NASA’s Dawn mission has revealed evidence that the protoplanet Vesta contains many dark patches that were caused by the collision of asteroids. Previously it was thought the Vesta’s dark areas were caused by geological processes on the planet. However, new evidence, which began surfacing in November, points to a different origin: carbon-rich asteroids.
The NASA research team found their conclusions by closely studying the composition of the dark spots as well as creating maps and models of the areas. They discovered that the distribution of the dark materials suggests that it was transferred to Vesta when a number of asteroids crashed into the protoplanet. Dawn captured the images that make up the 3D mosaic while orbiting Vesta from an altitude of 420 miles (680 km), researchers said, noting that additional collaboration with NASA allowed them to better examine the craters rimmed with carbon.
Lead author of the study, Vishnu Reddy, said the thorough analysis of Vesta’s dark spots led his team to an solid conclusion: asteroids rich in carbon bombarded the minor planet.
“The evidence suggests that the dark material on Vesta is rich in carbonaceous material and was brought there by collisions with smaller asteroids,” he said.
Many of Vesta’s dark spots were found around the large impact basins that were previously located in the southern hemisphere of the protoplanet. This cluster of dark material further supports the NASA scientists’ theory that the dark spots were caused by asteroids. When studying the southern hemisphere of Vesta, the researchers found that the dark materials were most likely brought the protoplanet when the older Veneneia basin was formed. This older, large impact basin was created when a slow-moving asteroid hit the surface an estimated two to three billion years ago. This impact also produced dark material, but it was covered up when another impact formed the Rheasilvia basin.
In addition, the NASA scientists found more evidence to support their hypothesis through HED meteorites. HED meteorites that have left Vesta include dark areas that are rich in carbon. Additionally, the color spectra of the dark material on these HED meteorites and the surface of Vests are identical.
Lucille Le Corre, who works at the Max Planck Institute and was involved in the study, believes the correlation between the HED meteorites and the proroplanet Vesta is an important discovery.
“Our analysis of the dark material on Vesta and comparisons with laboratory studies of HED meteorites for the first time proves directly that these meteorites are fragments from Vesta.”
Perhaps the most important aspect of the Vesta study is that the dark materials are rich in carbon. If asteroids crashed into the protoplanet and left materials that contained a lot of carbon, it could mean that the same thing happened on Earth. Carbon is an absolutely essential element that is considered the building block of all organic materials including planets, animals, and humans. It is believed that early on in the development of the solar system, asteroid collisions similar to those on Vesta took place on Earth. Perhaps this was how carbon came to be on our planet.
“The aim of our efforts was not only to reconstruct Vesta’s history, but also to understand the conditions in the early solar system,” says Holger Sierks, a co-author of the Dawn mission study at the Max Planck Institute for Solar System Research.
The study’s results are a major accomplishment for NASA. The space agency has invested numerous resources into its new focus, asteroids. The U.S.-based space agency announced plans earlier this year to begin a training program that will teach astronauts how to operate vehicles, conduct spacewalks and gather samples on the surface of an asteroid.
The $466 million Dawn mission is managed by NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, California. The spacecraft has spent the better part of its mission examining Vesta. In September 2012, Dawn departed for the dwarf planet Ceres, the largest resident of the asteroid belt, where it will spend time orbiting in an effort to better understand how it evolved over the years.