月球和地球的尘土在显微镜下有什么不同的特点?What are the differences between lunar dust and Earth dust under the microscope and how it behaves?

https://www.quora.com/What-are-the-differences-between-lunar-dust-and-Earth-dust-under-the-microscope-and-how-it-behaves

As posed, your question is meaningless, as “Earth dust” could mean anything from clay to talcum power to cat dander.

您的问题毫无意义,因为“尘土”可能意味着从黏土,滑石粉或猫皮屑之类的任何东西。

Let’s rephrase the question to ask what you really mean to ask: Why do boots leave clear prints in lunar regolith when boot prints in most Earth soils would collapse without moisture to stick the particles together.

让我们重新定义一下问题,弄清楚您真正要问的是什么:为什么在大多数地球土壤中的靴印会塌陷,而没有水分将颗粒粘在一起的情况下,却能在月球表面留下清晰的印记。

First let’s only discuss sand, as it’s the best example we have of Earth soil that won’t hold a print when dry, and because most other Earth soils contain organic matter that make a comparison essentially meaningless.

首先,我们仅讨论沙子,因为这是我们拥有的最好的地球土壤实例,它在干燥时不会留下印迹,并且因为大多数其他地球土壤都含有有机物,因此进行比较几乎没有意义。

Here are fresh shoe or boot prints in dry Earth sand:

这是在干燥的地球沙子中的刚踩出的鞋子印记:

Notice you can see individual grains of sand. That’s because on Earth, there is wind and water, and any time weathering sand particles get below a certain size, the resulting dust blows or is washed away and winds up going into solution forming sediment somewhere and/or chemically reacting with some surface.

请注意,您可以看到单个沙粒。那是因为在地球上,有风有水,而且任何时候风化的沙粒达到一定尺寸以下,所产生的粉尘就会被吹走或冲走,并逐渐进入溶液中形成沉淀物,并/或与某些表面发生化学反应。

That means that natural sand on Earth has a fairly consistent grain size, with few larger or smaller particles. It also means that Earth sand is essentially a bunch of little silica balls:

这意味着地球上的天然沙粒尺寸相当一致,几乎没有大小相差过大的颗粒。这也意味着地球上的沙子实际上是一堆小二氧化硅球:

[Libyan desert sand—particle size 500–1,000 microns]

【[利比亚沙漠沙-粒径500-1,000微米]】

See all those rounded edges? Those come from constant movement of particles against each other, either by the action of wind or waves.

看到所有那些圆角的边缘吗?它们来自于粒子在风或波的作用下不断相互运动。

On the moon, there is no wind and no waves. Moon dust is created by the constant bombardment, over millions of years, of surface rocks by meteorites large and small. Unlike Earth, there is no wind to carry away dust, and no water to cause it to bind chemically. It just builds up, giving the regolith a fractal symmetry of boulders large and small.

在月球上,没有风也没有浪。数百万年来,大小不一的陨石不断轰击地表岩石,形成了月尘。与地球不同,没有风可以带走灰尘,也没有水可以使灰尘化学结合。于是它们慢慢堆积起来,在月球的表层沉积物上形成一些大小不一的,有分形形状的石头。

[Lunar regolith from Apollo 17, particle size 20–50 microns]

【来自阿波罗17号的月球表层沉积物,粒径20–50微米】

Lunar dust is much, much smaller than Earth sand, and see all those jagged edges? They readily lock particles together. Further, on the moon there is no air between the particles, either to lubricate or “fluff” them. There is just dust, settled by millions of years of impacts and moonquakes, and tightly locked together.

月球尘埃比地球沙尘小得多,并且看到那些锯齿状的边缘吗?他们很容易将粒子固定在一起。此外,在月球上,粒子之间没有空气润滑或“疏松”它们。尘土被数百万年的撞击和地震所沉降,并紧密地固定在一起。

Here is Buzz Aldrin’s boot print on the moon:

这是Buzz Aldrin在月球上的靴子印记:

Note how fine the dust is inside the compressed print. The undisturbed surface appears rougher because it’s made up of ejecta paticles of all sizes that have fallen after meteoritic impacts, leaving a “fluffy surface.”

请注意脚压上去后的尘土多么整洁漂亮。旁边没被踩过的表面看起来更粗糙,因为它由各种大小的喷射颗粒组成,这些颗粒在陨石撞击后掉落下来,留下了“蓬松的表面”。

The closest thing you can find to lunar regolith on Earth is rock dust from a mechanical crusher that has not had the opportunity to weather.

您可以找到最接近月球表层土的地球上的物质,是来自没有机会风化的机械破碎机产生的岩屑。

Portland cement is a good example, and behaves similarly.

波特兰水泥是一个很好的例子,特性很类似。

[Clear shovel imprint in pile of dry portland cement.]
[在干的波特兰水泥中清晰的铲痕。]

Lunar regolith has a finer grain size even than cement, and it is electrically charged, which further helps particles stick together. This is very different from sand or other Earth soils, which generally contain more volatiles and organics, and at least some moisture.

月球表层土的粒径甚至比水泥还要细,并且带电,这进一步有助于颗粒粘在一起。这与地球上的沙子或其他地球土壤大不相同,后者通常包含更多的挥发物和有机物,以及一些水分。

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