科学美国人60秒 太空尘埃的潜在危险（在线收听）

Aside from all the satellites, and the space station orbiting the Earth, there's a lot of trash circling the planet, too. Twenty-one thousand baseball-sized chunks of debris, according to NASA. But that number's dwarfed by the number of small particles. There's hundreds of millions of those.

除了人造卫星和太空站，环绕地球运行的还有很多垃圾。据美国国家航空航天局称，有21000个棒球大小的碎片在环绕地球运行。但这一数字与微小颗粒的数量相比显得很微不足道。因为微小颗粒有数亿之多。

"And those smaller particles tend to be going fast. Think of picking up a grain of sand at the beach, and that would be on the large side. But they're going 60 kilometers per second."

“那些较小的微粒更倾向于快速运行。可以试想一下在沙滩上捡起一粒沙子，而现实中微粒的数量要比这大得多。而且这些微粒的速度还高达60千米每秒。”

Sigrid Close, an applied physicist and astronautical engineer at Stanford University. Close says that whereas mechanical damage—like punctures—is the worry with the bigger chunks, the dust-sized stuff might leave more insidious, invisible marks on satellites—by causing electrical damage.

西格丽德·克洛斯是斯坦福大学的一名应用物理学家和航天工程师。克洛斯表示，像爆胎穿孔这样的机械损伤只是对较大块碎片的担忧，而灰尘大小的物质可能会通过引起电学损伤给卫星留下更隐秘、更无形的痕迹。

"We also think this phenomenon can be attributed to some of the failures and anomalies we see on orbit, that right now are basically tagged as 'unknown cause.'"

“我们认为这一现象还可能是导致卫星轨道上出现一些失败和异常现象的原因，而目前出现这些现象的原因基本上全被标记为‘未知原因’。”

Close and her colleague Alex Fletcher modeled this phenomenon mathematically, based on plasma physics behavior. And here's what they think happens. First, the dust slams into the spacecraft. Incredibly fast. It vaporizes and ionizes a bit of the ship—and itself. Which generates a cloud of ions and electrons, traveling at different speeds. And then: "It's like a spring action, the electrons are pulled back to the ions, ions are being pushed ahead a little bit. And then the electrons overshoot the ions, so they oscillate, and then they go back out again.”

克洛斯和同事亚历克斯·弗莱彻根据等离子体物理学行为对这一现象进行了数学建模。以下是他们的想法。首先，灰尘极为快速地猛烈撞进飞船，进而蒸发并使自身及一点点船体发生电离化，而后产生一团离子和电子，并以不同的速度移动。然后:“这就像弹簧作用一样，电子被拉回至离子，离子则又被向前推进一点点。再然后，电子超越离子，两者产生振荡，最后它们再次飞出船体。”

That movement of electrons creates a pulse of electromagnetic radiation, which Close says could be the culprit for some of that electrical damage to satellites. The study is in the journal Physics of Plasmas.

电子的这一运动产生了电磁辐射脉冲，克洛斯称，这可能就是对卫星造成某些电学损伤的罪魁祸首。这项研究发表在《等离子体物理期刊》杂志上。

The implications of these small particles on future spaceflight is huge. "One of my dreams is interstellar travel. I love Star Trek. I grew up hoping I could build something to get outside our solar system, and I feel like this is just one of the many things we have to worry about. I think the space environment as a whole is still something we need to tackle." Before it tackles any astronauts a long way from home.

这些微小粒子对未来太空飞行的影响非常大。“我的梦想之一就是星际旅行。我很喜欢《星际迷航》。从小我就希望能造出一些能飞出太阳系的东西，我感觉这只是我们需要担忧的许多事物中的一个。我认为太空环境作为一个整体仍然是需要我们去探索解决的问题。”——在它解决掉任何一个远离家园的宇航员之前。