[X] My Assistant

[SigurRosFan]

- http://arxiv.org/abs/astro-ph/0604079 - Shoemaker-Levy 9 Impact Modeling: I. High-Resolution 3D Bolides

--- We have run high-resolution, three-dimensional, hydrodynamic simulations of the impact of comet Shoemaker-Levy 9 into the atmosphere of Jupiter. We find that the energy deposition profile is largely similar to the previous two-dimensional calculations of Mac Low and Zahnle (1994), though perhaps somewhat broader in the range of height over which the energy is deposited. As with similar calculations for impacts into the Venusian atmosphere, there is considerable sensitivity in the results to small changes in the initial conditions, indicating dynamical chaos. We calculated the median depth of energy deposition (the height z at which 50% of the bolide's energy has been released) per run. The mean value among runs is approx 70 km below the 1-bar level, for a 1-km diameter impactor of porous ice of density rho=0.6 g cm^{-3}. The standard deviation among these runs is 14 km. We find little evidence of a trend in these results with the resolution of the calculations (up to 57 cells across the impactor radius, or 8.8-m resolution), suggesting that resolutions as low as 16 grid cells across the radius of the bolide may yield good results for this particular quantity. ---

[ljk4-1]

Speaking of comets breaking apart (if only we had a well-shielded probe
following this one. Who needs to make a crater with a copper ball when
you've got the whole comet revealing its interior to you):

Space Weather News for April 7, 2006

http://spaceweather.com

Dying comet 73P/Schwassmann-Wachmann 3 continues to break apart. Astronomers are
tracking at least 20 fragments approaching Earth for a harmless but beautiful
close encounter in May.

In particular, fragment B of the comet has brightened 15-fold since April 2nd.
This signals a possible breakup of "73P-B" into even more fragments. Amateur
astronomers with backyard telescopes and CCD cameras can monitor the ongoing
disintegration. Visit Spaceweather.com for sky maps, images more information.