Microbialites on Mars: a fractal analysis of the - PowerPoint Presentation

1. Microbialites on Mars: a fractal analysis of the Athena’s microscopic imagesGiorgio Bianciardi (1), Vincenzo Rizzo (2), and Nicola Cantasano (3)1) Dpt. Medical Biotechnologies, University of Siena, Siena, Italy2) National Research Council - retired -, Via Repaci 22, Rende, Cosenza, Italy3) National Research Council, Institute for Agricultural and Forest Systems in the Mediterranean, Rende Research Unit, Cosenza, Italy

2. Stromatolites/Microbialites are a frequently named target of life-detection missions on Mars (McKay CP, J.Phys. France,2004; Jepsen SM et al., Astrobiology, 2007; Clarke JD, Stocker CR, Icarus, 2013)Microbialites, such as stromatolites, are the oldest evidence of life on Earth; they are rocks formed by microbial mats trapping, binding and/or precipitating mineralsFossil stromatolites that lived on the anoxic Earth 3.5 billion years agohttp://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/lifeform.htm

3. Stromatolites/Microbialites are an organization of primitive cyanobacteria intolarge structures, analogous to coral reefs. They grew in vast colonies. http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/lifeform.htm

4. A living stromatolite (La Brava lagoon, Chile)Microbialites can be identified through their mineral structures that results from the growth patterns of their constituent  bacteria . http://www.open.ac.uk/earth-research/tindle/AGT/AGT_Home_2010/RMS-Info-Stromatolite.htmlMicrospherules and filaments in a living stromatoliteat high magnification.Scanning Electron Microscope, 500 X. M.E. Farias.

5. A fossil stromatolite (Minnesota, USA) The microspherules and filaments at the same magnification (X30) and resolution of the Athena camera aboard of the Martian rovers . Microspherules and filaments in the fossil stromatolite (X 30). Precambrian stromatolite (Banded Iron Formation type, Minnesota, USA, James St. John Collection), that lived billion years ago in an anoxic Earth (as Mars today).

6. Are there fossil stromatolites/ microbialites/ on Mars?that lived perhaps billion years ago, when liquid water was extensively present on the Red Planet?

7. 1) Rizzo and Cantasano in 2009 claimed the presence of microstructures that resembled stromatolites/microbialites in the Opportunity Rover images atvisual inspection of the Athena imagesRizzo, V., Cantasano, N., “Possibile organosedimentary structures on Mars”, International Journal of Astrobiology, Vol. 8, No. 4, 2009, pp. 267-2802) Wagstaff and Corsetti in 2010 wrote on the absence of stromatolites in the Opportunity images, analyzing 4 Martian photos at macro levelWagstaff, K.L., Corsetti, F.A., “An evaluation of information-theoretic methods for detecting structural microbial biosignatures”, Astrobiology, Vol. 10, No. 4, 2010, 363-379

8. To solve the problem, we have performed a quantitative morphometric approach of the microstructures present inthe stromatolites and other microbialites, Earth > comparing them with the microstructures present in the outcrops photographed byOpportunity and Spirit Rovers, Mars >

9. at the same level of magnification, resolution and acutance than the Martian images.. EARTH MARS

10. SamplesMicrobialites mages were collected by us at museums or catched all over the WEB (n=20 > 45 samplings, corresponding to about 25,000 terrestrial microstructures analyzed)or selected from the Athena Martian images (Opportunity and Spirit Rovers) (n=43 > 95 samplings, corresponding to about 25,000 Martian microstructures analyzed).

11. Image analysis The contours present in the terrestrial and Martian images were automatically extracted from the images and converted to single pixel outlines by a canny-edge filter

12. Fractal analysis A fractal analysis was performedevaluating on the terrestrial or Martian images:- Geometric complexities at low andhigh scales- Information dimensions (entropy)at low and high scales- Algorithmic complexity (Lempel-Ziv index ,“randomness”)- Fractal dimension of the minimum path (tortuosity)- Maximum diameterMinimum diameter analyzing 25 000 terrestrial and 25 000 Martian microstructures

13. Geometric complexity To evaluate the geometric complexity of the patterns, the local fractal dimension was measured using the box-counting algorithm. Resulting our texture multifractals, as identified by the two straight lines on the log-log plot, the algorithm was applied for the two regions: 200-10 pixels = 2 mm - 0.1 mm and 10-5 pixels = 0.1mm - 0.05 mm. Briefly, each image was covered by a net of L square boxes and the number of boxes containing any part of the outline Nb(L) was counted. The slope of the log-log plot of Nb(L) vs. 1/L represented the fractal dimension of the distribution. The existence of log-log straight lines (p<0.001) justified the use of the fractal analysis, applied here as a tool to obtain the morphometric indexes. The method was validated by measuring computer-generated Euclidean and fractal shapes of known fractal dimensions (Circumference = -0.7%; Square = +0.4%; Triadic Koch island = -0.9%; Sierpinski’s Triangle = -1.5%)EntropyTo evaluate the information (entropy) present in the patterns, information dimension, D1, a robust estimate from a finite amount of data that gives the probability of finding a point in the image, was calculated. The set was covered with boxes of linear size, d, from 200 to 10 pixels and from 10 to 5 pixels as above, keeping track of the mass, mi (the amount of pixels) in each box, and the information entropy I(d) from the summation of the number of points in the i-th box divided by the total number of points in the set multiplied for its logarithm was measured. The slope of the log-log plot of Information entropy vs. 1/box side length represented the information dimension of the distribution. The method was validated by measuring computer generated Euclidean and fractal shapes of known information dimensions. The existence of log-log straight lines (p<0.001) justified the use of the fractal analysis, applied here as a tool to obtain the morphometric index.

14. Algorithmic complexity (L-Z, randomness) Relative Lempel-Ziv, L-Z, values were calculated according to the Kaspar and Schuster algorithm [27] using the Chaos Data Analyzer version 2.1 software package (CDA Pro, Academic Software Library, North Carolina State University, USA). Briefly, patterns of the original image were transformed into 16,732 points containing one dimensional vector, where each datum point was converted into a single binary digit according to whether the design is touched (=1) or not (= 0). Relative L-Z values is close to 0 for a deterministic equation, close to 1 for totally destructured random phenomena. Fractal dimension of the minimun path (Dmin, tortuosity)Tortuosity, or the fractal dimension of the minimum path, Dmin, was computed for each cluster present in the image from the power law Ic = rDmin , where Dmin is the exponent that governs the dependence of the minimum path length between two points (Ic) on the Pythagorean distance r between them in a fractal random material. To obtain Dmin, the maximum diameter and the half perimeter of the microstructures present in the textures were measured using an automated procedure (Image Pro Plus software, Media Cybernetics, USA). For each image 100-500 microstructures were measured. The slope of the log-log plot (maximum diameter vs. perimeter) represented Dmin. The existence of a log-log straight line (p<0.001) justified the use of the fractal analysis in order to obtain the morphometric index. The method was validated with the original one by Hermann and Stanley [28] with a maximum shift of ± 3%.Minimum and maximum diametersMinimum and maximum diameter of the microspherules /intertwined filaments (Earth and Mars) were automatically measured by Image Pro Plus software (Media Cybernetics, USA)

15. Results (1) Amplified image selected samplings, from Earth (biogenic stromato-lites and other microbialites) as well from Mars (images photographed by Athena camera, Opportunity and Spirit rovers), reveal: a continuum pattern of micro-spherules aggregations, dimen-sions of about 0.1 mm – 0.3 mm; 2) intertwined filaments of microspherules

16. Results (2) The morphometric analysis reveals that both the textures, from biogenic microbialites (Earth) and from selected rover images (Mars), present a multifractal aspect (2 lines in the log-log plots): the texture as a whole (200 - 10 pixels, corresponding to 2 mm - 0.1 mm)and the microstructure inside the microspherules and the inter-twined filaments of microspherules (10-5 pixels, corresponding to 0.1 mm – 0.05 mm)

17. Results (3) While, interestingly, abiogenic pseudostromatolites, and other abiogenic microspherules-containing minerals (Earth) synthetic stromatolites, amethyst geode,alabaster, chalcedony, malachite, siltstonespresent a simple fractal aspect (1 line in the log-log plot)

18. Results (4): Opportunity Rover- Meridiani planum The morphometric analysis of the Athena images, Opportunity rover, reveals1)the remarkable similarity between fractal indexes of biogenic microbialites (Earth) and Athena selected images (Mars): the probability of this occurring by chance is less than 1/28, p<0.004. 2) While, abiogenic pseudostromatolites have morphometric indexes statistically different from the ones of biogenic stromatolites or Martian microstructures (a more disordered/random structure)Published on IJASS, 30th December 2014:I nt ’l J. of Aeronautical & Space Sci. 15(4), 419–433 (2014), Opportunity Rover’s image analysis: Microbialites on Mars?, Bianciardi G, Rizzo V, Cantasano N.

19. Results (5): Spirit Rover – Gusev crater-on the other side of the planet The morphometric indexes of the Athena images obtained by Spirit rover, analyzing 10,000 microstructures, once again, reveal fractal parameters that are overlapping the ones of terrestrial biogenic microbialites. The probability of this occurring by chance is less than 1/28 (p<0.004), also at Spirit location.

20. Conclusion (1) Microtexture indexes, multifractality and diameter values present in biogenic stromatolites and other microbialites , fossil and living samples, are extremely similar to those present in the Martian images taken by the Opportunity and Spirit Mars Rovers. The probability of this occurring by chance is less than 1/28 (p<0.004). While abiogenic pseudostromatolites morphometric indexes differ (more random, simple fractality).

21. Conclusion (2): “Curiosity” Seven months ago, Nora Noffke, at macro level visual inspection , hypothesized the presence of microbialites at the Curiosity landing site (Gale crater)Ancient Sedimentary Structures in the <3.7 Ga Gillespie Lake Member, Mars, That Resemble Macroscopic Morphology, Spatial Associations, and Temporal Succession in Terrestrial Microbialites Noffke Nora. Astrobiology. February 2015, 15(2): 169-192. Now, we are starting to study those Curiosity outcroppings:the characteristics microstructures evidenced by us are present > showing the same morphometric indexes previous described(Opportunity and Spirit rovers) The evidence of the presence of microbialites in the Martian outcroppings is clear: unicellular life was widespread on the ancient Mars.