Impact Events and the Erosion of Planetary Atmospheres: Some Surprising Results from Theory and Simulation
Abstract
We investigate the evolution of the atmospheric blast waves produced by a K-T sized meteoritic impact on a terrestrial planet. Extending the mathematical analysis due to Kompaneets (1960) for a localized explosion in an isothermal atmosphere, we explore the response of an adiabatic atmosphere as well as model atmospheres for Earth and Venus to a 5 times 10^30 erg event. A principal outcome is that the blast waves will not spread laterally by more than pi times the scale height, approximately 30 km. for the Earth, the result of the upward diversion of the expanding blast, into the direction of least resistance. This effect was first noted in the simulations due to Jones and Kodis (1982). Further extension of the analytic methods provides exact particle trajectories for the ejecta and the prediction that virtually no material would escape from the planet. Our calculations show a factor ten less atmospheric loss than the Vickery and Melosh model (1990) and are confirmed by Los Alamos' CAVEAT finite difference code.
- Publication:
-
Lunar and Planetary Science Conference
- Pub Date:
- March 1996
- Bibcode:
- 1996LPI....27..955N
- Keywords:
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- ATMOSPHERES;
- COMETS;
- DYNAMICS;
- IMPACTS;
- VOLATILES