Central Pit Craters on Saturns Icy Moons Sierra

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Central Pit Craters on Saturn’s Icy Moons Sierra Ferguson Mentor: Dr. Nadine Barlow Northern

Central Pit Craters on Saturn’s Icy Moons Sierra Ferguson Mentor: Dr. Nadine Barlow Northern Arizona University

Introduction Mars g=3. 711 m/s^2 d=6, 799 km Ganymede g=1. 428 m/s^2 d=5, 268

Introduction Mars g=3. 711 m/s^2 d=6, 799 km Ganymede g=1. 428 m/s^2 d=5, 268 km

Introduction Rhea Dione Tethys g=0. 147 m/s^2 d=1, 066 km g=0. 233 m/s^2 d=1,

Introduction Rhea Dione Tethys g=0. 147 m/s^2 d=1, 066 km g=0. 233 m/s^2 d=1, 123 km g=0. 265 m/s^2 d=1, 528 km 40 km 36 km 250 km

Formation Models Melt-Drainage of Subsurface Ice Collapse of Weakened Material � Impactor hits icy

Formation Models Melt-Drainage of Subsurface Ice Collapse of Weakened Material � Impactor hits icy surface � Crater originally has a peak � Heat from impact melts the ice and leaves a Another model suggests that the collapse is from the weaker surface material � Weaker peak material collapses to form a pit (Senft and Stewart, 2011)

Data �

Data �

Analysis Pit vs. Crater Diameter 30 25 Pit Diameter (km) R 2 = 0,

Analysis Pit vs. Crater Diameter 30 25 Pit Diameter (km) R 2 = 0, 8679 20 15 10 5 0 0 10 20 30 40 50 60 70 80 Crater Diameter (km) Dione Ganymede (Alzate and Barlow, 2011)

Results Comparison of Crater Diameters vs Pit Diameters 70 60 Pit Diameter (km) 50

Results Comparison of Crater Diameters vs Pit Diameters 70 60 Pit Diameter (km) 50 40 Rhea Dione 30 Tethys 20 10 0 0 50 100 150 Crater Diameter (km) 200 250

Results Moon Surface Gravity (m/s 2) # of pits Dp/Dc median Crater value diameter

Results Moon Surface Gravity (m/s 2) # of pits Dp/Dc median Crater value diameter ranges (km) Pit Diameter ranges (km) Tethys 0. 147 13 0. 175 20 -60 3 -12 Dione 0. 233 12 0. 21 20 -80 3 -25 Rhea 0. 265 12 0. 22 20 -80 10 -20 Ganymede 1. 428 471 0. 19 10 -90 4 -43 Mars 3. 711 1604 0. 13 5 -90 2 -23

Conclusions �As crater diameters increase, pits increase as well �No indication that latitude and

Conclusions �As crater diameters increase, pits increase as well �No indication that latitude and pit distribution are related �Fewer pits found on smaller bodies �More pits were seen at smaller crater diameters �Larger Dp/Dc ratios support the melt drainage model Rhea: 0. 22 Dione: 0. 21 Tethys: 0. 17

Future Work �Results will be incorporated into a larger survey of central pit craters

Future Work �Results will be incorporated into a larger survey of central pit craters throughout the solar system including : Mercury, Mars, Ganymede, Callisto, and the moon �Results will be used to further constrain the formation models for central pits

Acknowledgements �Dr. Barlow �Kathleen Stigmon �NAU/NASA Space Grant �NAU � ASU �JMars �Cassini team

Acknowledgements �Dr. Barlow �Kathleen Stigmon �NAU/NASA Space Grant �NAU � ASU �JMars �Cassini team

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