A recent analysis of the photographs, captured by NASA’s Cassini Orbiter has shown the evidence suggesting the idea that Like Enceladus,the moon may also have a global, under-ice sea.The Casssini Orbiter is currently touring Saturn and its moons. The analysis will be published this Friday in the journal Science.
The team doing the analysis, found that the measurements they made could indicate to a frozen solid moon having a rocky core shape just as the rugby ball. But if we consider the under-ice sea explanation, Mimas could depict the potential habitat for simple form,s of organic life.
However, Mimas is getting more and more intriguing than expected . Radwan Tajeddine is a research associate and an astronomer at Cornell University in Ithaca, N.Y.She is the lead author of the study. She explained that
“This moon is more complex than we imagined”.
Mimas, among the Saturn’s moons, is more likely to act as a low key cousin than its more closer relatives like Enceladus and Titan.
Enceladus is Saturn’s sixth largest moon,completely covered with ice. Evidences suggests that it has ocean beneath its ice crust.Moreover it is geologically active and venting out plumes of water near its south pole by the series of cracks.
Titan is the largest moon of Saturn. Its atmosphere is thick and is rich in organic compounds. It has also been said that before life emerged on Earth, it was more like Titan. Titan’s surface also has lakes of hydrocarbons. Evidences also indicates the presence of a sea. It’s salinity can be comparable with Dead Sea beneath its surface.
Astro-biologist are very much interested in both the moons. They foresee them as potential habitat for simple forms of organic life for which liquid water is thought to be essential .
Mimas has been interesting because of its unusual out-of-round shape and its function in clearing a pronounced gap between Saturn’s two widest rings – a 4,800-mile-wide clearing known as the Cassini Gap. Moreover its most important feature is Herschel Crater, which is a ring up to six miles deep in moon present at 246 miles only. If these proportion are held constant and applied to Earth,the crater would span about 2,500 miles. It will engulf almost whole United States and large parts of Mexico and Canada as well. That’s the reason why, the crater give the moon the appearance of the Death Star.
Earlier the heavily cratered surface of Mima was not the point of interest for the researchers. They thought surface is quite old and boring as it has not undergone recent geological repaving which was seen on Enceladus. But still the frozen moon could have fossil structures beneath the surface. which became interesting.
Consequently, Dr. Tajeddine and colleagues from universities in France and Belgium attempted for the first time to determine the interior nature of that moon. Her findings gave rise to the mystery that If Mimas is mostly water ice with a little bit of rocks, why does it appears to be frozen solid at a bracing -334 degrees Fahrenheit while Enceladus, also an ice world, hosts an interior sea?
This sea is made possible by elliptical orbit of Enceladus and an enormous gravitational tug around Saturn. These give rise to tidal forces within the moon and produces frictional heat. This heat prevents the internal ocean of Enceladus from freezing.
Moreover Mimas’ orbit present a more eccentric ellipse than Enceladus’ orbit. So There is more tidal heat. This heat leads to melt the ice somewhere inside the moon but due to the absence of geyser like activity and the presence of heavily cratered surface it appears to be frozen since ages. a long time.
Researchers used 40 high-resolution images from Cassini’s narrow-angle camera from which they designed a 3-D map with 260 reference point on pockmarked surface of moon.They applied mathematical techniques to determine any changes in positions of these marks like Mimas orbits. They found changes in the form of movements(sideways) across the field.
“If the moon was solid, with a core matching the shape of the outer shell, the size of the wobble should have been about 1.9 miles from one side to the other. Instead, it was twice of that. Only two of the models represented plausible explanations. But each explanation still had problems. For instance, if you have a rugby-ball shaped core, the final shape of the moon should resemble that. Mimas does not.”
The team suggested additional ways to answer many questions related to Mimas interior. The first suggestion was he requirement of close flyby top have additional information about their changing features. The other suggestion is to have detailed temperatures measurements of the surface to detect any unexpected warmth.