I wonder what the optimal timing would look like. I mean, if you transform it into soup at the moment of impact, you have gained next to nothing. If you do it too far out in space it'll just refreeze. So probably at the moment it enters the atmosphere so it is dispersed by air resistance? Or, if you can fly alongside it in space, perhaps you can re-heat it constantly and keep it up long enough to shrink the giant ball of soup via evaporation...