"At the time, scientists didn't even agree that craters were caused by impacts.
Amalthea has a remarkably low density, implying a highly porous structure that probably resulted from internal shattering by impacts.
Professor Steven Benner, a geochemist, has argued that the "seeds" of life probably arrived on Earth in meteorites blasted off Mars by impacts or volcanic eruptions.
Eros appears to be solid rock that, although cracked extensively by impacts from other bodies, is not a collection of small rocks and debris held together by gravity.
Nor is it clear, paleontologists said, what life forms in what ecological niches were destroyed by impacts at this time to clear the way for a new epoch.
"Since late 2008, crafts villages have faced so many difficulties caused by impacts of the global economic decline, such as a lack of capital and production materials and a shrinking consumer market," Mr. Dan said.
Meteorites collected in Antarctica include not only remnants from the formation of the solar system billions of years ago, but also pieces of the Moon and Mars that were blasted away by impacts with asteroids and comets.
Moreover, NASA says, "most of the planet's small, inner moons appear to orbit within partial or complete rings formed from particles blasted off their surfaces by impacts of micrometeoroids".
"It was known that planets were battered by impacts, but nobody had envisioned that the [moon's] crust was so beaten up," said Maria Zuber, Grail's principal investigator and a geophysicist at the Massachusetts Institute of Technology.
Forced oscillations of delaminated sandwich structures are dominated by impacts.
This implies that most of the casualties were caused by impacts from high-speed ballistic blocks.
