Studies of Phobos polar illumination and thermal conditions

我们将分析2012-2015年间从火星快车获得的数据，以更新火卫一当前的形状和旋转参数。然后，我们使用新的形状和方位模型来研究这颗火星小卫星极地地区的照明和热条件。由于自转轴相对于火星系统轨道平面的倾斜，极地地区在夏季享受了数月的日光。由于火卫一的奇怪形状，我们预计会有复杂的照明区和阴影图案。我们将制作照明图，将其与图像中的阳光和黑暗分布进行比较，以可能确定我们的形状和照明模型是否有改进的潜力。我们还将研究来自附近火星的太阳光和热辐射进入火卫一表面附近的热状况。由于火星及其卫星的太阳轨道略呈椭圆形，预计北半球和夏半球全年的热周期会有很大不同。我们还考虑了短暂日食的影响(火星挡住了入射的阳光)。利用热传导数值模式和适用的土壤参数，我们研究了近侧、远侧、极地和赤道地区昼夜热波和季节热波的穿透深度，以限制建议的水冰水库在火卫一内的最小深度。我们的项目将支持在未来几年计划的火卫一飞行任务，它将极大地提高我们对这颗小卫星上不同地理区域环境条件变化的日常和季节性周期的理解。

We will analyze data from Mars Express obtained from 2012-2015 to update the current shape and rotation parameters for Phobos. We then use the new shape and orientation models to investigate the illumination and thermal conditions of the polar areas of this small Martian satellite.Owing to the tilt of the rotation axis with respect to the orbital plane of the Mars system, the polar areas enjoy daylight for many months during the summer seasons. Owing to the odd shape of Phobos we expect intricate patterns of illuminated areas and shadows. We will produce illumination maps, which will be compared with distribution of sunlight and darkness in images to possibly identify potential for improvement of our shape and illumination model.We also study thermal conditions near the surface of Phobos as a result of incoming sunlight and thermal radiation from nearby Mars. Owing to the slightly elliptic solar orbit of Mars and its satellites, thermal cycles over the year are expected to be quite different on the Northern and Summer hemisphere. We also consider the effect of short eclipses (with Mars blocking incoming sunlight). Using numerical models of heat conduction and applicable soil parameters, we study the penetration depth of the diurnal and seasonal heat wave, for nearside, farside, polar and equatorial areas, to constrain the minimum depths of suggested water ice reservoirs within Phobos. Our project will support missions to Phobos, which are being planned in the coming years and it will greatly improve our understanding of the daily and seasonal cycle of changing environmental conditions for different geographic areas on this small satellite.