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New research of NASA scientists reveal that more than four billion years ago, giant asteroid bombardments played a significant role in the geological evolution of the uppermost layers of Earth during the Hadean period. The paper was published in the July 31 edition of Nature.
In the very beginning of Earth's formation, first 500 million years, there's a less well-known period that was typically called Hadean (meaning "hell-like") .It was wildly hot and volcanic, and magma covered everything unlike the present day.
According to the study, the Hadean Earth was hit by three to seven asteroids that were more than 300 miles wide, and each of those collisions would have vaporized all of the planet's oceans. Additionally, the planet was blasted by one to four asteroids that were more than 600 miles wide, large enough to sterilize the entire globe, the study adds.
Elkins-Tanton, director of the School of Earth and Space Exploration at Arizona State University in Tempe, says that currently they have a fair understanding of tectonic plates, volcanism and all kinds of processes that have happened more or less in the same manner over the last couple of billion years.
The studies revealed similarities and differences between the present day conditions of Earth and the conditions that prevailed earlier. These have tried to bridge time in understanding the activities from the time the last giant accretionary impact that largely completed Earth and produced the moon, to the point where we have something like today's plate tectonics and habitable surface.
Terrestrial planet formation models indicate that Earth has undergone with a sequence of a large number of major growth phases.
According to the Los Angeles Times, the study was performed by taking crater-history estimates from the moon and projecting similar estimates on Earth, among other factors.
Using this data, scientists developed a model to reveal the impact of Earth's conditions 500 million years ago.
Simone Marchi, NASA's Solar System Exploration Research Virtual Institute at the Southwest Research Institute in Boulder Colorado, says, "Prior to approximately four billion years ago, no large region of Earth's surface could have survived untouched by impacts and their effects".
