So far, Earth is the only place in the Universe where life reliably exists. However, researchers have discovered many exoplanets with conditions that might be suitable for terrestrial organisms. Theoretically, we could use comets to populate them. The question is whether we should.
There are many theories of the origin of terrestrial life, and one of them, the panspermia hypothesis, says that our planet is just a suitable place, while life itself was brought to it from outer space. Scientists suggest that, as a result of a sufficiently strong impact on the planet, chunks of rock with microbes encased in them could be thrown into space. And if these microbes survive the long journey in a vacuum and reach a habitable world, they could give rise to a new branch of evolution.
This is accidental, or natural panspermia. However, there is also the possibility of intentional settlement of other celestial bodies by forces of a sufficiently advanced civilization. For years, people have been arguing about whether aliens played a role in the settlement of the Earth or the formation of human civilization. Now American astronomers have posed the question differently: Can we ourselves play the role of such "aliens"?
There are about 200 billion stars in the Milky Way, which means an inconceivable number of planets, satellites, asteroid belts and other celestial objects. At the same time, the experience of the solar system shows that it is not easy to build a developed biosphere: we still do not know whether life exists on Europa and Enceladus. But it is already obvious that in the subglacial ocean it is difficult to expect a biosphere of the same level as on Earth.
Nevertheless, this does not mean that we cannot try, because we already know of the existence of several planets potentially suitable for terrestrial life forms. Sending spacecraft to them looks economically unprofitable. But there is an opportunity to use natural "ships" that have been wandering in space for millions of years - comets.
By waiting for a suitable interstellar comet to arrive in the solar system, we could attach to it a microbiological inoculum containing a variety of organisms capable of surviving in a variety of conditions on Earth. With the help of the comet, the "parcel" would sooner or later reach another star system, where it could carry the "seeds of life" to a suitable planet.
Of course, it is possible that the entire project will be a waste of effort: either the inoculum will not reach the comet, or it will not survive interstellar travel, or there will be no suitable planet in the star system (and if it is already populated, this will lead to a clash of different life forms). In addition, even if the mission goes perfectly, the question will inevitably arise: didn't our interference destroy the possibility of the birth of a unique ecosystem, which is trivial not enough time?
On the other hand, by spreading life across the Universe, we could prepare the ground for our future survival: sooner or later mankind will have to go into deep space to find habitable worlds. And in that case, the crazy idea of the scientists of the present might become the greatest hope of the earthlings of the future.
