Data from NASA's Dawn mission show that a common form of weathering, which occurs on many airless bodies in the inner solar system like the Moon, does not age Vesta’s outermost layer.
This image from NASA's Dawn spacecraft shows a close up of part of the rim around the crater Canuleia on the giant asteroid Vesta. Canuleia, about 6 miles (10 kilometers) in diameter, is the large crater at the bottom-left of this image. This close-up image illustrates the structure of the interior of the crater and complex details of the fresh rays across the soil of Vesta. The image was taken by Dawn's framing camera on Dec. 29, 2011, from an altitude of about 130 miles (210 kilometers).
Carbon-rich asteroids have also been splattering dark material on Vesta's surface over a long span of its history. The results are described in two papers reported on Nov. 1 in the journal Nature.
David Williams, an associate research professor in ASU’s School of Earth and Space Exploration, is a co-author of the Nature article on Vesta’s dark material, titled “Dark Material on Vesta: Delivering Carbonaceous Volatile-Rich Materials to Planetary Surfaces.”
“The dark material on Vesta has been a perplexing problem, one we first noticed as Dawn approached Vesta in the summer of 2011,” said Williams, a member of the science team task force investigating the dark material. “Through Dawn’s mission at Vesta, it became clear that the dark material was mostly derived from carbon-rich asteroids that impacted Vesta’s surface.”
Early pictures of Vesta showed a variety of dramatic light and dark splotches on its surface. These light and dark materials were unexpected and show Vesta has a brightness range that is among the largest observed on rocky bodies in our solar system.
“Most of the smaller dark material patches are associated with impact craters, forming dark rays of ejecta spreading outward,” Williams said. “There are also large regions of dark material, whose composition suggests they are derived from carbon-rich asteroids – perhaps from one or more large impacts early in Vesta’s history.”
Dawn scientists suspected early on that bright material is native to Vesta. One of their first theories for the dark material suggested it might come from the shock of high-speed impacts melting and darkening the underlying rocks or from recent volcanic activity.
An analysis of data from Dawn’s visible and infrared mapping spectrometer and the framing camera revealed that distribution of dark material is widespread and occurs in small spots and in diffuse deposits, without correlation to any particular underlying geology. The likely source of the dark material is now shown to be carbon-rich asteroids, which are also believed to have deposited hydrated minerals on Vesta.
To get the amount of darkening we now see on Vesta, Williams and colleagues said, scientists estimate about 300 dark asteroids with diameters between 0.6 to 6 miles (1 and 10 kilometers) likely hit Vesta during the last 3.5 billion years. This would have been enough to wrap Vesta in a blanket of mixed material 3 to 7 feet (1 to 2 meters) thick.
“This perpetual contamination of Vesta with material from elsewhere in the solar system is a dramatic example of an apparently common process that changes many solar system objects,” said Thomas McCord, lead author of the Nature paper, who worked with Williams on this study. “Earth likely got the ingredients for life – organics and water – this way.”
Launched in 2007, Dawn spent more than a year investigating Vesta. It departed in September 2012 and is currently on its way to the dwarf planet Ceres.
Williams is a participating scientist on NASA’s Dawn mission. JPL manages the Dawn mission for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Ala. The University of California at Los Angeles (UCLA) is responsible for overall Dawn mission science.
Orbital Sciences Corp., Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team. The California Institute of Technology, Pasadena, manages JPL for NASA.
For more information about Dawn, visit: http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov.
Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)
Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences