Hörst says it's possible this bombardment has left MU69 covered in a global layer of the material. (discovermagazine.com)
If both caps are composed completely of water, the combined volumes are equivalent to a global layer 66 to 100 feet deep, about one third the minimum volume for the ancient seas of Mars. (scientificamerican.com)
Yet some species survived, and the global layer of impact debris doesn't contain as much soot as would be expected from burning the world's forests, raising questions about the extent of post-impact wildfires. (newscientist.com)