A quarterly research and development magazine
Technical contact
Mark Boslough
(505) 845-8851 mbboslo@sandia.gov
Media contact
Neal Singer
(505) 845-7078 nsinger@sandia.gov
Forest devastation in Siberia a century ago may have been caused by an asteroid only a fraction as large as previously published estimates, according to supercomputer simulations that more closely match the known facts about the Tunguska asteroid’s destruction than earlier models.
The research is funded by Sandia’s LDRD program.
“That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider,” says principal investigator Mark Boslough of the impact that occurred June 30, 1908.
The new simulations show that the center of mass of an asteroid exploding above the ground is transported downward, causing stronger blast waves and thermal radiation pulses at the surface than would be predicted by an explosion limited to the height at which the blast was initiated. Previous scientific estimates ignored the downward momentum of the asteroid’s mass.
“Our previous understanding was oversimplified,” says Boslough. “We no longer have to make the same simplifying assumptions, because present-day supercomputers allow us to do things with high resolution in 3-D.”
Simulations show that as the asteroid penetrates deeper into the atmosphere, increasing atmospheric pressure becomes more and more resistant and causes the asteroid to explode as an airburst.
Because of the additional energy transported toward the surface by the fi reball, what scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons.
“Any strategy for defense or deflection should take into consideration this revised understanding of the mechanism of explosion,” says Boslough.
Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, “we should be making more efforts to detect the smaller ones than we have till now.”
Movie clips showing simulations of asteroid impacts are available at www.sandia.gov/news/resources/releases/2007/asteroid.html.