Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dawn Reveals Complexities of Ancient Asteroidal World

14.05.2012
New findings from NASA’s Dawn spacecraft lay the groundwork for the first geological overview of asteroid (4)Vesta and confirm the existence of not one but two giant impact basins in its southern hemisphere.

The findings, published today in a set of Science papers, will help scientists better understand the early solar system and processes that occurred as it formed and evolved.

The Dawn spacecraft, orbiting asteroid Vesta since July 2011, has already acquired several thousand images of the asteroid’s surface, revealing a complex landscape. The images provide many details that help scientists to understand how the surface has evolved since its formation.

The first paper provides an overview of the true complexity of this ancient world. Vesta is not just a ball of rock; its surface is dominated by abundant impact craters of all shapes and sizes, from small fresh craters to giant basins as seen in the southern hemisphere. The surface of Vesta is complex and varied, with preserved ejecta blankets clinging to some craters, large troughs extending around the equatorial region, enormous mountains, and unevenly distributed enigmatic dark material, but as yet an absence of volcanic features.

“As a volcanologist, and as one who expected to find evidence of volcanism on Vesta based on what we knew from the Howardite–Eucrite–Diogenite (HED) meteorites and prior models of Vesta’s formation, the biggest surprise for me was the absence of any evidence of volcanic features. Vesta’s surface has been so heavily modified by impact cratering that any evidence of its early volcanic activity has been destroyed,” says Dawn mission participating scientist David Williams, co-author on the papers and faculty research associate in Arizona State University’s School of Earth and Space Exploration.

The present lack of volcanic features detected on Vesta suggests that volcanism was only active during the short period of rapid cooling of Vesta’s interior within the first 100 million years after formation, and that the surface has been eroded by impacts over time.

Like Earth and other terrestrial planets, Vesta has ancient basaltic materials in its crust and a large iron core. It is an irregular asteroid that also has tectonic features, troughs, ridges, cliffs, hills and a giant mountain. But comparisons of the slopes and topography of Vesta show that they are intermediate between planets and small asteroids, underscoring Vesta’s unique role as a transitional solar system body.

Prior to the arrival of the Dawn spacecraft, some Vestan surface features had already been resolved using the Hubble Space Telescope and ground-based telescopes. The most prominent of these surface features is an enormous crater Dawn found to be about 500 kilometers (310 miles) in diameter, centered near the south pole, named Rheasilvia after the mother of Romulus and Remus. Its width is 90 percent the diameter of Vesta and it is estimated that the impact responsible excavated about 1 percent of the volume of Vesta.

The second paper is a geological description of this large impact basin.

“Dawn observations enabled us to recognize that there are actually TWO large basins at the south pole, an older one named “Veneneia” and a younger one named “Rheasilvia”,” explains Williams.

The Rheasilvia basin dominates the geology of Vesta, as the basin itself and its impact ejecta cover most of the southern hemisphere. The center of Rheasilvia has a central peak taller than Mt. Everest or Mauna Loa on Earth, similar in height to Olympus Mons on Mars. This basin appears to have excavated into the mantle of Vesta, exposing material spectrally similar to diogenite meteorites; Vesta’s crust is spectrally similar to eucrite and howardite meteorites, thus confirming that Vesta and its family of asteroids are the source of the howardite-eucrite-diogenite (HED) family of basaltic achondrite meteorites.

“For most planets and moons we see the pictures first, then have samples collected later to confirm our geologic interpretations. In the case of Vesta, thanks to the HED meteorites, we have the samples first, and must try to relate them to our emerging geologic picture of Vesta from the Dawn mission,” said Williams.

ASU SOURCE:
David Williams, david.williams@asu.edu
480-965-7029
ASU MEDIA CONTACT:
Nicole Cassis, ncassis@asu.edu
602-710-7169

Nicole Cassis | Newswise Science News
Further information:
http://www.asu.edu

More articles from Physics and Astronomy:

nachricht Innovative LED High Power Light Source for UV
22.06.2017 | Omicron - Laserage Laserprodukte GmbH

nachricht Spin liquids − back to the roots
22.06.2017 | Universität Augsburg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

A new technique isolates neuronal activity during memory consolidation

22.06.2017 | Life Sciences

Plant inspiration could lead to flexible electronics

22.06.2017 | Materials Sciences

A rhodium-based catalyst for making organosilicon using less precious metal

22.06.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>