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  Wafers and Collectors

Solar Wind Collector (small)
Hexagonal collector's
array used to capture bulk solar wind.
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.
Team member is bunny suit holding a vial of wafers
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.

Closeup of 10 wafer fragments in a transparent dish
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. button
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Curator: Aimee Meyer
Updated: November 2009

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