Search Publications
Assessing global trends in Mars magma compositions using ground truth
Head, James W.; Rogers, A. Deanne; McSween, Harry Y. +1 more
Global magmatic trends inferred from gamma-ray, visible/near-infrared, and thermal infrared spectrometers on Mars-orbiting spacecraft have been used to constrain planetary petrogenetic processes and global thermal evolution models. Inferred magmatic trends include temporal variations in the relative proportions of low-Ca and high-Ca pyroxenes, and…
Measuring impact crater depth throughout the solar system
Beyer, Ross A.; Robbins, Stuart J.; Watters, Wesley A. +9 more
One important, almost ubiquitous, tool for understanding the surfaces of solid bodies throughout the solar system is the study of impact craters. While measuring a distribution of crater diameters and locations is an important tool for a wide variety of studies, so too is measuring a crater's "depth." Depth can inform numerous studies including th…
Testing landslide and atmospheric-effects models for the formation of double-layered ejecta craters on Mars
Head, James W.; Weiss, David K.
Double-layered ejecta (DLE) craters are distinctive among the variety of crater morphologies observed on Mars, but the mechanism by which they form remains under debate. We assess two ejecta emplacement mechanisms: (1) atmospheric effects from ejecta curtain-induced vortices or a base surge and (2) ballistic emplacement followed by a landslide of …
Martian cratering 11. Utilizing decameter scale crater populations to study Martian history
Daubar, I. J.; Hartmann, W. K.
New information has been obtained in recent years regarding formation rates and the production size-frequency distribution (PSFD) of decameter-scale primary Martian craters formed during recent orbiter missions. Here we compare the PSFD of the currently forming small primaries (P) with new data on the PSFD of the total small crater population that…
Investigating target versus impactor influences on Martian crater morphology at the simple-complex transition
Hynek, Brian M.; Herrick, Robert R.
Comparing craters of identical diameter on a planet is an empirical method of studying the effects of different target and impactor properties while holding total impact energy nearly constant. We have analyzed the Martian crater population within a narrow diameter range (7 km < crater diameter < 9 km) at the simple-complex crater transition…
Ages of rampart craters in equatorial regions on Mars: Implications for the past and present distribution of ground ice
Jaumann, R.; Neukum, G.; Hauber, E. +3 more
We are testing the idea of Squyres et al. (1992) that rampart craters on Mars may have formed over a significant time period and therefore the onset diameter (minimum diameter of a rampart crater) only reflects the ground ice depth at a given time. We measured crater size frequencies on the layered ejecta of rampart craters in three equatorial reg…