Printing the future of space telescopes

无论是用于地球、太阳系还是天文观测的太空望远镜，对于绘制气候变化的影响和理解宇宙的起源和演化都至关重要。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——只有这些反射镜的质量达到最高，我们才能获得最好的观测结果。由于制造定制的精密硬件需要时间和专业知识，太空望远镜中的镜子通常是该系统中最昂贵的一件物品。镜面形状通常需要精确到小于人类头发的宽度，并在DNA的尺度上平滑（即纳米尺度）。此外，为了降低发射成本，反射镜通常需要采用轻量化结构，从而进一步增加了时间和成本。镜子的制作只是第一个挑战，即使光学完美，镜子安装不当也会造成形状扭曲，使其无法使用。我提出的研究重点是未来空间光学制造的一种可能的颠覆性技术。增材制造（AM； 3D打印）是一层一层地创建3D对象，每一层都是在前一层的基础上添加的。与传统方法相比，这种制造过程是“增材制造”，传统方法是将材料从实体（铣床，钻头或车床）中移除，或者将材料设置在模具中（铸造，锻造）。增材制造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。传统方法通过从物体/模具中移除材料所需的工具和通道来限制可能的几何形状。相比之下，增材制造不需要额外的工具来创建复杂的结构，除了打印每层的激光（或喷嘴）。通过分层方法构建零件的自由显着增加了可能的几何形状和设计选项-本质上，设计师免费获得结构复杂性！增材制造技术有可能彻底改变轻型定制镜子的生产。设计空间的增加使轻质结构能够针对其特定功能进行优化，从而创造出传统方法无法实现的几何形状。这将使镜子比现有的更轻，更坚固。更强大的能力可能是将镜子及其安装打印为一个结构，从而减少由界面和紧固件引起的变形。此外，制造这种轻型镜子所需的成本和时间也将减少，从而提高从太空成像的可负担性。尽管增材制造在镜面制造方面具有优势，但有两个关键的研究挑战是我研究的一个重点。首先，随着设计空间的增大，如何最好地确定理想的轻量化结构？选择包括规则和非规则晶格，计算机优化，以及从自然中适应结构-为给定的镜子确定最佳方法是一个困难的设计问题。第二，镜面制造的合适材料和结构性能是否适合AM的使用？镜面制造需要一套独特的材料属性和特性来产生最佳的表面。到目前为止，AM还没有针对这种应用进行优化，最佳参数和材料需要详细的研究。我研究的第二个要素集中在建立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增材制造组件面临的最大挑战。由于昂贵的发射成本，所有的太空硬件都需要在发射前进行认证（即批准运行），而这一认证过程既昂贵又耗时，还会产生变革阻力。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.