Life in the Universe
Part 1: The Solar System
It is a virtual certainty that we will discover extraterrestrial life within the next 20 years. There are many places in our solar system that would seem to make good cradles for life. Some of the best prospects include Mars, Europa, and Enceladus.
Mars has been tantalizing us for decades with its prospects for life. We have recovered a meteor blasted off of the surface of Mars that seems to contain fossilized life forms, although not all scientist agree with this premise. There have been experiments conducted by Mars landers that gave ambiguous results on the presence of life. But perhaps the most tantalizing sign comes from the seasonal methane cycles on Mars. Methane can be produced by either biological or geological processes. But there is no geological explanation of seasonal methane cycles. The prospects are good that these seasonal methane cycles are produced by organisms on Mars undergoing seasonal transformations. Methane, that gas from decaying garbage dumps and bovine flatulence is a necessary byproduct of organic life.
Europa has a vast ocean underneath a planetary ice cap. Ice fissures allow the subsurface ocean to leak through to the surface. When we look at the surface of Europa we see a fractured ice cap covered by reddish-brown crud along the fissures. It may be that this surface crud is some sort of life form resembling an algae bloom.
The extraterrestrial life be find in our solar system will be simple, single celled organism.
Life on Earth is a thousand times more diverse than I was taught in high school biology class. In school we were taught that there are plants and animals. The Sun was the source of all biological energy. Plants converted sunlight into sugars through photosynthesis. Herbivores ate the plants and carnivores ate the herbivores. All life was beholden to the Sun.
But now we know much more. There is life everywhere on Earth, and much of it totally cut off from the Sun. There are tube worms and shrimp in the deepest ocean trenches, using chemosynthesis to convert sulfur into energy in extreme high temperatures and pressures. There are organisms living in the boiling, caustic paint pots of Yellowstone Park. There are organism living deep underground, drawing their energy from the rocks. There are organism living in frozen glaciers. When glaciers calve, these life forms create a rich biomass in the ocean, a biomass that is the bottom of the food chain for all life in the polar oceans. There is even life forms living in the cooling ponds of nuclear reactors.
Along with plants and animals, there are fungi such as mushrooms, slime molds, algae, protozoa, and these are just our closest relatives. It has been suggested that there is more biomass below ground than there is above ground.
With life on Earth this diverse and abundant, we can expect that life will be prolific throughout vast sections of the Universe. Our own solar system is full of water and organic compounds, the two essential ingredients for life as we know it. Comets and asteroids have both in abundance. Spectroscopy of the Universe suggest that the same chemistry exists everywhere. Water and organic compounds exist throughout the Universe. On Titan there are lakes of liquid methane. On Europa there is more water than exists on Earth.