The Martian Guessing Game is in full swing. Triggered by an interview with Mars Curiosity Rover P.I. John Grotzinger, NPR's Joe Palca reported on Tuesday (11/20/2012) that a very exciting result has been returned from the Sample Analysis at Mars instruments (SAM), the onboard miniature chemistry laboratory. With such loaded teasers as "the analysis shows something earthshaking", "one for the history books" and the data "are looking real good", how can any close observer of the mission not fantasize about the Holy Grail of space exploration... the first sign of extraterrestrial life? Is it real this time?
To today's implication of stunning news, I say let's all join in the fun of guessing what they found... but there is a ground rule if you want to play with the Big Nerds; speculations must be grounded with facts. For example, you can't predict the scientists spotted a herd of Martian dinosaurs grazing on the carbon-fiber shrubs, because 1) the results came from the chemistry lab, not one of the 17 onboard cameras, 2) dinosaur herds have never been spotted by decades of orbiter recon, and 3) dinosaurs are much too large to fit in the sample collector. While the sparse data we have seen may not disprove that herd of dinosaurs is just over the next hill, we must confine the guesses to what the data actually tell us.
The SAM package is a technical marvel to behold, but the fact that it was conceived, built, rocketed to Gale Crater, and now roams the planet powered by plutonium-238 should elevate this and the whole rover to be celebrated among the greatest manmade wonders ever. The pyramids and Taj Mahal?... large rock tombs. Curiosity and our other space robots? ... nothing less than the pinnacle of mankind's reach. But what is so special about this very expensive box full of wires, gears, magnets and lasers? There are three devices -- a mass spectrometer, gas chromatograph, and tunable laser spectrometer -- which work in a complimentary way to measure chemical elements and compounds, and their isotopic ratios, to great accuracy.
(N.B.G. [nota bene, youse geeks!]: please follow this link for a basic overview: http://mars.jpl.nasa.gov/msl/mission/instruments/spectrometers/sam/, or if you're into the hard stuff, start here: http://msl-scicorner.jpl.nasa.gov/Instruments/SAM/)
SAM feeds on Mars, literally swallowing powdered rock and sucking in atmospheric gases. Here we have established some important constraints on what so excites Dr. Grotzinger, something in the rocks or dust surface or something in the Martian "air". There was something else to be found in the instruments, however, some things not so unexpected: contaminants from Earth. Part of the carefully planned commissioning phase of the rover science packages is to rinse out or otherwise account for whatever chemicals got into the sampling system, and this has taken the majority of the time since landing in August. That concluded without any technical issues, it is time to taste Mars with a cleansed and calibrated palate.
The planetary explorer's mantra is "follow the water", with the understanding that life does not exist without it. Did Curiosity find water on Mars? That would hardly be news: water has been well documented there, from ancient rivers to frozen ice caps and seasonal dampened soils. The Phoenix Lander even touched ice, melting it with its landing rockets. If the newest rover found water ice, you would expect a muffled yawn.
Atmospheric methane, a simple single carbon molecule, is often, but not exclusively, a sign of microbial life. Methane has been detected on Mars using remote sensors and after "follow the water" is "follow the methane". The Tunable Laser Spectrometer in SAM is specifically designed to detect methane at parts per million. The first results were announced last month... no methane within the limits of detection. Not a final blow to life on Mars, but certainly a disappointment for some ET enthusiasts.
That leaves something exciting in the powdered Martian dust (Curiosity has not drilled into rocks yet). Using another instrument on the rover, the Chemistry and Mineralogy (CheMin) experiment which is not part of the SAM package, x-rays passed though the powder revealed crystalline feldspar, pyroxenes, olivine mixed with some non-crystalline material. Nothing unexpected here, just minerals you would expect from a nearby Martian volcano. Passing the same material through SAM should characterize the amorphous non-crystalline portion. The gas chromatograph, in concert with the mass spectrometer, are designed to find organic compounds, i.e. carbon molecules more complex than methane. Complex carbon chemistry is another red flag for life... but, again, not exclusively. Carbon is an abundant element made by exploding stars, radio telescopes can see carbon compounds suspended in interstellar space, and carbon compounds are routinely extracted from fresh meteorites. Most interesting to note is that organic compounds are found in most of the known Martian meteorites discovered on Earth. These carbon compounds, while determined to be from Mars and not terrestrial contamination, were formed as carbon trapped inside molten magma and not from living organisms.
We know what the scientists are looking for, we know which instruments have seen (or not seen) some things, and we know what they might measure. OK, I am now ready to stick my neck out with a guess. First, let's eliminate dinosaurs, water (ice or liquid), methane and simple organic compounds already known from Martian meteors. I think they found long chain carbon molecules, with cyclic and polycyclic organics... and carbon-nitrogen compounds such as amino acids. Please note: this discovery of simple organics would not be proof of life, and the magnitude of this discovery might be measured by the size of the organic molecules. I think any aliphatic carbon chain longer than 6 carbons would knock their socks off.
... or I could be totally wrong, running wild with conjecture, with too few facts and too much wishful thinking. I'm biased toward extraterrestrial life existing somewhere.... there, I said it and I'm not ashamed.
Can anything bad come from playing the guessing game? Absolutely -- in fact, I expect you to have already encountered the sugar rush of mass media hype before reading this article. By the end of the week (sooner with slow news days) the mainstream media will again resemble a pack of ill-bred dogs, running through the halls of JPL, tracking mud into the labs, leaving doorknobs sloppy with drool, sniffing at real data and each other's butts before running outside to chase the next squirrel. The story will have been covered, the mission declared a failure for not finding little green men (despite how much the rover cost!) and, of course, some fluff about how very adorable but confusing scientists are.
That is, unless this is one for the history books....
Pete Goldie holds a Ph.D. and 2 other graduate degrees from “old East Coast universities.” “I merely wish it known that I am a licensed ceramic tile & natural stone contractor and everything I write about space science is not only freely available but eagerly disseminated by federal government agencies through the judicious expenditure of income tax revenue.”
