RE: moon dust info - please help

Glenn R. Morton (grmorton@waymark.net)
Tue, 03 Nov 1998 17:55:43 -0600

At 09:56 AM 11/3/98 -0500, mullerd_at_chpis@chplink.CHP.EDU wrote:
>
> Glen, I believe it was you who related a story about the
> scientist who placed large pans atop the tallest (Andes?)
> mountains to measure meteoric dust. I don't remember the
> results.
>
> Is the 30 years that has passed since the first landing
> enough time to have accumulated enough dust to make a
> calculation of how much should have accumulated, (in 4
> billion vs 10,000 years)?

I will cite Van Till et al in this regard.

"Additional measurements of particle flux have been based on impact pits
in the windows of many spacecraft (including the Apollo vehicles) and parts
of the Surveyor-3 spacecraft which were returned to earth by Apollo-12
astronauts after Surveyor-3 had been exposed to micrometeorite bombardment
for 31 months on the moon. These measurements plus continuing measurements
by penetration detectors and by modified microphone detectors have provided
the most reliable estimates for the accumulation of meteoritic material on
earth and moon. Gault (1972) reports 20,000 tons per year on earth.
Millman (1973) gives 10,000-20,000 tons, and Hughes (1978) gives 16,000
tons. Petterson's 1960 estimate based on atmospheric dust is a thousand
times higher than these results: Petterson's samples were apparently
contaminated with far more terrestrial dust than he had accounted for.
"To compute a reasonable estimate for the accumulation of meteoritic dust
on the moon we divide the earth's accumulation rate of 16,000 tons per year
by 16 for the moon's smaller surface area, divide again by 2 for the moon's
smaller gravitational force, yielding an accumulation rate of about 500
tons per year on the moon. By best current estimates, then, the
accumulation of meteoritic dust on the moon would contribute a layer less
than one centimeter thick in four billion years." ~ Howard J. Van Till,
Davis A. Young, Clarence Menninga, Science Held Hostage, (Downers Grove:
Intervarsity Press, 1988), p. 70-71

Petterson in 1960 was one of the first and thus one of the worst measurers
of cosmic dust. We have had much information from outside of the
atmosphere today. Petterson's mountaintop data is totally wrong.
Whitcomb and Morris Genesis Flood p. 379-380 cite the 14 million tons each
year. But those who continue to cite this are way out of date.
Here are some more modern measurements:

"Love and Brownlee measured the diameters and depths of the craters to
determine the masses of the impacting particles, which ranged from 10 -9 to
10 -4 gram. They conclude that every years the Earth collects about 40,000
metric tons of microscopic debris. This exceeds the values of other
researchers - who used less direct means of estimating the quantity of dust
- but it is comparable to rates crudly calculated from the long term
accumulation of the rare element iridium in sea sediment and Antarctic
ice."~----,"Earth's Cosmic Dusting," Sky and Telescope, March 1994, p. 13,
see also Science Oct. 22, 1993.

Cosmic dust 1600 tons per year +/- 300 Susand Taylor, James H. Lever and
Ralph P. Harvey, "Accretion Rate of Cosmic Spherules Measured at the South
Pole," Nature 392(1998):899-903, p. 902

"Integration of the LDEF influx distribution yields an accretion rate for
20-400 [micro]m micrometeoroids of 30,000 ton yr-1 . Love and Brownlee
reported 40,000 +/- 20,000 ton yr-1 to account for all cosmic dust. This
value agrees with the average extraterrestrial accretion rate over the past
80 million years derived from marine osmium, 37,000 +/- 13,000 ton yr-1 ."
~ Susan Taylor, James H. Lever and Ralph P, Harvey, "Accretion Rate of
Cosmic Spherules Measured at the South Pole," Nature, 392(1998):899-903, p.
902
glenn

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