**4.1 Morphology**

The study was based on Mahli (Mars Hand Lens Imager), ChemCam and Mastacam images uploaded on NASA web site (https://mars.nasa.gov/msl/multimedia/raw-images), and especially those from the Sols range 750–1400. A selection of images (**Table 2**) was made which were considered particularly interesting and have been morphologically analyzed in detail by amplification and color/brightness/contrast modifications, in order to evaluate possible comparison to analogous terrestrial form of life. In particular, Mahli employs a macro lens color camera able to focus on targets at working distances of 2.1 cm to infinity, with a maximum resolution of about 14 μm/pixel. We have used a scale for Mahli images using the relation between motor count and the pixel dimension values provided by NASA and whose pixels are in the range from 20 μm to 30 μm. Consequently, the dimensions of microstructures analyzed in this article are, at least, about 10 time higher than image resolution.

**103**

*Life on Mars: Clues, Evidence or Proof? DOI: http://dx.doi.org/10.5772/intechopen.95531*

Carbon-chain molecules with 1 to 5 carbons

Alkylbenzenes/benzoate ion (C8H9/C7H5O−

*thiophenic, aromatic and aliphatic molecules in Mojave target.*

Toluene/tropylium ion (C7H8/C7H7

Methanethiol (CH4S) Dimethyl sulfide (C2H6S) Thiophene (C4H4S) Methylthiophenes (C5H6S) Benzothiophene (C8H6S)

**4.2 Morphometry**

**Table 1.**

Benzene (C6H6)

Chlorobenzene (C6H5Cl)

Naphthalene (C10H8)

*and algae*

(NIH), Bethesda, USA [42–44].

quoted were unreliable.

*4.2.1 Euclidean morphometry: comparison of "rice grains" with various crystals* 

*Carbon-containing compounds revealed by Sample Analysis at Mars (SAM) aboard of Curiosity rover:* 

)

+ )

The purpose of this section was to investigate quantitatively the features referred by NASA as light toned lozenge-shaped microstructures (**Figure 2**). This investigation determined, using a series of metrics, including degree of dispersion, variability in lengths and widths, length/width ratio, fit of lengths to a log-normal distribution, fit of orientations to a rectangular distribution, and morphological analysis, the similarity between the "rice grains" and various abiotic mineral deposits and terrestrial life forms. In particular: images of Gypsum and Jarosite crystals, an image of Feldspar phenocrysts, and a population of terrestrial *Euglena viridis* (O. F. Müller) Ehrenberg, 1830, (**Table 2**) were observed. These images were analyzed using 'Image J' software developed by the National Institute of Health

Each image was magnified to clearly reveal the objects of interest. Images were manipulated using brightness, contrast, sharpening and edge detection to optimize the appearance of the objects and to establish their boundaries. A grid of squares was then superimposed over each image to establish a number of sample fields. Each of the "rice grains", with at least 50% of its area within a sample field, was measured. Various relative measures based on degree of variation, ratios, fit to various distributions and proportions exhibiting a specific morphology, were used because scale measures were not always available for all images or those that were

The following data were obtained from each sample field containing "rice grains": (1) total number of profiles, (2) the maximum length of each profile in relative units, (3) the width of each profile taken at the midpoint, (4) the orientation of each profile, measured as the angle between the horizontal and a line drawn along the maximum length of the profile, (5) the proportion of the profiles which had a fusiform shape and (6) the proportion which exhibited a degree of flexibility or curvature relative to a straight line drawn connecting the two ends of the profile. A number of metrics based on the profiles were analyzed and compared: (1) spatial


#### **Table 1.**

*Carbon-containing compounds revealed by Sample Analysis at Mars (SAM) aboard of Curiosity rover: thiophenic, aromatic and aliphatic molecules in Mojave target.*

### **4.2 Morphometry**
