A small group of scientists have long suggested that the seeds of life may have been distributed across the vast distances of space via cosmic dust, asteroids, or comets — a theory known as panspermia.
Some, including late astronomer and planetary scientist Carl Sagan, have gone as far as to raise the possibility that those seeds may have been deliberately spread to distant planets by intelligent civilizations.
It’s an intriguing albeit far-fetched hypothesis that most recently caught the interest of Harvard astronomer Avi Loeb. Following months of observations of mysterious interstellar object 3I/ATLAS, which came surprisingly close to a number of solar system planets during its brief visit last year, Loeb proposed that it could’ve been shedding the building blocks of life during its journey — or even have been designed to seed planets like our own intentionally.
In a recent blog post, Loeb suggested that extrasolar life could’ve survived the journey by being embedded inside the comet’s ice reservoirs, before being released near other planets in the solar system, likening it to a “dandelion flower shedding its seeds to be carried by wind towards a fertile ground.”
“In addition to natural origins, there is the possibility of directed panspermia, whereby an interstellar gardener seeded 3I/ATLAS on a fertilization mission targeting the habitable planets in the Solar System,” he wrote. “This would explain the rare alignment between the trajectory of 3I/ATLAS and the orbital plane of the habitable planets around the Sun, as well as the sunward jet with large fragments that plowed through the solar radiation and wind.”
Loeb previously painstakingly built a case around his widely disputed hypothesis that 3I/ATLAS may have been an alien spacecraft that was sent to visit us. His latest blog post suggests that the wealth of observational data strongly suggesting it was a comet made up of ice and rock has yet to fully weaken his resolve when it comes to the possibility that aliens are behind the interstellar visitor.
That’s not to say his new idea is a slam dunk. Panspermia itself remains a hotly debated subject among scientists, with many arguing that building blocks of life may have always been present on Earth. How such a process could play out in far more hostile environments in other parts of the solar system is an even bigger question.
Still, it’s a fascinating thought experiment with some vast implications — and should inspire us to actively seek answers by intercepting objects like 3I/ATLAS, Loeb argues.
“By directing a probe on a crash course towards the surface of these icebergs, we can diagnose the composition of the material they shed and infer whether it carries extrasolar life,” he wrote in his latest blog. “In case it does, the most pressing question is whether extrasolar life resembles life-as-we-know-it.”
“If so, perhaps life on Earth was seeded by an interstellar gardener,” he added.
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