The search for our siblings

“Two possibilities exist; either we are alone in the Universe or we are not. Both are equally terrifying.” – Arthur C Clarke

Since the inception of the idea that there are worlds beyond our own, the idea of the presence of life on those worlds also gained popularity. With the advancement of technology, we have detected planets beyond our solar system called exoplanets. These exoplanets might host alien lives.

In our solar system, there are worlds with great prospect and they might host life. Venus, with a surface temperature of 480 degree celsius and a crushing pressure, is the last place where life would get a foothold. But above the thick clouds, some scientists agree that there might be microbial colonies. A recent detection of phosphine gas on the cloud tops of Venus initiated a great stir among scientists with some suggesting that it was caused by certain microbes. Though it’s still a topic of debate, if it turns out to be biogenic, then it will profoundly impact the human society and science.

Mars, though lonely and desolate, might have had life in the past. Various evidences suggest that Mars had flowing water in its surface which was later on lost during its premature planetary demise. The Perseverance rover that was sent to Mars by NASA discovered deltaic deposits on an ancient lake that once existed in the Jezero crater where the rover was landed. These sedimentary deposits indicate that some surficial streams might have drained themselves in that lake. The presence of water also indicates that life might have existed once on Mars before the planetary Armageddon. Perseverance is currently searching for signs of life on Mars. Some planetary geologists speculate that there might be underground brines (water bodies with high amount of salt) on Mars which might host living organisms. However the search for evidence is still on.

In the outer solar system, planets like Jupiter and Saturn can also be promising. Though Jupiter and Saturn can’t host life since they don’t have a surface for life to get a foothold and also have extremely high temperatures and pressures, their moons might be promising. Europa; the icy world orbiting Jupiter has been hypothesized to have a subsurface ocean of liquid water with ambient conditions for life as the icy crust can shield the ocean from Jupiter’s life threatening radiation. Some planetary models also suggest presence of hydrothermal vents within the ocean. On Earth, we have hydrothermal vents which are known to host colonies of sulphur loving bacteria. Aliens might not be the green, long eyed individuals with no hair afterall. Instead they might be as simple as a bacteria or any unicellular organism.

On Titan, there might be life forms that make methane a source of energy for their individual metabolism. Titan is the second largest moon of the solar system with a thick atmosphere and freezing surface. It has rivers and huge lakes of liquid methane and meteorological activity in which methane rains down from the sky. Radar imagery by NASA’s Cassini orbiter and further imagery by Voyager 1 alongwith the analysis by European Space Agency’s Huygens lander that landed on Titan confirmed the existence of liquid methane on it. However whether there is life on that distant moon needs further assessment and exploration. In the mid-2020s, NASA plans to send a mission dubbed ‘Dragonfly’ where a drone will survey the moon for gaining a better insight of what happens on that world.

Saturn also has another moon which has a great chance of hosting life. The moon Enceladus is also icy like its distant cousin Europa with confirmed existence of subsurface ocean mixed with organic compounds. The confirmation was done by Cassini when it flew past the geysers emanating oceanic water from the south of Enceladus for sampling them. Upon further analysis, the discovery of organic compounds vital for life was made. This further cleared the haze that troubled the scientists to answer the age old question, “Are we alone”. It turns out that life might be a very common thing in our cosmic neighbourhood. But what about the other solar systems within our own galaxy? Are we the only paradise of life in the lifeless void, or is it teeming with life? Can other worlds also give rise to intelligent beings who can think about their origin story and also search for their cosmic siblings scattered in the vastness glittering with stars?