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Cassini Scientist for a Day -- Fall 2008 Winners, Target 3: Mimas, Grade 9 to 12

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Congratulations Cassini Scientist for a Day Winners
Target 3: Mimas

Sarah Cottrell-Cumber
Grade 9 to 12
Sarah Cottrell-Cumber
North Stafford High School
Stafford, Virginia

"There are two main features of Mimas that make it the best target for the Cassini probe: the creation of Herschel Crater, and Mimas’s dormancy compared to Enceladus’s activeness. Herschel Crater, one-third the diameter of the moon, is the largest known crater compared to a parent body. The force of the collision that created Herschel Crater caused stress fractures on the opposite side of the moon.

Mimas’s surface is also covered with other craters which show no clear pattern, and in the southern polar region of Mimas, larger craters are not present. What removed these larger craters from that region or what prevented larger astronomical bodies from impacting that region? How big of an impact can a celestial body take before being completely destroyed? Closer images of Herschel Crater might provide evidence to help answer these critical questions.

Scientist suggest the surface of Mimas has been frozen and has existed for a long period of time, but closer images and data of Mimas could reveal the internal structure and geological history in comparison to Enceladus.

The surface of the moon is icy and cold, with only a rocky core. Mimas is located closer to Saturn, yet is frozen solid. Mimas’s orbit is more erratic and should cause more tidal heating, yet does the opposite. How is it that Enceladus has water geysers while Mimas remains one of the most heavily cratered bodies within our solar system? Enceladus has a higher density and is believed to be composed of mostly silicates and iron with a water-ice surface.

Enceladus is heated by a tidal system and the core, while now liquid, could have been frozen millions of years ago. Mimas, on the other hand, has remained frozen and appears solid with only a water-ice surface. The differences between these two seemingly similar satellites cause such different patterns and characteristics in their geologic history.

Evidence from Herschel’s Crater, surface features, and internal structure could give more insight into the formation and history of Mimas. Little is known about the impact that caused Herschel Crater and the process that eliminates larger craters in the southern hemisphere. Closer images could provide signs of how or what created the crater and any internal elements that prevent large craters in the polar region.

Images could also reveal more data pertaining to the internal structure. Information on the internal structure would help to solve questions about physical processes that created the surface of the moon today and composition of elements within the moon.

Evidence over the internal structure would also help to either support or contradict the “Mimas test”, a theory developed to explain that the thawed water of Enceladus must also explain the frozen water of Mimas. The implications of what could be discovered or learned on the large scale of these images from Mimas taken by the Cassini probe would help us to gain more insight and knowledge over the processes and characteristics that formed Mimas."