According to a fringe theory known as panspermia, lifeforms could be spreading across planets by hitching on meteor rides.
Search For Life Beyond Earth
The new study suggests that if life can spread across planets in a concept called panspermia, detection could be possible.
This comes as part of a long-standing hunt for life outside of Earth. Though the solar system has several promising locations, exoplanet abundance implies that life could likely be found on a planet that orbits a different star. To date, there are over 5,000 confirmed exoplanets, with such numbers always going up.
However, there is a major roadblock faced in such searches. Astronomers are unaware of what they are exactly looking for. Only one planet, Earth, is known to be definitely capable of fostering life. Moreover, only one kind of life is known.
Nevertheless, astronomers believe that life could have different forms across the galaxy. In fact, it is possible to find a replica of Earth with the same life type.
Some astronomers recently proposed an alternative approach. They focused less on what forms life could take and more on the possibilities of what life could do.
Aliens Hitching on Meteors To Colonize Planets
In the new study, which is available in a preprint server, they specifically proposed a detection strategy that is grounded on the concept of panspermia, which refers to the idea that life can begin on one planet and move to others through meteorite hitching.
Though the concept of panspermia goes beyond scientific research, it cannot be totally regarded as pseudoscience. There have been Martian meteorites spotted on Earth. Scientists have also been regularly surprised by living creature hardiness and the extreme environments that they are capable of thriving in
A key characteristic of any life form is its capacity to alter the natural balance of the planet. For instance, on Earth, more atmospheric oxygen is present than in conditions where life is not present. Distant observers may also see significantly more green over the landmasses compared to otherwise.
The exact exoplanet properties of what an alien life could alter remains unknown. However, if such life can perform panspermia, then it would try to alter each planet it comes across as it moves from planet to planet. At times, it would end up failing if the conditions are not right for life to thrive. However, it may end up succeeding at times, making this novel world similar to the original one. The new planet could then serve as the new starting point for another round of panspermia.
As part of the study, the scientists developed a statistical test wherein if sufficient properties of sufficient planets are measured, it would be possible to identify a nearby planet cluster with similar characteristics. Since such planets would not have any other reason to share similarities, the cluster would end up standing out from all other exoplanets.
While this discovery will not be a life identification smoking gun, it would serve as a major clue that there was something strange happening to these worlds.
The scientists acknowledge the limitations of their work. For one, the hypothesis of panspermia is untested, yet they assume that it is possible. Secondly, the method can only work if sufficient data about several exoplanets are collected. Nevertheless, their method's advantage is its agnosticism, which means that it is capable of identifying possible life signatures without greater assumptions regarding the works of this life.
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