Japanese multinational electronics manufacturer三菱电has come up with a new approach that enables the freeform 3D printing of satellite antennas in-orbit.
三菱电’s technology revolves around a newly-developed liquid resin, which is not only custom-made for manufacturing in a vacuum, but is capable of photopolymerization via the sun’s ultraviolet (UV) rays. With further R&D, the process is expected to allow for the fabrication of high-gain antenna reflectors in space, as well as large-format parts, far bigger than the dimensions of satellites’ fairings.
“The technology specifically addresses the challenge of equipping small, inexpensive spacecraft buses with large structures,” says Mitsubishi Electric. “Resin-based on-orbit manufacturing is expected to enable spacecraft structures to be made thinner and lighter than conventional designs, which must survive the stresses of launch and orbital insertion, thereby reducing both total satellite weight and launch costs.”
替代“弹簧”卫星？
目前，卫星天线倾向于以全尺寸发射到轨道上，或者是弹簧/电动机在适当的位置后展开的弹簧/电动机。三菱电气说，虽然前者自然地占用了很大的空间，但要发射昂贵，但后者说后者“机械上很复杂”，容易出现故障。同时，由于尺寸的限制，较小的卫星根本无法部署大型高增益天线。
Given the growing popularity of such devices, often described as ‘SmallSats’ or ‘CubeSats,’ the company has therefore identified a pressing need for one with enhanced signal-relaying capabilities. While Mitsubishi Electric revealed little about its new solution to this issue during the technology’s recent unveiling, its researchers published a paper on it back in 2019 that does shed some light on its functionality.
在他们的研究中，工程师强调了如何通过团队在Massachusetts Institute of Technology（麻省理工学院）和NASA’s Jet Propulsion Laboratory。尽管团队承认这些设备具有“储藏量与最终部署直径的高比例”，但他们补充说，这种卫星天线“缺乏X波段以上频率的表面质量”。
实现truly-optimized SmallSat Mitsubishi Electric researchers say that antennas must therefore avoid being compromised by any need for folding or deflating. The team’s alternative to this? a 3D printer and novel resin, designed to be immune to shocks, and once in-orbit, to be polymerized into parts with a submillimeter-level of smoothness and high-frequency capabilities.
三菱电气的3D印刷研究
尽管团队很可能在三菱电’s Research Laboratories（MERL）在过去三年中对其方法进行了改进，他们的论文确实至少表明了它的工作原理。
从本质上说,拟议中的乌鸫3 d打印机是一个迷你malist hub, complete with an extruder, spin motors and positioning actuators, designed for mounting onto a spacecraft bus. Once installed, the system is built to extrude a custom resin into freeform antenna patterns, which is formulated specifically to be photopolymerized by the sun, and not under other conditions, such as fluctuations in heat or radiation.
To validate their in-orbit 3D printing approach, the MERL team established an experimental test setup, in which an Arduino-controlled extruder was used to eject material into a 500mm spherical vacuum chamber. Even though the chamber’s dimensions limited the size of the researchers’ initial builds, they found it possible to remotely print 160mm-wide paraboloid reflectors, via an extrusion control software.
During later experiments, the resulting parts were then subjected to radio frequency (RF) characterization, in tests that saw 10, 13.5 and 20 GHz waves fired at them in an anechoic RF test chamber. While results showed that the components offered a weaker gain than that needed by a conventional CubeSat, the team maintained that with a better dipole feedpoint, they could focus wavelengths as short as 1mm.
Back in 2019, the engineers concluded that their work had demonstrated a “proof of concept of some, but not all” the technologies needed to carry-out freeform 3D printing in-orbit, but given Mitsubishi Electric’s recent revelation that its method is ready for action, it appears that any obstacles to this have now been overcome.
“Mitsubishi Electric’s innovative approach—resin-based on-orbit manufacturing—efficiently realizes high-gain, wide-bandwidth, large-aperture antennas deployed from a lightweight, vibration-resistant launch package,” concludes Mitsubishi Electric. “By developing a 3D printer that extrudes a custom ultraviolet-curable resin formulated for vacuum, resin-based low-power freeform additive-manufacturing in space has now become possible.”
Advancing in-orbit additive manufacturing
The idea of 3D printing advanced parts from a liquid resin in space using only the power of the sun, may sound more science fiction than science fact, but it’s not the first time this has been proposed. As long ago as 2016,Part Time Scientistsworked withAudi开发Alina Lunar Lander和Audi Lunar Quattro Rover，在一个移动的项目中lunar microwave 3D printing接近现实的一步。
When it comes to additive manufacturing satellites in-orbit, the technology has also come on leaps and bounds since then, with researchers at theMunich University of Applied Sciences开发新颖的低地轨道3D打印机。该团队的挤出系统是去年建造的，是“ AMIS-FYT”项目的一部分，专门设计用于在零重力条件下构建太阳能电池板或天线。
最近，工程师悉尼大学andUniversity of Science and Technology of Chinahave even managed to design anin-orbit FFF 3D printer with high-temp capabilities。Using Proportional Integral (PI) controllers, the system is capable of operating at up to 400°C in a vacuum, potentially making it ideal for carrying out orbital repair missions.
More on Mitsubishi Electric’s technology can be found within its study on the subject, entitled: “On-Orbit Additive Manufacturing of Parabolic Reflector via Solar Photopolymerization。” The paper was co-authored by Avishai Weiss, William S. Yerazunis, Patryk Radyjowski and Richard Cottrell.
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特色图片显示了研究人员最初的抛物面反射器构建之一是印刷的。通过三菱电气照片。
