However, landings performed by robotic Surveyor spacecraft showed that the lunar soil was firm enough to support a spacecraft, and astronauts later explained that the surface of the Moon felt very firm beneath their feet.
During the Apollo landings, the astronauts often found it necessary to use a hammer to drive a core sampling tool into it. Once astronauts reached the surface, they reported that the fine moon dust stuck to their spacesuits and then dusted the inside of the lunar lander.
The astronauts also claimed that it got into their eyes, making them red; and worse, even got into their lungs, giving them coughs. Lunar dust is very abrasive, and has been noted for its ability to wear down spacesuits and electronics. The reason for this is because lunar regolith is sharp and jagged.
This is due to the fact that the Moon has no atmosphere or flowing water on it, and hence no natural weathering process. When the micro-meteoroids slammed into the surface and created all the particles, there was no process for wearing down its sharp edges. However, standard usage among lunar scientists tends to ignore that distinction.
As NASA is working on plans to send humans back to the Moon in the coming years, researchers are working to learn the best ways to work with the lunar regolith. Future colonists could mine minerals, water, and even oxygen out of the lunar soil, and use it to manufacture bases with as well. Landers and rovers that have been sent to Mars by NASA, the Russians and the ESA have returned many interesting photographs, showing a landscape that is covered with vast expanses of sand and dust, as well as rocks and boulders.
Compared to lunar regolith, Mars dust is very fine and enough remains suspended in the atmosphere to give the sky a reddish hue. The dust is occasionally picked up in vast planet-wide dust storms, which are quite slow due to the very low density of the atmosphere. The reason why Martian regolith is so much finer than that found on the Moon is attributed to the flowing water and river valleys that once covered its surface.
Mars researchers are currently studying whether or not martian regolith is still being shaped in the present epoch as well. It is believed that large quantities of water and carbon dioxide ices remain frozen within the regolith, which would be of use if and when manned missions and even colonization efforts take place in the coming decades.
Mars moon of Deimos is also covered by a layer of regolith that is estimated to be 50 meters feet thick. The surface is known for its extensive fields of dunes, though the precise origin of them are not known. Another possibility is that a series of powerful wind reversals , which occur twice during a single Saturn year 30 Earth years , are responsible for forming these dunes, which measure several hundred meters high and stretch across hundreds of kilometers.
Asteroids have been observed to have regolith on their surfaces as well. These are the result of meteoriod impacts that have taken place over the course of millions of years, pulverizing their surfaces and creating dust and tiny particles that are carried within the craters.
To break it down succinctly, wherever there is rock, there is likely to be regolith. The thickness of the mantle of regolith depends in great part on the relative magnitude of the rate of production and the rate of removal. In some situations, as in regions with steep slopes, high relief, and rigorous climate, regolith is stripped away as fast as it is produced; in areas with gentle slopes and climates conducive to deep weathering, the layer of regolith is very thick.
Regolith resting on a sloping surface is pulled inexorably downward by the force of gravity or, more accurately, by the downslope component of the force of gravity Figure Such movement of the regolith may be imperceptibly slow or at speeds in excess of a hundred meters per second. An entire later chapter will be devoted to the subject of downslope movements of near-surface material by gravity, collectively termed mass movements absolutely no relation to sociopolitical mass movements.
The principal agent for the transport of regolith, aside from the direct pull of gravity, is the flow of water in streams and rivers. Of course, river flow is itself a consequence of the downslope pull of gravity—but regolith transport by flowing water involves physical processes and effects that are fundamentally different from the direct pull of gravity.
The mobilization and transportation of regolith by flowing water is the subject of part of the later chapter on streams and rivers. Movement of regolith by the action of land-based glaciers is of great importance in certain Earth-surface environments as well. Wind can also be a significant transporting agent, as described in the final chapter. The main distinction in kinds of regolith is between residual regolith also called sedentary regolith , on the one hand, and transported regolith , on the other hand Table With respect to transported regolith, several kinds are recognized, depending upon the agent of transportation.
Transported regolith is collectively termed sediment. There will be much more material, later in this chapter as well as in later chapters, on sediment, and how it is eroded, transported, and deposited. Colluvial deposits called colluvium are those transported down steep slopes by the pull of gravity.
Mainly, these are talus deposits also called scree deposits on steep slopes, and avalanche and landslide deposits of various kinds. Alluvial deposits called alluvium are those transported and deposited by rivers and streams.
In addition, there are glacial deposits and eolian wind-blown deposits. The Nature of Regolith What is regolith? Agents That Mobilize Regolith Regolith resting on a sloping surface is pulled inexorably downward by the force of gravity or, more accurately, by the downslope component of the force of gravity Figure Figure
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