Effects of gravity perturbation on developing animal systems

Developing systems provide unique opportunities for analyzing the effects of microgravity on animals. Several unusual types of cells as well as various extraordinary cellular behavior patterns characterize the embryos of most animals. Those features have been exploited as test systems for space flight. The data from previous experiments are reviewed, and considerations for the design of future experiments are presented.     

Two-dimensional radiation-hydrodynamics calculations of the formation of O-B associations in dense molecular clouds

Two-dimensional calculations of ionization-shockwave propagation into a curved molecular cloud are presented. Density enhancement occurs due to the combined effects of cloud curvature and radiation flow. The star formation process is expected to be enhanced near the edges of irregularly shaped molecular clouds.Authors listed alphabetically     

Magnetic energy storage and conversion in the solar atmosphere

A review of the theoretical problems associated with preflare magnetic energy storage and conversion is presented. The review consists of three parts; preflare magnetic energy storage, magnetic energy conversion mechanisms, and preflare triggers. In Section 2, the relationship between magnetic energy storage and the electrodynamic coupling of the solar atmosphere is developed. By accounting for the electrodynamic coupling of the solar atmosphere, we are able to examine the fundamental problems associated with the concept of in situ versus remote magnetic-energy storage. Furthermore, this approach permits us to distinguish between the roles of local and global parameters in the storage process.Section 3 is focused on the conversion mechanisms that can explain, in principle, the rapid energy release of a flare. In addition, we discuss how electrodynamic coupling eventually dictates which mechanism(s) is responsible for releasing the stored magnetic energy, and how the global coupling dictates the final evolution of the relevant mechanism. Section 4 examines preflare triggers and Section 5, we examine the most promising directions for future research into the problem of magnetic-energy storage and conversion of the Sun.     

Complex morphological variability in complex evaporitic systems: thermal spring snails from the Chihuahuan Desert, Mexico

Thermal springs in evaporitic environments provide a unique biological laboratory in which to study natural selection and evolutionary diversification. These isolated systems may be an analogue for conditions in early Earth or Mars history. One modern example of such a system can be found in the Chihuahuan Desert of north-central Mexico. The Cuatro Cienegas basin hosts a series of thermal springs that form a complex of aquatic ecosystems under a range of environmental conditions. Using landmark-based morphometric techniques, we have quantified an unusually high level of morphological variability in the endemic gastropod Mexipyrgus from Cuatro Cienegas. The differentiation is seen both within and between hydrological systems. Our results suggest that this type of environmental system is capable of producing and maintaining a high level of morphological diversity on small spatial scales, and thus should be a target for future astrobiological research.     

On the possibility of Earth-type habitable planets in the 55 Cancri system

We discuss the possibility of Earth-type planets in the planetary system of 55 Cancri, a nearby G8 V star, which is host to two, possibly three, giant planets. We argue that Earth-type planets around 55 Cancri are in principle possible. Several conditions are necessary. First, Earth-type planets must have formed despite the existence of the close-in giant planet(s). In addition, they must be orbitally stable in the region of habitability considering that the stellar habitable zone is relatively close to the star compared to the Sun because of 55 Cancri's low luminosity and may therefore be affected by the close-in giant planet(s). We estimate the likelihood of Earth-type planets around 55 Cancri based on the integrated system approach previously considered, which provides a way of assessing the long-term possibility of photosynthetic biomass production under geodynamic conditions.     

Finding extraterrestrial organisms living on thermosynthesis

During thermal cycling, organisms could live on thermosynthesis, a theoretical mechanism applicable to the origin of life and the early evolution of biological energy conversion. All extraterrestrial ice may be a repository for frozen dead or dormant organisms from earlier stages of evolution. In the presence of a thermal gradient within the ice, organisms might still be harvesting energy from thermosynthesis. Possible habitats for thermosynthesizers can be found throughout the Solar System, particularly in the cold traps on Mercury and the Moon, convecting waters on Mars, the oceans on moons in the outer Solar System, and smaller bodies rotating in the sunlight such as cosmic dust, meteorites, asteroids, and comets. A general strategy for detecting thermosynthetic organisms on Earth is offered, and highlights of current and upcoming robotic exploratory missions relevant to the detection of thermosynthesis are reviewed.     

Developing better artificial bones

Researchers at the Center for Commercial Applications of Combustion in Space at the Colorado School of Mines are preparing the Space-DRUMS (Dynamically Responding Ultrasonic Matrix Systems) materials processing facility for transport to the International Space Station. The Space-DRUMS uses acoustic pressure beams to maintain the position of a suspended liquid or solid. Space-DRUMS will be used to extend experiments with tricalcium phosphate in the development of artificial bone material.     

Induced abnormality in Mir- and Earth grown Super Dwarf wheat.

Super-dwarf wheat grown on the Mir space station using the Svet "Greenhouse" exhibited morphological, metabolic and reproductive abnormalities compared with Earth-grown wheat. Of prominent importance were the abnormalities associated with reproductive ontogeny and the total absence of seed formation on Mir. Changes in the apical meristem associated with transition from the vegetative phase to floral initiation and development of the reproductive spike were all typical of 'Super-Dwarf' wheat up to the point of anthesis. Observation of ruptured anthers from the Mir-grown plants revealed what appeared to be normally developed pollen. These pollen gains, however, contained only one nuclei, while normal viable pollen is tri-nucleate. A potentially important difference in the flight experiment, compared with ground reference studies, was the presence of a high level of atmospheric ethylene (1,200 ppb). Ground studies conducted by exposing 'Super-Dwarf' wheat to ethylene just prior to anthesis resulted in manifestation of the same abnormalities observed in the space flight samples.     

Comment on estimating the solar proton environment that may affect Mars missions.

Estimates of the energetic proton environment for a Mars mission are generally extrapolated from the solar proton observations at 1 AU. We find that solar particle events may be divided into two general classes. Events dominated by a near-sun injection of particles onto interplanetary magnetic field lines leading to the spacecraft position represent the "classical" solar particle event associated with solar activity. This class of event will scale in radial distance by the classical power law extrapolation. The extended-interplanetary-shock source generates a maximum flux as the shock passes the detection location. This class of event typically generates maximum fluence, but in this case, the flux and fluence will not scale in the classical manner with radial distance.