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Astrobiology in Houston: From Fossils to SETI

NASA’s teleconference from the Astrobiology Science Conference 2010 in Houston offered some interesting news about the discovery of microscopic fossils in gypsum from a period about six million years ago, when the Mediterranean Sea had all but dried up. Gypsum (calcium sulfate) precipitates out of sea water, and the find has implications for finding life on Mars, as I’ll explain in a moment.

What gave me a chuckle, though, was that after a discussion between four crack astrobiologists about life’s appearance on Earth and the best ways to search for it elsewhere, the first question from reporters was about Stephen Hawking’s views on aliens, and whether NASA had a policy on broadcasts to the stars.

The answer is clearly no, and NASA’s Mary Voytek noted the differences of opinion between the agency’s scientists on the issue, prompting Steven Squyres (of Mars rover fame) to note that our signals are already in play in the form of TV broadcasts and planetary radar signals. I’m thinking that Bill Schopf, who introduced the micro-fossil research, must have been bemused at having his work so quickly trumped. But Schopf (UCLA) and Jack Farmer (Arizona State) are onto something with implications for future sample return missions from Mars, so let’s put Hawking and aliens aside.

Micro-Fossils and Mars

It turns out that little work has been done with fossils preserved in gypsum because, as Schopf said, most scientists assumed that sulfate deposits undergo sedimentary changes that, as with carbonates, would crush such tiny fossils, which is why you don’t, for example, find micro-fossils preserved in limestone on Earth. But it turns out that Schopf and Farmer have found fossils in numerous deposits of gypsum. And the interesting follow-on is that Mars has huge areas at the north pole and the equatorial region near Valles Marineris where gypsum is common. The Opportunity rover, as a matter of fact, landed on a sulfate deposit.

Now that we know that a biosignature can be preserved in sulfates, we can think about mission implications. For gypsum is soft enough to trench with the robotic arm of a rover. It’s also soluble in water. Dissolve away the mineral material and you just might find clumps of organic material and perhaps fossils, all of which was fodder for Steve Squyres’ later discussion of a sequence of three Mars missions, incorporating a rover to collect samples, a lander that would pick them up, and an orbiter that would recover the samples and return the package to the Earth.

Asteroid Ice and Organics

Likewise of astrobiological note (and discussed briefly in the teleconference) were the new papers on the infrared spectra of the main-belt asteroid 24 Themis, which show a frosty coating of water ice and organics on the object. The ice was an unusual find, for at this distance (roughly 480 million kilometers from the Sun), ice is not stable and needs to be replenished. Themis is about 200 kilometers in diameter and it’s possible that replenishment is coming from within, which reminds us of scenarios in which incoming objects brought water to the early Earth.

This BBC story on the asteroid find quotes Andy Rivkin (Johns Hopkins) on the matter:

“Finding ice in Themis and the Themis family opens up the possibility that you might have brought in water from asteroids as well as comets; and that potentially allows a lot more water to be brought in and it also allows the isotopic compositions to work out the way we need them to, to match the Earth.”

That last reference is to the fact that Earth water does not match well with comets as the single origin. Adding icy asteroids to the mix could resolve the complication. For more on this, see Campins et al., “Water ice and organics on the surface of the asteroid 24 Themis,” Nature 464 (29 April 2010), pp. 1320-1321 (abstract) and Rivkin and Emery, “Detection of ice and organics on an asteroidal surface,” Nature 464 (29 April 2010), pp. 1322-1323 (abstract).

SETI Takes the Stage

The Astrobiology Science Conference ends today with morning sessions on biosignatures and the quest for life on Mars. Two SETI sessions have been held to the afternoon, the final one much in the spirit of the Hawking debate that has been raging on the Net all this week. That session is titled “Global Engagement and Interstellar Message Construction.” Chaired by Frank Drake and Douglas Vakoch, it goes into the intricacies of communication between intelligent beings of entirely different evolutionary and cognitive histories. It’s good to see that Jim and Gregory Benford will be discussing their ideas on cost-optimized interstellar beacons — much debated in these pages — in the earlier SETI session. Check the AbSciCon2010 site for abstracts.

Claudio Maccone also called yesterday from Houston. He’s at AbSciCon 2010 with poster presentations on the uses of the Karhunen-Loève Transform in SETI, especially as they relate to fast-moving sources, and our ability to use the KLT in future space communications with our own probes. Maccone’s idea of a ‘radio bridge’ using the gravitational lenses of both the Sun and Alpha Centauri — enabling interstellar communications with no more power than a cell phone — should play well to this audience. For more on the KLT, see this earlier post, and check here for the radio bridge.


Comments on this entry are closed.

  • James M. Essig April 29, 2010, 10:02

    Hi Paul;

    It is nice to know that such large asteriods have water and organics on or on and within them. I am also happy that such large asteroids exist. At 200 kilometers accross, I did not previously know that they come in such large sizes.

    These asteroids may be excellent for minable materials including materials for use in large planetary revolving space stations.

    I can imagine that the organics could be fashioned into carbon-graphite fiber composite materials for use in space station construction.

    Since there are so many large asteroids, the asteroids could be partially hollowed out and used as fusion rocket powered space craft and sent out in droves all over the Milky Way Galaxy, even if M0/M1 values are close to one thus barely inabling the achievement of borderline relativistic velocities.

    Now if we find an additional nuclear force or somehow learn how to decompose protons into unbound quark states, the non-quark rest mass energy of the protons released would result in about 99% of the mass being converted into energy. This would enable relativistic velocities to be obtained even with M0/M1 values that are close to one. Such a mechanism has been discussed in science fiction as a mechanism for so called quark bombs.

    We can always hope for rest mass specific reactions with energy release greater than E = M[C EXP 2].

    Regardless, we know we have nuclear fusion and even many generation ships formed from partially evacuated large asteroids, with an optional minimagnetosphere such as with permanent magnets or electomagnets could shield the crew from cosmic rays.

    I am pleased that President Obama wants manned missions to near Earth asteroids. If we can mine asteroids for rare Earth or exotic elemental and isotopic materials, this would jump start our civilization into a truly interplanetary civilization, and then onward to other star systems in seemingly relatively short order.

  • UncleDan April 29, 2010, 10:10

    It seems to me that there was a HUGE jump between the discovery of Mars gypsum and the UK newspaper The Sun screaming LIFE FOUND from the headlines. There is a very serious problem with this in my opinion: every three weeks we hear about another discovery that proves life somewhere in the universe or almost-life and it’s always exaggerated or poorly interpreted by the media. I would be very sad to see that we really DID discover life somewhere, even a microbe – what would be one of the greatest discoveries in human history – and the general public yawned because (on top of a depressing, collective ignorance of all things astronomical), they’ve heard it so many times before. Astronomical groups really should move to publicly denounce BIG HEADLINE stories quickly, explaining them for what they are – ways to sell papers. If a greater effort was made to combat this, (let’s imagine a group of scientists/astronomers tasked with the job of rapid-response to media nonsense), some of these silly stories might be stopped.

    Another way to look at this is that the astronomical community should collectively realize what a tremendous discovery they are sitting on. Life WILL be discovered, either today or a hundred years from now. Think of it – what other group of people anywhere on this planet are sitting on such an unbelievable time bomb of information? (Those fighting the deadliest diseases qualify – imagine a cure for cancer or Alzheimer’s, and if God ever returns, I guess the religious leaders qualify :) )
    But when life is discovered, it WILL be one of the greatest discoveries ever and it should not be squandered by being lost in the hodgepodge of news stories about false alarms, supermodels, Hollywood trainwrecks and political upheavals.
    Just an idea, feel free to add to my suggestion. :)

  • Administrator April 29, 2010, 10:36

    Out of curiosity, what was The Sun‘s headline this morning? I almost hate to ask…

  • NS April 29, 2010, 14:28

    A Mars sample return mission sounds like a really difficult proposition.

    A poster here had the idea of sending a microscope to Mars. I wonder if that actually wouldn’t be a more practical alternative, at least in the nearer term?

  • UncleDan April 29, 2010, 15:41

    The Sun headline was:
    Nasa: Evidence of life on Mars

  • Chris T April 29, 2010, 15:43

    “The answer is clearly no, and NASA’s Mary Voytek noted the differences of opinion between the agency’s scientists on the issue, prompting Steven Squyres (of Mars rover fame) to note that our signals are already in play in the form of TV broadcasts and planetary radar signals.”

    Except this isn’t true, the signals are not focused and spread out to a point where they’re indistinguishable from background noise due to the inverse square law. This happens after only three or four light years for TV signals.


  • UncleDan April 29, 2010, 15:52

    I forgot to add, the Sun article originally indicated that there was a type of pond scum discovered, but of course reading the article, one makes the discovery that no, nothing of the sort was found at all. But at least they got you to read the article. NASA could stop this kind of stuff from being done to their press releases by opening the press release with the statement ‘We have not found life, but we have found the following chemicals (or precursors or whatever)…’ Granted, this may not stop some of the media outlets from putting up ridiculous headlines to draw readers, but it may stop a few.

  • stephen April 29, 2010, 15:54

    We could return samples from other planets, to a lab on the International Space Station. It’s easier to keep cross-contamination from occurring if the lab, and the samples, are isolated from Earth’s biosphere. Expanding the Space Station would have other benefits, too.

  • NS April 29, 2010, 17:01

    “the signals are not focused and spread out ”

    Yup, and there’ll be fewer of them and they’ll be harder to detect as communication gets more efficient (cable, spread spectrum). Probably the only leakage signals aliens (and we) have any chance of detecting are something like radar scans for missiles/asteroids, or messages sent to deep space probes or other planets.

  • Matt April 29, 2010, 23:15

    I find it ironic that water was discovered on an asteroid named Themis, since Themis was a Greek goddess of the sea.

  • andy April 30, 2010, 11:57

    Matt: as far as I am aware, Themis was a personification of natural laws. Are you getting confused with Thetis?

  • Athena Andreadis May 3, 2010, 12:15

    As a native Hellene, I have to note that Andy is correct. Details for the curious:

    Themis, the goddess of natural justice, was one of the children of Uranus and Gaia and the mother of the Moirae (Fates). Thetis was one of the Nereids (daughters of Nereus/Proteus and Dhorís, granddaughters of the great sea-goddess Tethys/Thálassa and her consort, Oceanus) and the mother of Achilles. Tethys and Themis were sisters, so that would make Thetis the niece of Themis.

  • Eniac May 8, 2010, 22:36

    Athena: Shouldn’t that be grandniece?