Tunguska Workshop: Applying Modern Tools to Understand the 1908 Tunguska Impact

A one-day workshop was held at NASA Ames Research Center, January 16, 2018, to re-examine the 1908 Tunguska impact using modern computational tools, many of them developed in response to the 2013 Chelyabinsk airburst. Twelve international experts gave presentations, with another 40 attending in-person or remotely. The most likely models for Tunguska converged on an energy of 10-20 Megatons, released in an airburst at a height of about 10 km. If the Tunguska impactor was a stony asteroid similar to Chelyabinsk, the diameter was roughly 50-80m. A comparison with current understanding of the population of asteroids in this size range indicates that the interval between such events is millennia, not centuries as had been concluded previously. The primary constraints on our understanding of Tunguska are the dearth of quantitative data, not weakness of the computational models. The workshop was sponsored by the NASA Ames Asteroid Threat Assessment Project and supported the NASA Planetary Defense Coordination Office.