Saturn’s Moons Titan and Enceladus

Introduction

The solar system has a large number of natural satellites orbiting various planets, asteroids, and comets. Although most of these moons appear to be identical gray rocks moving in space, careful observation shows that they are diverse and have unique and intriguing features. One of the planets with many interesting moons is Saturn, which currently has 62 identified moons. The two Saturn moons that interest me the most are Titan and Enceladus.

Titan

Titan is Saturn’s largest satellite and it is only second in size to Jupiter’s Ganymede in the entire Solar System. The discovery of this moon is credited to Christiaan Huygens who was the first to observe it in 1655 (Battersby 44). The discovery was made possible by Huygens work on improving the available telescope technology so that astronomers could look deeper into space. Using one of his invented telescopes, he was able to identify the largest satellite orbiting Saturn and this moon came to be known as Titan.

Titan possesses an extensive and thick atmosphere that extends far above its surface due to the low mass and gravitational pull of the satellite combined with its high atmospheric pressure (Lang 329). The moon has a radius of 2575 kilometers and a mean mass density of 1880 Kilograms per cubic meter. From this density, scientists have deduced that Titan may be composed of nearly equal amounts of ice and rock (Lang 329). In addition to this, the moon has a large deposit of Tricolite and Carbonite crystals.

Titan does not have any detectable magnetic field, which suggests that it does not have the iron core responsible for the generation of magnetic fields in some planets and satellites (Lang 328). Just like on earth, nitrogen is the dominant gas in Titan’s atmosphere and it make up between 82 and 99 percent of the moon’s atmosphere, while methane is the minor gas and it represents between 1 and 6 percent. Regas reveals that Titan does not contain molecular oxygen since its freezing temperatures are not conducive for living things to supply oxygen (24). Titan has tectonic activity as well as volcanic activity. Images of the satellite indicate that there are regions filled with ridges or crevices suggesting past and possibly ongoing tectonic activity. It is theorized that volcanic activity exists on Titan. Tidal flexing from Saturn as well as energy from radioactive elements at the moon’s core facilitates this volcanic activity (Regas 25).

Titan is unique among the moons in that it is the only one known to have liquid on its surface. Explorations have revealed that there are dozens of lakes and three seas on Titan (Battersby 45). A puzzling feature of the moon is how the methane in its atmosphere is produced. At the moment, Titan’s atmosphere contains 5% methane. Battersby observes that since this gas is broken apart by sunlight, it must mean that some process is constantly replenishing the gas in Titan’s atmosphere (45). No convincing explanation has been offered to explain the process responsible for this phenomenon.

Due to the interest in Titan, the Cassini spacecraft was launched to Saturn on 15 October with a set objective of collecting data while in orbit around Saturn and dropping a probe into the dense atmosphere of Titan (Angelo 117). The repeated flybys made by Cassini over the past 10 years have provided most of the data available on Titan. A lander mission was included in the Cassini mission to Saturn. This lander, called the Huygens, was a probe designed to drop into the Titan’s atmosphere and settle on its surface (Angelo 117). The Huygens probe made a parachute assisted descent into the moon’s atmosphere after been separated from Cassini. This descent was successfully completed in January 14, 2005 when this probe touched ground on Titan.

There are plans to send a more elaborate space probe to Titan. The proposed mission would take up to 6 months floating in the moon’s atmosphere thus enabling it to provide a comprehensive picture of Titan’s surface (Battersby 47). It would also be equipped with sophisticated equipment enabling it to provide a gather a wide array of data from the moon. This mission has been approved by NASA and is set to be implemented in the early 2020s.

Enceladus

Enceladus is one of Saturn’s innermost moons and British astronomer William Herschel discovered it in 1789 (Seeds and Backman 222). Advances in telescope technology aided the initial discovery but little additional information was attainable due to the small size of the moon and its distance from the Earth. Data from flybys conducted by the Voyager I and Voyager II spacecrafts during the 1980s helped shed more light on the characteristics of Enceladus.

This moon has a diameter of 500Km and the relatively low mass density of 1240kilograms per cubic meter suggesting that it is composed almost entirely of water ice (Lang 72). Euceladus is very bright in appearance since the satellite is covered in clean water ice enabling almost all of the sun’s radiation on it to be reflected back into space. Due to this high reflection, the surface temperature of Enceladus is extremely cold at about -2010C (Seeds and Backman 222). The moon has many cracks and grooves on its surface although it lacks craters that characterize the surfaces of most satellites. The cracks and grooves present on its icy surface suggest that water has been released from below the surface within the last one or to billion years (Lang 72). It is estimated that liquid water is present just 30 meters or less below the moon’s icy crust. This has increased scientific interest in this satellite since there is a high probability that it could possess extraterrestrial microbes.

Data analysis by scientists suggests that Enceladus might have an atmosphere, albeit a very thin one (Regas 24). The surface of the moon contains numerous winding canyons, rifts and fractures leading to conclusions that it is undergoing geological activity (Greenstein 231). There are volcanic activities taking place within Enceladus and water vapor and ice particles are ejected through the dozens of cryovolcanoes present on it. Scientists have observed that the cryovolcanoes are more active when the moon is farther from Saturn since the tidal pull of the planet is reduced at greater distances.

An interesting aspect of Enceladus is that it has an eccentric orbit. Greenstein reveals that this orbit occurs since Enceladus is subjected to the gravitational pull of Saturn and the moon Dione (231). Another interesting aspect of Euceladus is that it rotates in sync with its orbital period which means that one of its sides is always facing Saturn.

The elaborate data on Enceladus has been obtained from the Cassini mission which was sent to study Saturn and its moons. This spacecraft, which entered Saturn’s orbit in 2004, has performed numerous flybys of Enceladus with some being as close as 50Km from the satellite’s surface. Cassini’s instruments were able to detect signs of water molecules from the moon during the first close flyby flight (Greenstein 231). An important result of the study of the Enceladus’ geological activity is that it has led scientists to consider that habitable zones are not only regions around a star but they can also exist around planets (Regas 24).

Follow-up missions have been proposed to help determine if this satellite has a habitable environment. One mission is to be a flyby carried out by a spacecraft containing specialized equipment to analyze the plume composition and structure of Enceladus (Regas 27). There are also proposals for a probe to be sent to the surface of Enceladus on a mission to collect and analyze material on the surface of the moon and drill into the ice to reach the water.

Conclusion

Saturn is one of the planets with many diverse moons and for me, its Titan and Enceladus are the most intriguing. Through this paper, I have described the two moons, their physical features, unique characteristics, and the missions that have been made to study them. Titan has and continues to elicit interest since it has the composition similar to that of an early Earth and it is speculated that it might sustain life in 2 billion year’s time. Enceladus contains salty water and organic molecules leading to a supposition that it can sustain microbial life.

Works Cited

Angelo, Joseph. Life in the Universe. NY: Infobase publishing, 2009. Print.

Battersby, Stephen. “Splash of the Titans.” New Scientist 222.297(2014): 44-47. Web.

Greenstein, George. Understanding the Universe: An Inquiry Approach to Astronomy and the Nature of Scientific Research. Oxford: Cambridge University Press, 2013. Print.

Lang, Kenneth. The Cambridge Guide to the Solar System. Oxford: Cambridge University Press, 2003. Print.

Regas, Dean. “Weird Moons of the Solar System.” Astronomy 42.6 (2014): 22-27. Web.

Seeds, Michael and Dana Backman. Universe: Solar System, Stars, and Galaxies. NY: Cengage Learning, 2013. Print.

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