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Title: HCI in rocket exhaust clouds: atmospheric dispersion, acid aerosol characteristics, and acid rain deposition

Journal Article · · J. Air Pollut. Control Assoc.; (United States)

NASA is examining Space Shuttle launch impacts. Solid rocket exhaust includes approx. 60 tons HCl and approx. 87 tones alumina particles emitted below 2.5 km, of which 50-80% forms an altitude stabilized exhaust cloud (EC). Several 60% smaller Titan-III EC were sampled by aircraft for this study. Three distinct features are presented: (a) an analysis of HCl (gaseous plus aqueous) data traces. Total range of peak HCl was 25-0.5 ppm (3-300 min) for 8 EC. Power-law decays of peak HCl applied. Calculated HCl dispersions for 7 standard meteorologies are also shown. (b) An analysis of simultaneous HCl (g), HCl (g + aq) data for 2 EC. Vapor-liquid HCl/H/sub 2/O equilibria were calculated for a flat surface aqueous aerosol. HCl partitioning varied with EC dilution and H/sub 2/O content. HCl (aq) and aqueous mass fraction maximized early at > 3 molal and > 0.1 mg/g air. Calculated H/sub 2/O (g + aq) compared favorably with independent EC measurements. (c) An analysis of wet deposition after EC interception at approx. 30 min by a convective storm. A 28 km/sup 2/ acid chloride (1 < pH < 3) footprint was defined. In conclusion, (a) HCl dispersion in large EC tends to follow power-law decay, but HCl concentration may vary widely (100 times after 1 h) with meteorology, (b) HCl (g/aq) and H/sub 2/O (g/aq) partitioning is consistent with equilibrated acid aerosol compositions, and (c) localized deposition of highly acidic rain may occur sometimes.

Research Organization:
Langley Research Center, Hampton, VA
OSTI ID:
6813333
Journal Information:
J. Air Pollut. Control Assoc.; (United States), Vol. 33:4
Country of Publication:
United States
Language:
English