Ingrid’s paper, “The current martian cratering rate,” reports on the discovery of 248 dated impact sites known to have formed on Mars within the last few decades.
Before and after images constrain the creation dates of these small, meter- to decameter-sized craters. A subset of the new impacts was scaled to the area searched, as well as the time over which it was searched, to minimize observational biases. Daubar and her coauthors used this new technique to measure the current martian impact rate, finding that more than 200 new craters larger than ~4 meters in diameter are forming on Mars each year.
Solid bodies in the solar system are dated using cratering chronology models: The number of craters of different sizes gives an estimate of how long that surface has been bombarded. These models are based on crater counts done on the Moon, and calibrated with known radiometric ages of returned Apollo samples. To apply these models to other bodies such as Mars, a number of approximations and assumptions must be made. The measurement Daubar and coauthors made of the current cratering rate on Mars allowed these models to be assessed. In fact, the measured rate is significantly lower than those predicted by the models, by a factor of three to five. This brings into question whether the ages resulting from these widely used models are accurate when applied to craters this small.
Ingrid's research was performed under the advisement of Dr. Alfred McEwen.
Emily’s paper, “Redox state during core formation on asteroid 4-Vesta”, presented research that coupled high-precision measurements of silicon isotopic ratios in achondrites with models of Si behavior during metal-silicate differentiation, to aid in understanding planetary core formation.
The primary differentiation of the terrestrial planets involved the separation of iron-rich metal from silicate to form a core and mantle, and their chemical and isotopic compositions are closely linked to the conditions (e.g. temperature, pressure, oxidation state) prevailing during core formation. As Si isotopes can be fractionated between metal and silicate under these conditions, they are particularly useful indicators of core formation processes.
The Si isotope compositions of Howardite-Eucrite-Diogenite (HED) meteorites, which represent samples from the silicate portion the asteroid 4-Vesta, are slightly offset from chondritic values, consistent with the core of 4-Vesta containing 1-2 wt.% Si.
Furthermore, since the amount of Si in the metal phase is dependent on temperature, pressure, and oxygen fugacity, it is possible to use to the calculated amount of Si in 4-Vesta’s core to probe the conditions during core formation. This represents a novel application of the Si isotope system to study core formation in differentiated planetary bodies.
Emily's research was performed under the advisement of Dr Frederic Moynier.
Each submission was reviewed by a panel of experts from a broad array of fields in meteoritical science.
History of the Award
In 1965, Dr. H.H. Nininger and Mrs. Addie D. Nininger endowed the Nininger Science of Meteoritics Fund to the Center for Meteorite Studies at Arizona State University in order to promote interest in meteorite-related topics among young scientists. The Fund supports the Nininger Meteorite Award, which recognizes outstanding student achievement in the “Science of Meteoritics” as embodied by an original research paper. Past recipients include Harry Y. McSween (University of Tennessee), Edward Stolper (California Institute of Technology) and the recipients of the 2005 Barringer Award (Billy P. Glass, University of Delaware) and Leonard Medal (Joseph Goldstein, University of Massachusetts, Amherst).
The original text of the Nininger endowment states that the "Science of Meteoritics embraces all aspects of the study of inert natural matter existing in space, passing through the atmosphere, or having come to Earth from space, together with any or all of the phenomena occasioned by its fall and its effect upon the Earth or upon any other member of the Solar System. Such science shall also be considered to include theoretical consideration as to the origin of such matter and special relationships". Research topics covered under this description include, but are not limited to, physical and chemical properties of meteorites, origin of meteoritic material and cratering. Observational, experimental, statistical or theoretical investigations are allowed.
Applicant must be an undergraduate or graduate student enrolled at a United States college or university.
The student must be first author of the paper, but does not have to be the sole author.
Paper must cover original research conducted by the student, and have been written, submitted or published between January 1, 2013 and December 31, 2013.