Winners - France
13 -15 years old - Tethys, Enceladus, Mimas, and Saturn's rings
Authors:
Louis Demiot
Alexandre Lucas
Hugo Piton
We are French students, entering the “Cassini scientist for a day” competition. We have chosen target number one because it’s an exceptional opportunity to have an image of the Saturn rings, with three of the Saturn’s moons at the same time.
Saturn is the most beautiful planet of the solar system. Its gorgeous rings are not visible from Earth with unaided vision. Moreover, scientists know that Saturn rings are mainly made of different sized rocks, ice and dusts. They measure a hundred and twenty-five thousand kilometre width and about only ten meters thick but nobody knows how old the rings are. There is still no consensus as to their mechanism of formation; some characteristics of the rings show the possibility of a relatively recent origin, but theoretical models indicate an early formation in the history of the solar system. It’s therefore a rare chance to study it.
Another reason we have chosen target number one is that it would permit to have exceptional and rare images of three of Saturn’s moons: Enceladus, Mimas, and Tethys. Enceladus is a really mysterious body, covered by a salty liquid water ocean, under a thin layer of ice. The others, Mimas and Tethys also have their particularities that must be studied.
Enceladus, is a really mysterious body, covered by a salty liquid water ocean, under a thin layer of ice. There are geysers observations on Enceladus surface that show that Enceladus is geologically active today. This is so a special moment to take photos of these phenomena. These geysers are erupting from four fractures on Enceladus surface. Their origin are unknown for the moment, it's so a divisive topic. Moreover, better understanding of the geysers could allow to discover what is happening in Enceladus subterranean environment. It is hence a marvellous chance to make new discoveries and enrich the science.
Mimas has a low density that let think that it is principally made of water ice, with a small part of rock. The cratering at Mimas surface is not uniform. The impact craters are littlest in the South Polar Region. It is there a way to discover what this phenomenon is.
Tethys, is a mid-sized moon of Saturn. It has the lowest density of all the major moons in the Solar System, 0.98 g/cm3, showing that it is made of water ice with just a small part of rock, like Mimas. The water ice is confirmed as the dominant surface material. A small amount of an unidentified dark material has also been viewed on this moon. Choosing target number one could allow scientists to discover what this unidentified dark material is! Another reason that shows that target number one is the greater one!
By allowing lots of possible and desirable discoveries, by taking incredible and rare photographs, target number one is the best choice for Cassini project. These photographs and discoveries would help scientists to better know how the Saturn's rings were created and better understand Enceladus, Mimas and Tethys. Being Cassini scientists for a day, we are convinced that target number one is the best one.
16 - 18 years old - Tethys, Enceladus, Mimas and Saturn's rings
Authors:
Sarah Boceno
Solène Guilbeau
Saturn’s rings and three of its moons : Tethys, Enceladus, and Mimas, are very interesting to study. They each have a specific and very complex structure that makes them unique and atractive to analyze. Why shall we work on them ? Because it will bring a lot of information to astronomers about the composition of Saturn and its moons.
The rings of Saturn are the most visible global rings of the solar system. They were discovered by the learned Italian Galilee in 1610. At the beginning he believed that it was just an appendix of Saturn. Their shine is so bright that we can see them from the Earth thanks to binoculars between 11 pm to 1 am in the morning.
These rings are consisted of in reality dust and ice, going from particles to big blocks. Each ring is called A, B, C, D, E, F according to its discovery. The real order is the ring D, then C, B, A, F, G, and E, the most distant ring. Their thickness is very variable, going from 3-4 meters up to a little less than a kilometer.
Tethys is the 5th biggest moon of Saturn and is a satellite made of ice. It was discovered by Giovanni Domenico Cassini (and his real name is Jean-Dominique Cassini) in 1684. At first named Saturn III, it is in 1847 that Tethys obtained its name by John Herschel the son of William Herschel (the discoverer of Mimas and Enceladus in 1789).
Its surface mainly consists of ice as indicates its density which is equal to the one of water. We can also observe that Tethys has mainly two characteristics:
- The 1st one is an important crater, appointed Odyssey, which should have completely destroyed the satellite: that proves that Tethys was not still so solid. It is very likely that it was almost liquid previously and that it solidified from hits crust going inward.
-The 2nd one is a very vast canyon, wich makes ¾ of th circumference of Tethys (around 100 km wide and 3 to 5 km deep, on a distance of 2000 km), which would doubtless have been caused by the movements of the water when its surface was freezing.
Mimas is an especially exciting moon. It has fascinating thermal activity which is mysterious and quite strange. One of the main reasons to continue researching on Cassini would be to discover the cause of its irregularities. For example, why does one of Cassini's area form a crescent ? And why is this specific area warmer while the sunlight doesn’t reach it ? It would suggest that there is thermal activity within Mimas. Also, why would Herschel Crater have a higher temperature ? It would be interesting to know if it’s because of the conductivity of the materials present within this specific crater. Researches have been made on the oscillation of its rotation : it suggests the presence of an ocean underneath the layer of ice, which may mean that there is indeed life on Mimas.
Enceladus has a very intense geological activity, which is abnormal for such a little space object. At its southern hemisphere is located a hot bubble sparse, which we don’t know the provenance. It is said it would return to the surface and that Enceladus would have switched for to rebalance. The bubble is then found at the south pole. This theory has been proven by Cassini. There could also be life on the sixth moon of Saturn : due to the presence of water under its a layer of ice and its geysers.
This theme is really addictive. Astronomy is a exciting subject that allows us to know a lot more about the world we live in. Cassini has enabled us to learn things about Saturn and its moon that we did not identify before, expanding our vision of the word and its origins. We now see that isn’t life just on the Earth and we hope that astronomers will find other information. We liked a lot working on this subject because it allowed us to discover things which we don't know such as the existence of Tethys, Enceladus and Mimas. We ignored its unusual characteristics and also the constitution of the rings of Saturn as well as their names.