Mars and Titan's atmosphere and interior

火星和土卫六(土星最大的卫星)是太阳系中最像地球的两个天体。无论是在过去、现在还是将来，这两颗行星都被认为是生物活动的可能地点。可能存在什么类型的有机体，以及它们是否存在，是激烈的科学辩论和研究的主题。如果在另一个星球上发现生命，它将对我们看待我们在宇宙中的位置的方式产生深远的影响，并将成为有史以来最伟大的科学发现之一。要了解这些天体上可能出现的生命类型，以及我们可能如何寻找它，需要深入了解每个行星的环境。这就是我计划与美国国家航空航天局(NASA)和欧洲航天局(ESA)等世界主要机构合作进行的研究重点。火星有稀薄的二氧化碳大气层和许多与地球相同的地表特征--例如河谷(现已干涸)和沉积岩。最近的证据表明，火星过去更宜人，温度更高，大气层更厚，类似于地球早期的大气层。美国宇航局火星探测车的最新结果表明，火星表面长期存在液态水。理解早期环境的关键是火星的内部结构，因为这在很大程度上决定了年轻火星的表面，包括保护大气免受太阳辐射的影响，火山可能提供了大量大气气体，以及影响地表地质的内部对流/热流。目前对火星内部的了解非常有限--我们甚至不知道火星的核心有多大，也不知道它是液体还是固体。探测地球内部的最好方法是地震学，就像我们在地球上所做的那样。外星人火星任务包括一个地震计，它将使用马斯克斯来探测火星内部。我将校准和测试地震仪，以确保数据可以正确解释，同时使用为全球地球地震学开发的技术改进火星内部的地震模型。了解火星过去环境的另一个关键是了解现在的大气和气候变化。目前还不知道火星目前的气候是否稳定--每年火星的夏天，水蒸气都会离开两极，也不知道它是否会回来。一种令人兴奋的可能性是，火星正在从一种气候状态转变为另一种气候状态。这个问题只能用宇宙飞船和望远镜观测相结合的方式来回答。NASA的火星勘测轨道器(MRO)航天器是进入火星轨道的最新和最先进的航天器。我将使用来自MRO的数据来确定火星大气中的水和尘埃的分布，并确定它们对气候的影响。泰坦是寒冷的外太阳系中类似地球的行星的一个例子。泰坦有厚厚的大气层，和地球上一样有云和雨，但它是由甲烷组成的，而不是水。最近的卡西尼号任务显示了许多迷人的表面特征，包括甲烷湖、山谷、火山和由微小冰晶组成的沙丘。土卫六的大气层是苯等有机分子的温床。一些非常复杂的分子预计会存在于北极，在那里，它们受到太阳光的保护，不会受到泰坦阴影的破坏。卡西尼号在2006-2007年间多次飞越极点，让我们第一次看到了这个令人兴奋的区域。测量的红外光谱中存在的许多有机分子尚未被识别。有机分子的全球分布可以用来探测泰坦的大气运动，如极地涡旋和全球环流单元。土卫六的春分是在2009年，模型预测大气将发生广泛而快速的变化--尤其是在冬季极地。从地球上永远看不到这一极，卡西尼号提供了一个独特的机会来观察极地涡旋的破裂，这至少在30年内是不可能再次发生的。

Mars and Titan (Saturn's largest moon) are the two most Earth-like bodies in the solar system. Both planets have been suggested as possible locations for biological activity, either in the past, present, or future. What type of organisms might exist and whether they do exist is the topic of intense scientific debate and research. If life is found on another planet, it would have far reaching effects on the way we view our place in the universe and be one of the greatest scientific discoveries of all time. To understand the type of life that could occur on these bodies, and how we might look for it, requires in-depth knowledge of the environment of each planet. This is what I plan to focus my research on - in collaboration with major world-wide institutes such as NASA and ESA. Mars has a thin CO2 atmosphere and many surface features in common with Earth - e.g. river valleys (now dry) and sedimentary rocks. Recent evidence shows Mars was much more hospitable in the past with warmer temperatures and a thicker atmosphere, similar to Earth's early atmosphere. New results from NASA's Mars Exploration Rovers show evidence for prolonged existence of liquid water on the surface. Key to understanding this early environment is Mars' internal structure as this determined much about the surface of young Mars, including protection of the atmosphere from solar radiation, volcanoes which may have supplied much of the atmospheric gases, and interior convection/heat-flow which influenced surface geology. Knowledge of Mars' interior is currently very limited - we do not even know how big Mars' core is and whether it is liquid or solid. The best way to probe the interior is with seismology, as we do on Earth. The ExoMars mission includes a seismometer, which will use Marsquakes to probe the interior. I will calibrate and test the seismometer to ensure that the data can be interpreted properly, while simultaneously developing seismic models of Mars' interior using techniques modified from those developed for global seismology of Earth. Also key to understanding Mars' past environment is understanding the present atmosphere and climate change. It is not known if Mars' current climate is stable - water vapour migrates away from the poles each Martian summer and it is not known if it returns. One exciting possibility is that Mars is changing from one climate state to another. This question can only be answered with a combination of spacecraft and telescope observations. NASA's Mars Reconnaissance Orbiter (MRO) spacecraft is the latest and most advanced to enter orbit around Mars. I will use data from MRO to determine water and dust distribution in Mars' atmosphere and determine what effect these have on climate. Titan is an example of an Earth-like planet in the cold outer solar system. Titan has a thick atmosphere and has clouds and rain just like on Earth, but made of methane instead of water. The recent Cassini mission has shown many fascinating surface features including, methane lakes, valleys, volcanoes, and sand dunes made of tiny ice crystals. Titan's atmosphere is a breeding ground for organic molecules like benzene. Some very complicated molecules are expected to exist at the North pole, where they are protected from destruction by sun light by Titan's shadow. Cassini performed multiple flybys over the pole during 2006-2007, giving us our first ever view of this exciting region. Many of the organic molecules present in the measured infra-red spectra are yet to be identified. The global distribution of organic molecules can be used to probe Titan's atmospheric motions like the polar vortex and planet-wide circulation cells. Titan's spring equinox is in 2009 when models predict extensive and rapid changes in the atmosphere - especially at the winter pole. This pole is never visible from Earth and Cassini provides a unique opportunity to observe the polar vortex break-up, which will not be possible again for at least 30years.