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. 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. There is a chance the samples were contaminated with more modern bacteria, and follow-up studies need to be done. And last year's discovery of living microbes deep in the Antarctic extends the range of extreme conditions under which life is known to survive.
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. Even the nearest stars known to have planets are many light-years away. And none has been shown to have habitable planets. Some nearby stars are becoming more interesting, however.