No / Raman spectra of an extremophile cyanobacterial colony in hydromagnesite from Lake Salda in Turkey have revealed a biogeological modification which is manifest as aragonite in the stratum associated with the colony. The presence of key spectral biomarkers of organic protectant molecules such as (8-carotene and scytonemin indicate that the survival strategy of the cyanobacteria is significantly one of UV-radiation protection. The terrestrial location of this extremophile is worthy of consideration further because of its possible putative link with the White Rock formations in Sabaea Terra and Juventae Chasma on Mars.

Astronomers have been observing the night sky for many centuries to establish a better understanding for our universe and solar system. As part of their observations, astronomers characterize celestial bodies by fundamental properties such as mass, motion, and composition in order to provide further insight about the objects in question. As technology and science have evolved, the methods for measuring these properties have become more precise and accurate. One such methodology is known as spectroscopy, and it is a significant tool for observational astronomy. In this paper, we shall describe how we used astronomical spectroscopy to determine orbital and rotational velocities for various objects in our solar system. This method was implemented specifically using the facilities of the Harry D. Powell Observatory on the campus of East Tennessee State University.

<p>While hypervelocity impacts are ubiquitous throughout the solar system and have received decades  of  research,  the dynamic  fragmentation that  occurs  during an impact has received relatively little attention. This is made more troublesome by the fact that, by volume, more material in the target is altered by the tensile stresses of the rarefaction wave that relieves the pressure of the shock wave, compared to the amount excavated by the impact itself. This tensionally affected material  can  include  Grady-Kippfragments,  fragments  of  material  that  were  broken  apart according to a dynamic fragmentation model developed by Grady and Kipp in 1980. By using their model and inserting it into the Eulerian hydrocode iSALE, we have been able to examine the role tensile stressesand dynamic fragmentation play in hypervelocity impacts. We started by finding the limits on Grady-Kipp fragmentation on an already well studied surface, the Moon. We found that fragment sizes are weakly dependent on impactor size and impact velocity. For impactors 1 km in diameter or smaller, a hemispherical zone centered on the point of impact contains meter‐scale fragments. For an impactor 1 km in diameter this zone extends to depths of 20 km. At larger impactor  sizes,  overburden  pressure  inhibits  fragmentation  and  only  a  near‐surface  zone  is fragmented. For a 10‐km‐diameter impactor, this surface zone extends to a depthof ~20 km and lateral distances ~300 km from the point of impact. This suggests that impactors from 1 to 10 km in diameter can efficiently fragment the entire lunar crust to depths of ~20 km, implying that much of the modern day megaregolith can be created by single impacts rather than by multiple large impact events.</p> <p>With the extent of in-situ fragmentation examined we turned ourattention to getting our dynamic fragmentation code to run smoothly with iSALE’s PorTens. PorTens is a change made to iSALE to allow for pore space creation in material undergoing tensile stresses and pressures in order to keep thermodynamic consistency. Importantly, wefound that when the two routines are combined, porosity increases substantially, and that the large basins currently observed on the Moon’s surface are likely most responsible for the high porosity detected by the Gravity Recovery and Interior Laboratory (GRAIL) mission. Additionally, we discovered that deep lying porosity seems to be additive, suggesting that even without the influence of the largest impactors it is possible for porosity to increase over time. The final, and possibly most consequential conclusion from this work is the ability of tensile stresses and pressures can create potential sitesof refugia for early life that may have existed on early Earth or possibly Mars.</p> <p>Our final dive into hypervelocity impacts focuses on modeling fragments of ejecta. To study this, we have restructured the original fragmentation code substantially. Because most of the damage occurring in the ejecta is done in shear, our previously used Grady-Kipp implementation is not able to provide any useful data, without first making some necessary changes. Much of shear stresses occurring during the passage of a shockwave is accommodated by ductile deformation. Thus, we allow tensile damage to accumulate independently of any calculated shear damage. This simple assumption allows us to track fragment size within ejecta curtains.We then present the results of fragment size vs velocity for different sized impactors.</p> <p><br></p>

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Space heating and cooling, as required for chicken poultry farming, is an energy intensive operation. Due to the continuous rise in the prices of fossil fuel, water and electricity, there is a need to develop renewable and sustainable energy systems that minimise the use of fuel or electricity, for heating, and water, for cooling of air. The HYDROSOL (HYDro ROck SOLar) system, developed at Stellenbosch University, is such a renewable energy system that potentially provides a low cost solution. Instead of using conventional gas and electricity heaters for the heating of air during winter, the HYDROSOL system collects solar heat, stores it in a packed bed of rocks and dispatches the heat as required. During hot summer days, when cooling is needed, the rocks are cooled during the night when the ambient temperatures are low and/ or by evaporative cooling by spraying water onto them. During the day, hot air is then cooled when it passes through the colder rocks with minimal water consumption compared to current systems. In this thesis, a prototype of the HYDROSOL system is presented, designed and built for experimental testing. A transient 2-D thermo flow model is developed and presented for the analytical and experimental performance evaluation of this system for solar heating and night air cooling operation. This model is used to conduct a parametric study on HYDROSOL to gain a better understanding of the operation and control of the system. The HYDROSOL concept is intended to be used for heating and cooling of residential buildings, office suites, warehouses, shopping centres, food processing industries e.g. drying of foods, and various agricultural industries e.g. greenhouses. In this thesis, a HYDROSOL system is developed mainly for poultry broiler houses in South Africa focussing on convective dry cooling, charging the rock bed with night-time ambient air, and convective heating, harvesting solar heat during the day, with different modes of operation available. / AFRIKAANSE OPSOMMING: Ruimte verhitting en verkoeling, soos benodig vir hoender pluimvee boerdery, is ‘n energie intensiewe bedryf. As gevolg van die voortdurende styging in fossiel brandstof-, water- en elektrisiteitpryse, het ‘n behoefte ontstaan om hernubare en volhoubare energie-stelsels te ontwikkel wat minder brandstof of elektrisiteit, vir verhitting, en water, vir verkoeling van lug, gebruik. Die HYDROSOL (HYDro ROck SOLar) stelsel, wat ontwikkel is by die Universiteit van Stellenbosch, is ‘n hernubare energie-stelsel wat ‘n potensiële lae koste oplossing bied. In plaas daarvan om konvensionele gas en elektrisiteit verwarmers vir verhitting van lug gedurende die winter te gebruik, maak HYDROSOL gebruik van son warmte, stoor dit in `n gepakte bed van klip en onttrek die warmte soos benodig. Gedurende die warm somer dae wanneer verkoeling benodig word, word die klippe gedurende die nag, met kouer omgewings lug en/of met verdampingsverkoeling, deur water op die klippe te spuit, afgekoel. Gedurende die dag word warm lug afgekoel deur die lug oor die koue klippe te forseer met minimale waterverbruik in vergelyking met huidige stelsels. ‘n Prototipe van die HYDROSOL word voorgestel, ontwerp en gebou vir eksperimentele doeleindes. ‘n 2-D tyd afhanklike termo- vloei model word voorgestel vir die analitiese en eksperimentele verrigting evaluering vir son verhitting en nag lug verkoeling. Hierdie model word gebruik om ‘n parametriese studie te doen om die werking en beheer van HYDROSOL beter te verstaan. Die HYDROSOL stelsel is bedoel om die verwarming en verkoeling vereistes van residensiële geboue, kantoor areas, pakhuise, winkelsentrums, voedsel verwerking nywerhede, soos bv. die droging van voedsel, en verskeie landboubedrywe, soos bv. kweekhuise, te bevredig. In hierdie tesis word ‘n HYDROSOL stelsel, hoofsaaklik vir pluimvee kuikenhuise in Suid- Afrika, ondersoek en fokus op die droë verkoeling, deur die rotsbed te laai gedurende die nag, asook droë- verhitting, wat gebruik maak van son energie gedurende die dag en kan beheer word op verskillende maniere.

No description available.

Asteroid missions are gaining interest from the scientific community and many new missions are planned. The Didymos binary asteroid is a Near-Earth Object and the target of the Asteroid Impact and Deflection Assessment (AIDA). This joint mission, developed by NASA and ESA, brings the possibility to build one of the first CubeSats for deep space missions: the ASPECT satellite. Navigation systems of a deep space satellite di er greatly from the common planetary missions. Orbital environment close to an asteroid requires a case-by-case analysis. In order to develop the Attitude Determination Control System (ADCS) for the mission, one needs detailed information about orbital disturbances in the vicinity of the asteroid. This work focuses on the development of a simulator that characterises the orbital disturbances a ecting the ASPECT satellite in the space environment near the Didymos asteroid. In this work, a model of orbital conditions and disturbances near the Didymos system was defined. The model integrates several classical and modern models of spacecraft motion and disturbance. An existing Low Earth Orbit (LEO) simulator was modified and updated accordingly to the ASPECT mission scenario. The developed simulator can be used to analyse the disturbances to be counteracted by the ADCS of the ASPECT satellite. The objective of the study was to quantify the e ect of both non-gravitational and gravitational disturbances. The simulator was used to analyse di erent orbit scenarios related to the period of the mission and to the relative distance between the spacecraft and the asteroid system. In every scenario, the solar radiation pressure was found to be the strongest of the disturbance forces. With the developed simulator, suitable spacecraft configurations and control systems can be chosen to mitigate the e ect of the disturbances on the attitude and orbit of the ASPECT satellite.

Nesta tese estudamos algumas regiões de aparente estabilidade no cinturão de asteróides e no cinturão de Kuiper, analisando a evoluçãao dinâmica dos objetos nessas regiões por intervalos de tempo muito longos, em geral, da ordem da idade do Sistema Solar. Centramos principalmente nossa atenção no estudo das populações de pequenos corpos ressonantes, analisando três exemplos diferentes: a ressonância 2/1 com Júpiter e seu entorno (falha de Hecuba), a ressonância 2/3 com Netuno (Plutinos), e a ressonância 1/1 com Júpiter (Troianos). Atacamos o problema com diferentes ferramentas numéricas e analíticas: integração numérica direta de modelos precisos, modelos estatísticos de caminhada aleatória, modelos semi-analíticos baseados no desenvolvimento assimétrico da função perturbadora, cálculo de expoentes de Lyapunov, análise de freqüências, determinação de elementos próprios e taxas de difusão, etc. Os resultados obtidos permitem elaborar conclusões sobre a possível origem e evolução dinâmica destas populações. / In this thesis, we study some regions of regular motion in the asteroid main belt and in the Kuiper belt. We analyze the dynamical evolution in these regions over time scales of the order of the age of the Solar System. We centered our study on the populations of resonant minor bodies, discussing three examples: the 2/1 mean motion resonance with Jupiter (Hecuba gap), the 2/3 resonance with Neptune (Plutinos), and the 1/1 resonance with Jupiter (Trojans). We attack the problem with several different tools, both analytic and numeric: integration of N-body models, random-walk statistical models, semi-analytical models based on the assymetric expansion of the disturbing function, calculation of the maximum Lyapunov exponent, frequancy analysis, estimates of the diffusion of proper elements, etc. The results allow to draw conclusions about the possible origin of these populations.

The term “homeland security”, seems to have become synonymous with terrorism in the minds of the general public. However, there are other threats to the security of the United States homeland that can be just as, if not more, devastating than terrorism. Included among these other threats is the potential of an asteroid collision with Earth. Historically, asteroid impact events have been responsible for the devastation of our planet and many of the mass extinction events encountered throughout the geologic record. Knowledge of physical parameters such as structure and rotational dynamics of the asteroid are critical parameters in developing interception and deflection techniques, as well as assessing the risk associated with these bodies and mitigation planning in the event of impact. This thesis encompasses the study of eight potentially hazardous asteroids identified in conjunction with NASA’s OSIRIS REX Mission and observed via the Target Asteroid Project, along with observations from the Robotically Controlled Telescope, and the Asteroid Light Curve Database of Photometry. Photometric data was extracted from all observations. Rotation periods of each target were confirmed using Lomb-Scargle time series analysis, with possible secondary periods indicated in the cases of Hathor (2.2169 hours), Bede (161.1501 hours), and Phaethon (4.5563 hours). Shape models for 2002 FG7, 2004 JN13, and Icarus were produced using light curve inversion techniques These are believed to be the first such models for these asteroids.

High order multistep methods, run at constant stepsize, are very effective for integrating the Newtonian solar system for extended periods of time. I have studied the stability and error growth of these methods when applied to harmonic oscillators and two-body systems like the Sun-Jupiter pair. I have also tried to design better multistep integrators than the traditional Stormer and Cowell methods, and I have found a few interesting ones.

Licentiatavhandling (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 2 uppsatser.