International Journal of Astrobiology - Current Issue

Volume 6 Issue 04

Sun, 30 Sep 2007 23:00:00 GMT

International Journal of Astrobiology, Volume 6 Issue 04

Astrobiology combines the sciences of biology, chemistry, palaeontology, geology, atmospheric physics, planetary science, astrophysics and cosmology in the study of the origin, evolution and distribution of life in the universe and the future of life both on Earth and beyond. The International Journal of Astrobiology is the forum for practitioners in this exciting interdisciplinary field. Coverage includes cosmic prebiotic chemistry, planetary evolution, the search for planetary systems and habitable zones, extremophile biology and experimental simulation of extraterrestrial environments, Mars as an abode of life, life detection in our solar system and beyond, the search for extraterrestrial intelligence, the history of the science of astrobiology, as well as societal and educational aspects of astrobiology. Occasionally an issue of the journal is devoted to the keynote plenary research papers from an international meeting. A notable feature of the journal is the global distribution of its authors.

The Cyborg Astrobiologist: porting from a wearable computer to the Astrobiology Phone-cam

Research Articles
Alexandra Bartolo, Patrick C. McGuire, Kenneth P. Camilleri, Christopher Spiteri, Jonathan C. Borg, Philip J. Farrugia, Jens Ormö, Javier Gómez-Elvira, José Antonio Rodriguez-Manfredi, Enrique Díaz-Martínez, Helge Ritter, Robert Haschke, Markus Oesker, Jörg Ontrup,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 255-261

Abstract
We have used a simple camera phone to significantly improve an for astrobiology and geology. This camera phone will make it much easier to develop and test computer-vision algorithms for future planetary exploration. We envision that the exploration system can be fruitfully used in other problem domains as well.

Equilibrium temperatures of porous spheres and their relevance to astrobiology

Research Articles
S.G. Coulson, N.C. Wickramasinghe,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 263-266

Abstract
Equilibrium temperatures are calculated for porous, organic spheres at a Solar distance of around 1 AU. It is found that the equilibrium temperature of porous grains is highly sensitive to their composition and radius. For porous organic grains of radius 0.1 m with 10% charring the corresponding range is from 448 to 431 K. Such superheated submicron grains, porous or otherwise, may have only a limited role as transporters of fragile biomolecules. Clumps of biological particles with radii in excess of 5 m are, however, at low enough temperatures to permit such transport at 1 AU.

Haematite–water system on Mars and its possible role in chemical evolution

Research Articles
Avnish Kumar Arora, Varsha Tomar, null Aarti, K.T. Venkateswararao, null Kamaluddin,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 267-271

Abstract
Recent findings on the presence of water on Mars (Baker, V.R. (2006). Geomorphological evidence for water on Mars. Elements 2(3), 139 25. American Chemical Society, Washington, DC; McSween, H.Y. Jr. (2006). Water on Mars. Elements 2(3), 135 43) strongly suggest that there existed a period of chemical evolution eventually leading to life processes on primitive Mars (Kanavarioti, A. Maneinelli, R.L. (1990). Could organic matter have been preserved on Mars for 3.5 billion years. Icarus 84, 196 202). Owing to the adverse conditions, it is quite likely that the process of chemical evolution would have been suppressed and any living organisms that formed would have become extinct over time on Mars. The presence of water as a necessity for the survival of living organisms and the presence of grey haematite, originated under aqueous conditions, have led us to investigate the possible role of haematite in the chemical evolution on Mars. Our observations suggest that iron oxide hydroxide (FeOOH), a precursor of haematite, has a much higher binding affinity towards ribose nucleotides (the building blocks of RNA) than the haematite itself. This would mean that during the process of haematite formation, especially through the probable process of Fe3+ hydrolysis by aqueous ammonia, the precursors of haematite might have played a significant role in the processes leading to chemical evolution and the possible origin of life on Mars.

Darwin to the double helix: astrobiology in fiction

Research Articles
Mark Brake, Neil Hook,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 273-280

Abstract
From Darwin to the double helix, the last 150 years have seen revolutionary changes in our understanding of life in the Universe. In this time, works of science fiction have provided a valuable, and often overlooked, reflection of the assumptions and attitudes held by society to such changes. This paper will consider key works of film and fiction as a commentary on emergent features of astrobiology, including the work of Fred Hoyle, Olaf Stapledon's Last and First Men (1930) and Star Maker (1937), and Arthur C. Clarke and Stanley Kubrick's cinematic classic, 2001: A Space Odyssey (1968). These popular culture texts represent a useful and inspiring communication of science. Their critical discourse is the reducible gap between the new worlds uncovered by science and the fantastic strange worlds of the imagination. As such, they exemplify a way in which the culture and science of popular astrobiology can be fused.

Laboratory simulation of UV irradiation from the Sun on amino acids. II. Irradiation of phenylalanine and tryptophan

Research Articles
F. Scappini, M.L. Capobianco, F. Casadei, R. Zamboni, P. Giorgianni,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 281-289

Abstract
The effects of near ultraviolet (UV) irradiation on water solutions of phenylalanine and tryptophan have been investigated using a broad-band xenon lamp in the region 200 -amino acids, with regards to the origin of life. Results are presented showing the photodegradation of phenylalanine and tryptophan against different UV doses. Some of the degradation products are still protein amino acids. An analysis of the irradiated solutions is carried out by spectroscopic and analytic techniques. The laboratory simulations are discussed in the wake of a life emerging scenario on the primitive Earth.

Directed exospermia: II. VUV-UV spectroscopy of specialized UV screens, including plant flavonoids, suggests using metabolic engineering to improve survival in space

Research Articles
Andreja Zalar, David Tepfer, Søren V. Hoffmann, Albert Kollmann, Sydney Leach,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 291-301

Abstract
We used synchrotron light to determine VUV-UV absorption spectra (125 -carotene, melanin and flavonoids (quercitrin, isoquercitrin, robinin and catechin). The objective was to extend known UV absorption spectra into the vacuum UV, and to evaluate the likely effectiveness of these molecules in shielding DNA from the unfiltered solar UV found in space, using similarity with DNA absorption spectra as the primary criterion. The spectroscopy indicated that plant flavonoids would be ideal UV screens in space. We suggest that flavonoids represent primitive UV screens, and offer explanations (including horizontal gene transfer) for their presence in plants. We also discuss the possibility of improving UV resistance by increasing flavonoid accumulation through metabolic engineering, in the hope of better adapting life for space travel, i.e. for its dissemination away from the Earth (exospermia). Finally, we propose using plant seeds as exospermia vehicles for sending life (including artificial life) into space.

Exotic amino acids across the K/T boundary – cometary origin and relevance for species extinction

Research Articles
Max K. Wallis,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 303-306

Abstract
High levels of an exotic amino acid (Aib) and enhanced levels of iridium are evident in sediments pre-dating the Chicxulub impact by several tens of millennia. The source is thought to be debris from the break-up of a giant comet or trans-Neptunian body, a large fragment of which was the 10 km sized impactor that caused the famous iridium spike identified with the K/T boundary. In this paper it is argued that the Aib is not extra-terrestrial but the indicator of exotic pathogenic microfungi that flourished through this era. Its abundance implies a significant role for the fungi in the ecology, in species extinction and in driving evolution as the Tertiary period got underway. Microfungi containing the complex of genes that underlie the synthesis of Aib peptides flourished early on in the K/T transition and attacked species that lacked counter immune mechanisms. Species (including mammals) that possessed or developed effective defence mechanisms won through in the early Tertiary-period flowering of new species. The genetic coding for Aib peptide synthesis might have evolved by natural selection. However, the coincidence in the boundary record between Aib peptides and the rise of iridium is indicative of the Aib blueprint arriving from space, in some carrier-organism or in microfungi themselves.

Correlation of a 140-year global time signature in cancer mortality birth cohorts with galactic cosmic ray variation

Research Articles
David A. Juckett,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 307-319

Abstract
An understanding of the cosmic ray modulation of life processes is critical to space exploration, evolution and current medical science. Previous evidence has implicated a role for cosmic rays in US female cancer, involving a possible cross-generational foetal effect. This study explores the global nature of that effect by examining cancer time variations for population cohorts in five countries on three continents. Age cohort analysis was used to separate cohort-related effects from period-related effects, generating time signatures for comparisons among both male and female populations in the United States (US), United Kingdom (UK), Australia (AU), Canada (CA) and New Zealand (NZ). The available cancer mortality data spanned most of the 20th century for US, UK and AU, with shorter periods for CA and NZ. The longest cohort series spanned 1825 to 1965 and exhibited two peaks of higher mortality likelihood approximately 75 years apart in all countries and in both sexes. The constancy of this oscillation on three continents and both hemispheres suggests the presence of a global environmental effect. To explore a possible source for this effect, the birth cohort oscillation is shown to correlate with the variations in background cosmic radiation one generation prior to the birth cohorts. This confirms an earlier study correlating human breast cancer mortality and galactic cosmic rays. A corroborating correlation is also noted between the latitude dependences of cancer incidence in 42 countries and the intensity of background cosmic rays. The role of germ cells as a possible target of this radiation is discussed, emphasizing the amplification that must occur to make this weak radiation relevant to human health. Germ cell timing for this effect has profound implications for evolution, long-distance space travel and the colonization of planets with high background radiation.

The origin of life in comets

Research Articles
W.M. Napier, J.T. Wickramasinghe, N.C. Wickramasinghe,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 321-323

Abstract
Mechanisms of interstellar panspermia have recently been identified whereby life, wherever it has originated, will disperse throughout the habitable zone of the Galaxy within a few billion years. This re-opens the question of where life originated. The interiors of comets, during their aqueous phase, seem to provide environments no less favourable for the origin of life than that of the early Earth. Their combined mass throughout the Galaxy overwhelms that of suitable terrestrial environments by about 20 powers of ten, while the lifetimes of friendly prebiotic environments within them exceeds that of localized terrestrial regions by another four or five powers of ten. We propose that the totality of comets around G-dwarf Sun-like stars offers an incomparably more probable setting for the origin of life than any that was available on the early Earth.

Evolutionary catastrophes and the Goldilocks problem

Research Articles
Milan M. Ćirković,
International Journal of Astrobiology, Volume 6 Issue 04 , pp 325-329

Abstract
One of the mainstays of the controversial hypothesis is the regarding various parameters describing a habitable planet, partially involving the role of mass extinctions and other catastrophic processes in biological evolution. Usually, this is construed as support for the uniqueness of the Earth's biosphere and intelligent human life. Here it is argued that this is a misconstrual and that, on the contrary, observation-selection effects when applied to catastrophic processes make it very difficult for us to discern whether the terrestrial biosphere and evolutionary processes which created it are exceptional in the Milky Way or not. This agnosticism, in turn, supports the validity and significance of practical astrobiological and SETI research.