The asteroid bombardment recorded in the Moon 3.9 billion years ago has its origin in a process of continuous impacts of the main phase in the formation of the earth.
Research by planetologists at the University of Münster has been based on very precise chemical measurements of lunar rocks formed during the bombardment. The results are published in the current issue of the journal Science Advances.
These rocks contain tiny globules of metal that consist of material from impactor asteroids. By studying the composition of these metallic globules, researchers can determine where in the Solar system these bodies originated.
They focused on the elements ruthenium and molybdenum because they show systematic changes in their isotopic composition, depending on where they formed in the solar system.
“Our research shows that the bombardment of the Moon was by the same bodies that formed the Land and the Moon, ”explains planetologist and lead author of the study, Dr. Emily Worsham.
The impact craters on the Moon, that said, are due to a continuous bombardment of asteroids left over from the Earth’s main phase of formation.. This also allows scientists to rule out a sudden increase in impact rate due to bombardment with bodies from the outer solar system.
“It has previously been suggested that the lunar rocks studied so far are composed mainly of material from a single impact basin: Mare Imbrium, on the north-central side of the Moon facing Earth,” Emily Worsham said in a statement. .
It is known from theoretical calculations, that the orbits of the gas giants changed at some point in the early history of the solar system, scattering a large number of bodies from the outer solar system to the interior, which collided with the Earth and the Moon, among others.
“This event must have taken place earlier than previously thought, because we found no evidence of asteroid or comet impacts from the outer reaches of the solar system on lunar rocks,” intervenes Professor Thorsten Kleine.
As a result, the change in the orbits of the gas giant planets it probably took place during the major formation phase of Earth-like planets, that is, in the first approximately 100 million years of the solar system, which in turn agrees well with recent dynamic models.
“Our study, therefore, also shows that Earth-like planets incorporated water-rich bodies from the outer solar system relatively early, during their formation, thus creating the conditions for the emergence of life,” adds Thorsten Kleine.
With information from Europa Press.