NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Environmental Perturbations Caused by the Impacts of Asteroids and CometsWe review the major mechanisms proposed to cause extinctions at the Cretaceous-Tertiary geological boundary following an asteroid impact. We then discuss how the proposed extinction may relate to the impact of asteroids or comets in general. We discuss the limitations of these mechanisms in terms of the spatial scale that may be affected, and the time scale over which the effects may last. Our goal is to provide relatively simple prescriptions for evaluating the importance of colliding objects having a range of energies and compositions. We also identify the many uncertainties concerning the environmental effects of impacts. We conclude that, for impact energies below about 10(exp 4) Mts (megatons of TNT equivalent) - i.e., impact frequencies less than in 6 x 10(exp 4) yr, corresponding to comets and asteroids with diameters smaller than about 400 m and 650 m, respectively - blast damage, earthquakes, and fires should be important on a scale of 10(exp 4) or 10(exp 5) km (exp 2), which corresponds to the area damaged in many natural disasters of recent history. However, tsunami could be more damaging, flooding a kilometer of coastal plane over entire ocean basins. In the energy range of 10(exp 4) to 10 (exp 5) Mts (intervals up to 3 x 10(exp 5) yr; comets and asteroids with sizes up to 800 m and 1.5 km, respectively) water vapor injections and ozone loss become significant on the global scale. In the submicrometer dust injection fraction from the pulverized target material is much higher than is presently thought to be most likely, then dust injection could be important in this energy range.
Document ID
19970030230
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Toon, Owen B.
(NASA Ames Research Center Moffett Field, CA United States)
Zahnle, Kevin
(NASA Ames Research Center Moffett Field, CA United States)
Morrison, David
(NASA Ames Research Center Moffett Field, CA United States)
Turco, Richard
(California Univ. Los Angeles, CA United States)
Covey, Curt
(Lawrence Livermore National Lab. Livermore, CA United States)
Date Acquired
August 17, 2013
Publication Date
January 1, 1997
Publication Information
Publication: Annals of the New York Academy of Sciences
Volume: 822
Subject Category
Astrophysics
Accession Number
97N28236
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available