Are we alone in the universe? It's hardly a new question. Just about everyone has entertained the thought, particularly as the cosmos as we know it grows infinitely bigger. Does anyone look back at us when we stare towards the sky at night? More than ever, the possibility is opening up, leading experts to believe that we will know the answer for sure within the next decade.
What can we expect to find? Fortunately, you most likely won't have to conjure up those nightmares of drooling xenomorphs -- or for that matter, the idea of a friendly E.T. Instead, microbes or bacteria are what astrobiologists (those who study the possibility of how life might evolve on outer planets) believe is the most likely scenario.
So where to begin? The circumstellar habitable zone of a planet has been the focus of high-powered telescopes like Kepler, also known as the Goldilocks zone: a range where planets get just enough light from their host star for supporting life, and where water can stay in liquid form without freezing or vaporizing. However, the Cassini spacecraft visited a viable candidate a bit closer than the "Earths" discovered by Kepler: Titan, one of Saturn's moons.
While Titan does not contain water and maintains a temperature of about -220 degrees Fahrenheit, it has a number of vast lakes, some up to 660 feet deep, filled with liquid methane. NASA is planning a 90-day submersible mission in the depths of Kraken Mare, the deepest sea on the moon. Waves can be seen breaking on the surface. The lake, full of hydrocarbons, is thought to contain the basic ingredients of life -- and a submersible mission, one of the space agency's seven new projects, could be ready in as little as two years' time.
Much of life on Earth began under water, and the discovery of high concentrations of bacteria under the icy waters of the Southern Ocean has drawn a great deal of attention to the region, where hydrothermal vents have allowed the colonies to thrive -- the perfect environment for single-celled life forms to thrive. While the surface of Titan is cold, molecules of ethane and ethylene work as a sort of net for trapping ultraviolet light, providing enough warmth to sustain life.
The moon also may heat up in the near future; perhaps you might think of it as having a window to the Cambrian age. In about six billion years, the sun will gradually die, turning into a red giant -- and the surface might heat up to just 95 degrees below zero, sufficient enough to create an atmosphere stable enough to support exotic life forms for at least several million years. Successful laboratory models have shown that methane is capable of bonding with nitrogen to create simple lifeforms: microbes that the Titan Sub might encounter, parts of an ecosystem so delicate that samples might not withstand a trip back to Earth.