Abstract
Deep Impact was a NASA spacecraft that released an impactor into the Tempel 1 comet. According to NASA's predictive models, the collision should have excavated a 100-m wide crater. However, post-impact images revealed a much larger crater. In addition, the impact released a far greater amount of water than originally predicted. It caused a brilliant flash of light and an increase in the brightness of the inner cloud of dust and gas. The photo records revealed a bright spray. The plume opacity and the amount of the produced light were surprising. The brightness of the visible data was explained by the melting of silicates. It was also suggested that the visible selfluminous plume could be due to carbon from thermally disassociated organics. This paper offers a different explanation for the larger than expected released energy, ejecta, and plume luminosity. It appears that similar phenomena were observed in our hypervelocity tests involving aluminum projectiles and wet sand at freezing temperatures. We recorded a large fireball, when no fireball was expected, and powerful luminous sand ejecta.
