In 2001, a bizarre red rain showered India’s southern state of Kerala. Godfrey Louis, a physicist now in Cochin University of Science and Technology’s astrobiology department, decided to collect samples and take a closer electron-microscope look. He noticed some particles in the rainwater that looked like biological cells, but when he went looking for DNA, he found none. That enticingly strange result led Louis to speculate that he had found extraterrestrial bacteria.
The new paper (pdf) appears in Arxiv.org, not a peer-reviewed journal. But it repeats earlier work by Louis and a collaborator that they say shows the cell-like particles can survive and grow at high temperatures that would kill most life as we know it (around 250 degrees Fahrenheit). At room temperature, particles appear as inert as, well, odd looking red rain dirt.
Louis and his colleagues hypothesize that extraterrestrial cell-like particles could have traveled on a meteor that burst in Earth’s atmosphere and seeded the rain cloud responsible for Kerala’s unusual weather. That would provide support for the “panspermia” theory–the idea that life on Earth came from outer space.
Louis’s earlier paper in Astrophysics and Space Science made him a media sweetheart and a target for critics. Plenty of people weren’t buying Louis’s story. As Popular Science reported in 2006, other earth-origin red rain theories ran the spectrum from commonplace to bizarre, including algae, fungal spores, and red blood cells (which don’t have DNA) juiced out of meteor-struck bats.
Technology Review reports that the new paper seems sure to precipitate more controversy. The work again says that high temperatures cause “daughter” cells to form in “mother” cells, and also notes that after the team bombarded the cell-like structures with light their emission had “remarkable correspondence with the extended red emission observed in the Red Rectangle planetary nebula and other galactic and extragalactic dust clouds.”
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Image: Wikimedia / Louis and Kumar