OPINION

The search for what we would deem to be "habitable" worlds orbiting other stars has reached a crossroads in recent years. As our technology and techniques improve, we've been able to identify small rocky worlds orbiting within other stars' "habitable zones."

So far, we can measure an exoplanet's mass, understand its physical size, even calculate its average density, revealing whether or not that planet may contain quantities of water, for example. Add these factors to our knowledge of that alien world's orbit and we are given tantalizing clues as to whether liquid water may persist on its surface.

These apparently habitable worlds are quickly labeled "Earth-like," but they may not be like Earth at all. There's a lot more to our planet besides its mass and orbit that makes it habitable -- namely our thick atmosphere and protective magnetosphere, both of which safeguarded burgeoning terrestrial life around four billion years ago from the ravages of space weather.

Lacking sufficiently powerful observatories, we're not able to detect atmospheres, let alone magnetospheres, around distant small exoplanets, so the "Earth-like" moniker is premature at best.

But as we continue to discover all the weird, wonderful and extremely varied exoplanets our galaxy has on offer, we're finding the potential for worlds that may be considered "habitable" for short periods, hypothetically allowing life (as we know it) to be sparked, only for the habitable conditions in these worlds' atmospheres to dramatically change, snuffing out the immature lifeforms.

An often-overlooked factor in the science behind the evolution of life is time, and many of the exoplanets we've found may well be habitable during short periods of their existence, but not long enough to allow life to gain a foothold.

In an interesting discussion published in the journal Astrophysics and Space Science, Claudius Gros from the Institute of Theoretical Physics at Goethe University Frankfurt investigates the possibility of giving life a helping hand by blasting it into interstellar space and flinging our ready-made biology toward exoplanets that may only have a very short window of habitability.

"It is therefore certain that we will discover a large number of exoplanets which are inhabitable intermittently but not permanently," Gros said in a statement. "Life would indeed be possible on these planets, but it would not have the time to grow and develop independently."

When basic life took hold on Earth, its very existence helped to shape the habitability of our atmosphere. For example, bacterial mats changed the chemistry of atmospheric gases, boosting its oxygen content and facilitating the evolution of complex eukaryotic cells, upon which all multicellular life is based.

WATCH VIDEO: Could Life On Earth Have Come From A Comet?

In Gros' discussion, he imagines sending a small interstellar probe to another star system. On arrival, that probe would somehow slow down and, using an on-board biological laboratory, would synthesize a selection of single-celled organisms that would then be dropped onto a habitable, yet lifeless world. Should this biological "Ark" of sorts seed the first microbial life, potentially billions of years of evolution would have been skipped on that world allowing life to take hold within the tight window of opportunity, possibly allowing it to spawn a self-sustaining alien ecosystem with a very terrestrial flavor.

"In this way, we could jump the approximately four billion years which had been necessary on Earth to reach the Precambrian stage of development out of which the animal world developed about 500 million years ago," he added.

This highly speculative method of seeding life is called, perhaps unsurprisingly, the "Genesis Project" and Gros sees it as a means for us to "give life something back."

Seeding life on other worlds is not a new concept; science fiction has tackled it countless times and there are some scientific foundations for the idea. 

The mechanism known as "panspermia" is a hypothesis that governs the transfer of life from one planet to another. Should a massive asteroid hit one planet brimming with life, sending a chunk of rock packed with living microbes into space, that rock may land on another planet with some habitable qualities, allowing a few of the surviving microbes that hitched a ride on the rock to make a new home.

But the mechanism described by Gros is a variation on the "directed panspermia" hypothesis where an intelligent civilization wants to seed life on other worlds in their image, sending biological capsules to spark their brand of life elsewhere.

However, we quickly fall into an ethical trap. Just because we have life on Earth, is it our biological obligation to share it with the rest of the galaxy? Or would such an act be no better than biological pollution or, even worse, a biological weapon? Just because we've got it, doesn't mean the rest of the universe wants it.

One obvious problem is the question of native lifeforms; say if a target world already has a rapidly evolving lifeform that's taken the opportunity to gain a foothold on that world? A Genesis Project capsule dropping on their heads filled with an out-of-the-box Earth BrandTM goo would be disastrous.

Though Gros points out that great pains should be taken to ensure the target planet isn't already inhabited, when talking about the potential genocide of the foundational biology of a future alien race, it would be hard to justify such a risky mission.

Aside: If you're thinking about Star Trek: The Wrath of Khan, you're not alone, so here you go:

Quelle: Seeker

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The Genesis Project: New life on exoplanets

Physicist Claudius Gros on the journey of an automated gene laboratory to celestial bodies outside our solar system