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Rampart Craters: A Case for Water on Mars. Eddie Brooks March 11, 2014 Earth 438. Outline. What What is a Rampart Crater? Cratering Mechanics and Types Why Rampart Crater Formation Theory Where Rampart Craters on Mars Location Implications How Resolving multiple theories.
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Rampart Craters: A Case for Water on Mars Eddie Brooks March 11, 2014 Earth 438
Outline • What • What is a Rampart Crater? • Cratering Mechanics and Types • Why • Rampart Crater Formation Theory • Where • Rampart Craters on Mars • Location Implications • How • Resolving multiple theories
What is a Rampart Crater? • Fluidized ejecta • Can have multiple ejecta blankets • Very lobate • Not found on all planetary bodies • Most common of Martian crater morphologies
Rampart Cratering Mechanics • Impactor strikes ground • Kicks up cloud of ejecta • Either: • Atmosphere causes ejecta to fall in layers • Fluidized ejecta flows out in groups • Layered, lobate crater is formed
Formation Theories Make Rampart Craters Intriguing The existence of these craters may suggest the presence of large quantities of subsurface volatiles, including water.
Rampart Crater Types • Three types of Rampart Craters: • Single Layer Ejecta • Double Layer Ejecta • Multiple Layer Ejecta
Theories on Formation • Subsurface Volatiles: • Frozen materials heated upon impact • Volatiles melt and mix with surrounding terrain • Fluidized ejecta flows like mud • Theory supported by absence of rampart craters on dry Moon and Mercury • Atmospheric Conditions: • Atmosphere allows for generation of vortex ring • Staggers depositionof ejecta • Confirmed mechanics in laboratory setting • Theory supported by absence of craters on atmosphere-less Moon and Mercury
Where do the Craters Form? Black – Rampart Craters Confirmed | White – Insufficient Data
Implications of Locations • Rampart craters are not location dependent • Widespread across Mars • Exception: Tharsis Region – geologically young • Crater type is location dependent • Subsurface volatile theory suggests correlation between frozen/liquid volatile and crater type • Atmospheric hypothesis alone lacks mechanism to explain location dependence
Reconciling Multiple Theories • Recent variations on atmospheric hypothesis incorporate volatiles to explain different crater types • Volatiles, when thrown into the air, may control descent into lobes • Raises the question: To what extent does the atmosphere play a role? • Enter: Ganymede and Europa
Ganymede and Europa • Planets without atmospheres • Water and other volatiles present • Rampart craters still form • Eliminates necessity of atmosphere for formation, emphasizes volatiles Ganymede
Conclusions and Further Work • Rampart craters are most likely the product of subsurface volatiles • Water is the most likely candidate, based on where craters are found • Further work can be performed to find out the exact influence an atmosphere may have on formation • Personal Project: Crater Catalogue