What type of asteroid is vesta

Understanding why this is so was one of the objectives of the Dawn mission. The answer turned out to be that Vesta formed early, within 1 to 2 million years of the birth of the solar system. Short-lived radioactive material that was incorporated into bodies that formed during this epoch heated them to the point where—in cases like Vesta—the objects melted, allowing the denser materials to sink to the asteroid's core and the lower density materials to rise.

Vesta has one of the largest brightness ranges observed on any rocky body in our solar system. The bright materials appear to be native rocks, while the dark material is believed to have been deposited by other asteroids crashing into Vesta. Scientists on the Dawn team estimate that about dark asteroids with diameters ranging from one to 10 km 0.

This would have been enough to wrap the Vesta in a blanket of material about three to seven feet one to two meters thick. An extensive system of troughs encircles Vesta's equatorial region. The largest, named Divalia Fossa, is bigger than the Grand Canyon. Vesta appears to be the source of the Howardite, Eucrite and Diogenite groups of meteorites that have been found on Earth. They help scientists understand the "Lunar Cataclysm," when a repositioning of the gas-giant planets billions of years ago destabilized the orbits of asteroids in the early asteroid belt and triggered a solar-system-wide bombardment.

They also provide clues to Vesta's geochemical evolution, a story that was tested and enhanced by the information Dawn provided about the asteroid's surface and interior. Vesta is believed to have lost about one percent of its mass less than a billion years ago in a massive collision responsible for the Rheasilvia crater, which is about miles kilometers wide—some 95 percent of the asteroid's mean diameter.

The Vesta family of asteroids is probably debris from this collision. This revealed a large crater at the south pole that slices into its interior. The crater averages km in diameter — remember: Vesta itself is only km across. It cuts an average of 13 km into the crust, and most likely formed from an impact in the asteroid's early life. The material ejected from this collision resulted in a number of smaller — Vestoid — asteroids that orbit near their parent, as well as some of the meteorites that have crashed into Earth.

Unlike most asteroids, the interior of Vesta is differentiated. Like the terrestrial planets, the asteroid has a crust of cooled lava covering a rocky mantle and an iron and nickel core. This lends credence to the argument for naming Vesta as a protoplanet, rather than as an asteroid.

Vesta's core accreted rapidly within the first 10 million years after the formation of the solar system. The basaltic crust of Vesta also formed quickly, over the course of a few million years. Volcanic eruptions on the surface stemmed from the mantle, lasting anywhere from 8 to 60 hours.

The lava flows themselves ranged from a few hundred meters to several kilometers, with a thickness between 5 to 20 meters. The lava itself cooled rapidly, only to be buried again by more lava until the crust was complete. Dawn's gravity put its core at about 18 percent of Vesta's mass, or proportionally about two-thirds as massive as Earth's core. In , a fireball streaking through the sky over Millbillillie, Australia, announced the arrival of a piece of Vesta on Earth.

Composed almost entirely of pyroxene, a mineral found in lava flows, the meteorite bears the same spectral signals as Vesta. NASA's Dawn spacecraft, which visited the asteroid in , discovered that the rocky body had a surprising amount of hydrogen on its surface. It also found bright, reflective regions that may have been left over from its birth. A massive mountain towers over Vesta's southern pole. The enormous mountain reaches up over 65, feet 20 kilometers in height, making it nearly as tall as Olympus Mons, the largest mountain and volcano in the solar system.

Olympus Mons soars about 15 miles 24 kilometers above the surface of Mars. Liquid water once flowed across the asteroid. Images captured by the Dawn spacecraft revealed curved gullies and fan-shaped deposits within eight different Vesta impact craters.

All eight of the craters are thought to have formed within the last few hundred million years, fairly recent in the lifetime of the 4. The surface is very cold and there is no atmosphere, so any water on the surface evaporates," study lead author Jennifer Scully, a postgraduate researcher at UCLA, said in a NASA statement. Scully and her team thought the features were created by debris flows, as opposed to pure-water rivers or streams, sculpted the Vesta gullies.

They proposed that meteorites bombarding the asteroid melted ice deposits beneath the surface, sending liquid water and small rocky particles flowing down the crater walls.

Such activity suggests the presence of ice buried beneath the surface. Ice could have been responsible for modifying Vesta's surface. In , a study suggested that smooth patches of terrain on the asteroid frequently possessed high concentrations of hydrogen, which is often seen when solar radiation breaks down water molecules.

Dawn also observed signs of hydrated minerals minerals containing water molecules on Vesta's surface, which could also hint at the presence of buried ice. Vesta, like Earth, is composed of rock in its crust and mantle, and it has an iron core.

Because of its large size for an asteroid and because Vesta has a crust, mantle and core, it is considered a planetesimal. Planetesimals are building blocks out of which planets form. Earth formed by accretion of several such planetesimals.

Klimczak is co-author on a new study that examines the large-scale troughs and impact basins on Vesta. Vesta was hit by two other large asteroids which left large impact craters so big they cover most of the southern hemisphere of Vesta. These impacts are thought to have ejected rocky material into space. Some of these rocks reached Earth as meteorites so scientists now have actual rock samples from Vesta to study its geochemistry.

According to Cheng, one big question is what triggered the formation of these large troughs. The two troughs are concentric around the two massive impact basins, Rheasilvia and Veneneia, respectively, and widely considered to be simultaneously formed by the impact events, though this assumed age relationship has never been tested before.

However, the uncertainties associated with the crater counts allow for the troughs to have formed well after the impacts. The origin of the troughs has long been a point of conjecture within the scientific community. Klimczak hopes their new geologic evidence can promote a more-durable theory about the troughs on Vesta.