NASA's Discovery about Saturn's Moon Enceladus

Enceladus

Enceladus; is the sixth-largest moon of Saturn. It is about 500 kilometers in diameter, about a tenth of that of Saturn's largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the solar system. Consequently, its surface temperature at noon only reaches −198 °C , far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide range of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrains that formed as recently as 100 million years ago.

Enceladus was discovered on August 28, 1789, by William Herschel, but little was known about it until the two Voyager spacecrafts, Voyager 1 and Voyager 2, passed nearby in the early 1980s. In 2005, the Cassini spacecraft started multiple close flybys of Enceladus, revealing its surface and environment in greater detail. In particular, Cassini discovered water-rich plumes venting from the south polar region. Cryovolcanoes near the south pole shoot geyser-like jets of water vapor, molecular hydrogen, other volatiles, and solid material, including sodium chloride crystals and ice particles, into the space, totaling about 200 kilograms (440 lb) per second. Over 100 geysers have been identified. Some of the water vapor falls back as "snow"; the rest escapes, and supplies most of the material making up Saturn's E ring. According to NASA scientists, the plumes are similar in composition to comets. In 2014, NASA reported that Cassini found evidence for a large south polar subsurface ocean of liquid water with a thickness of around 10 km .

For More Information Click here

These geyser observations, along with the finding of escaping internal heat and very few impact craters in the south polar region, shows that Enceladus is geologically active today. Like many other satellites in the extensive systems of the giant planets, Enceladus is trapped in an orbital resonance. Its resonance with Dione excites its orbital eccentricity, which is damped by tidal forces, tidally heating its interior, and possibly driving the geological activity.

NASA Discovers Why Saturn's Moon Enceladus May Be the Best Place to Look for Alien Life

  NASA scientists announced its Cassini spacecraft found evidence that the ocean on Enceladus may contain all the ingredients necessary for the emergence of life.

Cassini flew through plumes of gas bursting out from under the ice covering the oceans and detected a clear presence of molecular hydrogen. This might indicate the existence of hydrothermal vents on the moon’s ocean floor. Such vents would be similar to Earth’s hydrothermal vents where some scientists believe life on our planet originated. 

In the new findings, described the journal Science, scientists consider the possibility of a chemical reaction called methanogenesis taking place in the moon’s underwater vents. This reaction has been shown to be crucial to the development of microbial life by providing an energy source for the microbes.


For More Information Click here

The researchers cannot at this point conclusively state if methanogenesis is indeed taking place under Enceladus’s ice. It is also possible that this moon may be too young to have undergone the life-creating process. 

Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate in Washington, was also optimistic about the scope of Cassini’s current achievement.

Since 2004, the Cassini spacecraft provided no shortage of discoveries. As its head of imaging science Carolyn Porco explained, Cassini conducted over a 100 more “close flyby maneuvers” than have been done so far in the entire planetary program. 

It has given us an unprecedented understanding of Saturn, with stunning new images, insights into its rings, atmosphere and moons. 

In 2005, the spacecraft landed the Huygens probe on Titan, Saturn’s largest moon, a historic first for landing human machines in the outer solar system. The probe discovered a wealth of information, including an underground super-salty ocean. The Cassini-Huygens mission was carried out in cooperation between NASA, the European Space Agency and the Italian Space Agency.

Cassini also came amazingly close to Jupiter, providing us with the best photos we have of the gas giant.

The spacecraft will be decommissioned on September 15, 2017 by being plunged to burn in Saturn’s atmosphere. The reason for just a drastic demise lies in the fear that Cassini will soon run out of fuel and crash into one of Saturn’s moons, the ones we now think may contain life. It’s safer for it to burn up on entry than possibly contaminate the moons.

On its way down, the spacecraft will transmit more data and images. These will include new maps of Saturn’s magnetic and gravity fields, and details on the composition of the planet’s rings.

Notably, another NASA team just published findings on a different ocean world that might have some form of life. Their paper on observations from the Hubble Space Telescope program showed new evidence of water vapor plumes found on Jupiter’s moon Europa. In fact, they think they spotted a huge 62-mile-high plume over Europa’s equator, in the same place a plume candidate was spotted in 2014. 

These warm plumes are thought to be potential hosts for life. Considering that Europa is billions of years older than Enceladus, the chances for life to have emerged there could actually be greater.

For More Information Click here