NASA's Dawn sees young face on giant asteroid

October 31, 2012

Like a Hollywood starlet constantly retouching her make-up, the giant asteroid Vesta is constantly stirring its outermost layer and presenting a young face. 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.

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. Download Full Image

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: and

Director, Media Relations and Strategic Communications


In Graham We Trust

October 31, 2012

Column by Nick Prete, ASU News

At the beginning of the season, everyone was excited about Todd Graham coming ASU. Everyone was excited about the season. Rose bowl, national championship, and Pac-12 champions, were all things uttered amongst the Sun Devil fan base. With a few little losses however, everything has changed. Todd Graham at Tontazona Download Full Image

You are a part of the Sun Devil nation your whole life! Getting bummed out and hopping off the bandwagon after a few losses is pointless! Take a look at the bigger picture. We still have a lot of games we can, and need to win. To get to a bowl game, to help the recruiting class… etc. If we create an awesome atmosphere here at the stadium, where we fill up the stadium every game, and make it loud every play the opponent has the ball that will draw in the top recruits, and make our team better and better. But if we go to less and less games when we lose, you create a negative feedback circle. YOU can make the change. If you want us to get better, fill up the stands! That starts the positive feedback. If the stands are full, we get better recruits. If we get better recruits, the team gets better. If the team gets better, we get more people there. On and on and on. Every person helps. Every part of the puzzle. If you were a recruit, would you rather go to a school where the kids don’t really care about the games, the stands are kind of full after half time and only a few people wear the team colors on Fridays? Or would you rather go to a school overflowing with school spirit, the stands are packed for every game and it looks like a sea of gold on Fridays and Saturdays? Obviously the second.

As a Sun Devil Nation, we have to know that this low is only temporary. There’s a lot of season left so people need to stop acting like it’s over. Turn the negativity around and let’s rally! Look at your expectations first off, everyone had some really high hopes that may have been a little unrealistic. You can’t turn a losing team into a championship team in one-season folks. To even get to a bowl game with a new team coach is a high goal. As of 2011, only 7 first-year head coaches led their teams to a BCS bowl game in its 14-year history. We’re still sitting at a very impressive 5-3 with at least 4 games to go. Plus, we still have one of our most important games of the season to play against U of A.

This season isn’t done people! Not even close.  Bowl games, recruits, and wins. We can get 'em all. But we need you.  If you don’t care about the Sun Devil nation, then fine. Sit at home. Do your homework. Contribute to the University in some other way. But if you care about the football team at all then support it! Fill the stands. Stand with Graham. Bleed maroon and gold. Be a Sun Devil.