Printing the future of space telescopes

无论是地球、太阳系还是天文观测，太空望远镜对于绘制气候变化的影响图和了解宇宙的起源和演化都是至关重要的。收集光线并将其传递给探测器的望远镜反射镜是最关键的部件之一--只有在质量最高的情况下，我们才能获得尽可能好的观测。由于制造一件定制的精密硬件所需的时间和专业知识，太空望远镜中的反射镜往往是系统中最昂贵的一件物品。镜面的形状通常需要精确到小于人类头发的宽度，并在DNA的尺度上(即纳米尺度)平滑。此外，为了降低发射成本，反射镜往往需要轻量化结构，导致时间和成本进一步增加。反射镜的制造只是第一个挑战，即使光学完美，安装不当的反射镜可能会造成形状扭曲而无法使用。我提议的研究集中在未来空间光学制造的一种可能的颠覆性技术上。添加制造(AM；3D打印)是逐层创建3D对象，其中每一层都添加到前一层上。与传统的从实体(磨床、钻头或车床)中取出材料，或将材料固定在模具中(铸造、锻造)相比，这种制造过程是“附加的”。AM的一个巨大优势是增加了设计工程师可用的潜在几何形状。传统方法通过从对象/模具中移除材料所需的工具和通道来约束可能的几何形状。相比之下，AM不需要额外的工具就可以在打印每一层的激光(或喷嘴)之外创建复杂的结构。通过分层方法构建部件的自由显著增加了可能的几何形状和设计选项--本质上，设计师免费获得了结构复杂性！AM有可能彻底改变轻质定制镜子的生产。设计空间的增加使轻型结构能够针对其特定功能进行优化，创造出传统方法不可能实现的几何形状。这保证了比目前可用的镜子更轻、更坚硬的镜子。更强大的功能可能是将镜子及其支架打印为一个结构，从而减少接口和紧固件造成的变形。此外，制造这种轻型反射镜所需的成本和时间也将减少，从而提高了从太空成像的负担能力。尽管AM在反射镜制造中具有优势，但有两个关键的研究挑战是我研究的重点。首先，随着设计空间的增加，理想的轻质结构如何最佳确定？选择包括规则和非规则格子，计算机优化，以及从自然中调整结构-为给定的镜子确定最佳方法是一个困难的设计问题。第二，制造反射镜的合适材料和结构性能能否适应AM的使用？镜面制造需要一套独特的材料特性和特性来生成最佳表面。到目前为止，AM还没有针对这一应用进行优化，最佳参数和材料需要详细的研究。我研究的第二个要素是将AM作为未来制造飞行硬件的首选技术。这可以说是为太空设计的AM组件面临的最大挑战。由于昂贵的发射费用，所有空间硬件在发射前都需要经过合格鉴定(即批准运行)，而这一鉴定过程既昂贵又耗时，并对变革造成阻力。因此，我将致力于AM组件的空间鉴定，以实验证明AM对未来飞行硬件的好处。

Space telescopes, for either Earth, Solar System, or astronomical observations, are vital for mapping the effects of climate change and understanding the origins and evolution of the Universe. The telescope mirrors that collect light and relay it to the detectors are one of the most critical components - only if these are of the highest quality can we obtain the best possible observations.Due to the time and expertise required to create a bespoke piece of precision hardware, mirrors in space telescopes are often the single most expensive item of the system. The mirror shape typically needs to be accurate to less than the width of a human hair and smooth on the scale of DNA (i.e. nanometre scale). Moreover, to reduce launch costs, mirrors often need to be lightweight structures, leading to a further increase in time and cost. The fabrication of the mirror is just the first challenge, even if optically perfect, poor mounting of a mirror can render it unusable by creating distortions in its shape.My proposed research focusses on a possible disruptive technology for future fabrication of space optics. Additive manufacture (AM; 3D printing) is the creation of a 3D object layer-by-layer, where each layer is added on the previous. This manufacturing process is `additive' in comparison to traditional methods where material is removed from a solid (mill, drill or lathe), or where material is set within a mould (casting, forging).A huge advantage of AM is the increase in potential geometries available to design engineers. Traditional methods constrain the possible geometries via the tools and access needed to remove material from the object/mould. In contrast, AM requires no extra tooling to create intricate structures beyond the laser (or nozzle) that prints each layer. The freedom of building a part via a layered approach significantly increases the possible geometries and design options - essentially, the designer gains structural complexity for free! AM has the potential to revolutionise the production of lightweight, bespoke mirrors. The increase in the design space allows lightweight structures to be optimised for their specific functions, creating geometries that are impossible via traditional methods. This promises lighter and more rigid mirrors than those currently available. Even more powerful could be the ability to print a mirror and its mount as one structure, thus reducing deformations caused by interfaces and fasteners. In addition, the cost and time required to fabricate such lightweight mirrors would also decrease, promoting the affordability of imaging from space.Despite the advantages of AM in mirror fabrication, there are two key research challenges that are the focus of one strand of my research. First, with the increase in design space, how is the ideal lightweight structure best determined? Options include regular and non-regular lattices, computer optimisations, and adapting structures from nature - identifying the best approach for a given mirror is a difficult design problem. Second, can suitable materials and structural properties for mirror fabrication be adapted for use by AM? Mirror fabrication requires a unique set of material properties and characteristics to generate the best surfaces. AM has not been optimised for this application to date, and the optimal parameters and materials require detailed research.The second element of my research focusses on establishing AM as a go-to technique for the future fabrication of flight hardware. This is arguably the biggest challenge facing AM components designed for space. Due to expensive launch costs, all space hardware needs to be qualified (i.e. approved for operation) prior to launch and this process of qualification is expensive, time consuming and nurtures a resistance for change. Therefore, I will work towards space qualification of AM components, to demonstrate experimentally the benefit of AM for future flight hardware.