Alumni Association seeks nominations for Founders’ Day Awards


November 17, 2014

Seeking to honor those who have made outstanding contributions to the Arizona State University Alumni Association and the Arizona State University community, the Alumni Association is accepting nominations for its annual Founders’ Day Awards.

The awards will be presented at the Founders’ Day 2015 celebration, scheduled to take place at the Arizona Biltmore Resort & Spa on Thursday, March 5, 2015. Founders' Day 2015 Download Full Image

First celebrated in 1960 on the eve of the institution’s 75th anniversary, Founders’ Day salutes the enterprising spirit of those who helped the university’s predecessor, the Tempe Normal School, become a reality on March 7, 1885.

The focus of this year’s event will be sustainability, and the awards will honor alumni, faculty and university supporters who are actively engaging in innovation to create a more sustainable world.

Potential honorees may be nominated from any field that touches upon sustainability, including basic science, innovation, technology, business, law and public policy.

The nomination deadline is 5 p.m., Friday, Dec. 5. Nominations are being accepted in the following categories:

Faculty Achievement – This award is presented to faculty members who have demonstrated exemplary contributions related to sustainability in any of three categories: Teaching, Research and Service.

Alumni Achievement –The association also will present the Alumni Achievement Award and the Young Alumni Achievement Award at the Founders’ Day event. These awards honor alumni who have excelled in their professions and contributed in significant ways related to sustainability, the Alumni Association and/or the community at large. To obtain an application to nominate an alumna/us for either award, email Janet.Osgood@asu.edu.

In addition to the awards presented by the Alumni Association, the ASU Foundation For A New American University will present its Philanthropist of the Year award at the Founders’ Day event. This award, first given in 2010, allows the Foundation and the university to recognize community-minded citizens who have made a difference by supporting ASU-affiliated organizations and institutions.

To make a nomination for the 2015 Founders’ Day Awards, visit: asu.edu/foundersday.

Geologic mapping of asteroid Vesta reveals history of large impacts


November 17, 2014

A team of 14 scientists led by David Williams of Arizona State University's School of Earth and Space Exploration has completed the first global geologic and tectonic map of the asteroid Vesta. The work reveals that Vesta's history has been dominated by impacts from large meteorites.

The mapping was carried out using images from NASA's Dawn spacecraft, which orbited Vesta between June 2011 and September 2012. The images let scientists create high-resolution geological maps, revealing the variety of Vesta’s surface features in unprecedented detail. Vesta's geological map Veneneia, Rheasilvia, Marcia impacts Download Full Image

"The geologic mapping campaign at Vesta took about two and a half years to complete," says Williams. "The resulting maps enabled us to construct a geologic time scale of Vesta for comparison to other planets and moons."

The geologic map and timescale appear in a paper by Williams and others in the December 2014 issue of the journal Icarus. The issue also has 10 other papers reporting on Dawn's investigation of Vesta. In addition to Williams, the mapping effort was also led by R. Aileen Yingst of the Planetary Science Institute, Tucson, Arizona, and W. Brent Garry of NASA's Goddard Spaceflight Center, Greenbelt, Maryland.

The mappers found that Vesta’s geologic time scale has been shaped by a sequence of large impact events. The biggest of these were the impacts that blasted the large Veneneia and Rheasilvia craters early in Vesta's history, and the Marcia crater late in its history.

In mapping an extraterrestrial object, scientists begin by studying its surface features to develop a relative chronology of events. They look to see which feature interrupts or disturbs other features, thereby placing them in a relative time sequence. Then, crater by crater, fracture by fracture, scientists build up a chronology of events.

But how long ago did specific events happen? An age in years is quite difficult to determine because the samples scientists have from Vesta – a family of basaltic meteorites called HEDs, for howardite-eucrite-diogenite – do not show a clear formation age (as dated by laboratory methods) that can be linked to specific features on the asteroid.

"So figuring out an actual date in years is a step-by-step-by-step process," explains Williams. "We work with rock samples from the moon, mostly from Apollo missions decades ago. These give actual dates for large lunar impacts." The tricky part, he says, lies in creating a model that links the lunar impact time scale to the rest of the solar system.

In the case of Vesta, scientists have developed two different models to estimate surface ages. One is based on the lunar impact rate, the other on the frequency of asteroid impacts. Thus scientists can use two approaches with crater statistics to date Vesta's surface, but these yield two different age ranges.

Applying the models to Vesta, Williams' team concluded that the oldest surviving crust on Vesta predates the Veneneia impact, which has an age of 2.1 billion years (asteroid system) or 3.7 billion years (lunar system). The Rheasilvia impact likely has an age of around 1 billion years (asteroids) or 3.5 billion years (lunar).

"Vesta's last big event, the Marcia impact, has an age that's still uncertain," says Williams. "But our current best estimates suggest an age between roughly 120 and 390 million years." The difference, he explains, comes from which cratering model is used.

The geologic mapping relied on images taken by the framing camera provided by the Max Planck Institute for Solar System Research of the German Max Planck Society and the German Aerospace Center (DLR). This camera takes panchromatic images and seven bands of color filtered images. Overlapping images provide stereoscopic views that create topographic models of the surface to help the geologic interpretation.

“Geological mapping was crucial for resolving Vesta’s geologic history, as well as providing geologic context to understand compositional information from Dawn's Visible and Infrared (VIR) spectrometer and Gamma Ray and Neutron Detector (GRaND),” says Carol Raymond, Dawn’s deputy principal investigator.

The objective of NASA's Dawn mission, launched in 2007, is to characterize the two most massive objects in the main asteroid belt between Mars and Jupiter. Vesta was thought to be the source of a unique set of basaltic meteorites (the HEDs), and Dawn confirmed the Vesta-HED connection. The Dawn spacecraft is currently on its way to the dwarf planet Ceres, the largest object in the asteroid belt. The spacecraft will arrive at Ceres in March 2015. The Dawn mission is managed by the NASA Jet Propulsion Laboratory in Pasadena, California.

The School of Earth and Space Exploration is an academic unit of ASU's College of Liberal Arts and Sciences.

Robert Burnham

Science writer, School of Earth and Space Exploration

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