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Astronomic Bioethics: Terraforming X Planetary protection 

Dario Palhares1 and Íris Almeida dos Santos2 
1. University of Brasília, Brazil - dariompm@unb.br 

2. Bureau of Education of Distrito Federal, Brazil - irisalmsan@gmail.com. 

 

Abstract: A hard difficulty in Astrobiology is the precise definition of what life is. All 

living beings have a cellular structure, so it is not possible to have a broader concept of 

life hence the search for extraterrestrial life is restricted to extraterrestrial cells. Earth is 

an astronomical rarity because it is difficult for a planet to present liquid water on the 

surface. Two antagonistic bioethical principles arise: planetary protection and 

terraforming. Planetary protection is based on the fear of interplanetary cross-infection 

and possible ecological damages caused by alien living beings. Terraforming is the 

intention of modifying the environmental conditions of the neighbouring planets in such 

a way that human colonisation would be possible. The synthesis of this antagonism is 

ecopoiesis, a concept related to the creation of new ecosystems in other planets. Since 

all the multicellular biodiversity requires oxygen to survive, only extremophile 

microorganisms could survive in other planets. So, it could be carried out a simulation 

of a meteorite by taking to other planets portions of the terrestrial permafrost, or ocean 

or soil, so that if a single species could grow, a new ecosystem would start, as well as a 

new Natural History. As a conclusion, ecopoiesis should be the bioethical principle to 

guide practices and research in Astrobiology.   

Key words: invasive species, ecology, oxygen, sulphur. 

Introduction: Technological advances in space sciences, expanding borders of 

knowledge and understanding of the universe, have widened our knowledge and 

deepened philosophical questions such as the origin of life, whether on Earth or on other 

planets. 

Research on extraterrestrial life as a scientific field was consolidated by NASA (National 

Aeronautics and Space Administration), the US space agency, with the creation of a 

programme on Astrobiology in 19981.  Galante et al.1 consider this policy to be a strong 

popular appeal for large funding required by this kind of research, that is, Astrobiology, 

which was created as a scientific and technological discipline by interaction among 

scientists, society, political and economic groups.  

Looking from the Universe, it is possible to highlight some important aspects of the 

terrestrial ecosystems, especially when human activities have produced unprecedented 

pollutants, disturbing climatic balance. Astrobiology also has bioethical nuances 

reflecting on the best for research on the Universe and on some terrestrial practices.   

Definition of life and delineation of the objectives of research: The first difficulty in 

the field of Astrobiology is to precisely define what life is. Although the recognition of 

a life being is simple, intuitive and instinctive, the formal definition of life is very 



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complex2. Life beings are distinguishable from the mineral due to their spontaneity and 

admirable ability of self-replication. They are fragile, perishable and doomed to death, 

but as they self-replicate, they show that life is strongly resilient: basically, where there 

is liquid water, life begins. 

Science can describe life in operational words, but not in essential words2. If there is a 

definition, life is closer to a verb than to a noun. The autotrophic life beings transform 

the brute mineral into themselves, that is, they give life to the brute environment. So, it 

is possible to infer an undefined border between brute minerals and life. Indeed, since 

1924, biochemical research Oparin had shown that small simple molecules such as 

carbon dioxide, ammonia, sulphur, water, etc., and random chemical reactions produce 

complex molecules such as amino acids, lipids and even polymers that combine in 

coacerved structures that somehow resemble a living cell1.  

However, despite the countless chemical reactions that occur inside a living cell and the 

possibility of laboratory synthesis of practically all chemical compounds of a living cell, 

the vital organization is something transcendent to the mere concrete matter3. Living is a 

metabolic and physiological adjective that describes a living being.  Overall, a living 

being can be in the stage of ‘living’, of ‘dormancy/latency’ or ‘dead’. A dead living 

being will never return to life. Some species produce propagules—seeds, spores, buds, 

etc.—that can remain latent (or dormant) for thousands of years, but when exposed to 

favourable environment can grow and self-replicate (living stage)4. However, the simple 

preservation of a living being in liquid helium, formalin, conservatives, etc. can 

maintain the skeletal structure but clearly it is a dead one . Until now, life remains  an 

abstract and an unknown concept, a mysterious force at the same time existing and 

transcending to a living being2.3. 

All living beings, with no exception, have a cellular structure. So, with absolute 

ignorance of a living being not organised in cells, it is not possible to have a broader 

concept of life, and in Astrobiology the search for extraterrestrial life is restricted to 

extraterrestrial cells. Such epistemic positioning is related to concrete questions. Space 

exploration must be restricted to mere observation of planets, under the belief that there 

are life forms that are not structured in the same way of the terrestrial cells? Or on the 

contrary, the living cell is considered so wonderful so that efforts must be made for 

colonisation with terrestrial living beings? 

Origin of living beings: Fossils show that living beings existed on the terrestrial 

surface at least for 3.8 billion years1,5. Considering that the age of Earth is 

approximately 4 billion years, it means, in astronomical terms, that as soon as the Earth 

was formed and contained liquid water on its surface, living beings began appearing. 

Terrestrial biodiversity is based on the cell with the genetic code of DNA/RNA, whose 

metabolism is based on the breakage of ATP. This points to what would be the first 

terrestrial microbe, or LUCA—Last Ultimate Common Ancestor—from which all the 

terrestrial biosphere originated1.  



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This geological aspect brings up deeper questions. If, according to the Theory of 

Spontaneous Generation, the cell originated on the terrestrial surface from random 

reactions on mineral substrates, then were there other patterns of cells? If so, what were 

they? Was LUCA a single event or had it been repeated several times? Were there other 

genetic systems supplanted by DNA/RNA? Why such primitive patterns are not seen 

nowadays? 

On the last question, Darwin wrote in 18711: "it is often said that all the conditions for 

the first production of a living being are now present, which could ever have been 

present. But if (and oh what a big if) we could conceive in some warm little pools with 

all sort of ammonia and phosphoric salts—light, heat, electricity present, that a protein 

compound was chemically formed, ready to undergo still more complex changes, at the 

present such matter would be instantly devoured, or absorbed, which would not have 

been the case before living creatures were formed". 

Indeed, the strong relation between liquid water and the presence of living beings is 

significant. However, no life form is found only in extremely arid deserts; otherwise, 

wherever there is liquid water there are living beings, including apparently hostile 

environments. This intrinsic relation guides the astronomical observation of what would 

be a habitable planet: the one with liquid water on the surface.  

In this sense, Earth, the Water Planet, is an astronomical rarity1,5. Although water is a 

common and abundant substance in the Universe, for a planet to show liquid on its 

surface a certain set of parameters, such as adequate distance from the star, the presence 

of a magnetic field that protects the atmosphere from the star winds, adequate 

concentration of glasshouse gases in the atmosphere, etc., are required. Apparently, the 

space probes sent up now suggest that the planet Mars and the moons Europa and 

Ganimedes that orbit Jupiter have liquid water in their subsoil, below an ocean of ice1. 

The moon Europe has an atmosphere rich in oxygen, similar to the terrestrial one, 

suggesting that liquid water on the surface is undergoing photolysis and releasing the 

gas. Moreover, the moons of Saturn, Titan and Enceladus, the Uranus moon Titanus and 

the Neptune moon Triton perhaps have liquid water under ice in the subsoil1.  

Since the ancient Greece, the origin of terrestrial life has been imagined as the result of 

a panspermia—that the Universe has living beings that are transported somehow from 

one planet to another6. Anaxagoras mentioned this idea as early as 500 BC, and this 

concept was recirculated at the end of the 14th century by scientists devoted to organic 

chemistry and biochemistry6. In 1908, the physicist Arrhenius published a book in 

which he discussed the Theory of Panspermia7. According to it, the living beings are 

one of the elements of the Universe, who would be transferred from one galaxy to 

another via comets and asteroids until they reach a favourable planet to grow. Indeed, 

recently, some rocks were found on the Earth, which originated from Mars and had 

traces of ancestral organic matter5,8. 



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The stronger criticism against the Theory of Panspermia is that it does not clarify about 

the exact mode of origin of the living cell. However, it has deep bioethical impact on it, 

if panspermia is a phenomenon intrinsic to the Universe, the living beings of each planet 

would have somehow gone to the neighbouring planets, and in the case of the Earth 

humans are the only species with the ability spread living beings outside Earth.  

Planetary protection: Astronomer Huygens had described channels on the surface of 

Mars as early as 16591. Arrhenius7 considered it plausible that there might be life on 

Mars, which however has not yet been confirmed. With effectively conquering space by 

the 1960s, with astronauts going to the orbit, it appeared as concern the physiological 

effects of microgravity and, in parallel, a fear of contraction of infectious diseases 

spreading from space and/or other planets that could cause massive human mortality9. 

Fearing cross-infection, and on the bioethical principle of planetary protection, the study 

and observation of neighbouring planets would be via sterilized equipment to avoid any 

interplanetary contamination. Indeed, studies on space have been confined to the study 

of the planets with probes and robots with no reports of intentional colonisation of 

neighbouring planets by terrestrial living beings. 

In the interests of planetary protection, it is important to highlight some aspects of the 

terrestrial Natural History. About 1.5 billion years after the appearance of the first living 

cells, the first photosynthesising living beings appeared and, after catalysing the 

photolysis of water, strongly enriched the terrestrial atmosphere with oxygen1. So, about 

2.1 billion years ago, the first multicellular living beings appeared. Now a days, all the 

multicellular mega biodiversity breathes and obtains energy from controlled combustion 

of organic compounds1. All the species that do not require oxygen are unicellular1. 

Oxygen is a highly reactive gas, so the living beings evolved to biochemically control 

this dimension10.  In comparison, sulphur belonging to the same family in the periodic 

table is also highly reactive, but is also highly toxic: in human beings, its inhalation at a 

concentration of 0.001 ppm is irritant to the respiratory mucosa, while it is lethal at a 

concentration of 0.01 ppm11. The atmosphere of the moon Io of Jupiter is highly rich in 

sulphur, and any terrestrial multicellular organism that went inside that moon would 

immediately be corroded by that strong oxidant1. Hypothetically, if a living being from 

Io went to Earth, it would be quickly oxidised by the corrosive oxygen. 

So, it is clear that the eventual biological colonisation of the neighbouring planets 

would be feasible only with microbes adapted to the environmental conditions in the 

colonising planets. So, one of the sub-disciplines of Astrobiology is the study of the so-

called extremophile microbes, that is, microbes adapted to some terrestrial environments 

whose physico-chemical characteristics are similar to other planets5. The principal 

categories of extremophiles are: thermophilic and hyperthermophilic (adaptation to 

extreme heat, close to the boiling point of the water); psychrophylic (adaptation to 

cold), acidophilic, alkaliphilic, barophilic (adaptation to acid, alkali and high pressure) 

and halophilic (adaptation to high saline concentrations)1. Some of these groups are of 



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particular interest like the ecosystems inhabiting the gabbroic rocks from 1,400 m below 

the ocean floor and the polar ecosystems living at a freezing temperature1,8.  

Beside extremophile microbes, the chemiolitotrophic microbes are also of interest. Such 

microbes are autotrophic and obtain energy from the oxidation of inorganic compounds 

such as phosphorus, sulphur, ammonia, iron, arsenic, selenium, etc. That is, the entire 

ecosystems exist in the absence of light. The case of the archea Desulforudis audaxvitor 

is intriguing because it grows in dark mines rich in uranium and obtains energy from the 

radiolysis of water from the decaying uranium1. 

Anyway, the fear of an eventual interplanetary colonisation with terrestrial microbes is 

related to the ecological field of invasive species, a phenomenon that is almost totally 

related to human travels and intentional or occasional transport of living beings from 

one ecosystem to another. Downey and Richardson12 listed essential aspects of the 

ecology of invasive species: data show that ecosystems related to restricted regions 

(islands, lakes, pools, etc.) are more vulnerable to invasive species, that the documented 

extinctions were caused by predator animals and the extinction of native plants related 

solely to the introduction of an invasive plant has not been observed, since the invasive 

plants often occupy places already disturbed by human activities. Anyway, the 

ecological inter-relationship among native and invasive plants is very complex and the 

extinction of native plants would take a long period, perhaps hundreds of years12. 

 On the ecological relationship among microbes, Veresoglu et al.13 highlight that all 

living species are doomed to extinction as we know them, either by disappearance or 

origin of new species. The microbes that lived on the Earth 3.8 billion years ago don´t 

exist anymore, although they are responsible for the origin of all living species today. 

Anyway, the microbial ecosystems have species with great ability to metabolic 

adaptation, such as microbes that can live in external environments but sometimes live 

with roots of plants or the guts of animals.  

On the introduction of new microbes into an ecosystem, Veresoglu et al.13  and also 

Guerrero et al.14 say that the microbial ecosystems are very complex and are organised 

in layers such that the simple presence of a new species would be insufficient to 

significantly impact them. Instead, the human modifications to the environment 

(asphalt, drainages, etc.) completely change the characteristics of the environment, and 

would strongly change the microbial ecosystems.  

 So, the group of ecological evidences points to  an eventual colonisation of planets with 

terrestrial living beings that would  be feasible only with extremofile microbes, which 

has  little potential of impacting an ecosystem if one  is already present in those planets. 

Terraforming: The word terraforming appeared first in science fiction literature in 

1942 in the magazine Astounding Science Fiction edited by Jack Williamson15.  From a 

bioethical position opposed to planetary protection, terraforming is the intention of 



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modifying the environmental conditions of the neighbouring planets, particularly Mars, 

in such a way that human colonisation would be possible. 

Alexandrov9 defends the bioethical principle of terraforming. He has identified the 

difference between anthropocentrism and biocentrism. Anthropocentrism attaches great 

value intrinsic to humanity, while biocentrism puts humans as a natural enemy of all the 

biosphere, including the extraterrestrial biosphere, if there was one. So, to Alexandrov9, 

if planetary engineering could be carried out to benefit humanity and create a human 

colony, then such effort should be made. He believes that if terraforming is feasible, 

somebody will do it sooner or later.  

The theoretical steps for eventual terraforming aslisted by Haynes and McCay16 are: 

first, a prospection of the surface of Mars; second, colonisation with terrestrial 

microbes; third, eventual environmental changes with engineering acitivities, for 

example, with nuclear explosions; fourth, the cultivation of food plants and finally 

human colonisation. The authors consider that microbial colonisation is relatively 

plausible with the existing technology, but human colonisation demands unimaginable 

technological resources17.  

 In Earth, the microbes are the beginning and the end of the ecological cycle. The 

ecological system is cyclical because the wastes of a given living being are substrate to 

other species, principally microbes. So, human pollution derives from the production of 

organic waste, principally plastics that, although chemically burnable, are not naturally 

degradable by any microbial species2. The ideal terraforming would be by microbial 

species that colonised the other planets and could change the environment, such as has 

occurred to Earth when the first photosynthesising living beings appeared16. 

So, one of the research fields in Astrobiology is to identify and select extremophile 

microbes and carry out experiments of resistance to space environment and survival in 

extraterrestrial environments. Tarashashvili and Aleksidze8 created in laboratory a 

growing medium similar to what the Martian soil would be, then they inoculated 

samples of extreme environments containing iron-bacteria, silicon-bacteria, sulphur-

bacteria, mycobacteria and cyanophytes that hadn´t been identified yet. It was possible 

to see the growth of colonies of those microbes, so the authors suggest cultivation and 

amelioration to obtain strains considered as promising to colonise Mars.  

Horneck et al.4 studied spores of the bacteria Bacillus subtilis in experiments carried out 

on satellites of ESA (European Space Agency) and showed that the spores were highly 

resistant to vaccum, to freezing temperatures and to radiation from  Space. Although the 

spores were highly sensitive to ultraviolet light, a thin layer of rock was enough to 

protect them. Those experiments suggest that spores of this bacterial species could 

survive for an undefined period, perhaps thousands of years, corroborating the Theory 

of Panspermia and show that it would be possible to transport viable microbial spores 

from Earth to other planets.  



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Friedmann and Ocampo-Friedmann18 suggested that Cyanophycea chroococcidiopsis 

would be an ideal candidate for transplantation to other planets, since it is ubiquitous on 

Earth, and can be considered as a microbial living fossil. However, Thomas et al.19 

simulated in laboratory the climatic conditions of Mars and tried growing 

Chroococcidiopsis and other photosynthesising microbes, but they did not survive.  

Paulino-Lima et al.20 studied the archea Deinococcus radiodurans and documented its 

resistance to radiation and ultraviolet rays, but since this is a heterotrophic aerobic 

microbe, it has a lesser chance of being a probable candidate to be a pioneer in 

extraterrestrial colonisation.  

Final consideration: The two bioethical positions—terraforming and planetary 

protection—are antagonistic. Space exploration needs large funding and support and up 

to now just a few worldwide agencies have invested on this field, and in a paradigm that 

astronomic biology is concerned with planetary protection. Terraforming is still at a 

stage of hypothesis and bioethical debate but till date, no experiments have been carried 

out to take microbes purposely to other planets. 

The fear of space agencies of damage to other planets with terrestrial living beings is 

not supported by ecological studies of the terrestrial ecosystems. It is clear that an 

eventual interplanetary colonisation could only be feasible by extremophile microbes, 

which, in case of matching living beings already existing, would be of great competitive 

disadvantage. But if those microbes found even minimally favourable conditions, they 

would create a new Natural History on that planet.4 

Notwithstanding, if anyone of our neighbouring planets has life, or at least life of the 

same duration as of the Earth (around 3.8 billion years), the living beings would have 

already developed a cover in these planets, occupying earth, depths, atmosphere. After 

all, life is one of the wonders of the Universe, and when established on a planet, will 

evolve in such a way as to occupy the maximally possible area of the planet2. The living 

being is born and dies, but after each replicating cycle, the living biomass of the planet 

increases continuously. However, our neighbouring planets do not have any form of 

life, either a cell or an unimaginable structure. 

From this bioethical antagonism, a third concept that synthesises the extremities, 

ecopoiesis, has emerged. Ecopoiesis is a word mentioned by Robert Haynes in 1984 and 

published in 198921 and is related to the creation of new ecosystems in other planets. 

This terminology summarises the former concept of planetary ecosynthesis, first coined 

in 1979 by Averner and MacElroy22. 

That is, neither a radical transformation to allow human colonisation nor the omission 

facing a scientific-technological ability. If a living being comes only from another living 

being, then life shows to be a force, something beyond our reach, present in the 

Universe, capable of transforming the inorganic into organic and, in the evolutionary 



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fight for survival, transform a whole planet in an ecosystem each time deeper and more 

complex23. 

The theories of origin of life—Spontaneous Generation and Panspermia—are not 

mutually excluding, and can be complementary. Under a cosmogonic perspective, since 

in a planet some kind of living beings appear, they somehow colonise the other planets, 

either by random means, such as collision with asteroids, or by means of intelligent 

forms that do that intentionally5,16,17. Moreover, if the Theory of Panspermia is correct, 

it is even possible that extraterrestrial microbes hit Earth with some frequency, but these 

life forms would face strong difficulties to resist to the toxicity of oxygen, to the 

stressful climate, but, foremost, to compete with other life forms already established 

here. 

Therefore, ecopoiesis is related to the bioethical position of cosmocentrism, that is, 

planets that house some form of life have an intrinsic value higher than the one with 

only mineral elements5,16,17. So, Mautner and Matloff17 and their Society for Life in 

Space defend that ecopoiesis is the cosmogonic proposal of human existence, that is, 

one of the tasks to Humanity would be one of disseminating terrestrial propagules to the 

neighbouring planets, as it is the only species able to do that.  

The idea of ecopoiesis can also guide future expedition to other planets: one line of 

research can be the complex task of identifying, isolating, cultivating and preserving 

‘the’ microbe candidate to colonise another planet. But if Panspermia occurs as a 

meteorite coming from a planet, what reaches the planets is not a single species, but a 

whole ecosystem preserved in rocks. So, for example, the colonisation of the moon 

Europa of Jupiter could be carried out by leaving there, or perhaps burying there, a 

portion (some kilograms, half  a ton, or so ) of the Artic or Antarctic permafrost. Or, 

samples of the oceans or of the terrestrial soils could also be transported. That is, if a 

whole microbial ecosystem is transported similar to what would be a meteor to the 

neighbouring planet, it would be enough if a single species grew to start a new 

ecosystem. Anyway, experiments towards ecopoiesis present high intrinsic scientific 

value, as to clarify how life beings appeared on Earth and if life beings can somehow 

jump from a planet to another.  

In conclusion, ecopoieses is based on bioethical principles that should guide space 

exploration in substitution to the principle of planetary protection.  

Acknowledgments: We thank the Indian company Content Concepts for English 

review and correction. 

Author Contribution: Both authors carried out bibliographical research, discussed the 

ideas and wrote the text. 
 
Conflict of Interest: None 
 



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References: 
1. Galante D, Silva EP, Rodrigues F, Horvath J and Avellar MG. Astrobiologia, uma 

ciência emergente. São Paulo: Tikinet Edição, IAG/USP, 2016. 

2. Palhares D. Biological evolution and evolution of spirits. São Paulo: Baraúna, 2013. 

3. Betto F. Conversa sobre fé e ciência. Frei Betto e Marcelo Gleiser com Waldemar 

Falcão. Rio de Janeiro: Agir, 2011. 

4. Horneck G, Rettberg P, Reitz G, Wehner J, Eschweiler U, Strauch K, Panitz C, 

Starke V and Baumstark-Khan C. Protection of bacterial spores in space, a contribution 

to the discussion of panspermia. Origins of Life and Evolution in the Biosphere 2001; 

31: 527-547. 

5. Mautner MN. Seeding the Universe with Life. Securing our cosmological future. LB 

Legacy Books: Christchurch, 2004. 

6. Wikipedia. Panspermia. Available at https://en.wikipedia.org/wiki/Panspermia. 

Access April/2017. 

7. Arrhenius S. Worlds in the making. The evolution of Universe. Harper and Brothers 

Publishers: New York and London, 1908.  

8. Tarashashivli MV and Aleksidze NG. Microbiological remediation of Martian soil 

for future terraformation of the planet. Astrobiology Science Conference 2010;  p. 5229.  

9. Alexandrov S. Planetary protection of Mars: time for reconsideration. Bangladesh 

Journal of Bioethics 2016; 7(2): 31-34. 

10.Makuch DS. A Busca por Vida Extraterrestre: Seríamos Todos Nós Marcianos? 

Available at http://noticias.uol.com.br/midiaglobal/derspiegel/2010/12/18/a-busca-por-

vida-extraterrestre-seriamos-todos-nos-marcianos.htm. Acess april/2017. 

11. Palhares D. Polvilho anti-séptico no tratamento de ectoparasitoses. Revista 

Brasileira de Medicina 2006; 63(3): 77-78. 

12. Downey P and Richardson D. Alien plant invasions and native plant extinctions: a 

six-threshold framework. AoB Plants 2016; 8: plw 047. 

13. Veresoglu S, Halley J and Rillig M. Extinction risk of soil biota. Nature 

Communications 2015; 6:8862. 

14. Guerrero R, Piqueras M and Berlanga M. Microbial mats and the search for minimal 

ecosystems. International Microbiology 2002; 5: 177-188.  

16. Wikipedia. Terraforming. Available at https://en.wikipedia.org/wiki/Terraforming. 

Acess april/2017 

17. Haynes Rh and McKay C. The implantation of life in Mars: feasibility and 

motivation. Advances in Space Research 1992; 12(4): 133-140. 

18. Mautner MN and Malof GL. Directed panspermia: a technical and ethical evaluation 

of seeding nearby solar systems. Journal of the British Interplanetary Society 1979; 32: 

419-423.  

19. Friedmann EI and Ocampo-Friedmann R. A primitive cyanobacterium as pioneer 

microorganism for terraforming Mars. Advances in Space Research 1995; 15(3): 243-

246. 

20.Thomas D, Eubanks LM, Rector C, Warrington J and Todd P. Effects of atmospheric 

pressure on the survival of photosynthetic microorganisms during simulation of 

ecopoiesis. International Journal of Astrobiology 2008; 7(3-4): 243-249. 

21.Paulino-Lima IG, Pilling S, Janot-Pacheco E, Brito AN, Barbosa JA, Leitão AC and 

Lage CA. Laboratory simulation of interplanetary ultraviolet radiation and its effects on 

Deinococcus radiodurans. Planetary and Space Science 2010, 58(10): 1180-1187. 



Bangladesh Journal of Bioethics 2017; 8(2):1-10  

10 

 

22. Haynes RH. Prospects for establishing a microbial ecosystem on Mars. Moscow: 

Biotechnology on the threshold of the XXI Century, Conference Proceedings, 1989, p. 

85-88. 

23. Averner MM and MacElroy RD. On the habitability of Mars: An approach to 

planetary ecosynthesis. NASA SP-414, 1976. 

24.Lutzenberger J and Gaia, O. Planeta Vivo. Cinco Continentes: Porto Alegre, 2012.  


