Sampling Interplanetary Dust Particles from Antarctic Air
Abstract
Abstract: Analyses of interplanetary dust particles (IDPs) collected in the stratosphere show that these are primitive materials, some of which have no meteorite counterparts and may be from comets. Evidence of their primitive nature includes their porous, fragile, fine-grained structures, unequilibrated chemistries and anhydrous mineralogies, high concentrations of presolar grains, presence of glass with embedded metal and sulfides, abundant organic matter, and H, C, or N isotopic anomalies in the organics.
Samples from melted Antarctic snow contain IDP-like grains. As they are present in Antarctic snow, they should also be present in the near surface air. Air filtering would eliminate particle contact with water, and improve temporal resolution, which is needed to detect episodic or periodic events, such as meteor streams from specific comets. We built a collector that suctions and filters the air stream upwind of South Pole station. A suction blower pulls air continuously through a 20-cm diameter polycarbonate filter etched with 3-μm pores. Given a flow velocity of 6 m/s, we expected to collect >300 extraterrestrial (ET) particles larger than 5 μm each month. Our collector has been running almost continuously since Nov. 2016 and we have exposed 28 filters to date. We are using optical and electron microscopy to look for ET particles and bulk measurements to analyze for organics and for 3He, the subject of this abstract. 3He measurements were made on 34, 1 cm2 samples taken from four filters (#1, Nov 2016; #4, Dec 2016; #10, June 2017; #17, Oct 2017; and #22, Dec. 2017). We found: ET matter in every cm2 of filter analyzed (Fig. 1); hints of a seasonal variation in the ET flux and; a large variability in 3He among samples. Interestingly, three of the five samples from filter #17 had high 3He values. Our results suggest that many small ET particles provide the low, but clear, extraterrestrial signal. Higher 3He values are likely larger ET particles not strongly heated during atmospheric entry. The 3He data can provide information not obtainable from looking at individual IDPs- namely temporal variation in the small particle ET flux and guidance on which filters contain the most ET material. Fig. 1. 3He and 3He/4He data for South Pole air filters. 3He pcc=10-12 ccSTP and RA is the 3He/4He divided by the air ratio of 1.39x10-6.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P53G3069T
- Keywords:
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- 0406 Astrobiology and extraterrestrial materials;
- BIOGEOSCIENCESDE: 1028 Composition of meteorites;
- GEOCHEMISTRYDE: 3662 Meteorite mineralogy and petrology;
- MINERALOGY AND PETROLOGYDE: 5215 Origin of life;
- PLANETARY SCIENCES: ASTROBIOLOGY