In the story we ran yesterday, “‘Compelling new evidence’ claimed for comets generating phosphates for earliest life,” we noted that our physics color commentator Rob Sheldon thinks that the idea that building blocks of life came from space is plausible and should be demonstrable. He offers his somewhat controversial thesis here:
I’ve argued elsewhere that the presence of cyanobacterial and eukaryotic microfossils on carbonaceous chondrites (comet fragments that land on the Earth), is evidence for ubiquitous cometary transport of life throughout the solar system and galaxy. This makes Darwin’s theory moot, because extraterrestrial transport destroys any “tree of life” that relies only on terrestrial modifications. It may also explain why NASA is adamantly opposed to publishing/acknowledging these discoveries.
Every comet flyby or lander mission that has carried cameras or spectrometers has found evidence of organic molecules on comets, going back to the very first flyby of Comet Halley in 1986. Rather that attribute it to in situ life, NASA attributes it to abiotic manufacture of organics in space. What is remarkable about this claim, is that no laboratory duplication of such abiotic synthesis is ever presented. What is presented is a careful human-directed (non-equilibrium) synthesis using multiple exotic reagents, extraction, and purification steps. The Miller-Urey synthesis is a classic example.
The article purports to make some pre-biotic chemicals that function as the exotic reagents in human-directed abiotic laboratory synthesis. The implication is that we are a step closer to explaining the organics we see in comets without inferring life.
The article explains that they froze little drops of CO2, H2O, and PH3 at 4K. Four degrees above absolute zero is the temperature of deep space that is light years away from a star. Then they bombard these ice grains with keV electrons to simulate cosmic rays. For the record, a 1 keV electron is about 12,000,000K in temperature. So this combination of frozen ice and hellish electrons unsurprisingly leads to non-equilibrium chemistry, including the phosphoric acid “exotic reagents” mentioned earlier.
But where did the PH3 come from? Of all the elements that are essential for life, phosphorus is the least common, often requiring farmers to apply it as fertilizer supplements. (Nitrogen is abundant as a gas in our atmosphere, but rare as a molecule that plants can absorb, making it the other ingredient in fertilizer. This is yet another reason that finding nitrogen compounds on comets is quite unusual and proof that there must be life on comets.)
Well, there hasn’t been any PH3 identified by astronomers except for a fuzzy “maybe” published in 2008, which actually only measured a P-H bond. The remainder of the molecule was inferred. That is, it might have been a much bigger molecule than PH3. And even then, they said, PH3 didn’t fit any model for “gas phase” chemistry, so it had to somehow be leaking out of ice grains.
But the current article didn’t mention the 2008 paper. Instead, it quoted an old officemate of mine at the University of Bern, Katrina Altwegg. We worked on the mass spectrometer for the ESA ROSETTA mission together, an instrument called ROSINA. The spacecraft matched speeds with the Comet 67P/Churyumov-Gerasimenko and orbited it for about a year, collecting gas molecules and taking pictures. It measured the amino acid glycine and several “precursor” molecules (though of course, they could just as easily have been “post-cursor” UV degradation fragments.)
They also discovered the element phosphorus. What they didn’t find was the gas phosphine.
Nevertheless, they argued that the source of phosphorus had to be phosphine. Why? Because it was the smallest gas molecule containing phosphorus and it was abiotic. As with the other organics, however, it is equally possible that the phosphorus came from the UV degradation of some biological molecule like DNA. All we know for certain is that the instrument measured individual phosphorus ions.
So Altwegg’s paper was the one cited by the current University of Hawaii scientists for how to make exotic phosphorus reagents for abiotic synthesis. I hope what you gather from this history is the complete circularity of the logic. We assume abiotic synthesis in order to prove abiotic synthesis.
But the data is equally consistent, if not more consistent, with UV degradation of biological molecules made by in situ life. Like Behe’s loss of function or Sanford’s genetic entropy, degradation is far, far easier than synthesis it is only the resolute rejection of the 2nd law of thermodynamics that makes these stories plausible. The Darwinian demand for devotion contaminates not just biology, but chemistry as well. I suppose the day will come when someone claims that microfossils are also formed abiotically and provide the necessary information for the spontaneous origin-of-life on Earth.
See also: Rob Sheldon: How we know the 558 mya animal Dickinsonia remains really contained fats
New paper: Cambrian explosion driven by viruses from space
Skeptic: Panspermia (life came from elsewhere than Earth) is “pseudoscience”
Panspermia (maybe life came from outer space) is back, in Progress in Biophysics and Molecular Biology