Out of the 8 planets and 173 moons of our Solar System, only Earth is known to support life. The third, blue rock from the Sun is our home, but what if the 8th moon of the 7th rock from the Sun also harbors life? They would be our closest neighbors in the cosmos and maybe we could finally share our culture with them.
The SETI institute is devoted to the Search for Extraterrestrial Intelligence and believes that certain places in our own solar neighborhood could be sheltering alien life forms. However, if we ever do find extraterrestrial life in the solar system, it’s probably much more likely to look like a few cells than a tiny green man. With better photographing techniques and radio technologies, scientists are becoming more and more optimistic about discovering someone who’s really “not from around here”…
Considered by many as the best candidate in our Solar System for finding life, Saturn’s sixth largest moon is the first name on this list. The surface of the icy moon is apparently 99% ice, with liquid water floating underneath. In 2005, NASA’s Cassini probe flew close to Enceladus and discovered the presence of carbon, hydrogen, nitrogen and oxygen – basically every organic molecule required for Earth-like life. Enceladus also has hot hydrothermal activity in its core, which further validates the possibility of underground liquid water, and also heats the world to a welcoming temperature.
A major factor favoring this moon is that it can easily be explored. As SETI Institute researcher Cynthia Phillips says, “Samples of whatever exists in those hidden aquifers are being continuously thrown into space, just waiting for us to grab.” A satellite sent with today’s technology could sift through the geyser spray to detect life, and a lander could slip down through a geyser to the uncharted oceans below.
Some believe that the underground oceans are not old enough for life to have developed, but as NASA’s Chris McKay says, we don’t know how long it takes for life to ‘happen’. It could be five million years or 5 minutes.
Next on the list for potential life is Jupiter’s fourth largest moon, Europa, which is quite interesting in its own right. It contains more water beneath its surface than all of Earth’s oceans combined. Estimated to be 10 kilometers thick, the ice cover would prohibit any kind of photosynthesis, meaning that any possible life would have to rely on the moon’s geothermal energy. This is not too much of a stretch, as similar vents on Earth actually do support life, such as crabs and tubeworms. Creative astronomers have suggested using an irradiated submarine to melt a hole in the surface and reach the vast oceans underneath.
Microbial life could potentially survive near the hydrothermal vents on Europa, as it does on Earth. On May 12 2015, scientists announced that sea salt from a subsurface ocean may be coating certain geological features on Europa, suggesting that the ocean is interacting with the seafloor. This may be important in determining if Europa could be habitable for life.
The recent confirmation that liquid water does indeed flow on Mars has reopened the discussion about Martian life. Mars is our closest neighbor and scientists believe that it had the most Earth-like environment in all of Solar System a few billion years ago. Therefore, when we talk about Martian life, scientists are more optimistic about finding remains of life that had once been alive. It also looks like we have a great shot at some astro-paleontology on the red planet. Even dead microbes could answer many questions about how and if life spread across the Solar System.
Particularly intriguing are the dark stripes that appear during the Martian summertime at Horowitz crater. These are likely to be salty water only inches beneath Mars’ dusty epidermis. A relatively simple probe could sample this muddy environment and give us a lot more answers about what really happened on this planet, and whether life had anything to do with it!
Titan is Saturn’s largest moon and might hold the secrets of life developing under its hazy atmosphere. Its thick atmosphere is rich in compounds that often mark the presence of living organisms, at least on Earth. For example, it’s the only other body in the solar system that has beaches, which means it has oceans that mingle with the surface, along with an atmosphere to act as an umbrella. The biggest difference, of course, is that these oceans are filled with liquid methane instead of water. Titan’s air is also filled with methane, which is usually destroyed by sunlight. On Earth, life constantly replenishes methane levels in the atmosphere, so life might similarly be responsible for the methane levels on Titan.
Scientists believe that methane could act as a substitute for water for extraterrestrial life. When we talk about life on Mars, Enceladus or Europa, it could be very similar to life on Earth. However, life on Titan would be exciting because it would have to be totally unique. This would raise hopes of finding life on non-Earth-like environments.
The ingredients for life, including all the elements from the periodic table, the chemical reactions, and other building blocks of life are found abundantly in our Solar System, yet we haven’t found that elusive “proof” quite yet. Even then, Earth remains the only planet that is supporting life. It’s also important to remember that life doesn’t need to be Earth-like; it could be vastly different, as in the case of Titan or Venus, whose surface temperature is around 450 degrees Celsius. There could even be carbon-based life 100 kilometers above Venus’ surface in the clouds, which have a striking similarity to Earth’s own cloudy environment. If we continue to investigate, we might not only find life in unexpected and seemingly inhospitable places, but we might also find life that looks very little like the life we currently understand.