颗粒。它记录到了宽度仅约100纳米的超细颗粒，比人类头发细约500倍。
NASA's Perseverance rover, operating in and around an area called Jezero Crater in the Martian northern hemisphere since landing in 2021, has detected the finest particles of dust to date on Earth's planetary neighbor. It documented ultrafine particles as small as around 100 nanometers wide, about 500 times thinner than a human hair.
“更小的颗粒尺寸并不一定使尘埃更危险，但更小的颗粒确实更有可能深入人体，也更难被人体清除，”圣路易斯华盛顿大学行星科学家斯科特·范博梅尔说。他是“毅力”号科学团队成员，也是一项在《美国国家科学院院刊》上描述这些发现的研究的第一作者。
"A smaller particle size does not necessarily make dust more dangerous, but smaller particles do have a higher potential to penetrate deeper into the human body and are harder for the body to clear," said planetary scientist Scott VanBommel of Washington University in St. Louis, a member of the Perseverance science team and lead author of a study describing the findings in the journal Proceedings of the National Academy of Sciences.
“与任何物质一样，毒性取决于剂量和持续时间。火星尘埃含有二氧化硅、铁化合物以及高氯酸盐等氯化合物，这些物质在地球上达到足够高的剂量时已知是有害的，”范博梅尔说。
"Like any substance, toxicity depends on dose and duration. Martian dust contains silica, iron compounds and chlorine compounds such as perchlorate, which are known to be harmful at high enough doses on Earth," VanBommel said.
“毅力”号测量了附着在火星车硬件上的尘埃颗粒，包括这辆六轮机器人车辆上搭载的宇航服材料，目的是观察它们在火星恶劣环境中的耐受情况。
Perseverance measured dust particles that stuck to rover hardware including spacesuit materials carried aboard the six-wheeled robotic vehicle with the intent to observe how they hold up in the planet's harsh environment.
此前的测量只能分辨出直径约3微米的火星尘埃颗粒。但“毅力”号搭载的X射线岩石化学行星仪（PIXL）记录到了两类更小的颗粒。除了超细颗粒外，还有一类直径小于2.5微米的细颗粒，比一根头发丝细30倍。
Previous measurements resolved Martian dust particles down to about 3 micrometers in diameter. But Perseverance's Planetary Instrument for X-ray Lithochemistry, or PIXL, documented two categories of particles even smaller. Along with the ultrafine particles, there was a category of fine particles of less than 2.5 micrometers in diameter, or 30 times thinner than a strand of hair.
这些微小的颗粒可能小到足以进入宇航员的肺部、进入血液，并可能损害重要器官。另一个担忧是，火星环境和尘埃的物理特性可能会随着时间的推移使宇航服和栖息地材料退化。
Such tiny particles could be small enough to penetrate an astronaut's lungs, enter the bloodstream and potentially damage vital organs. Another concern is that the Martian environment and dust's physical properties could degrade spacesuit and habitat materials over time.
考虑到这一点，“毅力”号携带了可能的宇航服材料样本，例如人造纤维Vectran和保护涂层特氟龙，每个样本约3/4英寸（20毫米）见方。
With this in mind, Perseverance carries samples of possible spacesuit materials such as the manufactured fiber Vectran and the protective coating Teflon, each about three-quarters of an inch (20 mm) square.
范博梅尔说：“我们没有证据表明尘埃损坏了宇航服材料，只是材料与尘埃的相互作用方式不同。Vectran似乎会吸附较大的尘埃颗粒，在其编织物的底面最为明显。特氟龙样本吸附的尘埃较少，但吸附的尘埃更细，这反映出静电特性如何使不同大小的颗粒优先附着在不同材料上的差异。”火星上的宇航员：NASA计划最早在2030年代将宇航员送上火星。
"We don't have evidence that the dust damaged the spacesuit materials, just that the materials tended to interact with dust differently," VanBommel said. "Vectran appeared to hold larger dust particles, with the greatest prevalence on the underside of its weave. The Teflon sample held less dust, but the dust it held was finer, reflecting differences in how electrostatic properties can preferentially adhere particles of different sizes to each material." ASTRONAUTS ON MARS NASA is looking to send astronauts to Mars as early as the 2030s.
范博梅尔说：“这些发现将有助于为未来载人火星任务的人类支持系统设计提供信息，包括选择适用于亚微米颗粒尺寸的宇航服和栖息地材料以及清洁方法。它们还补充了NASA已制定的毒理学风险指南和规程。”
"These findings will help inform the design of future human support systems for crewed Mars missions, including the choice of suit and habitat materials and cleaning methods that work at sub-micron particle sizes. They also add to the guidelines and protocols NASA has established for toxicological risk," VanBommel said.
范博梅尔说：“有多少尘埃进入栖息地，将在很大程度上取决于宇航服和气闸的设计，这项工作正在进行中。NASA目前正在研究宇航服接口——宇航服的对接站——和双室气闸，以及其他概念，以将尘埃挡在生活区之外。”
"How much dust reaches a habitat will depend largely on how suits and airlocks are designed, and that work is ongoing. NASA is currently studying suitports — docking stations for spacesuits — and dual-chamber airlocks, as well as other concepts, to keep dust out of living areas," VanBommel said.
NASA从1969年至1972年阿波罗宇航员登月中积累了关于尘埃影响的经验。月球尘埃使宇航服外层退化，损坏密封件并划伤面罩。它还可能和一些宇航员出现的类似花粉症的症状有关。但火星尘埃与月球尘埃不同。
NASA has experience with the effects of dust from the Apollo astronaut moon landings from 1969 to 1972. Lunar dust degraded outer spacesuit layers, damaged seals and scratched visors. It also may have been associated with symptoms resembling hay fever among some astronauts. But Mars dust differs from lunar dust.
范博梅尔说：“在月球上，尘埃主要由地表撞击产生，包括微陨石撞击。由于没有大气或风来磨损它们，月球颗粒保持尖锐和棱角分明。对月球尘埃的大部分担忧来自其形状，而对火星尘埃而言，其主要担忧在于其化学成分和颗粒大小。”
"On the moon, dust is generated largely by surface impacts, including by micrometeorites. With no atmosphere or wind to wear them down, lunar particles stay sharp and angular. Most of the concern about lunar dust comes from its shape, whereas for Martian dust its chemistry and particle size are the primary concerns," VanBommel said.
火星尘埃主要来自火星上细粒玄武岩。颗粒的风化作用使其磨蚀性降低。
Mars dust arises primarily from the planet's fine-grained basaltic rocks. Weathering of the particles makes them less abrasive.
范博梅尔说：“活跃的风环境将其在全球范围内混合，使其成分相当均匀。同样的环境使颗粒变圆，并通过碰撞逐渐将它们分解成更小的颗粒。”
"The active wind environment mixes it globally, giving it a rather uniform composition. That same environment rounds the particles and gradually breaks them into smaller particles through collisions," VanBommel said.
“毅力”号的重点一直是寻找古代火星微生物生命的迹象。但美国宇航局也利用它来为载人任务做准备。
Perseverance's focus has been on searching for signs of ancient Martian microbial life. But NASA also has used it to prepare for human missions.
范博梅尔说：“这项研究的结果并不意味着火星对人类来说太危险。火星尘埃是一种必须加以设计应对的危害，就像辐射和与地球的距离一样。”
"The results from this study do not mean Mars is too dangerous for humans. Mars dust is a hazard that has to be designed for, in the same way radiation and distance from Earth are," VanBommel said.