Multiplication of microbes below 0.690 water activity: implications for terrestrial and extraterrestrial life

Since a key requirement of known life forms is available water (water activity; aw), recent searches for signatures of past life in terrestrial and extraterrestrial environments have targeted places known to have contained significant quantities of biologically available water. However, early life on Earth inhabited high-salt environments, suggesting an ability to withstand low water-activity. The lower limit of water activity that enables cell division appears to be ∼ 0.605 which, until now, was only known to be exhibited by a single eukaryote, the sugar-tolerant, fungal xerophile Xeromyces bisporus. The first forms of life on Earth were, though, prokaryotic. Recent evidence now indicates that some halophilic Archaea and Bacteria have water-activity limits more or less equal to those of X. bisporus. We discuss water activity in relation to the limits of Earth's present-day biosphere; the possibility of microbial multiplication by utilizing water from thin, aqueous films or non-liquid sources; whether prokaryotes were the first organisms able to multiply close to the 0.605-aw limit; and whether extraterrestrial aqueous milieux of ≥ 0.605 aw can resemble fertile microbial habitats found on Earth.

Dissociative electron attachment to HCCCN

Dissociative electron attachment to cyanoacetylene (propiolonitrile) HCCCN has been observed in the electron energy range 0-12 eV. Negative ions are formed in two main bands with maxima at similar to 1.6 eV (CCCN-) and similar to 5.3 eV (CCCN-, CN-, HCC- and CC-). There are also weaker resonances which lead to dissociative electron attachment to form CN-, HCC- and CC- with a maximum intensity at similar to 8.1 eV and CCCN-, CN- and CC- at similar to 11.2 eV. A trace of CCN- is observed at similar to 9.1 eV. The positions of the main dissociative attachment bands observed are close to positions of pi* resonances recently calculated by Sommerfeld and Knecht. Calculations have also been performed in this work, which confirm the position of the p* orbitals. The electron affinity of the CCCN radical is determined as 4.59 +/- 0.25 eV from the threshold for CCCN- formation at 1.32 +/- 0.15 eV. Dissociative electron attachment to this molecule will act as a source of negative ions in extraterrestrial environments where electrons are present with more than 1.3 eV energy.

ASTER: A Brazilian mission to an asteroid

The first Brazilian mission to an asteroid is being planned. The target is the asteroid 2001 SN263, which has a NEA orbit of class AMOR. Spectral analysis indicated that this is a C-type asteroid. This type of asteroids are dark and difficult to be studied from Earth. They hold clues of the initial stages of planetary formation and also the origin of water and life on Earth. In fact, radar data showed that 2001 SN263 is composed of three bodies with diameters of about 2.8 km, 1.1 km and 0.4 km. Therefore, the spacecraft will have the opportunity to explore three bodies on the same trip. The mission is scheduled to be launched in 2015, reaching the asteroid in 2018. It will be used a small spacecraft (150 kg) with 30 kg for the payload. The set of scientific instruments being considered to explore the target of this mission include an Imaging Camera, a Laser Rangefinder, an Infrared Spectrometer, a Synthetic Aperture Radar and a Mass Spectrometer. The main measurements to be made include the bulk properties (size, shape, mass, density, dynamics, spin state), the internal properties (structure, gravity field) and surface properties (mineralogy, morphology, elemental composition). The mission also opens an opportunity for some relevant experiments, not directly related to the target. Two such experiments will take benefit from being on board of the spacecraft along the journey to the asteroid system, which will take about three years. The first is an astrobiology experiment. The main goal of this experiment is to determine the viability of the microorganisms survival in extraterrestrial environments simulated in laboratory (chemical atmosphere, temperature, desiccation, vacuum, microgravity and radiation). The second experiment is a plasma package. The main objectives of this experiment are to study the structure and electrodynamics of plasma along the trajectory, the plasma instability processes and the density and temperature of plasma of solar wind origin along the trajectory and near the asteroids. This mission represents a great challenge for the Brazilian space program. It is being structured to allow the full engagement of the Brazilian universities and technological companies in all the necessary developments to be carried out. In this paper, we present some aspects of this mission and details of the payload that will be used and the scientific expectations. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

Poorly graphitized carbon as a new cosmothermometer for primitive extraterrestrial materials

The presence of carbon in primitive extraterrestrial materials has long been considered a useful indicator of prevailing geochemical conditions early in the formation of the Solar System. A recent addition to the suite of primitive materials available for study by cosmochemists includes particles collected from the stratosphere called chondritic porous (CP) aggregates1. Carbon-rich CP aggregates are less abundant in stratospheric collections and contain many low-temperature phases (such as layer silicates) as minor components2,3. We describe here the nature of the most abundant carbon phase in a carbon-rich CP aggregate (sample no. W7029* A) collected from the stratosphere as part of the Johnson Space Center (JSC) Cosmic Dust Program4. By comparison with experimental and terrestrial studies of poorly graphitized carbon (PGC), we show that the graphitization temperature, or the degree of ordering in the PGC, may provide a useful cosmothermometer for primitive extraterrestrial materials.

A multi-stage history for carbonaceous material in extraterrestrial chondritic porous aggregate W7029*A and a new cosmothermometer

A new set of primitive extraterrestrial materials collected in the Earth's stratosphere include Chondritic Porous Aggregates (CPA's) [1]. CPAs have a complex and variable mineralogy [1-3] that include 'organic compounds' [4,5] and poorly graphitised carbon (PGC)[6]. This study presents a continuation of our detailed Analytical Electron Microscope study on carbon-rich CPA W7029*A from the JSC Cosmic Dust Collection. This CPA is an uncontaminated sample that survived atmospheric entry without appreciable alteration [7] and which contains ~44% carbonaceous material. The carbonaceous composition of selected particles was confirmed by Electron Energy Loss Spectroscopy and Selected Area Electron Diffraction (SAED). Possible carbonaceous contaminants introduced by specimen preparation techniques are easily recognised from indigenous CPA carbon particles [8] and do not bias our interpretations.

Skill development for innovative procurement environments in construction

The construction industry should be a priority to all governments because it impacts economically and socially on all citizens. Sector turnover in industrialised economies typically averages 8-12% of GDP. Further, construction is critical to economic growth. Recent Australian studies estimate that a 10% gain in efficiency in construction translates to a 2.5% increase in GDP Inefficiencies in the Australian construction industry have been identified by a number of recent studies modelling the building process. They have identified potential savings in time of between 25% and 40% by reducing non-value added steps in the process. A culture of reform is now emerging in the industry – one in which alternate forms of project delivery are being trialed. Government and industry have identified Alliance Contracting as a means to increase efficiency in the construction industry as part of a new innovative procurement environment. Alliance contracting requires parties to form relationships and work cooperatively to provide a more complete service. This is a significant cultural change for the construction industry, with its well-known adversarial record in traditional contracting. Alliance contracts offer enormous potential benefits, but the Australian construction industry needs to develop new skills to effectively participate in the new relationship environment. This paper describes a collaborative project identifying skill needs for clients and construction professionals to more effectively participate in an increasingly sophisticated international procurement environment. The aim of identifying these skill needs is to assist industry, government, and skill developers to prepare the Australian construction workforce for the future. The collaborating Australian team has been fortunate to secure the Australian National Museum in Canberra as its live case study. The Acton Peninsula Development is the first major building development in the world awarded on the basis of a joint alliance contract.