Well, NASA’s made another of their cryptic pronouncements about “an astrobiology finding that will impact the search for evidence of extraterrestrial life.” Today’s press conference, streamed live over NASA TV at 2:00 p.m. EST, should fill us in on the details.
But let’s face it, the most scientific most us usually get is figuring out how to build a Cylon eye jack o’lantern or measuring the effect on your dog of taping bacon to your cat. So Tor.com’s asked me to step in and interpret the announcement. Scuttlebutt so far is that it’ll revolve around one keyword: arsenic.
The press conference participants are:
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Mary Voytek, director, Astrobiology Program, NASA Headquarters, Washington
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Felisa Wolfe-Simon, NASA astrobiology research fellow, U.S. Geological Survey, Menlo Park, Calif.
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Pamela Conrad, astrobiologist, NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Steven Benner, distinguished fellow, Foundation for Applied Molecular Evolution, Gainesville, Fla.
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James Elser, professor, Arizona State University, Tempe
2:19 PM: Ah, those wacky Californians. They just have to be different. NASA today is announcing a discovery made in Mono Lake, near Yosemite, where microorganisms are apparently thriving using arsenic in their metabolism.
2:20 PM: They’re showing off chains and talking about weak links right now… The Limits of Life in our Solar System is a book they’re suggesting has more information about this stuff.
2:23 PM: Pam Conrad is our next speaker, an astrobiologist at Goddard who’s working on the next Mars rover.
(Sorry about missing the beginning speakers, by the way: We had technical difficulties at the start of the broadcast.)
2:25 PM: The significance of this find, she’s saying, has to do with the idea that biological molecules now appear to be able to incorporate what she calls “substitutions” in them. Arsenic is the first we’ve found (apparently) but it opens up the question of what other ones we might be able to find in the future.
2:27 PM: Felisa emphasizes that this is not so much about arsenic. What we thought was that all life on Earth required phosphorus, but this one does not. This “cracks open the door” to new potentials. Rolling some footage now to show off various kinds of life… kinda corny, but cool, too.
2:28 PM: What this discovery does is expand the possibilities of discovery for the future.
Going to Q&A now.
2:30 PM: Question about the idea of “substition”—Felisa answers that this finding suggests new experiments, but to speculate, phosphate on Earth is locked up in rock. Phosphate chemistries are difficult, so we can speculate about alternatives, eg. in hydrothermal vents, that arsenic might be more useful because it does its chemistry more rapidly.
2:31 PM: Q: How might this affect the Mars science lab and other ongoing programmes?
2:32 PM: A: This broadens the possibilities for what we consider a potentially ’habitable’ environment.
2:34 PM: Q: What other elements might be substituted?
A: Felisa dodges the question skilfully!
2:38 PM: Q: Are there possible practical applications?
A: James Elser (offsite) Yes, there’s definite possibilities, because all existing plants, eg. for bio-energy, require phosphorus in their fertilizer. This is speculative, but a whole bio-energy technology based on arsenic might reduce our dependence on fertilizers for the biofuel sector.
More possible might be arsenic cleanup by using superbugs that are engineered using this biochemical channel.
2:39 PM: Felisa adds that the microorganism looked ordinary, has an otherwise ordinary metabolism. This means that there may be many other organisms in the environment around us that may have novel systems like this, or even totally different ones. If you don’t know to look for them, you won’t find them.
2:41 PM: This is a very interesting speculation, since we haven’t characterized more than a fraction of the life already existing on Earth, or even the microorganisms in our own bodies. This therefore is a fundamental discovery in the sense that it opens the door to exploring many more new areas of research. (As an idea of how this works, remember that carbon nanotubes and buckyballs are present in ordinary soot, yet we never looked for them so never knew they were there.)
Q: What do they mean by “weak links” in arsenic chemistry?
2:43 PM: A: Steven Benner (who was the researcher speaking when I came in) is being very very cautious. He’s not quite ready to commit to the proven existence of this organism. As to Arsenic, its orbitals are easier to break than phosphorus, which makes its chemical bonds inherently weaker than those of phosphorus.
2:45 PM: This isn’t the sort of consideration I’ve thought of before as an SF writer, but the relative strength of different kinds of bonds must be as fundamental a consideration as, eg. the solvent qualities of water vs., say, liquid methane, for building and carrying organic molecules.
2:47 PM: Felisa is elaborating on the actual experiments she’s done with the organism. The main fact is, there just isn’t enough phosphorus in these bacteria to sustain life. Yet there is arsenic, which could step in to make up for it. There is phosphorus in these cells, there just isn’t enough to sustain its growth rate.
In other words, this is indirect evidence, but indirect evidence is not necessarily weak; what it means is that they don’t yet have the details on how this bug lives—where the arsenic is, exactly what it does.
2:49 PM: Steven Benner is critiquing Wolfe-Simon’s research, and she’s vigorously responding… as things spiral into the details of scientific debate…
2:52 PM: What does this mean for science fiction? Does it mean the Star Trek Horta could exist? The usual SF alien life form is silicon-based life, but this is nowhere near that. Carbon forms the backbone of all life on earth; the idea of silicon life is that silicon might form a similar kind of backbone, however, that’s far more radical than what they’re presenting here. This is the substitution of specific elements in organic molecules that are, otherwise, carbon-based and ordinary.
Pamela Conrad, however, is saying that this is the equivalent of “finding that horta”! So maybe I’m being too cautious.
2:53 PM: She says this will “fundamentally change how we define life” and that we now have more information about what we’re looking for when we explore the universe.
2:56 PM: Steve Benner is wrapping up by talking about experiments to definitively prove these results. This speaks to how science proceeds: the evidence is compelling, but not yet direct. You get the same sort of thing with, say, the discovery/undiscovery/maybe-discovery of the planet Gliese 581g. The standards of proof are different in different scientific community, so it takes some time for a discovery to be confirmed in a settled sense.
2:58 PM: So, now I’m going to speculate a bit. One thing we’re on the verge of being able to do is to characterize the atmospheres of extrasolar planets. That data goes a long way to showing us the chemistry on the planet, and therefore, if we find a larger suite of chemical possibilities for organic life, we may be able to put entirely new categories of alien planetary environment into the “could have life on it” bucket.
2:59 PM: Now, once you can do this, and once you begin to get hard data on the numbers of different kinds of planets that are out there, average size, average composition, etc., you begin to be able to make broad statements about how many extrasolar planets are habitable.
3:02 PM: The further step is that once we’ve figured out the steps that can take a prebiotic chemical soup to a living state—once we know how life began, which we will figure out—we now, with this finding, have an extra new set of questions to ask: how easy/difficult is it for life with other chemistries to evolve? How many variations are there? What are the biogenetic pathways for each type?
Match up this data with the data about what kinds of planets there are and which chemistries are available, and we will be able to give hard numbers about the proportion of planets in the universe that must be inhabited by some kind of life.
3:03 PM: This is a statistical game, but it’s a pretty solid one in the sense that you’d have to come up with, well, science-fictional explanations as to why these planets wouldn’t have life on them, once you’ve fully characterized the chemstry, insolation, duration, etc. for a large sample of worlds.
3:05 PM: So, the ultimate result is, we may be able to say at some point—without having to visit any other solar systems—that yes, 10% (or some such number) of the planets in our galaxy have life, out of which seven percent are carbon-based like ours, one percent use arsenic exclusively in their chemistry, one percent use this that or the other more exotic chemistries. Simply because we’ll know the percentages and probabilities for all these things.
3:07 PM: This does not—yet—answer the questions of how much multicellular life there is, how many intelligent species etc., because those questions emerge at a different level and probably can’t be answered by knowing the basic chemistry of a world. Sadly, we may still have to go out there and look to find the answers for some questions. But it may be surprising just how much we’ll be able to know without leaving home.
Well, the conference is over, and now the punditry begins! Thanks for following along, and I hope you had fun!
Karl Schroeder has published seven novels through Tor Books. He divides his time between writing science fiction and consulting in the area of technology foresight. He is currently finishing a Masters degree in Strategic Foresight and Innovation. Karl lives in Toronto with his wife and daughter, and a small menagerie.
