Rosetta catches dusty organics

Rosetta’s dust-analysing COSIMA (COmetary Secondary Ion Mass Analyser) instrument has made the first unambiguous detection of solid organic matter in the dust particles ejected by Comet 67P/Churyumov-Gerasimenko, in the form of complex carbon-bearing molecules.

While organics had already been detected in situ on the comet’s surface by instruments on-board Philae and from orbit by Rosetta’s ROSINA , those were both in the form of gases resulting from the sublimation of ices. By contrast, COSIMA has made its detections in solid dust.

Their presence was only ever hinted at in previous comet missions, which flew by their targets at high speed and, as a result, disrupted the particles, making characterisation challenging. But Rosetta is orbiting Comet 67P/C-G and can catch dust particles moving at low speed.

Optical image of two of the dust grains collected and analysed by COSIMA, named Kenneth and Juliette, which show the signature of carbon-based organics. They were collected in May and October 2015 respectively.

Optical image of two of the dust grains collected and analysed by COSIMA, named Kenneth and Juliette, which show the signature of carbon-based organics. They were collected in May and October 2015 respectively. Credits: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S/ Fray et al (2016)

“Our analysis reveals carbon in a far more complex form than expected,” remarked Hervé Cottin, one of the authors of the paper reporting the result that is published in Nature today. “It is so complex, we can’t give it a proper formula or a name!”

The organic signatures of seven particles are presented in the paper, which the COSIMA team say are representative of the two hundred plus grains analysed so far.

The carbon is found to be mixed with other previously reported elements such as sodium, magnesium, aluminium, silicon, calcium and iron. It is bound in very large macromolecular compounds similar to the insoluble organic matter found in carbonaceous chondrite meteorites that have fallen to Earth, but with a major difference: there is much more hydrogen found in the comet’s samples than in meteorites.

But as this kind of meteorite is associated with reasonably well-processed parent bodies such as asteroids, it is reasonable to assume that they lost their hydrogen due to heating. By contrast, comets must have avoided such significant heating to retain their hydrogen, and therefore must contain more primitive material.

Comparing the spectra determined by COSIMA for the dust particles Kenneth and Juliette with the composition of organic matter (Insoluble Organic Matter, IOM) in the Murchison chondritic meteorite. The detections of hydrogen (H), Sodium (Na), Silicon (Si) and Iron (Fe) are also indicated. The red spectra are measured on the cometary particles while the black ones are measured next to them, and are representative of the instrument itself. Credits: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S/ Fray et al (2016)

Comparing the spectra determined by COSIMA for the dust particles Kenneth and Juliette with the composition of organic matter (Insoluble Organic Matter, IOM) in the Murchison chondritic meteorite. The detections of hydrogen (H), Sodium (Na), Silicon (Si) and Iron (Fe) are also indicated. The red spectra are measured on the cometary particles while the black ones are measured next to them, and are representative of the instrument itself. Credits: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S/ Fray et al (2016)

From analyses of meteorites and laboratory simulations, the team was also expecting to identify a wide diversity of organic material in Comet 67P/C-G, ranging from very small molecules to heavy (or ‘high molecular weight’) organics.

Although Rosetta’s ROSINA and Philae’s PTOLEMY and COSAC instruments detected numerous low-molecular weight volatile organic molecules, COSIMA only saw very large carbon-bearing macromolecules in the dust particles, with nothing in between. This suggests potentially different sources for the lightweight volatile and heavier refractory carbonaceous material detected in the comet.

“Although we cannot know if the organics seen in these dust particles were created in the interstellar medium before the protoplanetary nebula came together, or in the protoplanetary disk during early Solar System formation, COSIMA’s dust grains are certainly witnesses to early formation processes, including that of the comet itself,” says Nicolas Fray, first author of the paper.

“These particles have remained pristine and untouched for billions of years until they were released in the days or weeks before being ‘caught’ by COSIMA,” adds Martin Hilchenbach, principal investigator of COSIMA. “The results add to the growing picture that Comet 67P/C-G contains some of the most primitive material from our Solar System’s early history.”

High molecular weight organic matter in the particles of comet 67P/Churyumov-Gerasimenko” by N. Fray et al is published in Nature.

 

Comments

21 Comments

  • logan says:

    “…COSIMA only saw very large carbon-bearing macromolecules in the dust particles, with nothing in between.”

    From Flying StarDust to Grilling Star-Tanned, so intriguing 😀

    “…there is no detection by COSIMA of smaller molecules that would be an equivalent to the soluble organic matter found in carbonaceous chondrites (for example, carboxylic acids, aliphatic or polycyclic aromatic hydrocarbons, and amino acids)…”

    Whatever intermediate organics identity, that along the eons transmuted into this highly meteorized, insoluble organic material will remain ‘incógnito’, with a new library of questions, for our future Explorers.

    Doesn’t this Great Paper add to ‘cocooned’ and bi-directional, and multi-staged accretion concepts?

    Congratulations to: Nicolas Fray, Anaïs Bardyn, Hervé Cottin, Kathrin Altwegg and allies. Fully Open and carefully Out-Reach curated.

    Thanks to You also Emily, on your very accurate journaling.

  • logan says:

    Could carbonaceous chondrites be fragmentary material of transient bodies reaching a 3-phase threshold?

    This is totally speculative.

  • A.Cooper says:

    Cue a bun fight over ‘sublimely pristine’ vs ‘given an absolute pasting by stretch’…

    • ianw16 says:

      Quite frankly, I’m sick of hearing about ‘stretch’, and I suspect I’m not the only one.
      As Gerald said some time back; to paraphrase- “write it up or this will go on endlessly.” Never a truer word spoken.

      By the way, as I commented elsewhere the other day, you really need to remove this from your blog:
      https://scute1133site.wordpress.com/2016/09/02/part-60-150m-massif-slides-250m-on-maat/

      You are comparing two different areas!
      http://www.imagebam.com/image/49c5fb503074015

      • A. Cooper says:

        Hi ianw16

        I’m not sure why you’re reiterating your wish that Marco and I should do a paper on stretch theory after I made this comment to you on 5th September:

        http://blogs.esa.int/rosetta/2016/09/02/video-report-the-end-is-in-sight/#comment-603713

        It clearly states that we’re having difficulty in getting endorsement to write a paper. The only option left open to us is to draw attention to our ideas here on the Rosetta blog. Repeating the demand for us to write a paper and doing so in such an irritated tone is just just laughing in our face when all we’re trying to do is get the science right.

        Regarding Gerald’s comment, a year ago now, asking us to write a paper, it’s telling that you remember his comment but didn’t remember (or ever bother to read) my reply directly below it.

        Gerald’s comment:

        http://blogs.esa.int/rosetta/2015/09/28/how-rosettas-comet-got-its-shape/#comment-551999

        My reply (first 3 main paragraphs and last two; spin up calcs were in the middle):

        http://blogs.esa.int/rosetta/2015/09/28/how-rosettas-comet-got-its-shape/#comment-553840

        And since you were actively reading the threads at that time, perhaps you forgot or never read my reply to Dr. Massironi’s repudiation of stretch theory and suggestion we do a paper:

        http://blogs.esa.int/rosetta/2015/10/12/interpreting-images-more-on-how-the-comet-got-its-shape/#comment-558625

        which concludes with:

        “In conclusion, I don’t need to write a paper. Stretch theory doesn’t need to be proven in peer review before it’s entertained as one of three competing scenarios instead of the two you mention. That would mean jumping to your stage 4 in order to go back and compete with the other two at stage 2 or 3. That’s neither fair nor logical.”
        (In other words, putting the cart before the horse).

        Your objection to the gif showing two different areas is addressed in this link (posted yesterday and through moderation this morning with your comment above so you wouldn’t have seen it).

        http://blogs.esa.int/rosetta/2016/08/25/rosetta-captures-comet-outburst/#comment-603857

        As for your other objections to various aspects of stretch, I reply to them all showing why those objections don’t hold water. You don’t take the trouble to reply to them and yet find time to level the same objections at a later date. You haven’t even replied to my comment that points this out from 6th September:

        http://blogs.esa.int/rosetta/2016/09/02/video-report-the-end-is-in-sight/#comment-603776

        And yet you find time to continue voicing your disdain for stretch in the comment above.

        That’s six comment links I’ve dug out. If it seems tedious to go through them, it’s not half as tedious as it was having to dig them out. But I had to in order to tie up the loose ends you’ve left in your wake as you forge ahead making the same objections that have already been addressed. You don’t have to tie them up but if you choose not to, please don’t keep making the same objections. It’s not good for other readers trying to assess stretch and it’s certainly not good for science.

        • ianw16 says:

          @A. Cooper,
          And in case Gerald’s comments in particular, and mine, are not making sense, then let me sum it up from my point of view:
          ‘Stretch’ is not a ‘theory’. Theories, in a scientific context, are propositions that have stood the test of time. This is nothing more than a hypothesis, with no proof. What you are claiming as proof is, to my eyes, and presumably Gerald’s, little more than pareidolia heaped upon wishful thinking. Where matches may actually be apparent, there are a number of explanations that seem far more likely, in my view. Extraordinary claims require extraordinary evidence. I simply don’t see it. If some of the scientists who read this blog thought that there was anything to it, then I’m sure it would have been taken up by now.
          Even if the paper isn’t peer reviewed, write it up anyway, in a concise fashion. Then all you have to do is link to it, instead of every thread turning into an advertisement for it.
          As I posted elsewhere, which won’t have shown up at the time of your comment, something like this ought to suffice:

          “Fission and reconfiguration of bilobate comets as
          revealed by 67P/Churyumov–Gerasimenko.”

          Hirabayashi, M., et al.

          http://www.nature.com/nature/journal/vaop/ncurrent/full/nature17670.html (free access).

          That is the sort of analysis I would expect to see for any putative mechanism. And it took less than 15 pages, including references and methods.

    • Marco Parigi says:

      Hi Ianw16,

      Thank you for your continuing engagement with a variety of themes. With regards to being “sick of stretch”, you are free to ignore anything on the Internet if you are sick of it. I certainly skim past almost all Electrical facets as I have no interest in them.

      The pristine or otherwise nature of complex organics is a very interesting question. Of course the Earth is full of high molecular weight organics, both artificially derived and in nature, so I am not sure why this would be evidence of pristineness, per se, as the processes involved with complex organics on this planet are on-going, and all Earth complex organics are heavily processed rather than pristine.

      I would like to get at least this thread back to being relevant to the post at hand. The post insists that the grains are pristine, but I am at a loss as to what dust particles we would expect from a heavily processed nucleus. It seems very arbitrary.

      • ianw16 says:

        So engage with the scientists, yes? Posting on here is proving nothing, is it? Not to me, anyway.

      • Marco Parigi says:

        Hi ianw16,

        The purpose of the comments section of this fantastic blog is to talk about the post that the comments are attached to. Yes, this can extend to the science and questions may or may not be relayed to the scientist concerned. Some people may be privy to the answers a scientist would give, some might point to a scientific paper or an FAQ page that answers the question, but the difficult questions will obviously start a comment thread debate from time to time. Other times, the difficult questions will just be left hanging, unanswered.

        The comments section are also the only forum “citizen scientists” can talk about their, for instance, 3D models (Matt Malmer et al) or ground based amateur telscope observations and respond to calls for contributions and so forth.

        However, I believe at some level we are all scientists. You Ian, are a scientist no matter your qualifications, and we all have a brain that can sort science from fiction in our own way, and/or follow logical and mathematical arguments that may back up or falsify scientific claims.

        So you engaging with me, I consider to be engaging with scientists in both directions. Most professional scientists ignore most ideas in the comments section, yes, but from time to time they will respond and engage also.

        Therefore, I am not trying to prove anything in the comments section, but this blog has certainly been the most engaging, and I feel every post that I link to is relevant to the post that I am linking from. Please say so if you think that is not the case.

        I also try to avoid repeating myself or what others have said, nor expect people to give up their valuable time to respond to everything that I question – However if there is one question I have for you is if you have a response to A Coopers critique of your critique regarding whether the Anuket Boulder has moved or not. You mentioned that you are still convinced that all the the evidence points to it not moving. A Cooper seems to me to have poked holes in the evidence that you demonstrated, yet you have not responded to that “poke”, but continue insisting the evidence is clear in the negative without reference to it.

  • Could the macromolecules be chemical fossils? If not, were they formed abiotically?

    • Marco Parigi says:

      Hi Wretch,

      I think the macromolecules are formed biologically. As Ianw16 is bound to point out – This is thought to be an extraordinary claim requiring extraordinary evidence.

      I believe that the assertion that they can form primordially is the extraordinary claim.

      • ianw16 says:

        @Marco,
        Do you mean the macromolecules which have already been detected in the ISM? Or are they down to space bugs too?

        “The molecules detected by this technique (rotational spectroscopy; my addition), which range in size up to 13 atoms, are overwhelmingly organic in nature.”

        Introduction: Astrochemistry
        http://pubs.acs.org/doi/abs/10.1021/cr400579y
        Herbst, E. & Yates, J.T.

        One of just many papers I could have quoted.

        • Marco Parigi says:

          Hi Ianw16,

          Yes, of course the Interstellar Medium organics must also originate from life. Where they are found does not say anything about how they are formed.

          Yes. I do read a lot of astrochemistry papers. I have not seen an experimental basis (compounds formed in a vacuum in microgravity unrelated to life) that are high molecular weight organics. Life is just assumed rare, and life outside Earth considered an “extraordinary claim”

          Not sure if the onboard lab in Rosetta can detect chirality of organics. I know Philae’s Ptolemy has that as a feature.

          This won’t tell us much more about origins, but it will be another indicator…

        • Kelly Duke says:

          Which conventional theorists predicted that huge abiotically formed organic molecules would populate the ISM before the existence of such ISM molecules was confirmed?

          So what makes you think these molecules formed abiotically rather than biotically?

        • logan says:

          Hi Ianw16. No access to the document, but:

          “… “It is so complex, we can’t give it a proper formula or a name.” Not expecting those to be polymerized tholins. Expecting [residual] composites beyond our limited imagination.

    • logan says:

      Haven’t read previous papers, me thinks primigenial here refers to core’s ice grains.

      Nothing prevents the interstellar medium from containing heavily processed material. If considering biochemistry as a continuum from chemistry [of the many other paths that could take], Then agreeing with you at NOT DISCARDING as an impossibility, life as some time window.

      • logan says:

        Life as We know it is the result of aeons of a continuum of trial and error. That’s just OUR ONLY version.

      • logan says:

        Errata: Clean interstellar space is tremendously unforgiving. To the point that atoms eventually loss most, or all of their electrons. I’m referring here to the ISM at Mother nebulae.

  • Kelly Duke says:

    Why has a post-biotic explanation for these huge organic compounds been discounted?

  • logan says:

    .On biosignatures: Pattern dislocation, both spacial and temporal could be a fine bet. Quasi-crystals a single bit more ‘alive’ than their crystalline similes, on this line of thought.

    This is fiction.

    • logan says:

      .If some life processes take centuries -millennia, could We image of biochemistry cycles on the million of years?

Comments are closed.