Anything that disperses the contaminant or causes it to adsorb on pigment will prevent or reduce cratering
. Testing for sensitivity to in-paint contaminants is very complicated because it is more of a test of the ability of the paint to assimilate contaminants than it is a crater test.
This ejecta would have buried most pre-existing rays (and many of the craters that formed them), so only the craters that were formed after these basins, in the waning days of intense cratering
, would have had visible rays.
record on Earth isn't much better: Erosion and faulting obliterate traces of impacts.
Textbooks often illustrate the concept of cratering
by depicting the impact, excavation, and ejection events on a completely flat terrain.
That interpretation would mean that "cratering
models need drastic revision, [that] our understanding of lunar impactors is really lousy," says Lucey.
But those chronologies are suspect until we get samples of the rocks to provide "ground truth" for each cratering