300 m
Figure 13. An assortment of spherules from the SPWW. The large sphere in the upper left
corner is a copper contaminant (40).
yielding 50106-m, 106250-m, 250425-m,
ment focused predominantly on spherical par-
and >425-m size fractions. Using a binocular
ticles. Although not all spherical particles are extra-
terrestrial (there were copper spheres formed
microscope, spheres were separated from these
when pipes were soldered and dark, nonmagnetic
two samples by hand picking (Fig. 13). These two
"glue balls" thought to have formed during the
samples were processed in the field to assess the
fire), spheres can be rapidly separated with an or-
collector 's performance and to determine the type
dinary binocular microscope. Those that are "cos-
and amount of materials recovered. The remain-
mic" can then be separated by their several unique
ing three samples were placed in bags, sealed, and
properties. Previous studies have shown that cos-
shipped to CRREL for later analysis.
mic spherules have distinctive mineralogy, bulk
Other than well water, no solvents were used
chemistry, internal and surface textures, and are
in the separation process. We collected aliquots of
usually moderately magnetic (Brownlee 1981).
everything the particles may have come in con-
Here we used their abundance as a measure of the
tact with (drilling water, water, and residue left
amount of extraterrestrial material in our samples.
after backflushing and sieving a collection). We
All 6.01 g of the 250425-m size fraction of
also exposed a section of clean filter to the
pocket collection no. 1 and all 3.5 g of the 250
wellhouse environment, as suggested by Michael
425-m size fraction of the plateau collection were
Zolensky. These samples can be analyzed if any
examined. Table 3 lists the number of cosmic
unexpected contaminants are found in the par-
spherules found in these two fractions. Assuming
ticles.
an average particle weight of 3.5 105 g/particle
About 200 g of material were recovered from
(300 m diam., 2.5 g cm3) gives a weight of 7.9
the well bottom. Most of the material was terres-
103 g for the pocket collection and 4.4 103 g for
trial (Fig. 14), predominantly rust grains injected
into the well and originating either from the heat
the plateau collection, or about one part per thou-
exchanger or from the non-stainless steel compo-
sand melted meteoritic material. In addition to the
250425-m size fractions, 0.56 g of the 23.8 g of
nents within the pump. There were also wood
the 106250 m and 0.15 g of the 12.67 g of the 53
fragments, paint chips, wire, and aluminum flakes.
106 m were also examined for the pocket collec-
Our initial examination of the collected sedi-
16
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