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Hexagonal collector's
array used to capture
bulk solar wind. |
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To successfully capture raw solar wind, Genesis flew a
million miles away, outside Earth's magnetic field, which
alters the particles, and hovered in its own orbit for
29 months. Scientists grappled with several challenges
while pondering ways to keep the samples pristine during
and after collection. First off, they had to find a proper
way to collect and transport the samples. The largest
collector consists of five bicycle-tire-sized collector
arrays, each loaded with 54 or 55 hexagonal wafers measuring
about 4 inches (10 centimeters) in diameter. These wafers
consist of 15 different high-purity materials including
aluminum, sapphire, silicon, germanium, gold and diamond-like
amorphous carbon — all chosen for their durability,
purity, cleanliness, retentiveness and ease of analysis.
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JSC Curation Team Members displays some of the silicon wafers fragments collected |
Each collector array was assigned to catch various
types of solar wind. Genesis's goal was to collect billions
of atoms of solar particles heavier than hyrogen, equivalent
to "a few grains of salt," according to Genesis Principal
Investigator Dr. Donald Burnett of the California Institute
of Technology.
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Assortment of recovered fragments during cataloging phase |
Once the solar wind particles were collected, the wafers
had to be able to retain them while warming under the
Sun's rays. Each type of wafer will retain different
solar wind elements. Sapphire was used because it can
retain sodium under these conditions. Silicon, which
comprises approximately half of the materials used in
the collector arrays, does not retain sodium but does
retain many other elements, including the important
rock-forming element magnesium.
Geometry was also used to enhance researchers' ability
to analyze the sample. By making some of the collector
materials thin and mounting them on a rigid, inert structure
(e.g. silicon on sapphire), the effects of impurities
in the collector material were minimized by only analyzing
the thin layer. |
