Genesis Web Archive Overview 10/7/09

About 4.6 billion years ago, the solar nebula transformed into the present solar system. In order to chemically model the processes which drove that transformation, we would, ideally, like to have a sample of that original nebula to use as a baseline from which we can track changes. NASA’s Genesis sample-return mission ¹ is designed to give us just such a baseline composition ². It has collected solar wind, material which is ejected from the outer portion of the sun, and returned it to Earth. This material can be thought of as a fossil of our nebula because the preponderance of scientific evidence suggests that the outer layer of our sun has not changed measurably for billions of years. Moreover, for most rock-forming elements, there appears to be little fractionation of either elements or isotopes between the sun and the solar wind.

NASA’s Genesis spacecraft ^{1, 2}, built by Lockheed Martin and managed by the Jet Propulsion Laboratory, launched aboard a Delta 7326 vehicle from Kennedy Space Center in August 2001. It traveled to L1 Lagrange Point, where it stayed in a halo orbit for 886 days passively collected solar-wind samples; i.e., ions from the solar-wind impacted collectors at speeds over 200 km/sec and buried themselves in specially-selected materials. The spacecraft carried ion and electron solar-wind monitors which drove algorithms to deploy collector arrays that sampled specific solar wind regimes. Genesis also carried an electrostatic mirror that concentrated ions of important, light elements in the solar wind (eg., O, N). In addition to space-borne instruments, two Advanced Analytical Instrument facilities were funded as part of the payload and built while Genesis was flying.

After the collection period, the spacecraft closed-up and returned the samples to Earth in a Stardust-like sample-return capsule (SRC). On 8 September 2004 the SRC entered Earth’s atmosphere as planned, but its gravity switches were oriented incorrectly as the result of a design error and the parachute system failed to deploy³. The high-speed wreck compromised the SRC and shattered many of the Genesis collectors. However, the Genesis Preliminary Examination Team was able to show that, because the solar-wind ions were buried beneath the surface of the collectors, it is possible to detect and quantify elements in the solar-wind. Accordingly, in March 2005, Johnson Space Center curatorial staff started allocating solar-wind collectors to the international scientific community ⁴. Each allocation will allow scientists to glean information on the composition of the solar wind, thereby completing the circle and allowing us to piece together the chemical and isotopic composition of the solar nebula which formed our solar system. The cosmochemical and solar research on Genesis samples will continue for decades.

As of the closing of this web site, Genesis samples have provided data leading to several important scientific insights into questions related to planetary materials or cosmochemistry. Moreover, a number of projects in progress are nearing fruition. The first insightful result came from researchers based in Germany. They surmised that the “Solar Energetic Particles” inferred from some of the lunar and meteorite data did not exist and the bizarre isotopic compositions were simply an artifact of the mechanism by which solar wind implants into solid materials⁵. Noble gas analyses from research based at Washington University in St. Louis observed enriched ³⁶Ar/³⁸Ar ratios in Genesis samples and interpreted these ratios as possible evidence for atmospheric losses early in the Earth’s history⁶. Perhaps most tantalizing was a progress report on oxygen isotopic measurements out of the MegaSIMS laboratory at the University of California Los Angeles which suggested a simple, homogeneous, equilibrium model of our solar nebula was not sufficient; rather, there was at least one kinetic process (such as isotope-selective photochemical shielding or, perhaps, addition of extra-solar material from nearby stars) which differentially effected parts of our solar nebula⁷.

Of course, Genesis solar material was collected concurrently with the collection of in situ data from spacecraft monitoring the sun. This connection provides an opportunity for Genesis data to aide in the understanding of solar physics mysteries. This opportunity has not been missed⁸. At the time of the archive of this site, solar-physics researchers are emphasizing Genesis-sample data for the understanding of how material is ejected from the sun: using Genesis samples, multiple hypotheses can be tested^{6, 9, 10}.

We can expect more work on both solar-, cosmochemical- and planetary science in the future.

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