Ever since man first started to gaze out into the skies, he has always wondered if he is alone. Is life possible among the millions of stars he could see or even just in this small band of planets we call the Solar System? Ever since man has had the aid to his eyes and knowledge of science, he has been able to come closer to the conclusion of that question.
Places like Mars and The Moon (Lunar) have always had romanticisms about alien life living on their surfaces, and as of yet we are still to proven wrong. I’d like to introduce two more alluring worlds among our Solar System that show decent signs of a habitat for E.T.
These worlds are far out into the more inhospitable regions of our host star system; they both orbit huge gas giant planets and both have a temperature that is lower than -150 degrees Celsius.
These worlds are the small icy Moons; Europa, who orbits Jupiter, and Enceladus, who’s host planet is Saturn. These worlds, although some distance apart, share a few similarities in the essential aspects for them to support life. Both moons share the most important of these, water, and lots of it. In fact, Enceladus is believed to be made up of 91% water vapor.
As a species we know that water is an essential building block for life, you only have to look around you for proof. So it seems entirely plausible that these moons can be the habitat for some bizarre marine life as there is already so much of it here on Earth.
Enceladus is a tiny moon, smaller than Great Britain, which sits in the E-ring of the planet Saturn, over 147,000 miles away from its host. Discovered in 1789 by William Herschel, the man who also discovered Uranus, Enceladus is the sixth moon of Saturnian orbit and the brightest object in the solar system. Believed to reflect 99% sunlight off its surface, Enceladus is small but an incredible find. Scientists are excited about this moon because of it’s surface appearance and subterranean goings-on.
In 2005 a probe named ‘Cassini’ was sent passed Enceladus with instructions to take photographs. The satellite took some amazing images of giant jets of liquid water protruding into outer space some 80 miles. This indicated the presence of liquid water and the possibility of a subterranean ocean beneath its icy surface.
The area of interest became known as the ‘tiger stripes’, a series of linear depressions on the surface indicating a raised temperature in the south Polar Regions. This proved the presence of an ice volcano fuelled by underground heat.
‘This finding is a crucial new piece of evidence showing that environmental conditions favorable to the emergence of life can be sustained on icy bodies orbiting gas giant planets’ – Nicolas Altobelli, ESA project scientist for Cassini.
No impact craters in the surrounding area also implies that this region is young, therefore ever changing. A spectacle this moon shares with her step-sister Europa.
Europa is a Jovian moon, meaning it orbits within the realms of Jupiter, and is also one of four of the Galilean moons. Named by Galileo Galilei, in respect to a Greek queen, Europa was discovered in 1610, along with the three other closets moons to Jupiter. Although somewhat bigger than Enceladus, Europa is still smaller than our moon but with a high potential to preserve life due to its huge ocean. Scientists believe the surfaces layer, some -160 degrees Celsius, is tens of kilometers thick and the water layer below is thought to be 50 -105 kilometers deep, that’s more water than Earths oceans combined. This leads scientists to believe that the shear size of the ocean underneath, in comparison to the size and diversity to life on Earth, that life on Europa is a mathematical certainty.
‘we calculate that the odds of finding life in the waters of Europa are 122 out of 123. The 122 known bodies of saltwater harbor microbial life. The 123rd body of saltwater, Europa’s vast ocean, is the body that has yet to be tested. Therefore, the odds are 122 of 123 in favor of finding life, or above 99%’- David Darling, part time astronomer and science writer.
Europa is close to Jupiter, so close that the massive planet exerts tidal pressures on the moon much like the relationship the Earth has with it’s lunar neighbour. This causes ‘plates’ on the moons surface to crack and move due to warm temperatures below the surface most probably caused by underwater hydrothermal vents.
This below surface phenomena is also true of Enceladus and as we recently discovered, on our planet, life does not necessarily require sunlight to exist.
Hydrothermal vents were discovered just in the last decade, they prove that life can go on without heat provided for it by the Sun. These vents send columns of water reaching temperatures of 460 degrees Celsius from the core and out into the depths of our oceans. Crabs, worms and bacteria like creatures were discovered to be living within this eco-system and thriving well without sunlight. It was clearly all down to these vents and the heat they were giving off that allowed complex life to live in such an extreme enviroment. Now scientists were excited because they thought that this could just as easily be true of any other body supporting water or water ice.
So scientists from NASA and the European Space Agency (ESA) went on the hunt for worlds that looked like a suitable home for these hydrothermal vents and their answers were both Europa and Enceladus.
As mentioned before Enceladus has a satellite nearby already, named Cassini after the Italian/French astronomer of the 17th and 18th century. Launched in 1997 Cassini has beamed back tons of information surrounding Saturn and her moon system and will continue to do so for the 20-year duration of its mission.
ESA and NASA also had a similar, but far more advanced, probe that was scheduled for launch in 2020 in order to understand Jupiter’s moons Europa and Ganymede. NASA have since pulled out of the mission called, Europa Jupiter System Mission (EJSM) and have left ESA to fund its own quest to the region, Jupiter Icy Moon Explorer (JUICE).
Russian interests have also spurred this assignment forwards as they look to actually having a lander set up home on the moon. In an attempt to understand Europa’s icy surface and subterranean ocean the Europa Lander will be separated from the main rocket in order to carry out various fly-by missions. This launch looks likely to be scheduled far beyond its original date of 2020.
Until this mission we still have a lot to understand about both these moons complexity and intriguing imagery. They both leave us wondering just what lies beneath their surfaces and how much of it is Alien and how much is familiar.
For Galileo to have gazed up and wondered so much and known so little speaks the same of us today. With his help, along with Herschel and the understanding of the critical aspects of life, we can envisage, like Galileo did, the grandeur of celestial knowledge while still understanding so little.