Dwarka is proud of Ashwini Kumar Lal
Resident of Sector-6, Dwarka

Ashwini Kumar Lal, currently posted as Deputy Adviser in the Union Ministry of Statistics & Programme Implementation, New Delhi, is a civil engineer by profession. He has authored more than 70 technical papers on the diverse topics related to civil engineering such as concrete technology, low cost housing, innovative construction technologies, cost – effective building materials, disaster housing, rural housing, building maintenance, environmental issues including global warming, and project management, that have been published in several international/national journals of repute and symposia proceedings. He attended an advanced level training course on “Sustainable Urban Development and Pollution Control” at the University of New South Wales , Sydney ( Australia ) in 1997. Know more about him.

Article “searching for Life on Habitable Planets and Moons” that has been accepted for publication in the Feb. 2010 issue of the American journal, Journal of Cosmology, and since placed placed on the combined tracking systems of Harvard & NASA, and arXiv-world’s most prestigious repository of scholarly scientific papers maintained by the Cornell University, New York.

Brief of article – :

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Searching for Life on Habitable Planets and Moons

By Ashwini Kumar Lal

Earth is the only known inhabited planet in the universe to date. However, advancements in the fields of astrobiology and observational astronomy, as also discovery of large varieties of extremophiles with extraordinary capability to thrive in harshest environments on Earth, have led to speculation that lifemay possibly be thriving on many of the extraterrestrial bodies in the universe. Coupled with the growing number of exoplanets detected over the past decade, the search for the possibility of life on other planets and satellites within the solar system and beyond has become a passion as well as a challenge for scientists in a variety of fields. This paper examines such possibility in the light of findingsof the numerous space probes and theoretical research undertaken in this field over the past few decades.

1. IntroductionMany scientists and religious leaders believe life originated on Earth through processes that gave life to non-life. Many respond skeptically to the possibility there may be life on other planets. In contrast to the widely accepted beliefs in abiogenesis where the Earth is seen as the centre of the biological universe, theories of panspermia view life as widespread throughout the cosmos. Althoughpanspermia does not address the fundamental question as to when and where exactly life originated first in the universe, it nonetheless does lend support to the possibility of life being found on other planets (besides Earth) and satellites within the solar system and beyond (Lal 2008).

Central to theories of panspermia is the belief that the “seeds of life” are ubiquitous (Arrhenius 1908, 2009), and that these “seeds of life” i.e. living creatures were embedded in meteors, asteroids, and comets, and deposited upon Earth as well as to other habitable bodies in the universe (Wickramasinghe et al. 2009 ; Joseph 2009). Considerable evidence has been presented in support of pansermia by Joseph (2000, 2009) and by Hoyle and Wickramasinghe (Hoyle and Wickramasinghe 1977, 2000 ; Wickramasinghe 1995). Wickramasinghe and colleagues have provided nearly convincing evidence that dust grains in interstellar clouds could contain spores, desiccated bacteria,and living microbes which survive in comets on cloud condensation to stars and planets….

2. Circumstellar Habitable ZoneCircumstellar Habitable Zone (CHZ), also known as „Godilocks Zone‟, is a region of space within a solar system where an Earth-like planet cable of supporting life is most likely to be found (Fig. 1&2). Astronomers in the 1970‟s referred to Goldilocks Zone as a remarkable small region of space that is not too hot, not too cold, and is just right for sustaining life. However, in the 1970‟s, it was thought that life could not survive extreme conditions i.e. no colder than Antarctica, no hotter than scalding waters, no higher than clouds, no lower than a few miles…..

3. Galactic Habitable Zone (GHZ)The Galactic Habitable Zone (GHZ) is a hypothesized spherical band that may be a likely place for terrestrial life to develop in a galaxy. It is essentially extension of circumstellar habitable zone to a galactic scale…..

4. Evolution of Probable Habitable Planets and SatellitesLammer et.al. (2009) have proposed a very useful classification of for planets and the evolution of life, and has demarcated four habitat types:Class I habitats represent planets or moons where stellar and geophysical conditions allow Earth-like life to take root and which would enable complex multi-cellular life forms to evolve….

5. Probability of Life on Habitable Moons of ExoplanetsIn our solar system, it is observed that the larger a gas giant, greater the total mass of its satellites. Going by this norm, extrasolar giants-more massive than Jupiter may have moons as large as Mars or even Earth (Le Page 2008)…..

6. PanspermiaMost scientists subscribe to the view that life began through as yet unknown processes which yielded protocells possessing amino acids and nucleotides that were sparked with life (Menor Salván 2009; Sidharth 2009). It is reasonable to assume that if life could arise on Earth through biogenesis, then the same events can take place on other worlds if they possess the same chemistry. If so, life should be widespread, particularly microbial life. More complex life is another question….

7. Concluding Remarks
Discovery of over 400 exoplanets orbiting distant stars supports the likelihood that most Sun-like stars may be ringed with orbiting planets. Even if we accept the lower estimate that 10% of Sun like stars have planets (Marcy et al. 2005), this would indicate hundreds of millions of stars in our galaxy and in billions of other galaxies, may provide an environment favourable to life….

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Source: Dwarka Parichay News & Info Services

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