Ultraviolet (UV) radiation can act on putative organic/biological matter at the Martian surface in several ways. Only absorbed, but not transmitted or reflected, radiation energy can be photo-chemically effective. The most important biological UV effects are due to photochemical reactions in nucleic acids, DNA or RNA, which constitute the genetic material of all cellular organisms and viruses. Protein or lipid effects generally play a minor role, but they are also relevant in some cases. UV radiation can induce wavelengths-specific types of DNA damage. At the same time it can also induce the photo-reversion reaction of a UV induced DNA photoproduct of nucleic acid bases, the pyrimidine dimers. Intense UVB and UVC radiation, experienced on early Earth and present-day Mars, has been revealed to be harmful to all organisms, including extremophile bacteria and spores. Moreover, the formation of oxidants, catalytically produced in the Martian environment through UV irradiation, may be responsible for the destruction of organic matter on Mars. Following this, more laboratory simulations are vital in order to investigate and understand UV effects on organic matter in the case of Mars. We have designed a radiation apparatus that simulates the anticipated Martian UV surface spectrum between 200 and 400 nm (UVC–UVA). The system comprises a UV enhanced xenon arc lamp, special filter-sets and mirrors to simulate the effects of the Martian atmospheric column and dust loading. We describe the technical setup and performance of the system and discuss its uses for different applications. The design is focused on portability, therefore, the Mars-UV simulator represents a device for several different Mars simulation facilities with specific emphasis on Mars research topics.

Homochirality is an essential feature of biology, but how it developed in early life remains unclear. Our aim in this paper is to add to the discussion by taking a somewhat arbitrary but definite sequence of events and examining carefully the chirality at each stage. Our scenario for the development of life starts with the prebiotic, continues through a pre-RNA stage to the RNA world. This leads to the development of proteins and then to the incorporation of DNA in RNA–DNA–protein biochemistry.

We argue that homochirality probably did not develop prebiotically. We see the likely chiral bifurcation point to be during the development of RNA from an achiral pre-RNA. Surprisingly, we find the driving force for this to be enantiomeric cross-inhibition in which the addition of a ‘wrong-handed’ enantiomer to a growing polymer brings the polymerization to a halt. This, it is often argued, is a serious impediment to the development of chiral purity. We suggest that the sign of handedness at this stage was probably determined by chance. We then point out that homochiral RNA was unlikely by itself to lead to homochiral proteins. We identify the additional nonlinear feature required for bifurcation to be the rapid increase in enzymic power available when the amino acids in proteins approach single handedness and structural features such as α-helices and β-sheets become viable. If this is correct, then the handedness of the protein sector is indeed linked to that of RNA. However, the relative sign of the two handednesses will have depended on the precise stereo-sensitive interaction between the RNA and protein systems. We suggest that the most plausible scenario is via the recently discovered RNA binding sites for amino acids, which are both stereo-selective and have contact with the developing genetic code. The detailed steps that determine the handedness are not yet clear and may be specific to the precise development path.

It follows that if biochemistry similar to that on Earth developed extraterrestrially, we would surely have homochirality but at this stage we cannot be sure about the handedness of either the nucleic acid or the protein components.

The purpose of this paper is to review two mathematical models: one for the formation of homochiral polymers from an originally chirally symmetric system; and the other, to show how, in an RNA-world scenario, RNA can simultaneously act both as information storage and a catalyst for its own production. We note the similarities and differences in chemical mechanisms present in the systems. We review these two systems, analysing steady states, interesting kinetics and the stability of symmetric solutions. In both systems we show that there are ranges of parameter values where some chains increase their own concentrations faster than others.

How photosynthesis by Precambrian cyanobacteria oxygenated Earth's biosphere remains incompletely understood. Here it is argued that the oxic transition, which took place between approximately 2.3 and 0.5 Gyr ago, required a great proliferation of cyanobacteria, and this in turn depended on their ability to fix nitrogen via the nitrogenase enzyme system. However, the ability to fix nitrogen was not a panacea, and the rate of biospheric oxygenation may still have been affected by nitrogen constraints on cyanobacterial expansion. Evidence is presented for why cyanobacteria probably have a greater need for fixed nitrogen than other prokaryotes, underscoring the importance of their ability to fix nitrogen. The connection between nitrogen fixation and the evolution of photosynthesis is demonstrated by the similarities between nitrogenase and enzymes critical for the biosynthesis of (bacterio)chlorophyll. It is hypothesized that biospheric oxygenation would not have occurred if the emergence of cyanobacteria had not been preceded by the evolution of nitrogen fixation, and if these organisms had not also acquired the ability to fix nitrogen at the beginning of or very early in their history. The evolution of nitrogen fixation also appears to have been a precondition for the evolution of (bacterio)chlorophyll-based photosynthesis. Given that some form of chlorophyll is obligatory for true photosynthesis, and its light absorption and chemical properties make it a ‘universal pigment’, it may be predicted that the evolution of nitrogen fixation and photosynthesis are also closely linked on other Earth-like planets.

As humans expand into space communities will form. These have already begun to form in small ways, such as long-duration missions on the International Space Station and the space shuttle, and small-scale tourist excursions into space. Social, behavioural and communications data emerging from such existing communities in space suggest that the physically-bounded, work-oriented and traditionally male-dominated nature of these extremely remote groups present specific problems for the resident astronauts, groups of them viewed as ‘communities’, and their associated groups who remain on Earth, including mission controllers, management and astronauts’ families. Notionally feminine group attributes such as adaptive competence, social adaptation skills and social sensitivity will be crucial to the viability of space communities and in the absence of gender equity, ‘staying in touch’ by means of ‘news from home’ becomes more important than ever. A template of news and media forms and technologies is suggested to service those needs and enhance the social viability of future terraforming activities.

The emergence and spread of chirality on the early Earth is considered by studying a set of reaction-diffusion equations based on a polymerization model. It is found that effective mixing of the early oceans is necessary to reach the present homochiral state. The possibility of introducing mass extinctions and modifying the emergence rate of life are discussed.

This paper is a discussion on how reaction kinetics and three-dimensional (3D) lattice simulations can be used to elucidate the dynamical properties of micelles as a possible minimal protocell container. We start with a general discussion on the role of molecular self-assembly in prebiotic and contemporary biological systems. A simple reaction kinetic model of a micellation process of amphiphilic molecules in water is then presented and solved analytically. Amphiphilic molecules are polymers with hydrophobic (water-fearing), e.g. hydrocarbon tail groups, and hydrophilic (water-loving) head groups, e.g. fatty acids. By making a few simplifying assumptions an analytical expression for the size distribution of the resulting micelles can be derived. The main part of the paper presents and discusses a lattice gas technique for a more detailed 3D simulation of molecular self-assembly of amphiphilic polymers in aqueous environments. Water molecules, hydrocarbon tail groups and hydrophilic head groups are explicitly represented on a three-dimensional discrete lattice. Molecules move on the lattice proportional to their continuous momentum. Collision rules preserve momentum and kinetic energy. Potential energy from molecular interactions are also included explicitly. The non-trivial thermodynamics of large-scale and long-time dynamics are studied. In this paper we specifically demonstrate how, from a random initial distribution, micelles are formed and grow until they destabilize and can divide. Eventually a steady state of growing and dividing micelles is formed. Towards the end of the paper we discuss the relevance of the presented results to the design of a minimal artificial protocell.

In the next decade, numerous space missions will attempt to detect organic matter on planets and other objects in the Solar System. Recognizing carbon-based life or its remains will be a fundamental goal of future missions. In preparation, studies of organic matter in meteorites are enabling scientists how to discriminate between biogenic and abiogenic materials.

Life has probably existed on Earth for about 3.5 billion years and ever since people could wonder, they have tried to understand its origins. It is thought that organisms as complex as bacteria emerged within 0.5–1 billion years. Organic molecules, such as amino acids, organic acids and sugars have been observed in material from extraterrestrial sources in the solar system. But, to confirm the possibility of nucleic acid bases also being synthesized under these conditions, we have replicated the synthesis of monophosphates as dry pellets (5′-monophosphates, the predominant reaction products) under simulated Martian conditions. Our research task was to find out whether the main organic substances were able to survive in the absence of water. This reaction must proceed under solvent-free conditions and incident short ultraviolet radiation (UVC) in a vacuum. After 5 months of reaction time monophosphates could be identified in detectable quantities. These experiments utilized basalt and limonite as protectors and successfully shielded the products from decomposition by UVC. Our team has obtained more results concerning prebiotic synthesis of polypeptides and nucleotides in the presence of meteorite dust; these are the same kind of experiment, but using different extraterrestrial material.

Efficient life support systems are needed to maintain adequate oxygen, water and food for humans in extraterrestrial conditions. On the near-Earth missions, these are supplied by transport from the Earth, and by physical and chemical cleaning and recycling, but on long-term missions to far-away destinations, such as Mars, on-site production of the consumables may be required. Molecular oxygen and organic biomass can be most efficiently produced biologically, i.e. by photosynthesis. The conditions on Mars are distinctly harsh, and they strictly limit the growth and survival of any photosynthetic organisms to artificially maintained containments. For obtaining most economical growth conditions, minimal parameters need to be determined which still allow efficient growth of photosynthetic organisms. In this work we are testing how reduced air pressures (hypobaria) and increased CO2 concentrations, i.e. features typical for Martian conditions, affect the durability, growth and photosynthesis of laboratory strains of cyanobacteria, a group of prokaryotic organisms capable of plant-like photosynthesis. Our preliminary results show that air pressures down to 0.1 atm or CO2 concentrations up to 20% have no harmful effect on the photosynthetic oxygen production or growth rate of the cyanobacterial model species, Synechocystis sp. PCC 6803.