Space Taxi – Microbes on the Move: The Far-Out Theory of Panspermia
By Shruthi Venkatesh
Cosmofluencer (Season 03)
Hitchhikers of the Cosmos
For centuries, humanity has pondered the origins of life on Earth. But what if the answer lies not on our own planet, but scattered throughout the cosmos? This is the intriguing idea behind panspermia – the theory that life doesn’t originate solely on planets, but can travel between them.
Panspermia proposes that the building blocks of life, or even simple lifeforms themselves, could hitch a ride on meteoroids, asteroids, or comets, journeying from one world to another.
Imagine tiny microbes encased in proactive shells, hurtling through the vast empty space, waiting for a chance encounter with a suitable new home.
Two Main Flavours of Panspermia
There are two main flavours of Panspermia:
- Lithopanspermia: This version suggests microscopic life nestled within rocks gets blasted off planets by impacts, then travels to new worlds where it can potentially revive under favourable conditions.
- Directed panspermia: This more speculative idea proposes that life, perhaps intelligent life, could deliberately send microbes on interstellar journeys to seed new planets
The above diagram explains the Panspermia hypothesis with the emphasis on the OoL by using a material-based Panspermia seed (M-BPS).
A) a M-BPS that escapes from a particular planet (donating planet) via meteorites or other interstellar objects (omitted for clarity). The “seed” is then scattered into space, endures space exposure, and eventually lands on another habitable planet (receiving planet).
B) zoomed-in view of the receiving planet, where a M-BPS enters into a body of water (or other liquid) of the receiving planet, and then undergoes a phase transition to phase separate into microdroplets, which have been proposed as primitive compartments. These microdroplets can either release chemicals to their new ambient surroundings (either through degradation and diffusion of the chemicals it is composed of, or transport of any contents it had already encapsulated beforehand on the donor planet) or receive ambient (local) chemicals from its surroundings by segregating and compartmentalizing. Either of these processes ensures that M-BPS microdroplets have blended into their new environment, enabling chemical continuity towards developing nascent biology, assuming that the microdroplets themselves are stable to degradation during the transport process and in the new environment.
So, is there any evidence to support this far-out theory?
- Microbial Resilience: Extremophiles on Earth, organisms thriving in harsh environments, suggest life can be surprisingly tough. Some microbes can survive in the vacuum of space and endure extreme radiation for extended periods.
- Cosmic Delivery Systems: Asteroids and comets constantly bombarded planets, and some might have originated from regions with life-supporting conditions.
However, there are also challenges:
- The Great Leap: Panspermia doesn’t explain how life originated in the first place. It simply proposes a way for it to spread.
- The Long Journey: Space travel takes a long time. Microbes would need incredible resilience to survive the harsh conditions of interstellar space for millennia.
- The Seeding Dilemma: Even if life arrived on a new planet, it would still need to find the right environment and resources to establish itself.
Conclusion
Panspermia remains a controversial theory, but it continues to spark debate and inspire scientific exploration. As we search for signs of life beyond Earth, considering the possibility of interplanetary travel broadens our perspective. Perhaps life isn’t confined to planets, but woven into the very fabric of the cosmos, waiting to be discovered in the most unexpected places.
The quest to understand life’s origins is far from over. Panspermia might be a bold theory, but it reminds us that the universe is full of fascinating possibilities, and the answer to the question “Are we alone?” might lie not just on Earth, but amongst the stars.
References
- Astrobiology @ NASA | In Search of Panspermia
- Many Worlds | In Search of Panspermia
- Wikipedia | Panspermia
- Astrobiology | A Material-based Panspermia Hypothesis: The Potential of Polymer Gels and Membraneless Droplets