Printing the future of space telescopes

Space telescopes for astronomy and Earth observation revolutionise our understanding of the universe and the planet we live on. The mirrors that collect the light from the astronomical object (e.g. stars, planets, nebulae) or the Earth, and direct it to the detector, are arguably the most important parts of the telescope, as without them the light cannot be studied. However, mirrors for space telescopes need to be lightweight, that is, to have a low mass, due the size of the rockets that launch them; designed specifically for the given science goal (bespoke); and to be fixed within the telescope without distorting the reflecting surface. All these challenges make mirrors for space telescopes one of the most challenging, and therefore expensive, parts to make!

The goal of my research is to increase the use of additive manufacture (AM), also known as 3D printing, within space telescopes, but particularly for low mass mirrors. AM is a new method of manufacture that builds a part layer-by-layer from a digital design file. The primary benefit of AM is in the freedom of design offered by the layer-by-layer approach, which cannot be achieved by using today's manufacturing methods: mill, drill, lathe, casting, or forging. AM can print specialised low mass structures for the given science goal, combine multiple parts into one (mirror + mount), and it is a method of manufacture that is ideal for bespoke, one-off designs, like telescope mirrors. In Years 1 to 4 of my Future Leaders Fellowship (FLF), I investigated three key topics: 1) with more design freedom, how do you choose the correct low mass structure for your mirror; 2) AM is not a perfect method of manufacture, therefore, how can you reprogram the 3D printer to get the best print for your mirror; and 3) how do AM printed parts behave in a space environment and how can we encourage the use of AM in space telescopes.

Building upon Years 1 to 4, my FLF renewal aims to break, or lower, some of the barriers limiting AM use in space telescopes today. The focus of the renewal is to progress AM mirrors through the Technology Readiness Levels (TRLs); these levels represent how mature a technology is. TRL 1 is an idea and TRL 9 is technology that has been successfully flown on a space mission. The FLF renewal seeks to increase AM mirrors to TRL 6, which is where the technology is demonstrated within a relevant environment, in this case, applying vibrations and shocks equivalent to those felt by a rocket during launch, and applying heat to mimic the day-night cycle of an orbit around the Earth. To complement 'demonstration within a relevant environment', AM samples and prototype AM mirrors will be studied to understand how microscopic defects in manufacture can affect how well the mirror reflects light, and how these defects can be measured in terms of size and location.

A secondary focus of the renewal is to understand what holds an engineer back from designing with AM. Given the benefits of AM in hardware for astronomy, why is it not used more widely? Part of the answer lies in the perception that AM is just not ready yet, which I hope to solve by increasing the TRL. However, a part of the answer also lies within the experience that an engineer has and the existing procedures followed within an engineering team. The renewal seeks to understand what holds an engineer back and how engineers can be supported to include AM within their manufacturing toolkit. Supporting engineers and raising the TRL is a research challenge and requires multiple disciplines (e.g. optics, materials science, metrology, manufacture, and social science) coming together to learn the answers. My research vision is to see AM mirrors within future space telescopes, which then have enabled new discoveries within the fields of astronomy and Earth Science.