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Impact ejecta dynamics in an atmosphere - Experimental results and extrapolationsIt is noted that the impacts of 0.635-cm aluminum projectiles at 6 km/sec into fine pumice dust, at 1 atm, generate a ball of ionized gas behind an expanding curtain of upward moving ejecta. The gas ball forms a toroid which dissolves as it is driven along the interior of the ejecta curtain, by contrast to near-surface explosions in which a fireball envelops early-time crater growth. High frame rate Schlieren photographs show that the atmosphere at the base of the ejecta curtain is initially turbulent, but later forms a vortex. These experiments suggest that although small size ejecta may be decelerated by air drag, they are not simply lofted and suspended but become incorporated in an ejecta cloud that is controlled by air flow which is produced by the response of the atmosphere to the impact. The extrapolation of these results to large body impacts on the earth suggests such contrasts with laboratory experiments as a large quantity of impact-generated vapor, the supersonic advance of the ejecta curtain, the lessened effect of air drag due to the tenuous upper atmosphere, and the role of secondary cratering.
Document ID
19840042875
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Schultz, P. H.
(Lunar and Planetary Institute Houston, TX, United States)
Gault, D. E.
(Murphys Center for Planetology Murphys, CA, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1982
Subject Category
Geosciences (General)
Accession Number
84A25662
Funding Number(s)
CONTRACT_GRANT: NSR-09-051-001
Distribution Limits
Public
Copyright
Other

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