Asteroid Vesta is the second largest asteroid in our solar system. With a diameter of about 330 miles, it orbits the sun between the planets Mars and Jupiter.
Asteroids have long played a role in popular fascination with space. “Marooned off Vesta” was the first story published by American writer Isaac Asimov, the third story he wrote, appearing in the March 1939 issue of the science fiction magazine Amazing Stories.
“When we think of asteroid belts, we probably imagine Han Solo maneuvering the Millennium Falcon through a dense set of irregularly shaped gray rocks in space,” Christian Klimczak, associate professor in the geology department at Franklin College of Arts and Sciences. “While most of the rocks are indeed irregularly shaped and gray, they are far apart and NASA’s Dawn spacecraft did not have to maneuver around other asteroids to reach and explore Vesta.”
Dawn was the space probe launched by NASA in September 2007 with the mission to study two of the three known protoplanets of the asteroid belt, Vesta and Ceres.
Vesta, like Earth, is made up of rock in its crust and mantle, and it has an iron core. Due to its large size (for an asteroid) and because Vesta has a crust, mantle, and core, it is considered a planetesimal. Planetesimals are the building blocks from which planets are formed. Earth formed by accretion of several of these planetesimals. “Vesta was also on the verge of becoming an Earth-like planet, but the formation of the planet stopped along the way early in our solar system’s history,” Klimczak said. “Therefore, studying Vesta helps us understand the very early days of our planetary neighborhood and how our own planet formed.”
Klimczak is co-author of a new study that examines large-scale basins and impact basins on Vesta.
What made these giant drinkers on Vesta?
Vesta was hit by two other large asteroids which left large impact craters so large that they cover most of Vesta’s southern hemisphere. These impacts are believed to have ejected rocky material into space. Some of these rocks reached Earth as meteorites, so scientists now have real rock samples from Vesta to study its geochemistry.
“The properties of rocks are influenced by environmental conditions such as surrounding stresses and the presence of water,” said Jupiter Cheng, a doctoral student in the geography department and co-author of the study. “Since Vesta is much smaller than Earth, or even the moon, she has lower gravity, and rock would warp differently near the surface than what we see on Earth.”
According to Cheng, a big question is what triggered the formation of these great hollows. The two troughs are concentric around the two massive impact basins, Rheasilvia and Veneneia, respectively, and widely believed to be simultaneously formed by impact events, although this supposed age relationship has never been tested before.
“Our work used crater counting methods to explore the relative age of basins and troughs,” Cheng said. Crater counting is a common method of estimating the age of a planet’s surface, a method based on the assumption that when a piece of planetary surface is new, it has no impact craters; the impact craters then accumulate at a supposedly known rate.
“Therefore, counting the number of craters of different sizes in a given area allows us to determine how long they have accumulated and, therefore, how long ago the surface formed,” she said. declared. “Our result shows that the troughs and basins have a similar number of craters of different sizes, indicating that they share a similar age. However, the uncertainties associated with the counting of the craters allow the hollows to have formed well after the impacts.
The origin of the troughs has long been the subject of conjecture within the scientific community. Klimczak hopes their new geological evidence can promote a more lasting theory about Vesta troughs.
The study is published in the September issue of the journal Icarus.
A new theory is proposed in an upcoming article
“The main hypothesis suggests that these troughs are fault-bound valleys with a distinct escarpment on either side that together mark the descent (slip) of a block of rock. However, the rock can also crack and form such hollows, an origin that has not been considered before, “said Cheng, who is studying the origin of hollows as part of her thesis at UGA.
“Our calculations also show that Vesta’s gravity is not sufficient to induce surrounding stresses favorable to shallow sliding, on the contrary, physics shows that rocks there are favored to crack,” he said. she declared. “Therefore, the formation of these hollows must involve the opening of cracks, which is in contradiction with the dominant assumption of the scientific community. Overall, the overall project offers alternatives to the previously proposed trough origin and geological history of Vesta, results that are also important for understanding similar landforms on other small planetary bodies elsewhere in the system. solar.
Originally posted by Phyorg