Researchers simulated a collision on Vesta, the second-largest object in the asteroid belt, to determine how it got its signature grooves around its midsection.
A research team used images taken from NASA's ultra-high-speed cannon, taken at a million frames per second, and computer models to make their findings, Brown University reported. The scientists determined the equator-like belt was most likely caused by an impact on Vesta's south pole.
"Vesta got hammered," said Peter Schultz, professor of earth, environmental, and planetary sciences at Brown and the paper's senior author. "The whole interior was reverberating, and what we see on the surface is the manifestation of what happened in the interior."
The impactor most likely hit at an angle, as opposed to straight on, but was still able to do a shocking amount of damage. Only seconds after impact, rocks within the asteroid started to crack and crumble and faults occurred within two minutes.
For the study the researchers used Ames Vertical Gun Range, a cannon with a 14-foot barrel. The gun is able to compress hydrogen gas to launch projectiles at a whopping 16,000 miles per hour. In this particular study the team launched projectiles at softball-sized spheres made of an acrylic material called PMMA. They watched the impact with high-speed cameras to capture areas of clear material that turned opaque upon impact, indicating the point of stress.
The researchers then used numerical models to scale the lab collision to the size of Vesta, revealing an outward-blooming "rosette" of damage may have been responsible for the troughs that formed around the asteroid's equator.
Vesta's belt has puzzled scientists because it is crooked, which is not what one would expect to see in the event of a Rheasilvia impact.
"The belt is askew," Schultz said, "as if Vesta were making a fashion statement."
This new experiment suggests the belt is the result of an oblique impact, which causes the damage plane to tilt in respect to the crater. The team determined the object hit Vesta at an angle less than 40 degrees and was travelling at a speed of about 11,000 miles per hour.
"Vesta was lucky," Schultz said. "If this collision had been straight on, there would have been one less large asteroid and only a family of fragments left behind."
The findings will appear in the February issue of the journal Icarus.
WATCH:
