Exobiology: PRINCIPLE, Processes and Applications

Submitted By:- Guided By:-

Khooshboo Agarwal Mr. S. K. OjhaClass XII PGT BiologySession: 2011-2012 K.V. NEIST, JorhatAISSCE Roll No:- Assam

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CERTIFICATEI certify that, MISS KHOOSHBOO AGARWAL a student of class XII , Session – 2011-12 has prepared this Project report titled “Exobiology : principles, processes and applications” under my guidance for the partial fulfillment of AISSCE-2012 Biology Practical.

This is the bonafide record of her experiment she performed. During the project work, I found her sincere and hard -working.

I wish her every success in life.

Santosh Kumar Ojha PGT, Biology K.V., NEIST Jorhat

External ExaminerBiology Practical

AISSCE 2012

Preface2

Human mind is always curious to search for a new earth i.e. living planet. This project is an attempt to explore possibilities of existence of life on alien planets. Not only are these, the basic conditions necessary for origin of life also being discussed in this project elaborately.

From this project I grab the opportunity to know the principle and procedure of exobiology, its applications and the future prospects. I discussed this interesting topic in depth with our Biology teacher and also incorporated the insight of physical phenomenon associated to Biophysics from our honourable Physics teacher. A healthy and strong discussion on the topic with other concerned people also added up a new dimension in my findings.

In this investigatory project I have tried my level best to bring out all ins and outs associated with the same.

ACKNOWLEDGEMENT

No any constructive work can successfully be accomplished without the support and help of able hands.

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This project work is also not an exception.

Here I take the opportunity to express my heartfelt gratitude to those supporting hands. I am greatly indebted to Shri S.K.Ojha, PGT (Biology) for his constant guidance and constructive support in carrying out this project work successfully and for providing such an opportunity in learning. The undersigned is also thankful to Mr. M. C. Nath, Lab Attendant for the laboratory support in this context.

Last but not the least; I’m thankful to my parents who rendered their support in every possible way to complete the Project Work successfully.

Khooshboo Agarwal Class: - X II K.V. NEIST JORHAT

CONTENTSPage No.

CERTIFICATE 2

PREFACE 3

ACKNOWLEDGEMENT 4

INTRODUCTION 6

OBJECTIVES OF EXOBIOLOGY 7

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EXISTENCE OF LIFE OUT FROM EARTH 9

UNIVERSAL CIRCUMSTANCES OF LIFE 10

EMERGENCE OF LIFE: CONDITIONS 12

EXTRATERRESTRIAL ORGANISMS 21

EXTRATERRESTRIAL ENVIRONMENTAL CONDITIONS 22

CRITICISMS AGAINST EXOBIOLOGY 25

DETECTION OF BIOMOLECULES IN SPACE 28

RECENT FINDINGS 29

UP TO DATE EXPERIMENTATION 31

CONCLUSION 32

PHOTO GALLERY 33

BIBLIOGRAPHY 35

INTRODUCTION

From the biophysical background explain, we can obtain a conceptual definition of Exobiology. Exobiology is a term derived from three Greek roots :- Έξω= extension; external, outside; Βίος = life and Λόγος = science, treatise, discourse.

From here, the concept takes the following form:

Astrobiology is a biological science that studies the origin

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and the existence of living beings in the Universe, besides Earth.

SYNONYMS OF EXOBIOLOGY:

The synonyms of Exobiology are diverse; however, the synonyms were structured in relation to the most important sciences implied in its development, Astronomy and Biology:

OBJECTIVES OF EXOBIOLOGY

The efforts of the exobiology direct to the search of:

a. The origin and evolution of the Universe.

b. The origin and evolution of living beings on Earth.

c. The distribution of living beings in the known Universe.

d. The existence of living beings on other worlds besides Earth.

SCIENCES ON SUPPORT OF EXOBIOLOGY:

The exobiology is a biological science that is supported

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by other factual disciplines, for example, Physics, Chemistry, Geology, astrophysics, Astronomy, paleontology, Cosmology, Molecular Biology, Mathematics, etc. 

Relation of exobiology with physics:-

a. Because life can be reduced to well-known thermal phenomena.

b. Because the living beings obtain, store and manipulate the energy of the cosmos.

c. Because we can formulate the densities, positions and movements of the energy usable by living beings.

Relation of exobiology to chemistry:-

a. Because the biosystems are molecular systems.

b. Because the synthesis of living beings derived from the inorganic synthesis of simple and complex biomolecules.

c. Because the life of an organism is maintained and continued through chemical processes.

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EXISTENCE OF LIFE, OUT FROM EARTH

The number of stars in the Milky Way is from 200 to 400 billion stars. Besides, there are approximately 500 billion galaxies in the Universe. If each galaxy had from 200 to 400 billion stars, then there would be from 20 to 200 trillion stars in the observable Universe.  If each star were encircled by 10 planets, then there would be from 500 to 2000 trillion planets in the Universe. A quantity very low from the trillions that the actor Sam Neill claims in a program of Discovery Channel about Life in the Universe.

It would seem that the probabilities of the presence of Earth-like planets in the universe, inhabited by intelligent beings, would be very high. However, we do not have the most minimum evidence about their existence. We have not found a single extra solar planet alike Earth.

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UNIVERSAL CIRCUMSTANCES OF LIFE

a. The thermodynamic laws operate in the known Universe.

b. The particles are the same in the whole Universe.

Few inferences of Astrobiologists:

A) The living forms in the entire Universe should depend on liquid water.

Because:

1. Water is available in the entire observable Universe.

2. Water is a thermo regulator for the atmosphere and into the bodies of living systems by the next properties:

● Its specific heat, that is to say the quantity of heat needed to increase the temperature of one gram of a substance in one degree Celsius. For water, it is one calorie.

● Its boiling point, which consists of the change of phase of a substance from a liquid phase to a gas phase. We need to apply 540 calories to evaporate one gram of water.

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● Its solidification point, that is to say, the heat we have to extract so that a substance changes from the liquid phase to a solid phase.

3. Water is the universal solvent.

B) Life in the known Universe should be experienced by structures made with Carbon.

Because

1. It is an abundant element in the Universe.

2. It is available for living beings like carbon dioxide in the atmosphere and in water, and like carbonates in soil.

3. It is the most versatile element to form compounds.

4. The compounds formed by Carbon are very stable.

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EMERGENCE OF LIFE: CONDITIONS

A THREE-DIMENSIONAL SPACE- Living system (biosystems) needs a field in the Universe containing a space with three dimensions, longitude, width and deepness.  

TIME- Living systems need a field in the Universe that includes available microstates to which their internal energy can be transferred and from which they can obtain energy. The measurement of the flow of energy toward more available microstates is what makes perceptible the dimension of time. Time flow is constant, although it appeared to be changeable from the human perspective.

SOURCE OF ENERGY- Living beings must receive a stable and continuous supply of energy from a star. Earth receives a continuous and stable tide of energy from a star (the Sun); besides, Earth is positioned at a suitable distance from the Sun (the Earth is placed at 1 AU = 1.49597870691 x 1011 meters far from the Sun), not too near as to be scorched by the intense solar radiation (as Mercury and Venus), neither too far as to be frozen in the cold sidereal space (as the outer planets like Mars, Jupiter, Saturn, etc.). The source of energy may not be necessarily a star. The planet that shelters living forms can be itself the source of that energy needed for life.

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G class stars (yellow-white, with nuclear fusion reactions of Hydrogen and effective temperatures of 5300-6000 K. G Class are Sun-like stars) that belong to the main sequence (V or dwarf) are the most possible stars to have planets with optimal conditions for the origin and evolution of living beings. The Sun is a star of class G2V (surface effective temperature of 5800 K).

A STEADY AXIS OF ROTATION- The planet should have a stable axis of rotation. Earth has a big Moon that controls its spinning. The Sun and the Moon control the rotary motion and the orbital trajectory of Earth. However, even when this factor has been greatly important for living beings on Earth, it could be not obligatory for life forms on other planets. There are zones between the hemisphere that always faces to sun and the hemisphere that never faces to sun called twilight zones; life may flourish at twilight zones on planets without a big satellite as well as at planets with a stable axis of rotation.

A MAGNETIC FIELD- The planet that would hold living beings must have a protective field shield against massive particle's radiance during solar electromagnetic storms. Earth has an efficient magnetic field shield.

A PROTECTIVE ATMOSPHERE- The planet which would

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give shelter to living forms must have a protective atmosphere against cosmic radiation. Earth has an ozone layer, but it could be also dense clouds of dust and water vapor.

WATER- Living beings have to be formed in environments rich on water. This is certain because water has unique physicochemical qualities.

For example water molecules are disintegrated during the photosynthesis process, freeing oxygen atoms and electrons.

Water acts as a thermo regulator for climate and living systems. HOW THERMOREGULATOR?

Water maintains the climate of the Earth stable. Water works also as a thermo regulator in living systems, especially in endothermic animals.

It is possible because of the specific heat of water (specific heat is the heat in calories necessary to elevate the temperature of one gram of a substance in one degree Celsius), which for water is one calorie. In biological terms it means that before an elevation of the temperature in the surrounding environment, the temperature of a mass of water will rise with greater slowness than the temperature of other materials. Equally, if the surrounding temperature diminishes, the temperature of that mass of water will diminish with more slowness than that of other materials. Thus, this thermal property of water permits that the aquatic organisms live

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relatively placidly in an environment with a stable temperature.

Evaporation is the change of the physical phase of a substance from a liquid phase to a gaseous phase. We need 540 calories to evaporate a gram of water. At this point water boils (point of boiling). This means that we have to rise the temperature at 100°C to do water boils. When evaporates from the surface of the skin or from the surface of the leaves of a plant, the water molecules hold large quantities of heat. This feature works in the organisms like a cooling system.

Another advantage of water is its melting & freezing point. The extraction of heat from a substance changes it from a liquid phase to a solid phase. The temperature at which a substance changes from a liquid phase to a solid phase is called the freezing point. To change the water physical phase from liquid to solid we have to diminish the surrounding temperature at 0°C. The change of one gram of ice to liquid water requires a supply of 79.7 calories. When ice melts, the same amount of heat is released to the environment. This allows that the environmental temperature does not decrease to the point of annihilate all the life on the planet through winters.

Besides, water is a universal solvent. Almost all

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substances essential to sustain the living forms can be dissolved in water. Besides of being accessible for living beings, water acts as the best vehicle for food transporting so in the external environment as in the internal environment of all known organisms.

CARBON- Carbon is available for living beings mainly in the form of atmospheric carbon dioxide. It can be also found in carbonates in the soils. The Carbon has six electrons in its first level of energy and four in the second level of energy, sharing electrons with other elements in four covalent bonds (tetravalent), which makes it the most flexible element to form compounds (organic compounds, because they have Carbon in their skeletons) For example, Silicon atoms have also four electrons in its outer shell, but Silicon is heavier than Carbon (Silicon's atomic weight is 28.0855, instead, Carbon's atomic weight is 12); because of it, Silicon cannot offer the versatility presented by Carbon. The skeletons formed by Carbon atoms can vary in length and array (linear and ring structures of the same compound). Until now we have not found life systems based on other elements.

Recently, the scientists of NASA( National Aeronautics and space administration) and ESA (European Space Agency) discovered that the Calcium Carbonate can be synthesized in the interstellar and interplanetary media without the presence of water (Cooper et all, 2001). This put in doubt the affirmations that the small

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carbonated globules found on Mars have originated in deposits of water. It is more probable that those Carbonates have been placed on the planet by a continuous and prolonged precipitation of dust from the Martian planetary cloud and from the Interstellar Medium, just as it occurred and continues occurring until now on Earth. The fractals of Calcium Carbonate in the planetary nebula would be suitable for the synthesis of biopolymers.

CONDENSER AGENTS- Substances that promote the abiotic synthesis of biomolecules, from simple biomolecules to complex biomolecules. For example, the HCN (Hydrogen Cyanide) and Acetylene. These compounds abound in the early interplanetary media and both have been tested artificially as condenser agents. The evidence indicates that the bio-polymerization of proteins and carbohydrates was facilitated by these agents and through reactions promoted mainly by high energy discharge.

Fractals are granules of cosmic dust. Fractals could work in a similar way by:

a. Shielding the biomolecules against cosmic radiation of high energy density.

b. As agglomerative substrates that “dehydrated” the niches wherein the synthesis of polymers

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occurred by the action of light and heat on the globules contained by water into the holes and fissures of dust grains, helping to the polymerization of simple molecules to form larger biomolecules. Many fractals contained drops of water which suffered regular phase transitions from liquid to solid and vice versa. Those fractals, or dust granules, could also function like agglomerative substrates.

All our observations on the abiotic synthesis of biological polymers point to the previous conclusions.

The ozone has become necessary and indispensable for the living beings on Earth; however, not only the ozone functions like a protector of living beings against the Cosmic Radiation. Dust and water vapor also act like shields against Cosmic Radiation. From the theory on the origin of life that when living beings emerged on Earth there was not an ozone layer and that the first bionts had to be protected against the cosmic radiation, composed mainly by wide streams of X-rays, emitted by an incipient Sun.

The fractals with frozen water trapped in their holes and fissures can act like shields against cosmic radiation. The protoplanetary disks are constituted by fractals of diverse dimensions and by heterogeneous substances that can act like protective screens.

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The fractals or granules of forsterite or magnesium silicate are Olivines produced at very high temperatures. This indicates that the comet Wild-2 -from where we have obtained fractals of olivine- was formed in a zone very close to the Sun or at a very hot place out from our solar system, at temperatures near or over 1000 K.  In this class of comets there could not have been synthesized complex organic compounds. It is more feasible than the biomolecules have been synthesized in the environment of planetary nebulas.

The grains of silicon carbide ejected by supernovas could have acted like agglomerative substrates wherein the biomolecules and the microspheres with lipidic membranes could have been synthesized.  Those fractals have also holes and fissures that could have been filled with water and fundamental substances that would build biopolymers.

Also the sidereal porous fractals, as the type Porous Chondrites formed by silicates, which molecular structure is not altered by heat, water and the chemical reactions that occur among simple molecules, could have acted like agglomerative substrates for the formation of biomolecules. It has been confirmed experimentally that some biomolecules, like ribose and amino acids, were synthesized in porous fractals. Later, the polymerization

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into the holes of the granules there could happen.

The question is whether those processes that occurred during the gestation of our Solar System could be frequent events in the whole Universe.

At least, we know that the chronicle of life on Earth shows a sequence of events strictly connected to the physical and chemical universal laws. So, the life on Earth is not unique and it has not derived from events given by accident. (Christian de Duve; 2006)

The occurrence of life on Earth has been determined by the Universal physical laws; consequently, the life on other worlds of our Cosmos cannot be microstructurally very different to the terrestrial life.

If there were a possibility of existence of other biotic configurations, these would exist now on Earth because the Fundamental Laws operate in the whole Universe and the particles and their properties are the same in the whole Universe.

EXTRATERRESTRIAL ORGANISMS

We could speculate a great deal on the probable appearance of the extraterrestrial living beings whenever

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we had taken into account the conditions of the probable environments of other planets. For` example, we can guess on the homeostatic systems of an organism living on a planet with a more or less dense atmosphere than the terrestrial atmosphere, or under a gravity force greater or lesser than the terrestrial gravity force, under a sulfurous atmosphere, etc. However, the astrobiologists have verified that the probabilities to find extraterrestrial intelligent organisms are extremely low. The signal "Wow!” registered by SETI (The Search for Extra Terrestrial Intelligence) in 1951, was an electromagnetic oscillation reemitted or bounced back by a fragment of spatial waste.

However, we can almost be sure that apparently the life can only be experienced by systems built with organic compounds (those built with Carbon), and that the biosystems living on other worlds should be similar to the terrestrial biosystems; at least, on microscopic structure and thermodynamic qualities, although their macroscopic appearance be totally different to the terrestrial organisms.

EXTRATERRESTRIAL ENVIRONMENTAL CONDITIONS

There are organisms that live in highly hostile

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environments for most terrestrial species; for example, Sulfolobus solfataricus, which tolerates sulfurous environments with acidity at pH 3.5 and temperatures at 90 C. Recently, it was discovered that the cooler effect of the cytosol of Sulfolobus solfataricus is due thanks to a protein (enzyme) called Alcohol Dehydrogenase.

Throughout the last 15 years, the astrobiologists have centered their attention on extremophiles. That obeys to the inhospitable environmental conditions exhibited by the planets at the scope of our technology which would be lethal for almost all the terrestrial living beings. Perhaps, some day we will find an Earth-like planet on where we will find not only extremophile prokaryotes, but also protists, plants and animals.

Extremophiles are organisms that live in extreme environments that would be deadly for the greater part of the terrestrial living beings; for example:

A. Thermophiles: Resistant to high temperatures (Pyrococcus lives in water at 113° C).

B. Psychrophiles: Resistant to very low temperatures (Cryotendolithotrophus lives in water at -15° C).

C. Acidophiles: Resistant to acidic environments (pH 0).

D. Alkalophiles: Resistant to alkaline environments (pH 9-11).

E. Xerophiles: Organisms that live in waterless

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environments.

F. Halophiles:Organisms that live in hypersaline environments (some halophiles tolerate environments with a 30% of salinity).

G. Deinococcus survives after being exposed to 500 thousand rads; besides, it tolerates high levels of UV light and radioactivity at the same time.

The human beings are not extremophiles because we live in the middle part situated between the extremes of the environmental variables. The extremophiles live in those extremes.

However, the planets that could shelter extremophiles must have environments with the following features:

A) The conditions of the biosphere should be heterogeneous.

B) There must be sectors with conditions that permit the spontaneous synthesis, the molecular stability and the thermal activation of biomolecules.

C) Under these two conditions, the extraterrestrial biosphere must have the next physical characteristics:

● The climatic variability must occur into the ideal patrons for the survival of bionts.

● It should possess the basic nutrients, sufficient for the subsistence of bionts.

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● It should maintain protective units against intense oscillations of the flow of energy from the source (a star, a planet core, etc.).

● The fluctuations of the chemical surroundings should not be extreme or abrupt.

CRITICISMS AGAINST EXOBIOLOGY

Some censors say that the extremophiles could have adapted to the hostile environments millions of years after the emergence of the first biotic forms. I agree, although it could also have been the opposite. The conditions considered today like deadly conditions were the prevailing optimum conditions for the occurrence of abiogenesis, and that the modern extremophiles can be the offspring of the survivors of those times.

They also argue that the possible extraterrestrial biosystems could follow evolutionary trajectories different to the trajectories followed by the terrestrial biosystems. Those probable extraterrestrial organisms could follow evolutionary trajectories different to the evolutionary

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trajectories of the terrestrial living forms, but hooked on the set of potential trajectories in the cosmos, not in a set of trajectories invented by the scientists.

The detractors noisily express that to think that all the biotical structures in the Universe are based on Carbon and Water is dogmatic and restrictive, and that the exobiologists should be open-minded towards the opinion of others. We hold an open-mind, but only toward things that are adjusted to the behavior of nature. Our duty is to reject every vestige of ideological pseudoscience. One thing is how nature behaves and another very different thing is what we know about that behavior. Our ignorance or our erudition do not influence in facts of nature.

The anti-exobiologists adduce that any living form in the universe would possess complex molecular structures, and that there would be no reason to be similar to the terrestrial bionts. There are cosmic molecular structures more complex than the living beings and they are not alive; for example, the Earth, an asteroid, Jupiter, the Sun, etc.

Some detractors of Exobiology have expressed that it seems that the exobiologists do not bear in mind the evolution when they are only seeking for primitive microorganisms on Mars. The reason to seek only for microorganisms on Mars is because it is a planet that has been vastly explored on which we have not observed

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multicellular living forms as those macroscopic bionts on Earth. There is no moss, lichens, grass, trees, insects, snails, worms, fungus, etc. They look for primitive microorganisms because we know that the favorable conditions for the evolution of multicellular organisms ceased some four billion years ago on Mars.

The emergency of living beings on Earth is not special and we assume that it is not unique. We unquestionably know that the emergence of life on our planet obeyed to the universal physicochemical laws and that it occurred simply because it had to occur like a natural and basic process, as well as it has to occur at any place of the Universe where the conditions that propitiated its development on Earth restage. This it is not a matter of conjectures, but of scientific knowledge that we have found out from nature.

Many detractors say that exobiology is not a science because it does not have a real object of study. Those antiscientific people do not have idea about what they claim because the living beings on Earth are creatures of the Universe, open to be studied because we have them here. Earth is a tiny part of the Universe, and astrobiologists are qualified to study the life at any nearby segment from the Universe.

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DETECTION OF BIOMOLECULES IN SPACE

A) Through Indirect Observation. For example, through infrared radiation telescopes, radio-telescopes, space telescopes, etc.

B) Through indirect observation by robotized probes carrying specialized laboratories to the planets or other sidereal bodies to be investigated; for example, Spirit, Viking, Opportunity, Mars Explorer, etc.

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RECENT FINDINGS THROUGH INDIRECT OBSERVATION

The spectrum of the star HH46-IR of the nebula IC1396 in the constellation of Cepheus, made by the infrared telescope Spitzer, reveals the existence of methane, water, carbon dioxide, silicates and methanol.

In Antenna galaxy, which actually consists of two colliding galaxies, scientists have detected sulfurous compounds, carbonates, water and heavy elements, like iron and magnesium.

In Orion Nebula scientists have detected large volumes of water.

They have also detected Polycyclic Aromatic Carbohydrates, water, methane and oxygen in the Horse Head Nebula. They found Glyceraldehydes in the most brilliant zones.

Supernovas are sidereal deposits of carbonates. Scientists have detected large quantities of oxygen, water and sulfurous compounds in remnants of

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supernovas.

The findings achieved from the mission Huygens-Cassini on Titan, a satellite of Saturn, confirm one of the predictions of my theory about the ringed planetary cloud. The theory explains the presence of methane, acetylene and ethanol of abiotic origin in abundant quantities in the external sidereal bodies (external bodies are those which orbit more distantly from the Sun than Earth).

In the South Pole Martian, the European Space Agency (ESA) has verified the existence of frozen water in relatively small quantities.  The largest mass of the ice is frozen carbon dioxide.

UP TO DATE EXPERIMENTATION

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Currently, the astrobiological experimentation is focused on the following aspects:

a. The modeling of the early conditions of the terrestrial reductive atmosphere which data we have known through the paleontology and geological observation.

b. The synthesis of prebiotic molecules and other organized structures through abiotic procedures.

c. The Experimentation with diverse factors that could activate the synthesis of prebiotic molecules in the primal terrestrial atmosphere and that can be applied to the observation of other stellar systems.

d. Trials with diverse electrodynamic fields to recognize stellar systems where the synthesis of biotic compounds may be occurring currently.

In astrobiological experimentation the investigator must abstain to get involved in the processes to avoid the effect of "external operator".  

CONCLUSION

Until now, we know that we are alone at this side of the Cosmos. Nevertheless, may be we are not the unique "alone" living beings in the Cosmos.  Perhaps, at this

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time, on a sidereal body barely heated by a small star, or on a world illuminated by a binary or a multiple star system, someone is asking itself (him, her or both) the same thing.

If the humanity takes care of the own humanity, attends his non-human brothers, those that barely think or that do not think, and takes care of the non-living things, the future of Astrobiology is promissory… whenever we explore what we have to explore, on feasible places to be explored.

PHOTO GALLERY

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Fig: Panoramic view of planet Mars

Fig: Interactions with Physics Sir

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Fig: Browsing net with Biology Sir for search of project material

Fig:

Showing draft of the project to Biology Sir

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BIBLIOGRAPHY

Campbell, Neil A., et al. Biology. Addison Wesley Longman, Inc. 1999, Menlo Park, CA.

Chandrashekhar, Joshi. Plasma Accelerators. Scientific American. February 2006; Vol. 294, No. 2; pp. 40-47. New York.

Cooper, G., Kimmich, N., Belisle, W., Sarinana, J., Brabham, K., Garrel, L. Carbonaceous Meteorites as a Source of Sugar-Related Organic Compounds for the Early Earth. Nature 414, 879 - 883; 20 December 2001.

Duve, Christian de. Fox, S. W. and Pappelis, A. Synthetic Molecular Evolution and Protocells: a review of Blueprint for a Cell: the Nature and Origin of Life. 1993, Quarterly Review Biol. 68: 79-82.

Fox, S. W. The Emergence of Life; Darwinian Evolution from the Inside. 1988, Basic Books, Inc., Publishers, New York, New York.

Gawiser, E., Silk, Joseph. Extracting Primordial Density Fluctuations. Science 1998 May 29; 280: 1405-1411.

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