September 27, 2012
Is Vesta Actually A Stunted Planet Instead Of An Asteroid?
Lee Rannals for redOrbit.com - Your Universe Online
New research reinforces the idea that the asteroid Vesta may actually have more of a history to it than just being a floating space rock.
Scientists analyzed data taken by NASA's Dawn spacecraft and found that the enormous troughs that reach across the asteroid may be faults that formed when another asteroid ran into Vesta's south pole. This could indicate that Vesta has a layered interior, a quality shared by planets and large moons.
Asteroid surface deformities are normally just cracks that formed after crashes with other asteroids. However, Vesta's troughs encircle the asteroid.
The largest of these troughs surpasses the size of the Grand Canyon, spanning about 289 miles long, 13.6 miles wide, and 3 miles deep.
New measurements of the asteroid's topography indicate that a large collision could have created the asteroid's troughs. However, this would have only been possible if the asteroid has a core, mantle and crust, according to Debra Buczkowski of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
“By saying it´s differentiated, we´re basically saying Vesta was a little planet trying to happen," she said in a recent statement.
If the troughs are due to differentiation, then the cracks are not just troughs but are actually graben. This is a dip in the surface that forms when two faults move apart from each other and the ground sinks into the widening gap.
Images from Dawn show that Vesta's troughs may have qualities of graben, because the walls of troughs on simpler asteroids are shaped like the letter V, but Vesta's have floors that are flat or curved.
Measurements by the scientists' showed that the bottoms of the troughs on Vesta are relatively flat and slanted toward what is probably a dominant fault.
The scientists' observations indicate that Vesta is also unusually planet-like for an asteroid in that its mantle is ductile and can stretch under a lot of pressure.
“On many much smaller asteroid bodies, we´ve seen very narrow troughs that look just like cracks on the surface,” said Geoff Collins of Wheaton College, who was not involved in the new study. “But nothing that looks like a sort of traditional terrestrial graben that you´d find on Mars or the moon where things have really been pulled apart.”
Vesta is the second most massive asteroid in the solar system, and is about one-seventh as wide as the Moon. Buczkowski said it does not classify as a dwarf planet because the large collision at its south pole knocked it out of its spherical shape.
However, if Vesta has a mantle and core, then it could mean it has qualities often reserved for planets, dwarf planets and moons.
Scientists will continue to sort out Dawn's data and improve computer simulations of Vesta's interior.