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Resolving the Primary Mechanism Causing Floor-Fractured Craters Using GRAIL and LOLA Data

Mike Delmonaco
Education & Public Outreach
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Abstract Text: 

Floor fractures are found in relatively few craters on the moon and the cause of their formation is a mystery. There are two proposed ideas for the cause of these fractures. The mechanism causing floor fractured craters has been hypothesized to be either magmatic intrusions or viscous relaxation. Due to the lack of gravity data in earlier studies, a definite answer was not determined. Recently, gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) has provided new insight into how floor fractured craters form. For example, Clement et al. (2015) used GRAIL data to suggest the magmatic intrusion hypothesis is more likely. In this research, we expand on the previous work to further ascertain which of these proposed hypotheses is best supported by the data.To carry out this study, data collected by the GRAIL satellites and the LOLA data set were used. This data provided precise measurements of the moon’s gravitational anomalies and a list of floor-fractured craters respectively. The data is available to the public through Arizona State University’s Java Mission-planning and Analysis for Remote Sensing (JMARS) program, which provides detailed maps of the moon that display the data collected by satellites such as GRAIL.The average gravity anomaly of each crater we observed was calculated. Floor fractured craters were compared to craters with similar properties using a unique crater class scheme to determine if a significant gravity difference exists among them. Because magmatic intrusions would lead to a difference in gravity anomalies between floor fractured craters and normal craters that viscous relaxation would not produce, the results of our comparisons has allowed us to conclude the probable cause of floor-fractured craters. Floor-fractured craters were measured to have a higher gravity anomaly difference between the crater and its surroundings compared to non-floor-fractured craters with similar properties. This leads to the conclusion that magmatic intrusion is the cause of floor-fractured craters. This experiment is important because it allows for a better understanding of lunar surface activity.

"A. D. Rogers...
SSERVI Identifier: 

Recognizing that science and human exploration are mutually enabling, NASA created the Solar System Exploration Research Virtual Institute (SSERVI) to address basic and applied scientific questions fundamental to understanding the Moon, Near Earth Asteroids, the Martian moons Phobos and Deimos, and the near space environments of these target bodies. As a virtual institute, SSERVI funds investigators at a broad range of domestic institutions, bringing them together along with international partners via virtual technology to enable new scientific efforts."