Other researchers agree that both space rocks and comet dust might in fact harbor organic matter. But how these ingredients for life might travel from one star to another is hotly disputed.

Even as doubters are beginning to give panspermia advocates a little respect, most say the likeliest transfers of life would occur between planets.

This sample salt crystal from New Mexico shows a supposed 250 million-year-old Earth bacteria, inside the yellow circle.

"That bacteria, or at least their spores, can survive for such staggering amounts of time makes their transport from planet to planet on meteorites possible," said Matthew Genge, a meteoritic researcher at the London Natural History Museum. "Bacterial spores in their very own kind of suspended animation could perhaps survive the millions of years it takes for rocks to travel from planet to planet."

Few researchers question that life is hardy, and that it can hang on for a very, very long time. And some space rocks are known to make the trip from Mars to Earth in less than a year.

The trick for a much lengthier interstellar journey would be surviving deadly cosmic rays.

But even 56 light-years is a bit longer than your average commute.

"Herein lies the problem," Genge said. "In Earth rocks, bacterial spores may survive for millions of years cocooned beneath the Earth's surface because they are protected from radiation. On a meteorite in space, fast moving atomic and sub-atomic particles will plow through the meteorite like cosmic cannon balls. If they encounter an organism, DNA molecules will be shattered. If hit enough times, the organism will not survive."

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Several scientists suggest that to survive, a spore, seed, bacteria or other organism would need to be imbedded deep inside a good-sized space rock, perhaps 3 meters (10 feet) or larger, shielded from radiation. Even then, there is the problem of launching a star-orbiting rock or comet into interstellar space.

The only way to do this is through repeated, and tricky, gravitational interactions with planets, says Genge, explaining a process like the one NASA used to sling the Voyager spacecraft out of the solar system.

"The thing is, it's taken a lot of very clever people, powerful computers and cutting-edge technology to do this," Genge says. "Terrestrial meteorites are just rocks and even with microbial passengers they are pretty stupid and thus have to rely on chance."

Somewhat lost in the current panspermia revival is the intriguing flip-side of the "ubiquitous life" idea: If life could have come here from somewhere, why couldn't an Earth rock have been dislodged long ago, sending life to another planet or star system?

"It is possible that there are small fragments of the Earth out there in space today, some with microorganisms, that were blasted off the Earth's surface many millions of years ago," Genge says. "These could reach the Jovian moons and through extreme good fortune seed the water oceans with microorganisms."

Okay. How likely?

"The chances of this happening in reality are probably similar to someone finding their way home after being blindfolded and airlifted to another continent."

"I consider it almost inevitable that microorganisms have been transferred between Mars and Earth by hitching a ride deep inside rocks blasted off the surface by asteroid impacts," says physicist Paul Davies, author of The Fifth Miracle: The Search for the Origin and Meaning of Life.

While Davies says life could have moved in either direction, the Mars-to-Earth scenario is his favorite, based on presumed state of things a few billion years back.

"Mars was a more favorable environment for life to get started," Davies told SPACE.com. "Being a smaller planet than Earth, it cooled quicker, so the comfort zone for deep-living organisms (the ones safe from impacts) was deeper sooner. It is easier for rocks to go from Mars to Earth than vice versa, because Mars has a lower gravity."

Davies is rock-solid in his belief that it takes rocks, serving as protective vessels, to move life from one planet to another. He rejects the idea that "individual microbes waft naked through outer space" -- one of the original tenets of the panspermia theory.

"I still believe it exceedingly unlikely that life could hop from one star system to another that way, largely because of the radiation hazard," Davies says. "It is possible for such transfer to happen inside rocks, but the chance of a rock blasted off Earth ever hitting another Earth-like planet beyond our solar system is infinitesimal."

So does this kill the idea that life on Earth arrived from another star system, that we might have distant ancestors -- or maybe even cousins -- waving to us from an orbit around Iota Horologii?

"Clearly it's possible," Davies says, "but the odds are exceedingly low."

Wickramasinghe, the primary panspermia proponent, responded with a different view:

"Not all microbes in interstellar space would survive of course," Wickramasinghe said. "But the survival of even a minute fraction of microbes leaving one solar system and reaching the next site of planet formation would be enough for panspermia to be overwhelmingly more probable than starting life from scratch in a new location."

So despite all the new and important discoveries, we still don't know how or where life began. But the search for it has gotten a little more interesting, now that we know we might all be aliens.