2012 Edition -- Target 1: Pan, Grade 9 - 12 Winner
2012 Edition -- Target 1: Pan, Grade 9 - 12 Winner
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| Anissa Lee Grade and Ming Wang Grade | ||||||
| The Winsor School | ||||||
| 11th Grade Boston, Mass. Teacher: Rudy Sirochman | ||||||
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"In its next voyage to Space, the Cassini Spacecraft should focus on Pan, Saturn’s innermost moon. Discovered in 1990 by Mark R. Showalter using images taken by the Voyager 2 spacecraft, Pan may appear insignificant as it is only 16 miles in length. However, its odd walnut shape, icy porous composition, and ability to keep the Encke gap open make it a vital target for scientists to explore and understand. The Cassini spacecraft’s 2007 image of Pan revealed its odd shape and equatorial ridges. These features gave the moon a unique, UFO like appearance. Scientists initially postulated that Pan’s unusual, flattened shape was formed by fast spinning. However, astronomers soon realized that Pan takes about 14 hours to complete a rotation, much too slow to warp its form and shape it into a disc. In addition, information gained from the Cassini pictures showed that Pan’s ridges line up precisely to where Saturn’s rings surround it. This fact, combined with Pan’s light, icy and porous composition, suggest that Pan is composed of its nearby ring material. Further supporting this is Pan’s density: a mere 0.42 g/cm^3 in comparison to Earth’s 5.52 g/cm^3. Currently nothing more than computer simulations and theories can suggest how Pan’s surrounding debris could have aggregated to form the moon. Closer inspection of Pan and its formation could help scientists understand how, during the formation of the universe, debris around newborn suns could have combined to make planets and other celestial bodies in the same manner as Pan formed around Saturn. Another one of Pan’s unique characteristics is its role as a “shepherd moon.” Pan keeps the Encke Gap, a 200 mile stretch in Saturn’s A-Ring, open. As Pan orbits Saturn, the ring material on either side of Pan gets propelled along its trajectory as it moves past the moon. Pan’s gravitational force causes the particles to bunch up into “wakes,” which move away from Pan. The waves spread hundreds of kilometers into the ring and create ripples downstream. These ripples push the rest of the ring material away from Pan and keep the Encke gap open and free of ring particles. Another shepherd moon in Saturn’s orbit, Daphnis, keeps the Keeler gap open. This ability of moons brings up an intriguing question: How does such a small moon have such a significant role? By investigating more about Pan and the ring material around it, we can learn in more detail about the role of shepherd moons in keeping gaps within the universe open. Because of Pan’s similarity to many other celestial beings in the universe, both in composition and in behavior, exploration of Pan may lead to theories on its formation and properties that will be widely applicable to other bodies in the universe. Investigating Pan will not only help illuminate fascinating discoveries about celestial bodies like it, but also inform us about how debris could have amalgamated to form planets in the beginning of the universe." |
