Well it looks like our rather bold assertion that NASA had found fossils on Mars was a trifle inaccurate. And, as we thought about it a bit more, we realized that it would be impossible to deduce from mere photographs alone, the true nature of anything that we were seeing in the raw images being radioed back to Earth from the Curiosity rover traversing Yellowknife Bay in Gale Crater – no matter how awesome the images looked. And we realized what a cheap way it was to get people to visit our website! Ha ha! Got you! Well, maybe a few dozen of you, anyway… it didn’t work too well, actually. We really did believe that those photos were something quite extraordinary, though. Well, they weren’t.
Today, NASA’s Mars Science Laboratory team held another very interesting teleconference to describe their latest discoveries on Mars – but they weren’t primarily interested in our “barnacles” – which turn out to be spherical concretions called “spherules” like the ones discovered by the Spirit and Opportunity rovers years ago, but with a different mineral composition.
No, today, the NASA scientists were more interested in describing deposits of calcium minerals deposited in fissures all over an area they have named “John Klein”, in tribute to the former deputy project manager of the MSL who tragically passed away in 2011.
We saw these things before, and they intrigued us as well. But they definitely looked more inorganic than the “barnacles” we thought we’d spotted. Which only goes to show what we know about Mars geology!
Both of these features – our non-barnacles and the fissures or “veins” of whitish minerals, are described as providing strong evidence of the precipitation of minerals from water. It’s a sign that, not only was there water flowing for unknown periods of time here in Gale Crater, but that these minerals that were deposited in these fissures came from somewhere else, transported by that water after the rock formed and cracked.
These veins were blasted by Curiosity’s laser and analyzed for their chemical content. It turns out that they are composed of “a calcium-bearing mineral”.
This photo shows a sort of side-view of one of the “veins” of this calcium-bearing mineral. It’s got an interesting “cauliflower-like” appearance:
This is cool stuff. But what does it all mean? Is this in any way proof that life existed on Mars? When will scientists be able to make an announcement as world-shaking as that?
The answer, we found, is that they are not likely to make such an announcement. In the previous MSL press conference, held at the American Geophysical Union’s Fall Conference in San Francisco December 3-7, 2012 – you know, the one at which the NASA team was supposed to make a world- historic announcement of some sort, but didn’t – Drs. John Grotzinger and Paul Mahaffy explained why it’s not likely that any one discovery is going to provide that type of a moment – because scientific inquiry simply doesn’t proceed in that way.
These remarks are somewhat lengthy, but they are so important for people to understand if they don’t want to keep jumping to ridiculous conclusions like we tricked ourselves into making this past week. It will not be the results of a single experiment that will lead to these big, overarching discoveries, but the sum total of a large series of experiments made by the entire science payload of Curiosity that will allow the science team to amass enough compelling evidence to make well-founded assertions about such things as whether or not signs of ancient life on Mars have been discovered. We learned so much from these remarks that we took the time to produce a transcript of the comments made by the two scientists at the AGU meeting, which we present to you with no further adieu. Science proceeds “at the pace of science” as Dr. Grotzinger says; it’s a slow, methodical and careful process designed to obtain real rather than imaginary results. So be patient! We wish we had seen this video before we wrote that last article! Enjoy!
Excerpt from John Grotzinger, Paul Mahaffy remarks at AGU Conference, San Francisco, CA, 3 December, 2012
00:27:50 “OK, so now I want to move on to a somewhat different subject that we call our ‘Three Months of Terror’. Everybody’s seen that ‘blue-shirt moment’ where everybody was jumping up and down celebrating the successful “EDL” [entry, descent and landing – ed.] system. Ours really isn’t so much ‘three months of terror’ as it is ‘three months of tension’. Every day we turn on an instrument; we do the electrical baseline check – it looks like it’s gonna work, but you don’t really know what it’s gonna work until it’s actually done a measurement. And then once you’ve done the measurement, you wonder how well it’s done compared to all the calibration and baseline testing that you’ve done before you launched the spacecraft. And so, each day we go through that; and as we turn these on – as one of our team members from Texas decided to call them – we have a ‘hootin’ and hollerin’ moment’; and everybody’s jumpin’ up and down in the science team and we get all excited about that.
“But in the end, what basically happens, and with the SAM [Sample Analysis at Mars – ed.] instrument in particular… SAM just comes last. It’s at the end of the sample processing chain; it’s also an extremely complicated instrument – it’s practically its own mission… and when it works for the first time we have a ‘hootin’ and hollerin’ moment’; but when it works for the second time, you get something that all scientists live by, which is a ‘repeat analysis’. You see that what you saw the first time is probably not going to go away. And then when you do the third sample and the configuration is pretty much the same it was the first time, you believe maybe this just might be one for the history books, that this is going to stand the time of test [sic] as a legitimate analysis on the surface of Mars. That’s basically where we were at with that excitement by the Science Team.
“So the nature of scientific discovery, especially in this business, is also very important. We live by multiple working hypotheses: as Paul mentioned, even though his instrument detected organic compounds, first of all we have to demonstrate that they’re indigenous to Mars. Then after that, we can engage in the question about whether they represent the background fall of cosmic materials that are organic in composition that fall on the surface of every terrestrial planet; and then after that we can begin into the more complex questions of whether or not this might be some type of a biological material. But that’s well down the road for us to get to.
“And, finally: serendipity. As any of us that have worked on the Earth understand: on a planet that is teeming with life, you can go out into rocks that are billions of years old, and the probability of finding something that is actually a sign of life – or even something as simple as an organic material – those discoveries are so rare that every time we find one it makes it into ‘Science’ and ‘Nature’ [universally respected peer reviewed journals – ed.]. Every new discovery… new occurrence is actually a major discovery. So we have to take our time, and it’s gonna take a bit of luck; but it is serendipity because we’re gonna think it through well ahead of time and go about this exploration in the most intelligent way that we can, using all of our instruments. What this mission about [sic] is integrated science; there’s not going to be one single moment when we all stand up and, on the basis of a single measurement have a ‘halleluja moment’. What it’s gonna take is everything that you heard by my colleagues and all the other P.I.s [principal investigators – ed.] that build all their instruments, we’re gonna pull it all together and we’re gonna take our time, and then after that if we’ve found something significant, we’ll be happy to report that.
“So finally, then: where are we headed? Well, at this point, basically, our car is ready to go. This is a car that comes with a ten-thousand-page user manual that we also have to write as we read it; and, you know, that’s where the patience comes in. But we’re getting closer; we’re getting ready to go here now; we have one major test ahead of us which is the drilling; and we hope to do that and get started on that before the holidays begin; and then sometime early next year we’re gonna pack it up and start driving towards Mt. Sharp, which is the reason we picked this site; and it has what, from orbit, looked like a lot of materials that we’re interested in. So we’re gonna load up the car with the science team, uh, you know… we’ve been at the gas station; we’ve gassed it up, checked the oil, uh, you know, we’re gonna kick the tires around a little bit but then we’re ready for our trip and that’s when our science mission of exploration really gets into full gear.”
[Questions from audience:]
Q: “Hi, I’m Alex Witze with Science News for Dr. Grotzinger: Can you just take us through how you go about figuring out whether these organics are indigenous to Mars or not? Just [employing? in boring?] chemistry detail.”
A: [Grotzinger]: “I’ll pass that one to Paul, but lemme just first reiterate the sort of ‘high level’ approach before Paul gets into more of the details of the chemistry. So: you make a measurement… and what we know is that the instrument is performing perfectly well; it’s very, very sensitive, so that we know that the instrument has detected simple organic molecules. Then after that, you have to do a series of tests to verify that the organics that you’ve measured have not come from Earth; and there are a number of ways that we could bring them with us. Remember: the reason that we chose the soil is to try to clean out all that hardware; and we cleaned it as best as we can on Earth but there’s no guarantees; and so we pass soil through it, shake it around, and then dump it out; take another gulp of soil, shake it around, dump it out. We try to get it as clean as we can, but it could be riding along with the hardware.
“And then, within the instrument itself: there’s always a little bit of stuff that comes along every instrument that we make on Earth. Even the most sensitive instruments carry materials along with them that you have to work through and understand their properties. And then after that, if we believe that it’s indigenous to Mars, then we have to go through a second level of triage, which is to say: ‘O.K.: it’s on Mars, but maybe it didn’t come from Mars; it could be a material that comes from the cosmos.’ A lot of primordial material, as we know… there’s carbonaceous chondrites that, in some cases, have quite complex organic molecules in them. And then after that then you begin by the context; and this is where the other instruments really come in and are so important because they’re the things that allow us to establish that maybe this isn’t something that actually came from space but this was actually something that formed in the environment, where the particles that make up the rock, where they were also accumulating… this was something that was being formed at the same time. And then you have a pathway to decide whether or not those formation pathways are abiotic or may be, in the end, biologic. And so there’s… as you can see, it’s a complicated decision pathway there and we have to explore each one systematically. But, I’ll turn it over to Paul.”
[Paul Mahaffy]: “Yeah… I mean… we’ve gone to great care with this mission to address the potential confusion that might be caused by terrestrial contamination. The materials that we brought to mars with us – we’ve done a lot of analysis to understand what kind of gases they release that we might see. We have a… what we call an ‘organic check material’: it’s a very pure vitreous silica glass; and we have that doped with [deliberately infused with – ed.] four very distinctive fluorocarbons. And so, if we’re looking for terrestrial stuff not just inside of SAM, but stuff that might come from the sample processing chain, what we can do in the end to avoid confusion is we can drill into one of those five organic check materials, run that sample through, and really treat that as a blank. And if we see the same stuff that we saw that we thought might be from Mars, from either some drilled rock or from soil, then we gotta say: ‘Hold the show a minute; this might be terrestrial stuff.’
“We do, even more routinely, we run blanks on… internal to SAM. For every experiment that we did here, we ran, essentially, a blank beforehand and looked… there’s very trace residual amounts, for example, of our derivitization agent; a very little bit of vapor shows up. We’ve seen some of this as we calibrated the instrument and so on. That’s actually great ’cause it shows us that the chromatography is working beautifully; but then if we see that when we have a solid sample in our cup, we go back to the blank and we said: ‘Oh, did we see that compound?’ And if the answer is ‘yes’, then it’s not from Mars.
“So, we’ll do all of those things; but what really helps also is the great flexibility of… you saw those bars [see figure 1 – ed.]. We can select different slices of evolved compounds to analyze with chromatography; we can have different temperature sequences on the sample, to release organics. And so all those things combine, really, to get a story on whether, uh… give us confidence if what we’re seeing is from Mars or not from Mars. So that work is ongoing.”
Q: “Emily Lakdawalla from the Planetary Society; this question is for Paul: I’m wondering how many of the compounds you’ve identified so far are ones that would be present as those compounds in the soil or if they’re all evolved from other compounds that are in the soil – and particularly interested in the chlorine compounds and the hydrogen sulfide.”
A: [Paul Mahaffy]: “Yeah… the question really relates to whether the compounds that we were showing might exist in the soil or whether they might be made as we do our experiment.
“It’s certainly very possible that there… in fact I would suggest very likely that they are made. As we heat the sample up, the simple chloro… single carbon compounds are being released at the temperature that this oxygen signal is coming up… potentially a calcium perchlorate. And so, with the high temperatures and chlorine being released, perhaps hydrogen chloride being released, it’s very reactive. And then it latches on to whatever carbon is there and forms these very simple compounds. So it’s very, very possible; I would say even likely that those compounds were not existing and we really made them as part of our experiment.”
[Transcript produced by Independent Workers Party of Chicago, 15 January 2013. All errors are our own.]