#Ancient space travelers for free
Hospitality was usually provided by social peers for free (at least for the higher classes) but there were specific enterprises set up to provide basic food and accommodation, especially in the larger cities and great 'attractions' of the Panhellenic religious sanctuaries. But for now, it's time for scientists across fields to jump in and start filling in the gaps, Saraj said.Travel could be an expensive business, though, and if undertaken over long distances, required baggage porters and other attendants. There's reason to think that at least some bacteria might survive super-long trips through deep space, he said, based on how robust they are under extreme conditions on Earth and in orbit. He wants to know, he said, precisely what the biology of the upper atmosphere looks like, and how comets might react to it. Siraj didn't strongly challenge any of Kane's concerns, but reframed them one by one as opportunities for further study. Still, Kane said, the calculations in this study of how precisely a comet might skim through the atmosphere were new to him, and "very interesting."
But exporting life to an alien star system likely requires a more specialized scenario. And that's really the key idea of this paper: Researchers have long suggested that debris from major collisions might blast life around between our solar system's planets and moons. But there's little direct evidence that any bacteria might survive the thousands or millions of years necessary to travel to another habitable star system. It's plausible, he said, that some bacteria might survive decades in space - long enough to reach, say, Mars. The biggest question, though, Kane said, is what would happen to the microbes after they landed aboard the comet. It's also not clear, he said, whether any microbes would really have been up high in our atmosphere in the first place Those rocket experiments from the 1970s are old and questionable, he said, and we still don't have a good picture of what the biology of the upper atmosphere really looks like today - let alone hundreds of millions of years ago, when comet encounters were much more common. But the precise mechanism by which the microbes would adhere to the comet is unclear, Kane said, since the aerodynamic forces around the comet might make it impossible for any microbes to reach the surface and work their way deep enough below the surface to be protected from radiation. Siraj and Loeb point out that some bacteria can survive extraordinary accelerations. The first problem would occur when the comet slammed into the atmosphere, he said. However, Stephen Kane, an astrophysicist at the University of California, Riverside, told Live Science that he was deeply skeptical of the suggestion that microbes from Earth might have actually turned up alive on alien planets through some version of this process. "It's a brand new field of science," he told Live Science That alone is reason for scientists to take the idea seriously, Siraj said, and for researchers from fields like biology to jump in and figure out some of the details. Comets are porous, and might actually shield microbes from deadly radiation some microbes can survive a remarkably long time in space. Comets really do enter and leave our solar system from time to time, and Siraj and Loeb's calculations show that it's plausible, maybe even likely, this has happened to large comets that graze Earth.
#Ancient space travelers series
A series of experiments using small rockets in the 1970s found colonies of bacteria in the upper atmosphere. While the study's concept may seem far-fetched, humanity is constantly confronted with seeming impossibilities, like Earth going around the sun, or quantum physics, or bacteria hitching a ride into the galaxy aboard a comet - that turn out to be true, Siraj saidĪnd there's been reason to suspect that it might be possible. Siraj told Live Science that although a lot more work needs to be done to back up the finding, it should be taken seriously - and that the paper may have been, if anything, too conservative in its estimate of the number of life-exporting events.
But in a new paper, Amir Siraj and Avi Loeb, both astrophysicists at Harvard University, argue that at least the first part of this story - the depositing of the microbes into a comet that gets ejected from the solar system - should have happened between one and a few dozen times in Earth's history. We have no idea whether this ever actually happened –.and there's a mountain of reasons to be skeptical.
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