Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Asteroid's troughs suggest stunted planet

27.09.2012
Enormous troughs that reach across the asteroid Vesta may actually be stretch marks that hint of a complexity beyond most asteroids. Scientists have been trying to determine the origin of these unusual troughs since their discovery just last year.

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.

Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

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.

New measurements of Vesta's topography, derived from images of Vesta taken by NASA's Dawn spacecraft last year, indicate that a large collision could have created the asteroid's troughs. But, this would only have been possible if the asteroid is differentiated - meaning that it has a core, mantle and crust -- said Debra Buczkowski of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. Because Vesta is differentiated, its layers have different densities, which react differently to the force from the impact and make it possible for the faulted surface to slide, she added. "By saying it's differentiated, we're basically saying Vesta was a little planet trying to happen."

Her team's research will be published online this Saturday in Geophysical Research Letters, a journal of the American Geophysical Union.
Most asteroids are pretty simple. "They're just like giant rocks in space,"
said Buczkowski. But previous research has found signs of igneous rock on Vesta, indicating that rock on Vesta's surface was once molten, a sign of differentiation. If the troughs are made possible by differentiation, then the cracks aren't just troughs, they're graben. A graben is a dip in the surface that forms when two faults move apart from each other and the ground sinks into the widening gap, such as in Death Valley in California. Scientists have also observed graben on the Moon and planets such as Mars.

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.

These observations indicate that Vesta is also unusually planet-like for an asteroid in that its mantle is ductile and can stretch under a lot of pressure.

"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 Journalists

Journalists and public information officers (PIOs) of educational and
scientific institutions who have registered with AGU can download a PDF
copy of this paper in press by clicking on this link:
http://www.agu.org/journals/pip/gl/2012GL052959-pip.pdf
After the paper publishes on Saturday, 29 September, it will be accessible at:
http://dx.doi.org/10.1029/2012GL052959
Or, you may order a copy of the paper by emailing your request to Sean Treacy
at streacy@agu.org. Please provide your name, the name of your publication,
and your phone number.
Neither the paper nor this press release are under embargo.
Title:
"Large-scale troughs on Vesta: A signature of planetary tectonics"
Authors:
Buczkowski, D.L., Iyer, K.A., Kahn, E.G., and Barnouin O.S.: JHU-APL,
Laurel, Maryland, USA;
Wyrick, D.Y.: SWRI, San Antonio, Texas, USA;
Scully, J.E.C. and Russell, C.T.: UCLA, Los Angeles, California, USA;
Nathues, A., and Le Corre, L.: Max Planck Institute for Solar System
Research, Katlenburg-Lindau, Germany;
Reddy, V.: Max Planck Institute for Solar System Research, Katlenburg-
Lindau, Germany; and University of North Dakota, Grand Forks, North
Dakota, USA;
Gaskell, R.W., Yingst R.A., Mest S., and Garry, W.B.: PSI, Tucson,
Arizona, USA;
Roatsch, T., Preusker, F., and Jaumann, R.: DLR, Institute of Planetary
Research, Berlin, Germany;
Schenk, P.M., LPI, Houston, Texas, USA;
Williams, D.A.: Arizona State University, Tempe, Arizona, USA;
Raymond, C.A.: JPL, California Institute of Technology, Pasadena,
California, USA.
Contact information for the authors:
Debra Buczkowski, +1 (443) 778-2684, Debra.Buczkowski@jhuapl.edu
AGU Contact:
Sean Treacy
+1 (202) 777-7516
streacy@agu.org
JPL Contact:
Jia-Rui Cook
NASA Jet Propulsion Laboratory
Pasadena, Calif.
+1 (818) 354-5011
jccook@jpl.nasa.gov

Sean Treacy | American Geophysical Union
Further information:
http://www.agu.org
http://www.nasa.gov

More articles from Earth Sciences:

nachricht Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide
15.08.2018 | University of Washington

nachricht Algorithm provides early warning system for tracking groundwater contamination
14.08.2018 | DOE/Lawrence Berkeley National Laboratory

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Unraveling the nature of 'whistlers' from space in the lab

15.08.2018 | Physics and Astronomy

Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide

15.08.2018 | Earth Sciences

Early opaque universe linked to galaxy scarcity

15.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>