The Moon landing again - Fw: Neil Armstrong's Boots

[jim bell]

From: Tom <tom at vondein.org>
   
>> This massive thrust would have blown the dust away from the landing area
>> creating a massive dust cloud, so why was thick dust still on the ground
>> and no massive dust cloud? Please explain NASA.
>No atmosphere, no blowing.    - Tom
I'd answer this somewhat differently.  The rocket jet would indeed dislodge the dust:  The particleswould acquire velocities, and would follow mostly-parabolic paths and eventually collide with and stayon the surface again. While this might be labelled a "cloud", unlike in Earth's atmosphere these particles will presumably return to the Moon's surface in a few seconds, yet far away from the lunar lander. As to "why was thick dust still on the ground", most likely the dust was very thick.  (many meters).From:   http://curator.jsc.nasa.gov/lunar/letss/regolith.pdf
"The lunar surface is covered by a layer ofunconsolidated debris called the lunar regolith (fig. 53).The thickness of the regolith varies from about 5 m onmare surfaces to about 10 m on highland surfaces. Thebulk of the regolith is a fine gray soil with a density ofabout 1.5 g/cm3, but the regolith also includes brecciaand rock fragments from the local bedrock (reviewsby Heiken et al. 1974 and Papike et al. 1982). Abouthalf the weight of a lunar soil is less than 60 to 80 micronsin size. The grain size distribution is given in figure 55."

There may be an additional factor.  As I vaguely recall, there is an odd electrostatic attraction between the particles of lunar soil.  Perhaps not surprising, because except for subsurfacefrozen-water deposits (and some polar craters) the moon is 'dry as a bone'.  



  
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