The requirements of life are so basic at first glance; raw material, solvent (ideally, water), and energy. But looking out into the cold expanse of space, a planet with all three seems improbable if not impossible. However, even within our own galaxy there is the possibility of biological matter on an alien planet. Maybe not in our lifetimes, but in the distant future there are places where later generations of astronauts may find life.
Scientists believe 3 billions year ago Mars could have been a warm and wet landscape teeming with life. Which is why the Mars Rover Curiosity zigzags the unforgiving landscape, drilling into rocks and then heating them to 1,508 degrees Fahrenheit to analyze the gases for organic compounds. Those analyses revealed thiophenes, a biological compound found here on earth. Four carbon molecules surround a sulfur molecule in thiophene, and while they’re present in both chemical and biological processes, scientists think these may be the byproduct of bacteria on the alien planet. Scientists are cautious making predictions, but there’s a chance when astronauts reach Mars they may see moving microbes in their samples. (x)
There are massive oceans beneath the ice on this moon of Jupiter. And, in 2020, NASA plans on launching the Europa Clipper to perform a series of flybys of the frozen moon while in orbit around Jupiter. Scientists believe a second-genesis may have taken place in the water, with life developing independently of the organic matter found on Earth and Mars. The surface of Europa is smooth, without evidence of impact from meteors or space debris. That may be because warmer ice rises from below and smooths out craters. There’s evidence to suggest the chemical compounds necessary for life were present in Europa from the start. Combine water and chemistry with energy in the form of constant radiation bombardment from Jupiter, and you have all the ingredients necessary in the recipe for life. (x)
Another moon, but this time belonging to Saturn. Just last year, a plum of water shot from Enceladus’ underground ocean into the atmosphere. It carried with it organic compounds necessary for building amino acids; the building blocks of life. A similar process takes place here on Earth, where hydrothermal vents deep in the ocean super-heating hydrogen-rich water which fuels chemical reactions to form amino acids, all without sunlight. This proves that even on the dark moon of Enceladus, life may still form. (x)
This is Saturn’s largest moon, bigger than even the planet Mercury. It bears a few remarkable similarities to Earth. The first is that it has a thick atmosphere, also made up primarily of nitrogen, but with methane instead of oxygen. Titan orbits around the Sun with Saturn, taking 27 Earth years to make the journey. Titan also has seasons like Earth, also remarkable, a system of liquid evaporation to clouds and raining down moisture on the surface. Instead of water, its methane and ethane in liquid form. Beneath the crust of super-cold ice, scientists believe there’s a liquid ocean of salt water, which erupts in volcanic activity. Titan is the only other planetary body besides Earth to have liquid activity on its surface. (x)