NASA has released the latest update on its OSIRI-REx mission, which involves a spacecraft that is closely orbiting a very rocky, somewhat angular asteroid called Bennu. The space agency explains that Bennu is an asteroid made of rubble from other space rocks; it is the result of some massive collision in the past. Studying the rubble has revealed the presence of meteorites that originated from another — and much larger — asteroid nearby.
NASA notes in a new animated educational video that a handful of boulders found on Bennu are quite a bit brighter than the other boulders and rocks on the asteroid — and some of them are much brighter, raising questions about their origin. Here to solve the mystery is NASA’s OSIRIS-REx spacecraft, which has observed and studied the rocks, revealing that these lighter boulders come from asteroid Vesta.
These lighter boulders range in size from around 5ft to 14ft and they’re all located on the asteroid’s southern hemisphere near the equator. The material was likely deposited on Bennu as part of the violent vestoid impact on the parent asteroid, NASA explains.
Some of the rubble resulting from this impact, including boulders from the chunk of Vesta that hit the parent asteroid, was pulled together by gravity and eventually formed the angular rocky body we see today. Solving this mystery involved a variety of sophisticated equipment, including OSIRIS-REx’s Visible and Infrared Spectrometer (OVIRS) tool, which was used to split light bouncing off the bright rocks into its individual colors.
By doing this and looking at the light and dark portions of light in each color, the experts were able to piece together the composition of these boulders. According to NASA, the bright rocks are ‘characteristic of mineral pyroxene’ like what is ejected from Vesta as fragments when the celestial body is struck by other space rocks.