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Fig. 1 - The orange lunar soil discovered by Apollo 17 astronauts, as seen through a microscope. Some particles are spherical, indicating they were formed as molten drops ejected from an impact. Others are irregular, formed by mechanical fractures. (NASA)

The soil on the moon looks like it's wet, or is made of plaster or something. Look at how sharp the footprints and other impressions are?

Several powdered substances on earth exhibit this behavior. Anything finely powdered, such as cornstarch or flour, will clump when packed. Even earth dust, if sufficiently fine, will receive a print quite well even when dry.

The secret is in the microscopic structure of the individual soil particles, shown at right. On earth most soil particles rub against each other as they are acted upon by wind and water. This rubs off the rough edges. But lunar soil has no wind or water to erode it at the microscopic level, and so it retains those sharp edges that allow each particle to "catch" its neighbor and display the remarkable cohesion we can observe.

Couldn't earth powders like Portland cement, which are chemically similar to lunar dust and very anhydrous, be used to simulate the impressibility of lunar dust on earth?

The impressibility of the soil is not hard to duplicate. As noted above, many powders are impressible. But none of them has the combination of mechanical, optical, and aerosol properties that we observe in video and film from the lunar surface. Portland cement, for example, does not exhibit heiligenschein, or the peculiar halo effect seen around astronauts' photographs of their own shadow.

Any particulate will aerosolize, which means it will be carried as random billows appearing to float in the air. Large particles will not aerosolize as easily, but large particles do not have the mechanical impressibility as small particles and are unsuitable for simulating lunar soil. A particulate produced and handled in bulk will contain particles of nominal size, but also very small microparticles produced when the larger ones rub together during handling. Microparticles will aerosolize very easily, even in relatively thin air. They can be removed by washing, but only for very small quantities of bulk particulates, and must be used immediately after washing otherwise further handling will form new microparticles.

In short, impressibility is easy to simulate. The other observable properties of lunar soil are very difficult if not impossible to simulate.

How could there be soil without erosive forces like wind and rain?

First the conspiracists must make up their minds. They argue that the dust produced by the lunar module's descent engine would blind the pilot to the surface below. Then they argue there should be no dust. Which is it?

In Stanley Kubrick's 2001: A Space Odyssey the lunar mountains appear sharp and highly detailed. This was the prevailing opinion of lunar topography when Kubrick's production designers created their designs. People were surprised to see more rounded features in photographs returned by the first unmanned probes.

As a matter of fact, wind and water are not the only forces that cause erosion. The lunar soil is produced chiefly by the pulverization of the rocky surface by millions of years' worth of micrometeoroids. And larger ones as well. When a large meteor strikes the lunar surface, a blanket of pulverized material called "ejecta" is thrown for miles around the crater.

The moon was also once seismically active. The dark "seas" are in fact ancient lava flows. Moonquakes dislodge loose boulders, which tumble down mountains and in turn loosen other portions of the moon's crust. Rocks grinding against rocks produce gravel and dust -- the observed regolith.

Millions of years of micrometeoroid impacts, geological activity, and landslides have created the lunar regolith.
The moon is tidally locked, which is a fancy way of saying that the same side always faces earth. The process of tidal locking exerts considerable forces on the lunar surface which can warp and distort features. A rigid shell over a more elastic core will fracture as the core changes shape. These fractures, occurring over millions of years, can reduce the outer shell to small rocks.

Cornell geologist Dr. Tommy Gold maintained the lunar soil would be several feet thick and that the Apollo astronauts would sink into it over their heads. Fortunately he was wrong about that, but the lunar soil is in fact several feet thick. But only the top inch or so is loose. The rest is very densely packed, and this did not come as a surprise. But the top scientists at the time knew there would be particulate matter on the lunar surface, and they knew why.

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