First came the extraterrestrial speculation. Then came the actual answer. Then came the backlash.
NASA’s big astrobiology news last week had nothing to do with E.T., of course—the team behind a study in Science announced the find of a kind of bacteria that appear to thrive in arsenic and can even use it in place of phosphorus in the backbone of its DNA double helix. But after the big announcement finally happened and squelched the more imaginative rumors, scientists started asking some hard questions about the study online.
Over at Slate, DISCOVER blogger Carl Zimmer rounded up expert critiques from biologists, and many didn’t hold back.
Almost unanimously, they think the NASA scientists have failed to make their case. “It would be really cool if such a bug existed,” said San Diego State University’s Forest Rohwer, a microbiologist who looks for new species of bacteria and viruses in coral reefs. But, he added, “none of the arguments are very convincing on their own.” That was about as positive as the critics could get. “This paper should not have been published,” said Shelley Copley of the University of Colorado. [Slate]
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Nearly 150 years after scientists discovered the first specimen of the dino-bird archaeopteryx, we get to see what it was made of. Researchers who scanned one of the fossils with x-rays say the specimen contains not just impressions of fossils, but actually the remains of soft tissue with some of the chemical components intact. They published their findings (in press) today in the Proceedings of the National Academy of Sciences.
The team led by Roy Wogelius scanned a 150-million-year-old Archaeopteryx fossil using a synchrotron-type particle accelerator located at the Stanford Synchrotron Radiation Lightsource in California.
The synchrotron excites atoms in target materials to emit X rays at characteristic wavelengths. The scan reveals the distribution of elements throughout the fossil. The green glow of the bones in this false-colour image shows that Archaeopteryx, like modern birds, concentrated zinc in its bones. The red of the rocks comes from calcium in the limestone that had encased the fossil since the animal died [New Scientist].
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With its thick atmosphere, chemical makeup, and an atmospheric pressure not too far from Earth’s, Titan is one of the most likely candidates for finding life elsewhere in our solar system. But at a temperature close to -300 degrees Fahrenheit, the surface of this Saturnian moon in anything but what we humans would call hospitable. Since this frigid place is far too cold for liquid water, any life there would need an alternative survival method. A new study published in Astrophysical Journal Letters suggests that the simple hydrocarbon acetylene, proposed as a possible energy source for life on Titan, could be much more abundant than scientists previously thought.
Titan has previously been shown to be dotted with lakes of liquid hydrocarbons, primarily methane and ethane. An estimate made in 1989 suggested bodies of liquid hydrocarbons on Titan would contain a few parts in 10,000 of acetylene. But an updated estimate based on data from the Cassini-Huygens mission to Saturn now suggests the lakes contain much more food for any hungry alien life-forms that might be present [New Scientist]. Lead researcher Daniel Cordier says the acetylene abundance could be as high as one part in 100, or 1 percent, of the surface lakes on Titan.
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