The Condition of the Materials Returned by the Genesis Mission
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The Condition of the Materials Returned by the Genesis Mission Karen M. McNamara, Johnson Space Center, NASA, Houston, TX 77058, U.S.A. INTRODUCTION The Genesis mission returned to Earth on September 8, 2004 after a nearly flawless three-year mission to collect solar matter. The intent was to deploy a drogue chute and parafoil high over the Utah desert and to catch the fragile payload capsule in mid-air by helicopter. Unfortunately, both chutes failed to deploy, causing the capsule to fall to the desert floor at a speed of nearly 200 MPH. Still, Genesis represents a milestone in the US space program, comprising the first sample return since the Apollo Missions as well as the first return of materials exposed to the space environment outside of low Earth orbit and beyond the Earth’s magnetosphere for an extended period. We have no other comparable materials in all of our collections on Earth. The goal of the Genesis Mission was to collect a representative sample of the composition of the solar wind and thus, the solar nebula from which our solar system originated. This was done by allowing the naturally accelerated species to implant shallowly in the surfaces of ultra-pure, ultra-clean collector materials. These collectors included single crystal silicon (FZ and CZ), sapphire, silicon carbide; those materials coated with aluminum, silicon, diamond like carbon, and gold; and isotopically enriched polycrystalline diamond and amorphous carbon. The majority of these materials were distributed on five collector arrays. Three of the materials were housed in an electrostatic concentrator designed to increase the flux of low-mass ions. There was also a two-inch diameter bulk metallic glass collector and three larger area bulk solar wind collectors: gold foil, polished aluminum, and molybdenum coated platinum foils. With the exception of a few dedicated experiments, these materials are available for request by the scientific community for study. An independent allocation committee evaluates proposals on the basis of their scientific merit, reserving the collectors primarily for studies related to cosmochemistry and solar system formation. An excellent review of the Genesis collector materials is offered in reference [1]. CCoAuOS AuOS AlOS
Ge CZ
SOS SAP
DOSi
FZ
Figure 1. The distribution of materials on the arrays and a pre-flight image of an array.
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The entire Genesis spacecraft did not and was not intended to return to Earth on September 8, 2004. The spacecraft bus, including fuel tanks, star trackers, solar panels, and science monitors was redirected back to L1, where it had spent much of the last 2.5 years at the point of gravitational balance between the Earth and the sun. What did return to Earth was the interior payload canister and outer sample return capsule (SRC) which protected the payload during reentry. The sample return capsule consisted of a carboncarbon heatshield, super light ablator backshell, and a deployable backshell segment which shielded the parachute throughout the mission. In
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