March 26, 2013
NASA Scientists Find Striking Similarity Between Moon And Asteroids
Lawrence LeBlond for redOrbit.com - Your Universe Online
Scientists from NASA´s Lunar Science Institute (NLSI), along with researchers from abroad, have discovered that Earth´s own natural satellite shares a striking similarity with Vesta, and perhaps other large asteroids roaming around the Solar System.
A paper on the recent discovery is published in the March issue of Nature Geoscience.
"It's always intriguing when interdisciplinary research changes the way we understand the history of our solar system," said Yvonne Pendleton, NLSI director. "Although the moon is located far from Vesta, which is in the main asteroid belt between the orbits of Mars and Jupiter, they seem to share some of the same bombardment history."
Not only does the discovery lead to better understanding of the early evolution of terrestrial planets, but it also supports the theory that the repositioning of gas giants like Jupiter and Saturn from original orbits to their current ones destabilized the asteroid belt, triggering the bombardment of asteroids throughout the Solar System billions of years ago.
This new research provides new limitations on when this bombardment, known as the “lunar cataclysm,” began and how long it may have lasted. It also demonstrates that the cataclysm was an event that affected not only the planets in the inner Solar System, but the asteroid belt as well.
NASA has long studied the bombardment history of the moon via the lunar rocks returned from the Apollo moon landings. Now, ages derived from meteorite samples have been used to study the collisional history of the main belt asteroids as well. Howardite and eucrite meteorites, two common species found on Earth, have been used to study asteroid Vesta, their parent body. Using computer simulations, the researchers determined that meteorites from Vesta recorded high-speed impacts long ago.
Linking the two datasets, the NLSI team found that the same population of projectiles responsible for bombarding the Moon was also striking Vesta at very high speeds, enough to leave behind a number of telltale, impact-related ages. By making recent close-up inspections of Vesta´s surface via NASA´s Dawn spacecraft, the team´s interpretation of the howardite and eucrite meteorites was amplified.
Furthermore, the team used the latest dynamical models of early main belt evolution to discover the likely source of these high-speed projectiles. They determined that the population of projectiles that slammed into Vesta had orbits that enabled Moon bombardment at high speeds as well.
"It appears that the asteroidal meteorites show signs of the asteroid belt losing a lot of mass four billion years ago, with the escaped mass beating up on both the surviving main belt asteroids and the moon at high speeds" lead author Simone Marchi, of NLSI´s Southwest Research Institute in Boulder, Colorado and the Lunar and Planetary Institute in Houston, said in a statement. "Our research not only supports the current theory, but it takes it to the next level of understanding."