Searching for Life in Our Solar System
Scientists expect that Europa may have more liquid water than in all of Earth’s oceans. It has all the elements thought to be key for the origin of life: water, energy, and organic chemicals, the carbon-containing building blocks of life. Unlike Earth though, Europa’s vast, salty seas lie beneath roughly 10 miles of ice. Not only is it difficult to get a probe beneath this icy armor, but Europa’s oceans are darker than a cave — which means photosynthesis won’t work. However, something down there may subsist on geothermal heat or complex molecules from the surface. http://bit.ly/1trVzvX
NASA says it’s setting aside $25 million for designing scientific instruments to address questions about the habitability of Europa, an ice-covered moon of Jupiter. A Europa probe that could be launched in the 2020s. http://nbcnews.to/1pU2JJe
Titan is Saturn’s largest moon and the only world in the solar system (besides Earth) known to sport liquid lakes. These are lakes of ethane and methane — liquid natural gas — endlessly topped up by hydrocarbon rain. Despite the odd ingredients and Titan’s extremely cold temperatures (minus 290 Fahrenheit, or minus 179 Celsius), it is a world where chemistry’s a happening enterprise. It’s so cold that water ice is rock-hard—in fact, the rocks littering the moon’s surface are made from water. Water is everywhere on Titan, but it’s locked in a state that’s inaccessible for life-sustaining chemistries. On Titan, scientists would most likely be looking for bizarre life. Life that, instead of being water-based, uses liquid hydrocarbons as a solvent. Yet if life is found, it could demonstrate a different way in which it could begin and populate the cosmos.
Like its more celebrated neighbor Europa, scientists suggest that Callisto’s interior contains a salty ocean separated by ice layers, with a rocky seafloor underlying everything. The likely presence of an ocean within Callisto leaves open the possibility that it could sustain life. Because of its low radiation levels, Callisto has long been considered a suitable place among the Galilean moons for future exploration. http://bit.ly/1pra4Qx
The largest moon in the solar system, Ganymede, may feature liquid oceans layered between vast sheets of ice. Studies suggest that there may be a layer of salty water directly on top of Ganymede’s rocky core. Chemical interactions between rock and water could lead to the formation of life. http://cnn.it/1q8jCj2
Venus, with its scorching surface temperatures (850 F, or 454 C). The planet is generally assumed to be unlivable but some scientists believe that high in the Venusian atmosphere where temperatures are more tolerable atmospheric sulfur dioxide and carbon monoxide might serve as food for floating microbes. http://bit.ly/1l3sWVo
Mars remains popular for those hunting for otherworldly life. In 2013, scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon - some of the key chemical ingredients for life - in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed in Gale Crater. Also, particularly intriguing are the dark stripes that appear in the Martian summertime at Horowitz crater. These are likely to be salty meltwater only inches beneath Mars’ dusty top layer.
In 2005, NASA’s Cassini spacecraft photographed geysers of frozen water spewing from cracks in Enceladus’ southern hemisphere. Scientists think reservoirs of liquid water lie beneath the frozen surface and are warmed by gravitational interactions between Enceladus and other moons around Saturn. http://bit.ly/1pZu0bf
(Credit: List compiled from Space.com “6 Most Likely Places for Alien Life in the Solar System”)