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| Is There a Relationship Between Central Pit and Anomalous Dome Craters on Ganymede? |
| Presentation Time: Monday, 3:30 p.m. - 3:40 p.m. |
Nadine G. Barlow1, R. Godwin1
1Northern Arizona Univ.. |
| Presentation Number: 11.01 |
Central pit and anomalous dome craters were detected on Ganymede from Voyager analysis and can be studied in more detail with higher resolution Galileo Solid State Imager (SSI) data. Central pit (CP) craters contain a central depression - they are common on icy moons and on Mars but absent on volatile-poor bodies like the Moon, suggesting that target volatiles play a role in their formation. Anomalous dome (AD) craters display a central dome surrounded by a ring of chaotic massifs. Using Galileo SSI data, we are investigating the hypothesis that AD craters are CP craters which have excavated into lower-viscosity material that then rebounds to create the central dome. As part of the development of the Catalog of Impact Craters on Ganymede, we have classified over 4700 craters on the moon. Approximately 2200 of these display a classifiable interior morphology. AD craters constitute ~7% and CP ~24% of the craters with an interior morphology; most craters with an interior morphology display a central peak (~60%). There is no strong variation in these percentages between bright and dark terrains. The two morphologies are similar in size: CP craters range in size from 17 to ~100 km while AD craters have diameters between 10 and ~100 km. The ratio of pit to crater diameter averages ~0.18 for CP craters on both bright and dark terrains. We are currently measuring the central dome diameters of AD craters and determining the regional distributions of CP and AD craters. We also are using crater preservational information to constrain the formation periods of CP and AD craters. These results will allow us to test the hypothesis of a relationship between CP and AD craters on Ganymede.
This research is funded through NASA Outer Planets Research Program Award #NNG05G116G. |
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