Rampart Craters: A Case for Water on Mars
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Transcript of Rampart Craters: A Case for Water on Mars
Eddie BrooksMarch 11, 2014Earth 438
Rampart Craters: A Case for Water on Mars
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?
Where do the Craters Form?
Black – Rampart Craters Confirmed | White – Insufficient Data
Single Layer Ejecta
Double Layer Ejecta
Multiple Layer Ejecta
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