You and seven billion other humans were born and grew up on planet Earth. Earth is where you ate your first birthday cake, went to school, graduated, and experienced everything else in between and so forth. Earth is considered your home. But, what if one day, news broke out and newspaper headlines exclaimed that Earth was not actually our real home?
Astrobiology is the study of life throughout the universe. But it isn’t simply a quest for life beyond our Solar System and into other parts of the universe. Astrobiologists examine the origins of life, environments capable of sustaining life, how life develops, and the limits to what life can tolerate.
A plethora of specialists are intrigued to understand the environmental extremes to which life can be sustained on Earth. From the deepest and hottest hydrothermal vents to inside glacial Antarctic rocks, life has been discovered not only present but flourishing. Organisms that can be sustained in such extreme environmental chaos are referred to as extremophiles.
This discovery that these extremophiles can exist in the unimaginable depths of the Earth, where no sunlight exists, or lie in a state of dormancy inside a glacier for thousands of years dramatically inspired scientists’ hopes for the potential of life on other planets… or perhaps pointed towards evidence of life’s origin.
Image from Wikimedia Commons
Evidence is accumulating suggesting that life as we know it originated from Mars, transferred to Earth via meteorite. The element molybdenum, which may served as a crucial role in the origin of life, is believed to have been present in an oxidized form on the Red Planet billions of years ago before its availability spread to Earth. Molybdenum becomes capable of influencing the formation of early life when highly oxidized, but three billion years ago, Earth had a very modest supply of oxygen, indicating that this form of molybdenum could not have been present on Earth at the time life began.
But why molybdenum? Organic compounds are the building blocks of life, but sometimes these compounds require some assistance – a catalyst – to help instigate reactions. With an addition of molybdenum, or even boron, organic compounds would flourish.
Traces of boron were discovered on a Martian meteorite. Boron is only found in extremely dry areas. Early Earth was completely covered with water, which would have made it extremely unlikely for boron to develop in adequate concentrations on Earth when life first began evolving. Mars, around this time, held considerable amounts of dry land.
Image from Wikimedia Commons
Not yet have any Martian organisms been uncovered. But some of the microbes scientists have discovered bear a capability to withstand unbelievable amounts of radiation and environmental trauma. Would they be hardy enough to survive an interplanetary journey, blasted off their home from asteroid impact? This idea is coined panspermia – the idea that primitive life forms could travel between planets and survive the journey.
Nevertheless, regardless of whether Earth is our true home or just the pit stop in an interplanetary journey, science – and common sense, for that matter – proves that Earth turned out to be the better home of the two planets for life. But, with these ideas in mind, isn’t it fair to say we’re all just aliens?