Predicting the potential growth of biomass on planetary bodies

适当的能量供应，无论是永久的还是短暂的，都等同于我们所知道的宇宙中生命的成功。除了“追逐水”甚至“追逐动力学”之外，寻找能量可用性的迹象可能有助于为理解任何理论上的生命有机体的极限铺平道路，无论它是“我们所知道的”生命的例子还是其他。很少有人研究不同行星环境的能量可用性作为潜在生物活动的限制因素。该项目的目的是建立一个计算模型，能够量化给定环境中的可用能量，并利用这些信息来估计给定或假设的微生物可以生长的程度。这是根据最近对地球热液喷口微生物生长特征的研究得出的结论。该模型侧重于天体生物学应用，将允许研究各种独特的物理和化学环境，并探索它们是否抑制或促进潜在的微生物生长速度。能量模型将从现有的热化学理论和非标准条件下的氧化还原化学中建立可扩展性，其范围包括环境影响，如溶剂流动，风化或日晒及其对化学动力学的影响。在估计生物体如何利用可用能量时，也可以考虑环境因素，例如考虑由于高温或强辐射引起的生物降解，和/或开发量化营养共生作为生长节流的方法。例如，磷或硫的可用性等非生物因素可以对微生物的生长提供一个基本的限制——而提出的模型可能采取措施来量化它们的影响。有人提出了许多潜在的候选对象来测试模型的局限性，从地球上的小尺度、经验可测量的环境到更雄心勃勃的天文模拟，包括火星的地下、木卫二或土卫二的海洋，甚至可能是全球范围内的系外行星。模型最终采取的方向取决于它的最终形式；它可能在个案的基础上，深入考虑特定的环境，只沿着其中的一条或两条路线前进，或者专注于更广阔的图景。本项目将主要由C. S. Cockell教授指导，W. K. M. Rice教授为副导师。

An appropriate energy supply, whether perpetual or fleeting, is tantamount to the success of life in the Universe as we know it. Beyond 'chasing the water' or even 'chasing the kinetics', searching for signs of energetic availability could perhaps help pave the way to understand the limits for any theoretical living organism, be it an example of life 'as we know it' or otherwise. Few studies have been made into the energetic availability of different planetary environments as a limiter for potential biological activity.The aim of this project is to build a computational model with the ability to quantify the available energy in a given environment, and use this information to estimate the extent to which a given - or hypothetical - microorganism could grow. This follows from recent studies into characterising microbial growth in Earth's hydrothermal vents. The model, focused on astrobiological applications, will allow for the study of a variety of unique physical and chemical environments and the exploration of whether they inhibit or bolster potential microbial growth rates. The energetic model will be built with extensibility in mind from existing thermochemical theory and redox chemistry in nonstandard conditions, with the scope to include environmental effects such as solvent flows, weathering or insolation and their influence on chemical kinetics. Environmental factors may also be considered when estimating how an organism could make use of the available energy, for example by considering biodegradation due to high temperatures or harsh radiation, and/or developing methods to quantify nutrient colimitation as a throttle to growth. For instance, abiotic factors such as the availability of P or S can provide a fundamental limit on the growth of microorganisms - and the proposed model may take steps to quantify their impact.A number of potential candidates for testing the limits of the model are proposed, ranging from small scale, empirically measurable environments on the Earth to more ambitious astronomical simulations including the subsurface of Mars, oceans of Europa or Enceladus, and potentially even exoplanets on a global scale. The direction in which the model eventually takes depends on its final form; it may head down just one or two of these routes on a case-by-case basis considering particular environments in some depth, or focus on the broader picture. The project will be primarily supervised by Professor C. S. Cockell, with Professor W. K. M. Rice as secondary supervisor.