**4. Curiosity and SAM results**

The first chance for to this new approach occurred with the Curiosity mission (NASA, Mars Science Laboratory Press Kit, 2012), a rover of 900 kg that landed successfully on August 6, 2012 inside the Martian Gale crater (5.4°S 137.8°E) at a lower latitude than Viking (Cryse at 22,7°N and Utopia at 48,3°N), an ancient lake, with a layered mountain 5,000 m high in the center (the Mount Sharp). The task of Curiosity was to reach the mountain and to climb on it, in order to disclose the geological past of Mars, starting from the farter past (lower stratification) (**Figure 19**). The most interesting soils were found right at the base of Mount Sharp, where Curiosity encountered a dangerous expanse of dark sand (Bagnold Dunes), a long ridge rich of hematite (Vera Rubin Ridge), a clay-bearing unit (Glen Torridon), followed by Sulfur-rich uneven ground.

On January 1, 2018 (sol 1992) near the southern edge of the Vera Ruin Ridge, the Mars Hand Lens Imager (MAHLI) camera on Curiosity movable arm, pointed out a cluster of millimetric dark, stick-shaped features whose origin is uncertain. One possibility is that they are erosion-resistant bits of dark material from mineral veins cutting through rocks in this area (**Figures 20** and **21**).

But the morphological analogy with terrestrial fossil traces of life-substrate interactions is impressive [41]. Some studies even highlight occurrence, on Martian sediments, of widespread structures like the famous microspherules discovered by the Rovers Spirit and Opportunity, often organized into some higher-order settings (**Figure 22**). Such structures also occur on terrestrial stromatolites in a great variety

**Figure 19.** *The path of Curiosity inside the Gale crater, to reach the base of Mount Sharp.*

#### **Figure 20.**

*December 13, 2017 (sol 1903): Curiosity near the Vera Rubin Ridge, a formation very rich of hematite.*

of microscopic structures, such as voids, gas domes and layer deformations of microbial mats [42].

SAM (Sample Analysis at Mars) is a suite of instruments aimed at analyzing of soil samples on board of Curiosity (**Figure 23**).

It includes an improved and more sensitive (up to 100 times) version of the Viking GC MS [43] and a laser infrared spectrometer (TLS) [44] able to analyse any gaseous substance from both Martian atmosphere and GC–MS, with a sensitivity of 1 ppb (part per billion). The SAM works by accepting drilled or scooped Martian grit into a tiny cup made of quartz, that can be cooked in an oven up to 1100°C. Tiny puffs of helium gas move the gases from the sample cup into a MS (Mass Spectrometer), that sift through the resulting fumes for molecular signatures, directly (EGA, Evolved Gas Analysis) or after a previous separation inside one of 6 column GC (Gas Chromatographic) (**Figure 24**). There are 74 cups in a carousel: 59

are quartz tubes slated for "dry" chemistry, 9 are solvent cups, sealed with foil, contain solvents for 'wet' chemistry to tease out organic molecules, like amino acids and degraded fatty acids, that would otherwise resist vaporization; the last 6 are

*Examples of mesostructural parallels with occurrence of spherical bodies having similar shape and structure. On Mars, 'blueberries' could assume polycentric polispherules or concentric structures. Such parallels occur also for living colony of cyanobacteria (frame II), as polispherule and concentric structures and for stromatolites (the*

*January 1, 2018 (sol 1992): these enigmatic dark, stick-shaped features taken from the MAHALI camera on*

*board of Curiosity look alike terrestrial fossils of the Ordovician period.*

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

Among other capacities, the TLS [44], detecting the IR absorption band of CH4 at 3,27 micron, was aimed at confirming the existence and the seasonal cycle of methane discovered by terrestrial telescopes [45] and possibly confirmed by PFS

calibration cups (**Figure 25**).

*knot structure in the frame III.*

**Figure 21.**

**Figure 22.**

**151**

#### **Figure 21.**

*January 1, 2018 (sol 1992): these enigmatic dark, stick-shaped features taken from the MAHALI camera on board of Curiosity look alike terrestrial fossils of the Ordovician period.*

#### **Figure 22.**

of microscopic structures, such as voids, gas domes and layer deformations of

*December 13, 2017 (sol 1903): Curiosity near the Vera Rubin Ridge, a formation very rich of hematite.*

SAM (Sample Analysis at Mars) is a suite of instruments aimed at analyzing of

It includes an improved and more sensitive (up to 100 times) version of the Viking GC MS [43] and a laser infrared spectrometer (TLS) [44] able to analyse any gaseous substance from both Martian atmosphere and GC–MS, with a sensitivity of 1 ppb (part per billion). The SAM works by accepting drilled or scooped Martian grit into a tiny cup made of quartz, that can be cooked in an oven up to 1100°C. Tiny puffs of helium gas move the gases from the sample cup into a MS (Mass Spectrometer), that sift through the resulting fumes for molecular signatures, directly (EGA, Evolved Gas Analysis) or after a previous separation inside one of 6 column GC (Gas Chromatographic) (**Figure 24**). There are 74 cups in a carousel: 59

microbial mats [42].

**Figure 20.**

**150**

**Figure 19.**

*Solar System Planets and Exoplanets*

soil samples on board of Curiosity (**Figure 23**).

*The path of Curiosity inside the Gale crater, to reach the base of Mount Sharp.*

*Examples of mesostructural parallels with occurrence of spherical bodies having similar shape and structure. On Mars, 'blueberries' could assume polycentric polispherules or concentric structures. Such parallels occur also for living colony of cyanobacteria (frame II), as polispherule and concentric structures and for stromatolites (the knot structure in the frame III.*

are quartz tubes slated for "dry" chemistry, 9 are solvent cups, sealed with foil, contain solvents for 'wet' chemistry to tease out organic molecules, like amino acids and degraded fatty acids, that would otherwise resist vaporization; the last 6 are calibration cups (**Figure 25**).

Among other capacities, the TLS [44], detecting the IR absorption band of CH4 at 3,27 micron, was aimed at confirming the existence and the seasonal cycle of methane discovered by terrestrial telescopes [45] and possibly confirmed by PFS

#### **Figure 23.**

*The suite of instruments of SAM (Sample Analysis at Mars) laboratory on board of Curiosity.*

spectromenter on board of Mars Express [46]. The task of TLS was to continue the search for methane in order to establish its source (geological or biological).

*Seasonal variations of Martian methane, detected by the SAM-TLS spectrometer, during 55 months (about three Mars years from March 17 2014 to March 21, 2017.Potential methane sources include methanogenesis by microbes, ultraviolet degradation of organics, or water-rock chemistry. The methane could be later destroyed by atmospheric photochemistry or surface reactions, as examples. Seasons refer to the northern hemisphere.*

*The Carousel of SAM, called the SMS (Sample Manipulation System). It contains 74 cups, dedicated to receiving solid samples collected by the Curiosity rover. The 74 sample cups are separated into three categories: 59 solid sample quartz cups, 9 foil topped metal cups for wet chemistry experiments (7 with MTBSTFA, 2 with*

**Figure 25.**

**Figure 26.**

**153**

*TMAH), and 6 foil topped cups of reference samples.*

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

Really, TLS detected methane many times over the course of the mission, though with a very strange behaviour. Background levels of the gas seem to rise and fall seasonally (0,24–0,65 ppbv, parts per billion units by volume) [47] (**Figure 26**). The highest methane levels do appear just after the warmest time of the year, suggesting that heat spreading downward allows more of the gas to be released.

#### **Figure 24.**

*Inside the SAM lab., gases released by a sample of Martian soil heated up to 1000°C can be sent to a Mass Spectrometer (MS) directly (EGA-MS, Evolved Gas Analysis) or passing before though Gas-chromatographic column (GCMS).*

#### **Figure 25.**

**Figure 23.**

*Solar System Planets and Exoplanets*

**Figure 24.**

**152**

*column (GCMS).*

*The suite of instruments of SAM (Sample Analysis at Mars) laboratory on board of Curiosity.*

*Inside the SAM lab., gases released by a sample of Martian soil heated up to 1000°C can be sent to a Mass Spectrometer (MS) directly (EGA-MS, Evolved Gas Analysis) or passing before though Gas-chromatographic* *The Carousel of SAM, called the SMS (Sample Manipulation System). It contains 74 cups, dedicated to receiving solid samples collected by the Curiosity rover. The 74 sample cups are separated into three categories: 59 solid sample quartz cups, 9 foil topped metal cups for wet chemistry experiments (7 with MTBSTFA, 2 with TMAH), and 6 foil topped cups of reference samples.*

spectromenter on board of Mars Express [46]. The task of TLS was to continue the search for methane in order to establish its source (geological or biological).

Really, TLS detected methane many times over the course of the mission, though with a very strange behaviour. Background levels of the gas seem to rise and fall seasonally (0,24–0,65 ppbv, parts per billion units by volume) [47] (**Figure 26**).

The highest methane levels do appear just after the warmest time of the year, suggesting that heat spreading downward allows more of the gas to be released.

#### **Figure 26.**

*Seasonal variations of Martian methane, detected by the SAM-TLS spectrometer, during 55 months (about three Mars years from March 17 2014 to March 21, 2017.Potential methane sources include methanogenesis by microbes, ultraviolet degradation of organics, or water-rock chemistry. The methane could be later destroyed by atmospheric photochemistry or surface reactions, as examples. Seasons refer to the northern hemisphere.*

Finding methane in Mars's atmosphere is intriguing because chemical reactions should destroy the gas after about 300 years. So its presence today suggests that something on the planet is still sending the gas into the atmosphere. The source could be geological, such as reactions between certain types of rock and water (basaltic serpentinization) or could be linked to ancient methane trapped in clathrate hydrates; more intriguingly, the warmest season could 'awaken' buried microbes or other forms of life, taking in account that most of the methane in Earth's atmosphere comes from living processes. But a recent statistical analysis [48] casts doubt on the hypothesis of "seasonal variability" in Mars'surface methane, finding that it is unsupported by the Curiosity TLS data. This is because the data are too sparse over too limited timespan, to favor a seasonally cyclic explanation of the data over alternative hypotheses of stochastic variation or variation with other periods.

TLS detected also episodically increases ('spike') of Martian methane [49]: for example on June 16, 2013 and on early January 2014 readings averaged ten time the background level (6–8 ppbv). The largest concentration of methane detected in situ by the Curiosity reached a spike to 21 ppbv, on June 20, 2019, dropping quickly over a few days (**Figure 27**).

which includes the strongest fundamental absorption bands for hydrocarbons such as CH4, in particular the ν3 asymmetric stretching band on which all the previous

*On June 13, 2013, the PFS spectrometer on board of Mars Express observed a methane emission over the fractured terrain of Medusae Fossae, some hours before a spike of methane detected inside the Gale crater by the TLS-SAM instrument. Geological methane carried towards the Gale crater by the prevailing winds?*

Until the end of 2020 the SAM-GCMS made more than twenty complete ana-

Inside the Gale crater Curiosity discovered for the first time, Martian organic molecules, just after a few attempts (Rocknest, John Klein, Cumberland at Yellow-

Yellowknife Bay mudstone is thought to contain sediments transported by

sandy terrain of Rocknest, located about 550 meters away the landing site. The APXS instrument (Alpha Particle-X rays spectrometer) [52] detected on Rocknest a little amount of S and Cl [53]. The sandy texture of the soil was suitable to be easily transferred inside the SAM. Under the heating of the sample up to 800°C, many kinds of gaseous substances were released [54]. The release of molecular Oxigen (O2) at 300–400°C (**Figure 31**) was very important: together with the presence of

Between sol 56 and 100 (October 2 to November 16, 2012) Curiosity reached the

detections were made.

**Figure 28.**

**Figure 29.**

**155**

lyses on Gale crater soil (**Figure 29**).

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

knife Bay, not far from the landing site) (**Figure 30**).

fluvial and deltaic processes from the crater rim area to the north.

*A summary of all drill sites made by Curiosity at Gale Crater up the end of 2020.*

The PFS spectrometer of Mars Express found a possible geological origin of this n usual pattern [50]. Indeed, in a re-examination of archive data, PFS, on June 16, 2013, observed an elevated spot level (15.5 2.5 ppbv) of methane, from a nearby area called Medusae Fossae, located about 500 km east of Gale crater. The Mars Express observation was made 20 hours before the methane spike of 5.78 2.27 ppbv reported by TLS-SAM. Being Medusae Fossae a fractured and likely volcanic in origin, it is possible that a therein geological emission of methane has been carried by the prevailing winds towards the Gale crater (**Figure 28**).

Highly sensitive measurements of the atmosphere of Mars performed by the ESA-Roscosmos ExoMars TGO (Trace Gas Orbiter) from April to August 2018 made the problem of Martian methane even more enigmatic [51]. No trace of methane was indeed found by two instrument suites onboard TGO designed to perform such measurements: ACS (the Atmospheric Chemistry Suite) and NOMAD (Nadir and Occultation for Mars Discovery) that cover the 3.3 μm spectral range,

#### **Figure 27.**

*TLS-SAM methane measurements at Gale crater over an 4.5 Earth years (56 months) period (from 26 October 2012 to 27 May 2017), taken during the rover's journey of 16.5 km over highly varied terrain.*

#### **Figure 28.**

Finding methane in Mars's atmosphere is intriguing because chemical reactions should destroy the gas after about 300 years. So its presence today suggests that something on the planet is still sending the gas into the atmosphere. The source could be geological, such as reactions between certain types of rock and water (basaltic serpentinization) or could be linked to ancient methane trapped in clathrate hydrates; more intriguingly, the warmest season could 'awaken' buried microbes or other forms of life, taking in account that most of the methane in Earth's atmosphere comes from living processes. But a recent statistical analysis [48] casts doubt on the hypothesis of "seasonal variability" in Mars'surface methane, finding that it is unsupported by the Curiosity TLS data. This is because the data are too sparse over too limited timespan, to favor a seasonally cyclic explanation of the data over alternative hypotheses of stochastic variation or

TLS detected also episodically increases ('spike') of Martian methane [49]: for example on June 16, 2013 and on early January 2014 readings averaged ten time the background level (6–8 ppbv). The largest concentration of methane detected in situ by the Curiosity reached a spike to 21 ppbv, on June 20, 2019, dropping quickly over

The PFS spectrometer of Mars Express found a possible geological origin of this n usual pattern [50]. Indeed, in a re-examination of archive data, PFS, on June 16, 2013, observed an elevated spot level (15.5 2.5 ppbv) of methane, from a nearby area called Medusae Fossae, located about 500 km east of Gale crater. The Mars Express observation was made 20 hours before the methane spike of 5.78 2.27 ppbv reported by TLS-SAM. Being Medusae Fossae a fractured and likely volcanic in origin, it is possible that a therein geological emission of methane has been

Highly sensitive measurements of the atmosphere of Mars performed by the ESA-Roscosmos ExoMars TGO (Trace Gas Orbiter) from April to August 2018 made the problem of Martian methane even more enigmatic [51]. No trace of methane was indeed found by two instrument suites onboard TGO designed to perform such measurements: ACS (the Atmospheric Chemistry Suite) and NOMAD (Nadir and Occultation for Mars Discovery) that cover the 3.3 μm spectral range,

*TLS-SAM methane measurements at Gale crater over an 4.5 Earth years (56 months) period (from 26 October 2012 to 27 May 2017), taken during the rover's journey of 16.5 km over highly varied terrain.*

carried by the prevailing winds towards the Gale crater (**Figure 28**).

variation with other periods.

*Solar System Planets and Exoplanets*

a few days (**Figure 27**).

**Figure 27.**

**154**

*On June 13, 2013, the PFS spectrometer on board of Mars Express observed a methane emission over the fractured terrain of Medusae Fossae, some hours before a spike of methane detected inside the Gale crater by the TLS-SAM instrument. Geological methane carried towards the Gale crater by the prevailing winds?*

which includes the strongest fundamental absorption bands for hydrocarbons such as CH4, in particular the ν3 asymmetric stretching band on which all the previous detections were made.

Until the end of 2020 the SAM-GCMS made more than twenty complete analyses on Gale crater soil (**Figure 29**).

Inside the Gale crater Curiosity discovered for the first time, Martian organic molecules, just after a few attempts (Rocknest, John Klein, Cumberland at Yellowknife Bay, not far from the landing site) (**Figure 30**).

Yellowknife Bay mudstone is thought to contain sediments transported by fluvial and deltaic processes from the crater rim area to the north.

Between sol 56 and 100 (October 2 to November 16, 2012) Curiosity reached the sandy terrain of Rocknest, located about 550 meters away the landing site. The APXS instrument (Alpha Particle-X rays spectrometer) [52] detected on Rocknest a little amount of S and Cl [53]. The sandy texture of the soil was suitable to be easily transferred inside the SAM. Under the heating of the sample up to 800°C, many kinds of gaseous substances were released [54]. The release of molecular Oxigen (O2) at 300–400°C (**Figure 31**) was very important: together with the presence of

#### **Figure 30.**

*December 24, 2012 (sol 137): this mosaic of images from Curiosity-Mastcam shows the rocks of Yellowknife Bay formation, that record superimposed ancient lake and stream deposits that offered past environmental conditions favorable for microbial life. Rocks here were exposed about 70 million years ago by removal of overlying layers due to erosion by the wind. Yellowknife Bay mudstone is thought to contain sediments transported by fluvial and deltaic processes from the crater rim area to the north.*

But alternative hypotheses could have been given. The water and carbon dioxide seen by SAM could be breakdown products of organic substances under the action of perchlorates. This claim results from another discovery of GCMS on board SAM: the detection of simple chlorinated molecules, such as CH3Cl and minor amount of CH2Cl2 and CHCl3 [25]. At the end of February 2013 the SAM made a second series of analyses on a powdered sample of a sedimentary terrain named John Klein (**Figure 33**), located about 50 meters away from Rocknest, confirming results of first analysis, i.e. emission of CO2 and H2O, of O2 over 250°C (probably generated

*Thermal decomposition of perchlorates measured by the Author on a TGA (Thermal Gravimetric Analysis) instrument. Each perchlorate shows a specific temperature of decomposition with release of Oxygen.*

Therefore, the SAM and Viking GCMS results look strikingly similar, in the sense that a sufficient amount of perchlorates could mask occurrence of organics.

*February 2013: results by SAM-Curiosity from a powdered material drilled into the John Klein sedimentary*

*rock. On top the EGA evolved gases, on bottom some CGMS light chloro-derivatives.*

by perchlorates dissociation), and release of CH3Cl + CH3Cl2 [55].

**Figure 32.**

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

**Figure 33.**

**157**

#### **Figure 31.**

*November 2012 (sol 93–117): results from analysis of Rocknest Aeolian deposit by SAM-Curiosity. On top the EGA evolved gases, on bottom some CGMS light chloro-derivatives.*

Cl, this emission is a suggestion of Ca (ClO4)2 (Calcium perchlorate), a salt that decomposes under heat just to this temperature.

Laboratory–based TGA (Thermal Gravimetrical Analysis, performed by the Author with a Perkin-Elmer TGA 7 instrument) on synthetic perchlorates shows clearly that the Calcium perchlorate starts to release molecular oxigen at 350°C, leaving a main residue of Calcium chloride (CaCl2) (**Figure 32**). Therefore, after the discovery of perchlorate at high latitude by Phoenix, SAM demonstrated an occurrence of perchlorate also at equatorial latitude: so its occurrence also at mid-latitude (i.e. Viking landing sites) comes out strengthened.

Actually, between 200 and 500°C, the soil of Rocknest released water and two peaks of CO2 (i.e. two releases at two different temperatures). The origin of this water and Carbon dioxide is doubtful. Being released at more than 200°C, the water cannot be free, but bound to soil minerals as water of crystallization. In addition, a lab simulation shows that the two peaks of CO2 could arise from the thermal decomposition of Mg and Fe carbonate [54].

**Figure 32.** *Thermal decomposition of perchlorates measured by the Author on a TGA (Thermal Gravimetric Analysis) instrument. Each perchlorate shows a specific temperature of decomposition with release of Oxygen.*

But alternative hypotheses could have been given. The water and carbon dioxide seen by SAM could be breakdown products of organic substances under the action of perchlorates. This claim results from another discovery of GCMS on board SAM: the detection of simple chlorinated molecules, such as CH3Cl and minor amount of CH2Cl2 and CHCl3 [25]. At the end of February 2013 the SAM made a second series of analyses on a powdered sample of a sedimentary terrain named John Klein (**Figure 33**), located about 50 meters away from Rocknest, confirming results of first analysis, i.e. emission of CO2 and H2O, of O2 over 250°C (probably generated by perchlorates dissociation), and release of CH3Cl + CH3Cl2 [55].

Therefore, the SAM and Viking GCMS results look strikingly similar, in the sense that a sufficient amount of perchlorates could mask occurrence of organics.

#### **Figure 33.**

*February 2013: results by SAM-Curiosity from a powdered material drilled into the John Klein sedimentary rock. On top the EGA evolved gases, on bottom some CGMS light chloro-derivatives.*

Cl, this emission is a suggestion of Ca (ClO4)2 (Calcium perchlorate), a salt that

*December 24, 2012 (sol 137): this mosaic of images from Curiosity-Mastcam shows the rocks of Yellowknife Bay formation, that record superimposed ancient lake and stream deposits that offered past environmental conditions favorable for microbial life. Rocks here were exposed about 70 million years ago by removal of overlying layers due to erosion by the wind. Yellowknife Bay mudstone is thought to contain sediments*

*transported by fluvial and deltaic processes from the crater rim area to the north.*

Laboratory–based TGA (Thermal Gravimetrical Analysis, performed by the Author with a Perkin-Elmer TGA 7 instrument) on synthetic perchlorates shows clearly that the Calcium perchlorate starts to release molecular oxigen at 350°C, leaving a main residue of Calcium chloride (CaCl2) (**Figure 32**). Therefore, after the discovery of perchlorate at high latitude by Phoenix, SAM demonstrated an occurrence of perchlorate also at equatorial latitude: so its occurrence also at mid-latitude

*November 2012 (sol 93–117): results from analysis of Rocknest Aeolian deposit by SAM-Curiosity. On top the*

Actually, between 200 and 500°C, the soil of Rocknest released water and two peaks of CO2 (i.e. two releases at two different temperatures). The origin of this water and Carbon dioxide is doubtful. Being released at more than 200°C, the water cannot be free, but bound to soil minerals as water of crystallization. In addition, a lab simulation shows that the two peaks of CO2 could arise from the thermal

decomposes under heat just to this temperature.

*EGA evolved gases, on bottom some CGMS light chloro-derivatives.*

**Figure 30.**

*Solar System Planets and Exoplanets*

**Figure 31.**

**156**

(i.e. Viking landing sites) comes out strengthened.

decomposition of Mg and Fe carbonate [54].

After many months of stop due to a serious pollution problem (see later), the SAM team started again its analytical work, on a soil sample of the site of Cumberland that was taken an year before, on May 2013 not far from John Klein. The SAM results were crucial [56]: aside from the usual light Chloro-derivatives, many chlorinated aromatics were detected [57] suggesting that they could be derived from organic molecules present in the mudstone (from bacteria or from a meteoric extract): between them also an abundant release (about 250 ppb) of Chlorobenzene was detected (**Figure 34**), so reaching for an other resemblance to the Viking results, in which Chloro-benzene (as mentioned before) was found after a recent accurate re-examination of the original GCMS data [29].

One of the most extraordinary SAM discovery was made at Pahrump Hills (at the base of3.5-billion-year-old Murray mudstone), located at the lowermost portion of the Sharp Mons (Gale Crater central mound), about 6–7 km southwest of Yellowknife Bay. This 3.5-billion-year-old Gale lake environment is expected to have been ideal settings for concentrating and preserving organic matter [58]. Two samples were drilled: Confidence Hills on sol 759 (24 Sep 2014), and Mojave on sol 882 (29 Jan 2015) (**Figure 35**). Confidence Hills soil was rich of hematite, Mojave soil was rich of jarosite, evidence of ancient passage of water. Because ultraviolet radiation and oxidizing compounds in the Martian soil would destroy any compounds exposed at the surface, Curiosity's scientists used a robotic drill to penetrate several centimetres into the mudstone.

To unlock organic molecules from the samples, the oven baked them to temperatures of between 600°C and 860°C and fed the resulting fumes to the Mass Spectrometer, which identified a welter of closely related organic signals reflecting dozens or hundreds of types of small carbon molecules, such as aromatic rings and short aliphatic chains [59]. Abundant sulfur-bearing carbon rings called thiophenes, were also detected and identified in the GC (**Figure 36**).

The mass patterns looked like those generated on Earth by kerogen (aromatic rings, short aliphatic chains, sulphur containing molecules), a goopy high molecular material that is formed when geologic forces compress, during million of years, the ancient remains of algae and similar critters. Kerogen is sometimes found with sulfur, which helps preserve it across billions of years; the Curiosity scientists think the sulfur compounds in their samples also explain the longevity of the Mars compounds. At the moment, it is impossible to say whether ancient life explains the Martian organics. The signal, being found at the base of a lake 3,5 billion years old, when Mars environment was warm and wet, could be a potential catchment for the presence on Mars of archea bacteria in primordial epoch, possibly still present today

*SAM-EGA evolved gases from Majave drilled material: sulfur-bearing carbon rings, short aliphatic chains and*

*aromatic rings are typical decomposition products of keragenic material.*

*Confidence Hills and Mojave drill sites, at Pahrump Hills location, were SAM made the main discovery of*

**Figure 35.**

**Figure 36.**

**159**

*possible keragenic material.*

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

#### **Figure 34.**

*December 2014: results by SAM-Curiosity from a powdered material drilled into the Cumberland sedimentary rock. Very important (bottom), between the GCMS evolved chloro-derivatives, the presence of chloro-benzene, a byproduct certainly of Martian origin.*

#### **Figure 35.**

After many months of stop due to a serious pollution problem (see later), the SAM team started again its analytical work, on a soil sample of the site of Cumberland that was taken an year before, on May 2013 not far from John Klein. The SAM results were crucial [56]: aside from the usual light Chloro-derivatives, many chlorinated aromatics were detected [57] suggesting that they could be derived from organic molecules present in the mudstone (from bacteria or from a meteoric extract): between them also an abundant release (about 250 ppb) of Chlorobenzene was detected (**Figure 34**), so reaching for an other resemblance to the Viking results, in which Chloro-benzene (as mentioned before) was found after a

One of the most extraordinary SAM discovery was made at Pahrump Hills (at the base of3.5-billion-year-old Murray mudstone), located at the lowermost portion of the Sharp Mons (Gale Crater central mound), about 6–7 km southwest of Yellowknife Bay. This 3.5-billion-year-old Gale lake environment is expected to have been ideal settings for concentrating and preserving organic matter [58]. Two samples were drilled: Confidence Hills on sol 759 (24 Sep 2014), and Mojave on sol 882 (29 Jan 2015) (**Figure 35**). Confidence Hills soil was rich of hematite, Mojave soil was rich of jarosite, evidence of ancient passage of water. Because ultraviolet radiation and oxidizing compounds in the Martian soil would destroy any compounds exposed at the surface, Curiosity's scientists used a robotic drill to penetrate

To unlock organic molecules from the samples, the oven baked them to temper-

*December 2014: results by SAM-Curiosity from a powdered material drilled into the Cumberland sedimentary rock. Very important (bottom), between the GCMS evolved chloro-derivatives, the presence of chloro-benzene,*

atures of between 600°C and 860°C and fed the resulting fumes to the Mass Spectrometer, which identified a welter of closely related organic signals reflecting dozens or hundreds of types of small carbon molecules, such as aromatic rings and short aliphatic chains [59]. Abundant sulfur-bearing carbon rings called thiophenes,

were also detected and identified in the GC (**Figure 36**).

recent accurate re-examination of the original GCMS data [29].

several centimetres into the mudstone.

*Solar System Planets and Exoplanets*

**Figure 34.**

**158**

*a byproduct certainly of Martian origin.*

*Confidence Hills and Mojave drill sites, at Pahrump Hills location, were SAM made the main discovery of possible keragenic material.*

#### **Figure 36.**

*SAM-EGA evolved gases from Majave drilled material: sulfur-bearing carbon rings, short aliphatic chains and aromatic rings are typical decomposition products of keragenic material.*

The mass patterns looked like those generated on Earth by kerogen (aromatic rings, short aliphatic chains, sulphur containing molecules), a goopy high molecular material that is formed when geologic forces compress, during million of years, the ancient remains of algae and similar critters. Kerogen is sometimes found with sulfur, which helps preserve it across billions of years; the Curiosity scientists think the sulfur compounds in their samples also explain the longevity of the Mars compounds. At the moment, it is impossible to say whether ancient life explains the Martian organics. The signal, being found at the base of a lake 3,5 billion years old, when Mars environment was warm and wet, could be a potential catchment for the presence on Mars of archea bacteria in primordial epoch, possibly still present today where there are sources of liquid water over the surface (superficial melting of ices rich in salts) [60] or below the surface (sub-glacial lakes identified by radar tecniques) [61]. However, we must not forget that Carbon-rich meteorites and comets contain kerogenic like compounds, and constantly rain down on Mars …

It's disappointing that we can't figure out where the carbon-rich large molecules came from. But digging a little deeper could find better-preserved molecules in Mars rocks, to determine whether these molecules came from space, from igneous rocks, from hydrothermal activity, or – the most exciting possibility – ancient Mars life. Europe's ExoMars rover, due for launch in 2022, will drill deeper than Curiosity, to soil depths better protected from radiation. But probably, detection of past life may ultimately take the precision analysis of labs on Earth, bringing samples back. Fortunately, NASA Perseverance rover, that was successful in landing inside the Jezero crater on February 18, 2021 (**Figures 37** and **38**), is set to collect some 30 rock cores for return to Earth in subsequent missions.

SAM is able to give a further usefull help to determine the nature and origin of the kerogenic materials discovered on Mars, by the so called 'wet chemistry' experiments.

In summary, if organic molecules cannot enter the GCMS because a low volatility or breaking dawn under heating, they can be "derivatized" before they're heated – meaning that they react with some chemicals in order to become more volatile – so that they can be analyzed at a lower temperature. This derivatization process uses special chemical reagents dissolved in suitable solvents, so this experiment is called "wet chemistry". As yet mentioned, SAM only has nine Inconel steel cups containing these derivatizing agents: 7 containing a derivatization-silanizing

compound named MTBSTFA (N-tert-butyldimethylsilyl- N-

*The two derivatizing reagents for 'wet chemistry' on board of SAM-Curiosity.*

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

TMAH (tetramethylammonium hydroxide) (**Figure 39**).

*The MTBSTFA chemical mechanism of derivatization, called silanization.*

**Figure 39.**

**Figure 40.**

**161**

methyltrifluoroacetamide), 2 containing a thermochemolysis compound named

MTBSTFA is an organic compound containing Florine and Silicium, able to instantly replace active hydrogens on OH and NH2 (carboxylic acid, amine, aminoacid) with a N-tert-butyldimethylsilyl group (**Figure 40**): this non-polar moiety increases the volatility of the original compound by removing its polar nature, resulting in a much lower temperature needed for a GCMS analysis [62]. Due to the limited number of cups for 'wet chemistry', these kinds of experiments were obviously saved for only the most interesting rock samples. But an incredible accident caused the first wet chemistry trial to be postponed for six years. During the

#### **Figure 37.**

*The Jezero crater, an ancient lake where the rover Perseverance landed on February 18, 2021.*

#### **Figure 38.**

*February 21, 2021: Perseverance sees Jezero crater rim in 360° Mars panorama.*

#### **Figure 39.**

where there are sources of liquid water over the surface (superficial melting of ices rich in salts) [60] or below the surface (sub-glacial lakes identified by radar tecniques) [61]. However, we must not forget that Carbon-rich meteorites and comets contain kerogenic like compounds, and constantly rain down on Mars … It's disappointing that we can't figure out where the carbon-rich large molecules

came from. But digging a little deeper could find better-preserved molecules in Mars rocks, to determine whether these molecules came from space, from igneous rocks, from hydrothermal activity, or – the most exciting possibility – ancient Mars life. Europe's ExoMars rover, due for launch in 2022, will drill deeper than Curiosity, to soil depths better protected from radiation. But probably, detection of past life may ultimately take the precision analysis of labs on Earth, bringing samples back. Fortunately, NASA Perseverance rover, that was successful in landing inside the Jezero crater on February 18, 2021 (**Figures 37** and **38**), is set to collect some 30

SAM is able to give a further usefull help to determine the nature and origin of the kerogenic materials discovered on Mars, by the so called 'wet chemistry'

"wet chemistry". As yet mentioned, SAM only has nine Inconel steel cups containing these derivatizing agents: 7 containing a derivatization-silanizing

*The Jezero crater, an ancient lake where the rover Perseverance landed on February 18, 2021.*

*February 21, 2021: Perseverance sees Jezero crater rim in 360° Mars panorama.*

In summary, if organic molecules cannot enter the GCMS because a low volatility or breaking dawn under heating, they can be "derivatized" before they're heated – meaning that they react with some chemicals in order to become more volatile – so that they can be analyzed at a lower temperature. This derivatization process uses special chemical reagents dissolved in suitable solvents, so this experiment is called

rock cores for return to Earth in subsequent missions.

experiments.

*Solar System Planets and Exoplanets*

**Figure 37.**

**Figure 38.**

**160**

*The two derivatizing reagents for 'wet chemistry' on board of SAM-Curiosity.*

compound named MTBSTFA (N-tert-butyldimethylsilyl- Nmethyltrifluoroacetamide), 2 containing a thermochemolysis compound named TMAH (tetramethylammonium hydroxide) (**Figure 39**).

MTBSTFA is an organic compound containing Florine and Silicium, able to instantly replace active hydrogens on OH and NH2 (carboxylic acid, amine, aminoacid) with a N-tert-butyldimethylsilyl group (**Figure 40**): this non-polar moiety increases the volatility of the original compound by removing its polar nature, resulting in a much lower temperature needed for a GCMS analysis [62]. Due to the limited number of cups for 'wet chemistry', these kinds of experiments were obviously saved for only the most interesting rock samples. But an incredible accident caused the first wet chemistry trial to be postponed for six years. During the

examination of the results the SAM obtained on Rocknest and on John Klein, the SAM team discovered that a vial of MTBSTFA was broken, so polluting all the analytical system.

The problem was that MTBSTFA, being itself an organic compound, reacts under heat with perchlorates, giving the same kind of light chloro-derivatives (CH3Cl and CH2Cl2) found by the SAM on the Martian samples! From here a dreadful doubt that the origin of the 'positive' results obtained so far by the SAM could be 'terrestrial' and not Martian [25]. More than a year was needed to clean the system, during which a sample from Cumberland remained stored inside SAM, waiting the right moment to be analyzed. The sample remained 1280 sols (!) in contact with MTBSTFA vapors, a situation that also provided an opportunity [63]: baking the sample up to 900°C to verify if some reaction between MTBSTFA and Martian soil had happened. This so called 'opportunistic derivatization' was a success, because the GC–MS detected interesting compound such as Chlorobenzene, Thiophene, light Chloro-derivatives and many other unknown compounds (**Figure 41**).

Lab tests demonstrated that Chloro-benzene, an organic compound containing 6 Carbon atoms, could not be formed from the heating of MTBSTFA in presence of perchlorates [64] but only when various types of Martian organic materials are pyrolyzed (i.e. heated at high temperature) in presence of Chlorine source.

The first 'complete' wet chemistry experiment was made on December 19, 2017. The target was a Ogunquit Beach (OB) sand sample from the Bagnold dune field, chosen being easy to manipulate after months of trouble due recurrent problems with the drill feed mechanism (**Figure 42**).

About 45 mg of the Ogunquit Beach sand were added to one of the MTBSTFA cups and the mixture was heated up to 900°C. Reactions clearly occurred and produced derivatized compounds. GCMS results showed the detection of derivatized benzoic acid as well as excess, unreacted MTBSTFA. However, no amino acids or fatty acids were detected [65].

During the following months engineers found a way to fix the drill problem. So the next step was to perform wet chemistry experiments on drilled clay deeper samples, as these phyllosilicate-rich minerals are known to preserve organic matter exceptionally well. A unusual Mn- and P-rich clay-bearing unit named Glen Torridon (GT) (**Figure 43**) was discovered in the foothills of Mount Sharp by CRISM spectrometer aboard the Mars Reconnaissance Orbiter (strong absorptions at 2.24 and 2.29 μm. EGA analyses in many locations inside Glen Torridon showed emission of free and strongly linked water and, surprisingly, absence of emission of

O2 from perchlorates [66]: a promising situation in order to search for organic compounds. SAM activities in Glen Torridon included an EGA/GCMS analysis, a new MTBSTFA derivatization experiment, followed by the first TMAH experiment. On Sept. 24, 2019 (sol 2536) the rover placed in the SAM the powderized drilled

*The clay-bearing unit named Glen Torridon where SAM performed also the first derivatization with TMAH*

*Ogunquit Beach where SAM performed the first complete derivatization with MTBSTFA.*

aliphatic and aromatic compounds: dimethylsulfide, thiophene, and likely ethanethiol and dithiapentane. EGA also indicated results within the medium to high molecular weight ranges of masses, suggesting the presence of a complex

EGA/GCMS detected an abundance of S-bearing organic compounds, including

sample from GT- Glen Etive 2 site (**Figure 44**).

mixture of compounds.

**Figure 42.**

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

**Figure 43.**

**163**

*(called thermochemolysis).*

#### **Figure 41.**

*The GCMS result of the so called 'opportunistic derivatization', performed on Cumberland material, that stayed in touch for months with MTBSTFA vapors accidentally leaked from a broken cup.*

examination of the results the SAM obtained on Rocknest and on John Klein, the SAM team discovered that a vial of MTBSTFA was broken, so polluting all the

The problem was that MTBSTFA, being itself an organic compound, reacts under heat with perchlorates, giving the same kind of light chloro-derivatives (CH3Cl and CH2Cl2) found by the SAM on the Martian samples! From here a dreadful doubt that the origin of the 'positive' results obtained so far by the SAM could be 'terrestrial' and not Martian [25]. More than a year was needed to clean the system, during which a sample from Cumberland remained stored inside SAM, waiting the right moment to be analyzed. The sample remained 1280 sols (!) in contact with MTBSTFA vapors, a situation that also provided an opportunity [63]: baking the sample up to 900°C to verify if some reaction between MTBSTFA and Martian soil had happened. This so called 'opportunistic derivatization' was a success, because the GC–MS detected interesting compound such as Chlorobenzene, Thiophene, light Chloro-derivatives and many other unknown compounds

Lab tests demonstrated that Chloro-benzene, an organic compound containing 6 Carbon atoms, could not be formed from the heating of MTBSTFA in presence of perchlorates [64] but only when various types of Martian organic materials are pyrolyzed (i.e. heated at high temperature) in presence of Chlorine source.

The first 'complete' wet chemistry experiment was made on December 19, 2017. The target was a Ogunquit Beach (OB) sand sample from the Bagnold dune field, chosen being easy to manipulate after months of trouble due recurrent problems

About 45 mg of the Ogunquit Beach sand were added to one of the MTBSTFA cups and the mixture was heated up to 900°C. Reactions clearly occurred and produced derivatized compounds. GCMS results showed the detection of derivatized benzoic acid as well as excess, unreacted MTBSTFA. However, no

During the following months engineers found a way to fix the drill problem. So the next step was to perform wet chemistry experiments on drilled clay deeper samples, as these phyllosilicate-rich minerals are known to preserve organic matter exceptionally well. A unusual Mn- and P-rich clay-bearing unit named Glen Torridon (GT) (**Figure 43**) was discovered in the foothills of Mount Sharp by CRISM spectrometer aboard the Mars Reconnaissance Orbiter (strong absorptions at 2.24 and 2.29 μm. EGA analyses in many locations inside Glen Torridon showed emission of free and strongly linked water and, surprisingly, absence of emission of

*The GCMS result of the so called 'opportunistic derivatization', performed on Cumberland material, that*

*stayed in touch for months with MTBSTFA vapors accidentally leaked from a broken cup.*

analytical system.

*Solar System Planets and Exoplanets*

(**Figure 41**).

**Figure 41.**

**162**

with the drill feed mechanism (**Figure 42**).

amino acids or fatty acids were detected [65].

**Figure 42.** *Ogunquit Beach where SAM performed the first complete derivatization with MTBSTFA.*

#### **Figure 43.**

*The clay-bearing unit named Glen Torridon where SAM performed also the first derivatization with TMAH (called thermochemolysis).*

O2 from perchlorates [66]: a promising situation in order to search for organic compounds. SAM activities in Glen Torridon included an EGA/GCMS analysis, a new MTBSTFA derivatization experiment, followed by the first TMAH experiment. On Sept. 24, 2019 (sol 2536) the rover placed in the SAM the powderized drilled sample from GT- Glen Etive 2 site (**Figure 44**).

EGA/GCMS detected an abundance of S-bearing organic compounds, including aliphatic and aromatic compounds: dimethylsulfide, thiophene, and likely ethanethiol and dithiapentane. EGA also indicated results within the medium to high molecular weight ranges of masses, suggesting the presence of a complex mixture of compounds.

#### **Figure 44.**

*The Glen-Etive-2 site (Glen Torridon clay unit) where SAM-EGA discovered high molecular weight carbon molecules, possibly resulting from the breakdown of keragenic material.*

The possible discovery of high molecular molecules, was the long awaited reason for the first in situ TMAH wet chemistry experiment (**Figure 46**), the so called thermochemolysis, performed by hearing a sample of Martian soil in contact with one of the two cups onboard of SAM, containing tetramethylammonium hydroxide

This strongly alkaline reagent causes hydrolysis and methylation of -OH, -O-, -NH, and -SH groups bonds and, upon heating, thermal bond breakage (of big molecules) also enuses. Volatile products of thermochemolysis were directly analyzed by the mass spectrometer (EGA) or trapped and analyzed with gas chromatography mass spectrometry (EGA-GCMS). This amazing experiment was successfully executed in September 2020 at the Mary Anning (MA) drill site

'Bands' of masses grouped together and having mass-to-charge (m/z) 190 to 485, represent high molecular weight molecules detected by the SAM-MS. These

*The Mary Anning drill site (Glen Torridon clay unit) where the first TMAH derivatization was perfomed on*

(TMAH), dissolved in Methanol [68].

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

**Figure 46.**

**Figure 47.**

**165**

*September 2020.*

(**Figure 47**) in the Glen Torridon region [69, 70].

*The TMAH chemical mechanism of derivatization, called thermochemolysis.*

#### **Figure 45.**

*SAM EGA + CGMS have revealed a range of organic fragments detected above 500°C, indicating the presence of recalcitrant organic matter (e.g. macromolecles). Compounds in blue were only detected via GCMS. Compound in yellow are from Glen Torridon.*

The diversity of aromatics seems consistent with recalcitrant organic materials such as kerogenic-type macromolecules (remembering what was found at Cumberland and Mojeve five years before) (**Figure 45**).

MTBSTFA experiment showed the highest abundance of sulfur-bearing organics ever measured by the SAM instrument and a wide range of aromatic organic molecules including methylated polycyclic aromatic hydrocarbons (methylnaphthalene), a potential methylated ester carboxylic acid (benzoic acid) and Benzothiophene, all detected for the first time on Mars. However, no amino acids or fatty acids have been identified [67].

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

#### **Figure 46.**

*The TMAH chemical mechanism of derivatization, called thermochemolysis.*

The possible discovery of high molecular molecules, was the long awaited reason for the first in situ TMAH wet chemistry experiment (**Figure 46**), the so called thermochemolysis, performed by hearing a sample of Martian soil in contact with one of the two cups onboard of SAM, containing tetramethylammonium hydroxide (TMAH), dissolved in Methanol [68].

This strongly alkaline reagent causes hydrolysis and methylation of -OH, -O-, -NH, and -SH groups bonds and, upon heating, thermal bond breakage (of big molecules) also enuses. Volatile products of thermochemolysis were directly analyzed by the mass spectrometer (EGA) or trapped and analyzed with gas chromatography mass spectrometry (EGA-GCMS). This amazing experiment was successfully executed in September 2020 at the Mary Anning (MA) drill site (**Figure 47**) in the Glen Torridon region [69, 70].

'Bands' of masses grouped together and having mass-to-charge (m/z) 190 to 485, represent high molecular weight molecules detected by the SAM-MS. These

#### **Figure 47.** *The Mary Anning drill site (Glen Torridon clay unit) where the first TMAH derivatization was perfomed on September 2020.*

The diversity of aromatics seems consistent with recalcitrant organic materials such as kerogenic-type macromolecules (remembering what was found at Cumber-

*SAM EGA + CGMS have revealed a range of organic fragments detected above 500°C, indicating the presence of recalcitrant organic matter (e.g. macromolecles). Compounds in blue were only detected via GCMS.*

*The Glen-Etive-2 site (Glen Torridon clay unit) where SAM-EGA discovered high molecular weight carbon*

*molecules, possibly resulting from the breakdown of keragenic material.*

MTBSTFA experiment showed the highest abundance of sulfur-bearing organics

ever measured by the SAM instrument and a wide range of aromatic organic molecules including methylated polycyclic aromatic hydrocarbons (methylnaphthalene), a potential methylated ester carboxylic acid (benzoic acid) and Benzothiophene, all detected for the first time on Mars. However, no amino acids or

land and Mojeve five years before) (**Figure 45**).

fatty acids have been identified [67].

*Compound in yellow are from Glen Torridon.*

**Figure 44.**

*Solar System Planets and Exoplanets*

**Figure 45.**

**164**

#### **Figure 48.**

*The preliminary astonishing results of the TMAH thermochemolysis on the Martian soil drilled at Mary Anning. Separation was performed using a gas-chromatographic column (GC2) able to separated molecules with more than 15 Carbon atom. The red continuous line shows the ramp of temperature (adapted from A. Williams, fall 2020 AGU meeting).*

data may indicate that large, complex molecules were present. A variety of methylated, oxygen-, sulfur-, or nitrogen-bearing aromatic organics were detected in GCMS and/or EGA data. The presence of methylated single and double ring aromatics (included benzene, toluene, trimethyl- and tetramethyl-benzene, naphthalene, and methylnaphthalene) suggests that these organics might derive from a macromolecular source that was cleaved and methylated by TMAH thermochemolysis (**Figure 48**).

Examples of the organics detected in GCMS only include pentamethyl-benzene, benzoic acid methyl ester, dimethyl-, trimethyl-, and tetrame-thyl-benzenamine, dihydronaphthalene, 2-butyl-thio-phene, and benzothiophene. Pentamethylbenzene may be part of a multi-methylated benzene suite. The benzoic acid methyl ester reflects the reaction of TMAH methylating benzoic acid of indeterminate source. The multi-methylated benzenamine suite is also of indeterminate source. A non biological source of these organics on the surface of Mars could be the impact of meteoritic material. Several similar organics were indeed identified applying the TMAH thermochemolysis benchtop experiment to the Murchison meteorite, including toluene, trimethylbenzene, methylnaphthalene, 2-butylthiophene, and benzothiophene. Amines and amides are not prevalent in pyrolyzed Murchison material and benzenamines are also not generated during TMAH thermochemolysis of Murchison, so the origin of these amines remains at least problematic.

**Author details**

GAT/Milano Planetarium, Tradate, Italy

*New Insights into the Search for Life on Mars DOI: http://dx.doi.org/10.5772/intechopen.97176*

provided the original work is properly cited.

\*Address all correspondence to<EMAIL_ADDRESS>
© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Cesare Guaita

**167**


Chapter 18 **Climatic Conditions and Production of Soybean in Northeastern Brazil 377**

Jeandson Silva Viana, Edilma Pereira Gonçalves, Abraão Cicero Silva and Valderez Pontes Matos

### **Section 4 Soybean Genetics 393**

**Section 3 Soybean Agronomy and Physiology 181**

Chapter 10 **Drought Stress and Tolerance in Soybean 209**

Chapter 11 **Biologically Active Constituents of Soybean 239**

Chapter 12 **Cell Death Signaling From the Endoplasmic Reticulum**

Pedro A.B. Reis and Elizabeth P. B. Fontes

Chapter 13 **Soybean Under Water Deficit: Physiological and Yield**

Chapter 14 **Interaction of Photosynthetic Source-Sink Balance and**

Minobu Kasai and Wataru Takahashi

Chapter 16 **Explanations for the Rise of Soybean in Brazil 341**

Silveira Pinto and Felipe Gustavo Pilau

Eduardo Antonio Gavioli

**Activities of Membrane H+ Pumps in Soybean 299**

Chapter 15 **Soybean Urease: Over a Hundred Years of Knowledge 317**

Chapter 17 **Climatic Restrictions for Maximizing Soybean Yields 367**

**Natural Products 183**

**VI** Contents

**in Soybean 261**

**Responses 273**

P. Soratto

Chapter 8 **Molecular Design of Soybean Lipoxygenase Inhibitors Based on**

Hilton S. Pinto, Ana Maria H. de Avila and Andrea O. Cardoso

Yee-Shan Ku, Wan-Kin Au-Yeung, Yuk-Lin Yung, Man-Wah Li,

Gustavo M. Souza, Tiago A. Catuchi, Suzana C. Bertolli and Rogerio

Rafael Real-Guerra, Fernanda Stanisçuaski and Célia Regina Carlini

Ana Maria Heuminski de Avila, José Renato Bouças Farias, Hilton

Isao Kubo, Tae Joung Ha and Kuniyoshi Shimizu

Chapter 9 **Challenges to Increased Soybean Production in Brazil 199**

Chao-Qing Wen, Xueyi Liu and Hon-Ming Lam

Tzi Bun Ng, Randy Chi Fai Cheung and Jack Ho Wong


**Acknowledgements**

With financial support from the state government of North Rhine-Westphalia and the Indo-German Science & Technology Centre (IGSTC). TEM acknowledges the support of Fraunhofer-Institut für Umwelt-, Sicherheits- und Energietechnik UMSICHT. P. Tomkins and E. Gebauer-Henke are gratefully acknowledged for the characterisation of the Ru/CNT catalyst, C. Herwartz (GFE) for TEM measurements, M. Hermesmann for the literature searches on environmental impact, as well as D. Panke for drawing the chemical structure of biomass fractions.


2.1.3. UERD

UERD [10] is a steganographic embedding scheme that aims to minimize the probability of steganographically encoded information's presence being detected, by minimizing the embedding's impact on the statistical parameters of the cover information. It achieves this by analyzing the parameters of DCT coefficients of given modes, as well as whole DCT blocks and their neighbors. Through this, the method can determine whether the region can be considered "noisy" and whether embedding will impact statistical features such as histograms of the file. "Wet" regions are those where statistical parameters are predictable and where embedding would cause noticeable changes. The scheme does not exclude values such as the DC mode coefficients or zero DCT coefficients from being used when embedding, as their statistical profiles can make them suitable from the security perspective. UERD attempts to uniformly spread the relative changes of statistics resulting from embedding. UERD employs syndrome trellis coding (STC) to hide message bits in the desired values.

Figure 1 shows a sample clean image, the same image with random data hidden using the UERD algorithm at 0.4 bpnzac (bits per non-zero AC DCT coefficient) rate, and an image which is the difference between them. As can be observed, despite there being almost 5% hidden data in the image (b) no artifacts can be perceived. What is more, it is hardly possible to observe any difference between the clean and steganographically-modified image, even if they are displayed next to one another. It is only the differential image (c) that proves the manipulation. The same refers to nsF5, J-Uniward, and other modern algorithms realizing image steganography—their manipulations are often imperceptible and difficult to detect, considering that the original image is rarely available.

#### *2.2. Detection Methods*

In recent years, several methods of detecting image steganography have been researched. They usually involve the extraction of some sort of parameters out of analyzed images, followed by applying a classification algorithm. They are usually based on an ML approach, employing either shallow or deep learning algorithms. Therefore, in this subsection, we first describe the features most frequently used with steganalytic algorithms, and then briefly describe typical examples of shallow and deep learning-based detection algorithms.

**Figure 1.** (**a**) Clean image, (**b**) image with data hidden using UERD algorithm, and (**c**) differential image between them, scaled 100 times. Density of steganographic data: 0.4 bpnzac, which means here 2638 B of hidden data in each 53 kB image file. Clean image source: unsplash.com (accessed on 8 April 2022).

#### 2.2.1. Feature Extraction

In the literature, several feature spaces for image steganalysis have been researched. One of them is based on discrete cosine transform residuals (DCTR) [12], the main purpose of which is to analyze the data resulting from obtaining the DCT value for a given image. First, in this method, a random 8 × 8 pixel filter is created that will be applied to the entire analyzed set. Then, a histogram is created after applying the convolution function with the previously mentioned filter, iterating through each fragment of the analyzed image. In [13], an example of using DCTR parameters in connection with a multi-level filter is proposed. A different variation of this approach is a method based on gabor filter residuals (GFR) [14]. It works in a very similar way to DCTR, but instead of a random 8 × 8 filter, Gabor filters are used. Article [15] describes a successful application of GFR features in JPEG steganography detection. Another approach to parameterization is using the phase aware projection model (PHARM) [16]. In this approach, various linear and non-linear filters are used, while the histogram is constructed from the projection of values for each residual image fragment.

#### 2.2.2. Shallow Machine Learning Classifiers

A number of shallow classification methods have been proposed for JPEG steganalysis. These include the use of algorithms such as support vector machines (SVM) [17–19] or logistic regression [20]. A method often appearing in recent publications is an ensemble classifier built using the Fisher linear discriminant (FLD) as the base learner [21]. In certain cases [7], parameter extractors coupled with this ensemble classifier outperformed more recent deep learning-based systems. As such, this algorithm has become a point of reference when looking into the performance of shallow ML methods in detecting steganography. The rationale driving attempts to increase its detection accuracy is the fact that data is split randomly into subsets used to train each base learner. Thus, it may be possible that certain base learners are assigned less varied datasets. Their detection accuracy may suffer from poor generalization capabilities. Simple ensemble vote-combining methods such as the one used by default do not take such effects into consideration.

#### 2.2.3. Deep Learning Methods

In recent years, neural networks have often been reported as being used for detecting steganographically hidden data in digital images. As input data, extracted image parameters based on decompressed DCT values such as DCTR, GFR, or PHARM have been used. Proprietary variants of convolutional networks such as XuNet [22], ResNet [23], DenseNet [24], or AleksNet [25] are most often used for this purpose. The common feature of these networks is combining the convolution-batch normalization-dense structures, i.e., the convolutional function, the normalization layer, and the basal layer of neurons with the appropriate activation function. Functions such as sigmoid [26], TLU [27] (threshold linear unit), and Gaussian [28] are used, but the most common are rectified linear unit (ReLU) [29] or TanH [22].

#### **3. Materials and Methods**

In our experiments, we compared how shallow and deep learning methods cope with detecting hidden data in JPEG images. We tested a variety of deep and shallow ML-based classifiers and various feature spaces. Initially, we used raw DCT coefficients as input for the tested methods. As it did not produce satisfactory results, we extracted various parameters from the images. We performed experiments in DCTR, GFR, and PHARM feature spaces. We taught our models features extracted from pairs of images: without and with steganographically hidden data. Details of the data and the classifiers used are presented in the next subsections.

#### *3.1. Datasets Used*

We used the "Break Our Steganograhic System" (BOSS) image collection [30], which contains 10,000 black and white photos (with no hidden data). The photos were converted into JPEG with a quality factor of 75. Then, we generated three other sets of images, hiding random data with a density of either 0.4 or 0.1 bpnzac, using three different steganographic algorithms: J-Uniward, nsF5, and UERD. We used their code published at [31]. All experiments, including generation of the steganographic files, were run on a virtual machine with 64 GB RAM and 8 vCPU cores of Intel Xeon Gold 5220 processor, running on a DELL PowerEdge R740 server. Each dataset was divided in parallel into training and test subsets, in the ratio of 90:10.

#### *3.2. Configuration of Ensemble Classifier*

The base component of the shallow classifier is the ensemble classifier based on the FLD model [21]. A diagram presenting the way the ensemble classifier operates is shown in Figure 2. The set of feature vectors created by extracting DCTR, GFR, or PHARM characteristics from pictures is used to generate smaller subsets through a random selection of samples from the original set (a process called bootstrapping). These subsets are then used to train individual base learners independently from each other to diversify their classification logic. Throughout the training process, the size of the subset and the population of the ensemble (the number of base learners) is adjusted to minimize the out-of-bag error of the system. These subsets are then used to train individual base learners. Upon testing, each base learner reaches its decision independently of others and the results from the whole "population" are aggregated to produce a single decision.

**Figure 2.** A diagram showing the structure of the ensemble classifier.

In our work, we focused on maximizing the detection ability of this classifier through the use of various methods to combine the votes of base learners. While the individual votes in the original ensemble were fused by simply choosing the more popular classification decision, we decided to explore the potential gain of employing machine learning for this. We trained the original ensemble classifier and then used it to obtain the decisions of all base learners for both the training and testing sets. The resulting data formed new feature vectors, which were used for further analysis with different ways of combining the votes of individual base learners. We performed this analysis using primarily methods implemented in the scikit-learn library [32]. As such, the original ensemble became a dimension-reducing layer.

#### *3.3. Deep Learning Environment*

The neural network environment was based on the Keras [33] and Tensorflow [34] library due to the simplicity of the model definition. The network architecture was mainly based on the Dense-BatchNormalization structure, but not using the convolution part as described in the available literature. We also tested various activation functions for the dense layer, such as sigmoid, softsign, TanH, and softmax, but the best results were obtained for the ReLU function. We used two optimizers: adaptive moment estimation (Adam) [35] and stochastic gradient descent (SGD) [36], which gave different results depending on the type of input parameters. The last parameter that significantly influenced the model learning efficiency was the learning rate. We found that lowering it gave very promising results without changing the network architecture and the optimizer. One of the network configurations used is displayed in Figure 3.

**Figure 3.** Example of 3 Dense-BatchNormalization neural networks used for detecting data hidden by a JPEG-based steganographic method.

#### *3.4. Testing Scenarios*

For the shallow ML-based algorithms, we decided to focus on the ensemble classifier, which has been reported in related studies as one of the most promising. During our experiments, we verified a number of ML-based methods used to combine the set of votes coming from all base learners to return the final classifier decision. These include: linear regression, logistic regression, linear discriminant analysis (LDA), and *k* nearest neighbors (*k*-NN). Moreover, the majority voting scheme (i.e., choosing the most popular classification decision, which is the original ensemble vote fusion method), as well as unquantized majority voting (i.e., classification based on the sum of non-quantized decisions of the whole ensemble) was included for comparison.

As for deep learning methods, two network architectures were selected for experiments:

We decided not to use any convolutional layers due to their high computational requirements. However, we used additional normalization layers (BatchNormalization) between the dense layers. Half of the three-layer dense models used the Adam optimizer and half used SGD models, while the two-layer dense model used only the Adam optimizer. In the case of learning rate for the Adam optimizer, the values 1 × *e*−4 or 1 × *e*−5 were used, while for SGD, 1 × *e*−3 or 1 × *e*−4 were used. The version of the SGD optimizer with learning rate 1 × *e*−3 or 1 × *e*−4 and the 1 × *e*−4 version of the Adam optimizer were omitted here, because they yielded much worse results compared to the version with three dense layers. In total, five different neural network configurations were tested for steganography detection.

#### *3.5. Evaluation Metrics*

To evaluate the models created, we employed commonly used metrics. The first is accuracy, which indicates what percentage of the entire set of classified data is the correct classification. The second metric is precision, which determines what proportion of the results indicated by the classifier as belonging to a given class actually belongs to it. Another metric is recall, which determines what part of the classification results of a given class is detected by the model. The fourth metric analyzed is the F1-score, which is the harmonic mean of precision and recall. It reaches 1.0 when both components give maximum results. The last metric we used to test the effectiveness of the model is the area under the ROC curve (AUC). We will also present the ROC curves themselves, as they visually present the effectiveness of the detection model.

In our results, we focus on evaluating the accuracy for each model combination, while for the best parameters we also provide the values of the other metrics. Since the testset is ideally balanced, the accuracy score is not biased and reflects well the detection ability of a given classifier.


**Solving Inverse Heat Transfer Problems When Using CFD Modeling**

Paweł Ludowski, Dawid Taler and Jan Taler

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/63807

### **Abstract**

The chapter presents solving steady-state inverse heat transfer problems using Computational Fluid Dynamics (CFD) software. Two examples illustrate the applica‐ tion of the proposed method. As the first inverse problem determining the absorbed heat flux to water walls in furnaces of steam boilers is presented in detail. Three different measurement devices (flux tubes) were designed to identify steady-state boundary conditions in water wall tubes of combustion chambers. The first meter is made of a short eccentric tube in which four thermocouples on the fire side below the inner and outer tube surfaces are installed. The fifth thermocouple is situated at the rear of the tube on the housing side of the water wall tube. The second meter has two longitudi‐ nal fins that are welded to the bare eccentric tube. In the third option of the instru‐ ment, the fins are attached to the water wall tubes but not to the flux tubes as in the second version of the flux tubes. The first instrument is used to measure the heat flux to water walls made from bare tubes, while another two heat flux tubes are designat‐ ed for measuring the heat flux to membrane walls. Unlike the existing devices, the flux tube is not attached to neighboring water-wall tubes. The absorbed heat flux on the outer surface and the heat transfer coefficient at the inner surface of the flux tube are determined from temperature measurements at internal points. The thermal conduc‐ tivity of the flux-tube material is a function of temperature. The nonlinear inverse problem of heat conduction (IHCP) is solved using the least-squares method. Three unknown parameters are determined using the Levenberg–Marquardt method. In each iteration, the temperature distribution in the cross section of the heat flux instrument is determined using the ANSYS/CFX software.

Another inverse heat transfer problem will be a CFD simulation carried out for the platen superheater placed in the combustion chamber of the circulating fluidized bed (CFB) boiler. Velocity, pressure, and temperature of the steam, as well as the tempera‐ ture of the tube wall with the complex cross section, were computed using the ANSYS/ CFX software. The direct and inverse problems were solved. In the first inverse problem, the heat transfer coefficient on the flue-gas side was determined based on the meas‐

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ured steam temperature at the inlet and outlet of the three pass steam superheater. In the second inverse problem, the inlet steam temperature and the heat transfer coefficient on the flue-gas side were estimated using measured steam temperatures at selected locations of the superheater. The Levenberg–Marquardt method was also used to solve the second inverse problem. At every iteration step, a direct conjugate heat transfer problem was solved using the ANSYS/CFX software. The CFX program was called and controlled by an external program written in Python language. The Levenberg– Marquardt algorithm was also included in the Python program.

**Keywords:** CFD modeling, inverse heat transfer problem, heat flux measurement, pulverized coal-fired boiler, furnace, water wall, circulating fluidized bed boiler, plat‐ en superheater


**Preface to "Circuits and Systems Advances in Near Threshold Computing"**

Modern society is witnessing a sea change in ubiquitous computing, in which people have embraced computing systems as an indispensable part of day-to-day existence. Computation, storage, and communication abilities of smartphones, for example, have undergone monumental changes over the past decade. However, global emphasis on creating and sustaining green environments is leading to a rapid and ongoing proliferation of edge computing systems and applications. As a broad spectrum of healthcare, home, and transport applications shift to the edge of the network, near-threshold computing (NTC) is emerging as one of the promising low-power computing platforms. An NTC device sets its supply voltage close to its threshold voltage, dramatically reducing the energy consumption. Despite showing substantial promise in terms of energy efficiency, NTC is yet to see widescale commercial adoption. This is because circuits and systems operating with NTC suffer from several problems, including increased sensitivity to process variation, reliability problems, performance degradation, and security vulnerabilities, to name a few. To realize its potential, we need designs, techniques, and solutions to overcome these challenges associated with NTC circuits and systems. The readers of this book will be able to familiarize themselves with recent advances in electronics systems, focusing on near-threshold computing.

> **Sanghamitra Roy** *Editor*


New Approaches in ADHD Diagnostic

#### **Chapter 1**

## Introductory Chapter: ADHD Has Many Faces

*Hojka Gregoric Kumperscak*

#### **1. Introduction**

Attention deficit hyperactivity disorder (ADHD) is nowadays not only the most prevalent neurodevelopmental disorder [1] but also the most troublesome mental disorder that I have come across. A problem arises already with the name. International Classification of Diseases (ICD-10) uses the term Hyperkinetic Disorder [2] whereas as per the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the term is ADHD [3]. This is not only a semantic problem but the diagnosis criteria are significantly different (DSM has broader and less strict diagnosis criteria, so it encompasses more people) and lead to substantial differences in both its prevalence and treatment [4].

Not so long ago, students at medical faculties were taught that ADHD was a children's disorder that abated during adolescence and was non-existent in adulthood. Today, both clinical experience and all of the studies show that, in the majority, the disorder persists into adulthood but manifests itself differently.

#### **2. From symptoms to broader diagnostic thinking**

The most recognisable symptom group of ADHD is hyperactivity that is only seen in childhood. It does not take much knowledge to think of ADHD in a child that moves, runs and climbs incessantly, regardless of the dangers, and of that child being hyperactive. The problem of recognising ADHD in a child is already posed by clinical presentation without hyperactivity (ADD).

Although most children with ADHD have hyperactivity, it already abates in adolescence. It gets replaced by an inner restlessness. Again, we find ourselves in front of a major differential diagnostic problem. Which adolescent is not internally restless or tense? The developmental tasks that adolescents face lead to inner restlessness in at least some developmental periods in almost all of them. Inner restlessness is also a common complaint of adolescents and adults with depression, anxiety, psychosis or other mental disorders. Few experts think first of ADHD in case of inner restlessness.

Another group of ADHD symptoms is equally 'problematic'–impulsiveness. Impulsiveness is also a norm in adolescents since youth is essentially a synonym for quick, reckless decisions–jumping over a ditch where there is a bridge. Impulsiveness is also characteristic of many other mental disorders apart from ADHD. It is at the heart of behavioural disorders, some personality, organic and other mental disorders. The problem with recognising ADHD is its varied symptoms shared with so many other mental disorders or life periods. Which expert would think first of ADHD upon hearing complaints of inner restlessness and impulsiveness in adolescents or adults?

For this reason, it is necessary to broaden the diagnostic thinking out of the boundaries of traditional assessment (based on questionnaires and behavioural scales) in work with patients and parents and diagnostic in general. When working with parents, it is good to know how hereditary the disease is and how important the etiological factor genetic is (around 75%) [1, 5]. It is necessary to know the influence of genetics and think of endophenotypes. The study of vulnerable traits associated with impulsiveness and attention deficit provides for an alternative diagnostic approach. Quantitatively, these traits could define a specific endophenotype. This view would allow for a more precise medical/psychological assessment focus on the patient along their lifespan, avoiding diagnosis based on the number of symptoms [6–8].

#### **3. ADHD can be a devastating disorder if not recognised and treated in childhood**

Children with ADHD usually stand out with their behaviour featuring hyperactivity and impulsiveness. Many also have comorbid language difficulties and other learning disorders, often resulting in academic underachievement. For this reason, these children find themselves more quickly, more frequently and more intensively subjected to criticism by teachers, parents and peers. Children with ADHD are more likely to be socially excluded by their peers than children without ADHD. The nature of ADHD makes it harder for children to concentrate and follow the playing rules, forcing them to react too quickly and inappropriately. Children with ADHD can do extremely well in individual sports (swimming, cycling, running), but they do not do well in team sports, sooner or later, they come into conflict with their teammates/coaches/referees precisely because of the characteristics described above. They develop a poor self-image, begin to withdraw from society, and may become anxious, depressed or behaviourally problematic. They are more likely than the general population to seek reassurance from alcohol and psychoactive substances (PAS), using them as a form of selfmedication.  Less studied, although also important, is the effect of ADHD on language. A 'pure' clinical presentation is no longer seen in adolescents with ADHD. It is hidden in depression/dysphoria/irritability, PAS abuse, anxiety, poor self-image and behavioural disorder. It is only when (if) all these layers are slowly peeled away that we get to the core problem—ADHD.

In adults, there is another problem: ADHD symptoms become internalised. If someone has always been forgetful, deviant, unpunctual, conflicting, then one adopts these symptoms as personality traits rather than symptoms of a disorder that could be treated. This is also how others see them—as distracted, unreliable, rarely finish what they start—not as someone with a mental disorder. Thus, in adults, the problem of ADHD continues into treatment. Even when we have diagnosed ADHD in an adult, it is difficult to motivate them to seek treatment. They ask questions like: if they have been like this since birth, are we going to change their personality with treatment? It takes a lot of education and motivation to get them to accept and persevere with treatment. It is necessary to explain that treatment will enable them to express all the creative and positive things that have not yet come out. It will allow them to concentrate on important things rather than running from one thing to another and finally completing only a few or none of the tasks. Their interpersonal relationships will also change for the better, as they will be able to listen to others and not react so impulsively without any consideration of the consequences.

### **4. ADHD: is there anything positive?**

We should not forget about the possible positive consequences of ADHD—high energy, the ability to react quickly, the ability to multitask, to have innovative ideas, not to stick to routines, and to find new solutions. The list goes on and on. It is said that a person with ADHD had an evolutionary advantage in the past. In the wild, it was vital to be able to pay attention to several stimuli at the same time, to react to any one of them quickly and without thinking about the consequences. Unfortunately, today's high-performance and efficiency-oriented times are not favourable to people with ADHD.  Nowadays, even 6-year-olds have to sit for 45 minutes at school, which is very questionable from a developmental point of view. Therein lies the answer to the question of how it is that we are diagnosing this disorder increasingly frequently. We are detecting it more because nowadays, people with it are significantly less able to function on a daily basis than they were a few decades ago. If we know that hyperactivity is a symptom of ADHD that abates first, it is understandable that children entering the school at 7/8 years of age did not have the same problems as today's younger first graders. In the not-so-distant past, children were free after school or involved in significantly fewer after-school activities than today, and their potential attention deficit disorder did not have so much 'space' to become a problem. The movement used to be something natural and given to all children, but today we find that children are physically incapable. It is not the present time that has made ADHD, but in today's time, people with ADHD, who are no more numerous than in the past, are simply decompensating sooner.

#### **Author details**

Hojka Gregoric Kumperscak1,2

1 Child and Adolescent Psychiatry Unit, University Medical Centre Maribor, Maribor, Slovenia

2 Faculty of Medicine, University of Maribor, Maribor, Slovenia

\*Address all correspondence to<EMAIL_ADDRESS>
© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### **References**

[1] Polanczyk G, de Lima MS, Horta BL, Biederman J, Rohde LA. The worldwide prevalence of ADHD: A systematic review and metaregression analysis. The American Journal of Psychiatry. 2007;**164**:942-948

[2] World Health Organization. International Statistical Classification of Diseases and Related Health Problems (ICD-10). 10th Revision ed. World Health Organization; 2010

[3] American Psychiatric Association. *Diagnostic and Statistical Manual of Mental Disorders*. 5th ed. Arlington, VA: American Psychiatric Publishing; 2013

[4] Taylor E, Döpfner M, Sergeant J, Asherson P, Banaschewski T, Buitelaar J, et al. European clinical guidelines for hyperkinetic disorder - First upgrade. European Child & Adolescent Psychiatry. 2004;(Suppl 13):17-30

[5] Van Loo KM, Martens GJ. Genetic and environmental factors in complex neurodevelopmental disorders. Current Genomics. 2007;**8**:429-444

[6] Miranda P, Cox CD, Alexander M, Danev S, Lakey JRT. In quest of pathognomonic/endophenotypic markers of Attention Deficit Hyperactivity Disorder (ADHD): Potential of EEG-based frequency analysis and ERPs to better detect, prevent and manage ADHD. Med Devices (Auckl). 2020;**13**:115-137. DOI: 10.2147/mder.S241205

[7] Slaats-Willemse D,

Swaab-Barneveld H, De Sonneville L, Van Der Meulen E, Buitelaar J. Deficient response inhibition as a cognitive endophenotype of ADHD. Journal of the American Academy of Child and Adolescent Psychiatry. 2003;**42**(10): 1242-1248. DOI: 10.1097/00004583- 200310000-00016

[8] Vargas JP, Díaz E, Portavella M, López JC. Animal models of maladaptive traits: Disorders in sensorimotor gating and attentional quantifiable responses as possible endophenotypes. Frontiers in Psychology. 2016;**7**(206):1-9. DOI: 10.3389/fpsyg.2016.00206

#### **Chapter 2**


**4. Collective response to carrying capacity deficit**

Earth has just added a seven-billionth person to its contemporary human population-load as I write this, a mere dozen years after this finite planet reached the six billion mark! Moreover, much of that enormous population has been living prodigally by lavish use of non-renewable resources. In the aftermath of "the" industrial revolution, adopting internal combustion engines for the accomplishment of many human tasks had made "developed" societies increasingly dependent upon Earth's inevitably dwindling stocks of crude oil. Since Earth's finite deposits of this fundamentally non-renewable natural resource were destined to become scarcer and scarcer as a result of rapid use, modern lifestyles, present or aspired to, were thus inherently self-destructive. A crescendo of difficult circumstances that will confront human societies has been forecast by a growing number of ecologically informed writers (Udall, 1980; Youngquist, 1997; Greer, 2011).

This developing predicament cannot be wished away, but many sociologists have disregarded its relevance to their discipline's concerns. However, at least collective behavior

But today again we live in a troubled time, in various ways reminiscent of those 1930s. Erosion of optimism today has deeper ecological roots than sociologists have been inclined to consider. The lack of vital ecological insights, both among the public (and their elected representatives in government) and among most sociologists is proving tragic. Principles of ecology as developed in the biological sciences suggest that this twenty-first century will most probably be seen in retrospect as "the bottleneck century." Human societies will have had to pass through a period of monumental hazards, resource insufficiencies, hostile interactions, and inequitably distributed hardships. Human numbers will have ceased growing; in many parts of the world, population will have actually declined. Standards of

Sociological attempts to explain these conditions and calamities will be constricted by lack of ecological understanding. Sociological predictions will likely founder in misconception of our true ecological condition, misconceptions enabled by our anthropocentric restriction of

Public recognition of, and adequate adaptation to, the deteriorating ecological context of human life has been impeded by conventional preoccupations. Short-term concerns tend to blind people at all societal levels to omens of a fundamentally altered future. To elude such preoccupations, sociologists must at last abandon the notion that "human ecology" is only a minor subdiscipline of sociology, of marginal relevance to "the big issues." That is a notion prevalent since "the Chicago School" of sociologists early in the 20th century imported into the sociological vocabulary a few ecological terms and applied them principally to the study

Certain crucial ambiguities in pioneer writings about the sociological applicability of ecological principles had enabled derailment of recognition that humans are inextricably involved along with other species in ecosystem patterns and principles. This necessary understanding was lost in treatment of human ecology as *merely analogous* to bio-ecology

Earth has just added a seven-billionth person to its contemporary human population-load as I write this, a mere dozen years after this finite planet reached the six billion mark! Moreover, much of that enormous population has been living prodigally by lavish use of non-renewable resources. In the aftermath of "the" industrial revolution, adopting internal combustion engines for the accomplishment of many human tasks had made "developed" societies increasingly dependent upon Earth's inevitably dwindling stocks of crude oil. Since Earth's finite deposits of this fundamentally non-renewable natural resource were destined to become scarcer and scarcer as a result of rapid use, modern lifestyles, present or aspired to, were thus inherently self-destructive. A crescendo of difficult circumstances that will confront human societies has been forecast by a growing number of ecologically

This developing predicament cannot be wished away, but many sociologists have disregarded its relevance to their discipline's concerns. However, at least collective behavior

**3. The new challenge**

living will have fallen.

of *urban* life.

(Catton 1992).

the scope of "human ecology" (Freese, 1997).

**4. Collective response to carrying capacity deficit**

informed writers (Udall, 1980; Youngquist, 1997; Greer, 2011).

theory in sociology (Turner, 1964) has developed enough research-supported insights to shed important light on the ways people, organizations and societies can be expected to respond to such circumstances. Such light may be as unwelcome as is the changed state of the world it reveals. Even if the facts made evident are unwelcome, sociologists are obliged to face and clarify them.

In coming decades, because of changes to planet Earth wrought by human activities since the industrial revolution, mankind is certain to experience frustrated hopes, declining material wealth, deteriorating quality of life in befouled and ravaged environments on every continent. Intensified worldwide competition for diminishing natural resources has become inevitable, as have mounting pressures toward social reorganization along unwelcome lines (see Brown, 1981; CEQ and Dept. of State, 1980; Hayes, 1979; Henshaw, 1971; Lerner, 1981; Peccei, 1981; Stoel, 1979). On the basis of collective behavior theory we can expect one or more of the following responses: panic, terror, genocidal wars. These are likely responses to our deepening ecological predicament. Only if accurately foreseen, may the pressures otherwise likely to induce destructive responses not have to impel people and nations to commit disastrously misguided and seriously counterproductive reactions.