Now, a new analysis supports the notion that the troughs are faults that formed when a fellow asteroid smacked into Vesta's south pole. The research reinforces the claim that Vesta has a layered interior, a quality normally reserved for larger bodies, such as planets and large moons.
An image taken by NASA's Dawn spacecraft on July 24, 2011, shows troughs along the equator of the asteroid Vesta, including Divalia Fossa, which is larger than the Grand Canyon. A new study analyzing these troughs finds that they are probably graben – a dip in the surface with faults on either side that would indicate that Vesta has characteristics much like a planet or large moon.
Asteroid surface deformities are typically straightforward cracks formed by crashes with other asteroids. Instead, an extensive system of troughs encircles Vesta, the second most massive asteroid in the solar system, about one-seventh as wide as the Moon. The biggest of those troughs, named Divalia Fossa, surpasses the size of the Grand Canyon by spanning 465 kilometers (289 miles) long, 22 km (13.6 mi) wide and 5 km (3 mi) deep.
The origin of these troughs on Vesta has puzzled scientists. The complexity of their formation can't be explained by simple collisions.
The images from the Dawn mission show that Vesta's troughs have many of the qualities of graben, said Buczkowski. For example, the walls of troughs on simpler asteroids such as Eros and Lutetia are shaped like the letter V. But Vesta's troughs have floors that are flat or curved and have distinct walls on either side, like the letter U - a signature of a fault moving apart, instead of simple cracking on the surface.
The scientists' measurements also showed that the bottoms of the troughs on Vesta are relatively flat and slanted toward what's probably a dominant fault, much as they are in Earth-bound graben.
"It can become almost silly putty-ish," said Buczkowski. "You pull it and it deforms."
Buczkowski and her colleagues' arguments for differentiation of Vesta are interesting, said planetary scientist Geoff Collins of Wheaton College, in Norton, Mass, who specializes in tectonics, the structure and motion of planetary crusts. "On many much smaller asteroid bodies, we've seen very narrow troughs that look just like cracks on the surface," said Collins, 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."
But Collins is not yet fully convinced that Vesta's troughs are graben. An example of rock-solid evidence of graben on Vesta that has yet to be discovered, he said, would be an obvious crater that had been torn in two by a trough.
There are other qualities of Vesta that could be clues to how the troughs formed. For example, unlike the larger asteroid Ceres, Vesta is not classified as a dwarf planet because the large collision at its south pole knocked it out of its spherical shape, said Buczkowski. It's now more squat, like a walnut. But if Vesta has a mantle and core, that would mean it has qualities often reserved for planets, dwarf planets and moons -- regardless of its shape.
The origin of that funny shape is the centerpiece of a different hypothesis about how the troughs formed. Britney Schmidt of the Institute for Geophysics in Austin, Texas, believes the south pole collision knocked Vesta into its current speedy rate of rotation about its axis of about once per 5.35 hours, which may have caused the equator to bulge outward so far and so fast that the rotation caused the troughs, rather than the direct power of the impact. "It's an enigma why Vesta rotates so quickly," said Schmidt, who was not a part of the current study.
Dawn has already left to explore Ceres, so all the data it will retrieve on Vesta is in hand. Buczkowski said scientists will continue to sort that data out and improve on computer simulations of Vesta's interior. As those analyses come along, she said she will keep an open mind toward any revelations that come to light, but she doesn't expect her conclusion will change. "I really think that these are graben," she said.
Notes for JournalistsJournalists and public information officers (PIOs) of educational and
Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments
22.01.2018 | Duke University
World’s oldest known oxygen oasis discovered
18.01.2018 | Eberhard Karls Universität Tübingen
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
22.01.2018 | Materials Sciences
22.01.2018 | Earth Sciences
22.01.2018 | Life Sciences