Additive manufacturing in space – moulding the way to build lighter, flexible, and cost-efficient satellite systems

Jabir Hussain, Ph.D. Fellow/ Early Stage Researcher (TESLA project H2020-MSCA-ITN) at the Microwave Components Group (MCG), Department of Electrical, Electronic and Communications Engineering, Public University of Navarre (UPNA)

What is Additive Manufacturing?

According to the International Organisation for Standardisation (ISO), additive manufacturing is a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies.
Let us break it down to have a better understanding.

• joining materials – instead of cutting the bulk raw material into the desired shape and size, the raw materials in powdered form or sheets are fused or bonded together.
• 3D model data – the object to be built is designed using computer-aided-design (CAD) software and the data is fed to the manufacturing machine.
• layer-upon-layer – the objects are build using a bottom-up approach.

We can use the analogy of ice-sculpting for the traditional subtracting manufacturing techniques such as the conventional machining techniques like milling or electro-erosion, whereas additive manufacturing can be thought of as using LEGO® blocks to build the objects.

  

In common parlance, additive manufacturing (AM) is most widely known as 3D-printing. Though technically 3D-printing is one of the many ways of AM, the term has become almost synonymous with AM and is used interchangeably. At the same time, AM is just a class of the new Advanced Manufacturing procedures currently being developed and used across industry sectors.

Additive Manufacturing dates back to the early 1980s for rapid prototyping and it has since then increasingly found its way into commercial and consumer markets as well as into the challenging sectors like the healthcare, automobile, and aerospace industries. Starting from the basic stereolithography (SLA) process, AM technology has evolved into wide variety of processes like Fused Deposition Modelling (FDM), Selective Laser Sintering (SLS) and Direct Metal Laser Sintering (DMLS). However, the general workflow of the process remains the same: to build layer by layer.

Why do we need it in space?

Going by very rough estimates, the cost to launch one kilogram to space (for instance onboard the European Ariane 5 or the future Ariane 6) averages about €20,000. Also, any rocket system designed for space is constrained (Tsiolkovsky’s rocket equation) to have at least 85 percent of its total weight to be the fuel propellant and only the remaining 15 percent to be the actual rocket structure and satellite payload system.

Ariane 5 ECA flight VA214, Alphasat (Credit: ESA)

Thus, one of the key challenges in space industry is to reduce the weight of the rocket-payload system, and additive manufacturing provides the right tools of engineering to achieve this goal. By incorporating novel organic and lattice structures into the design philosophy as well as using lightweight and dense materials (which are not quite suitable for machining), a weight reduction of 30 to 60 percent is possible using additive manufacturing. Apart from the advantage of weight reduction, additive manufacturing also has the following benefits:

• Rapid prototyping, meaning a prototype of the object can be tested and verified without restructuring and/or retooling the manufacturing process.
• Devices with complex geometries can be easily fabricated as compared to traditional techniques. This design freedom allows us also to envisage new forms that could not be manufactured with traditional techniques.
• Structures can be built with fewer functional parts, sometimes in one single piece (with any points of weaknesses removed and without needing screws for instance), thereby improving structural integrity, and reducing assembly and logistics cost.
• Freedom in part design allows also on-demand build in required quantity (low-volume), which also increases cost-efficiency.
• Reduced use of raw materials (due to adding and not removing) results in increased environmental benefits (waste management) as well as cost-benefits.

In the future context of global broadband communications using a space segment consisting of constellations of hundreds or even thousands of mini-satellites, AM promises to be a turning point for flexible, cost-effective satellite production. Another potential issue of consequence in the space industry is the requirement of high data rates for the next generation of large geostationary telecommunication satellites along with the increase in capability to support a greater number of users. These requirements, i.e., high data rates and more users, produces the need to design satellite payload components like antennas, filters, etc., with very high-power handling capability. Conventionally designed filters have reached a sort-of theoretical limit to support high-power, and so the need of novel designed filters less prone to high-power effects such as multipactor have arisen. Smooth-profiled rectangular waveguide filters such as those developed by the Microwave Components Group at UPNA are an excellent example of this new generation of power resistant devices and additive manufacturing is the ideal approach for fabrication.

Challenges of AM in space

Additive manufacturing opens up new possibilities in fabricating devices for the next generation telecommunication satellites. However, there are a few technical barriers and bottlenecks that it has to overcome in order for it to become a standard for space industry. A few of these are listed below:
• There is an inherent variability due to factors such as material powder distribution, flow of melt pools or alignment of build platforms. As such there are issues with reproducibility, reliability, and accuracy. This also hinders its application in mass production.
• As objects are build layer-by-layer from bottom-up, some angled-structures requires the need of supports which needs to be removed after printing.
• Postprocessing treatments like polishing and silver-plating to improve surface roughness and RF performance respectively are required.
• The need to develop new standards and verification methodologies for 3D-printed parts.

Current state-of-the-art of AM in space and how UPNA is forging ahead?

Additive manufacturing capability has been successfully demonstrated in building components for both rocket launch systems as well as satellite payload systems.
Under rocket launch systems, spacecraft support structures such as wing systems, nozzles, combustion chambers etc. have been additively manufactured. The advantages reported were fewer part counts, reduced complexity, and reduced weight. Because additive manufacturing builds objects from bottom-up, it allows the use of new materials with improved thermal and mechanical properties like cooper alloys, polymer-ceramic composites, and high temperature plastics (PEEK, PEI).
ESA under its AMTAC project developed the world’s first spacecraft thruster with 3D-printed platinum-rhodium alloy combustion chamber and nozzle. In recent news, the coaxial injector head of a liquid rocket engine was manufactured using laser beam melting (a process of AM) under the EU project SMILE (SMall Innovative Launcher for Europe).

In addition to this, there has been a massive push for what is known as “in-space” additive manufacturing. The International Space Station is equipped with a 3D-printer capable of printing polymer-based tools and hardware components on demand – without the need of waiting for a visiting vehicle to deliver a required component.
When it comes to satellite payload systems, additive manufacturing is still in a nascent stage. Heavy metal components like filters, antennas, diplexers, etc., have very stringent specifications and the low tolerances of AM fabrication coupled with non-standardisation of processes proves a barrier for it to be adopted by the space industry.

As such, low tolerance structures like antenna supports or placeholders for waveguides and cavity filters have been extensively built using AM and deployed in space missions. In 2018, Hispasat in partnership with SSL launched its HISPASAT 30W-6 satellite with the largest and most complex antenna support structure till date having more than 200 additively manufactured metal and polymer components.

In recent years however, building on previous research, ESA in partnership with Airbus DS and 3D Systems has developed a 3D-printed RF waveguide filter and tested and validated for use in commercial telecommunication satellites. ESA has also developed and tested a 3D-printed dual-reflector antenna which was built as a single piece of polymer and then coated with copper.

Under its ARTES 5.1 programme, ESA, in collaboration with leading space companies such as Airbus DS, Thales Alenia Space, RUAG or TESAT, and other players such as various research institutes in the TESLA network, has been massively driving the R&D in regards to manufacturing and optimizing RF components using AM.

In this regard, UPNA has been a forefront in the research and development of new technologies benefitting the rise of additive manufacturing. The Institute of Advanced Materials (InaMat) is working on developing microreactors for photocatalytic applications using 3D printing directly or 3D printing as a manufacturing tool. The Institute of Smart Cities (ISC), by means of the Microwave Components Group, is a beneficiary of the TESLA project under which one of the aims is to build new design techniques for telecommunication payloads of space systems suitable for additive manufacturing in the context of large platforms. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 811232. The project will entail manufacturing RF passive components using additive manufacturing processes in both metals as well as ceramics. This is a pan-European project collaborating with various research institutes in Europe as well as various partner organisations in space and additive manufacturing industries.

A shift from small constellation system of large satellites towards large constellation system of small satellites in space architecture

Abdul Sami, Ph.D. Fellow/ Early Stage Researcher (TESLA project H2020-MSCA-ITN) at the Microwave Components Group (MCG), Department of Electrical, Electronic and Communications Engineering, Public University of Navarre (UPNA)

Satellites are objects or machines orbiting around the earth for a purpose. There are two types of satellites. Natural satellites and artificial satellites. A basic example of natural satellite is moon orbiting around the earth which exists naturally, therefore, moon is a natural satellite. Artificial satellites are man made machines which orbit around the earth for special purposes. The purposes include communication, defense, weather forecasting and research etc. Constellation system is a group of satellites combine to enhance operation capabilities in space. Traditionally, small constellations of large and complex satellites have been installed in space to carry out desired operations. But form the last decade, a new trend has been initiated by space industries where the idea of large constellations of small satellites has emerged in the market. This new idea is become feasible due to the rapid advancements in technology in the recent years. In this article, I will discuss the strengths and weaknesses of both constellation systems, evolution of space architecture, the current challenges for large constellation of small satellites and the market trends.

Constellation system of small satellites

Satellite mass is generally related with complexity and cost. Therefore, satellites are classified into different classes based on their mass at the time of launching. Satellites which have mass 1200 kilograms or less are categorized as small satellites, similarly satellites in the mass range between 1201 to 2500 kilograms are classified as medium, 2501 to 4200 kilograms are intermediate, 4201 to 5400 kilograms are large, 5401 to 7000 kilograms are heavy, 7001 and above are extra heavy satellites. Small satellites are further classified into six sub-categories from femto to small. Satellites of mass 0.01 to 0.1 kilograms are classified as femto, 0.11 to 1 kilogram are pico, 1.1 to 10 kilograms are nano, 11 to 200 kilograms are micro, 201 to 600 kilograms are mini, and 601 to 1200 kilograms are small satellites. The difference between the mass of smallest to the largest satellite categories represents the development in the space technology and shift in the space architecture. Currently, small constellations of large and complex satellites have dominated the commercial space industry. This dominance is measured in terms of mass shared by currently active large and small satellites in space architecture. The Union of Concerned Scientist (UCS) has shared the mass of 225 out of total 235 active European commercial satellites in their database. There are 163 pico to small satellites out of 225 satellites which represents 72% share by number while the mass share of these satellites is 16%. Similarly, there are 8 medium satellites and their share by number is 4% and by mass is 5%, 19 medium satellites with 8% share by number and 21% by mass, 12 large satellites with 5% share by number and 20% by mass, 19 heavy satellites with 8% share by number and 38% by mass. Even though the large and complex satellites have dominated the current commercial space market in terms of capabilities and investment, small satellites are also emerging as alternate options for investment in the space market. The growth in number of small satellites installed in recent times is seen because of the lower cost, greater capability now possible with small satellites and the possibilities of large constellation systems. In the recent past, Planet a space company has completed a constellation system of 175 small satellites for optical imagery purpose [1]. A huge constellation of small commercial satellites is initiated by OneWeb and Airbus for global internet service. Currently, they are planning a constellation of 720 satellites with weight of 150 kilograms of each satellite and per unit cost varies from $500000 to $1 million [2]. Installation of constellation has been started in 2019 and is projected to start services by the end of 2020. This project is planned to add more 1260 satellites until 2027 [3]. Projects like these show that the number of small satellites in space will grow in the coming years. According to a forecast, a number nearer to 11600 small satellites are planed by different space companies to be placed in orbit between 2018 to 2030 with an annual average of approximately 1000 satellites [4]. These numbers still suggest that large and costly satellites will dominate the space industry for at least one more decade but still a major shift will be observed towards large constellation systems in the space market. Trends in the miniaturization in electronics and other related technologies to satellites and satellite launch cost and launch vehicles will shape the small satellites market.

The miniaturization trends in various technologies like communication equipment, electronics, computing, and sensors has benefited all type of satellites. The most important are electronics and computing for space industry. Both these technologies have achieved significant improvement in the miniaturization in the past years. Today’s smart phones have greater processing power than mainframe computers a few decades ago. Apart from computing technologies, other technologies like mechanical parts and sensors have also experienced significant improvement in miniaturization. These trends not only enable to reduce the size of satellite payloads but also reduce the cost. Because of the above miniaturization trends, the capabilities of small satellites have been improved and developed small satellite market. Despite all these advancements, launch cost is still a big challenge to small satellites. Small launch vehicles are very less efficient than heavy launch vehicles which makes launch cost a big challenge for small satellites. The important point is when will the space industry be able to develop cost effective small launch vehicles. It is still not very clear but according to some observers, a big break through is expected soon.
It is very much expected in the coming years that big constellation systems of small satellites will be more cost-effective with respect to small constellation of large satellites due to the miniaturization and more importantly due to launch cost. These trends can be predicted due to the placement of small constellation of large satellites in geostationary orbit (GEO) which is 35700 kilometers above the earth whereas large constellation of small satellites are placed in lower earth orbital (LEO) which is some hundred kilometers above the earth. So, LEO much nearer to earth than GEO. Due to large distance between earth and GEO, these satellites must be equipped with high power communication equipment and high cost sensors than satellites in LEO. Currently, small satellites are not cost effective when compared with large satellites mainly due to the launching cost. Small launch vehicles or micro launchers are used to launch small satellites up to 350 kg in LEO while medium and heavy launch vehicles are used for launching both GEO and LEO satellites. Micro launchers are like taxis for small satellites where they deliver small satellites at the exact points but at higher costs. On the other hand, medium and heavy launchers are like public buses for satellites which are less expensive but slower and lower availability (satellites must wait for their time slot to be launch). Therefore, medium, and heavy launchers are more efficient for big constellations but in case satellites are required to place in different orbits then it is better to use micro launchers and place satellites in their final exact orbit one by one. Moreover, large number of small satellites are launched to LEO in case of big constellation system whereas few satellites are launched to GEO in case of small constellation system, therefore, overall launching costs of LEO is relatively high when compared with GEO. In Spain, a space company called PLD Space has developed two micro launchers called Miura 1 and Miura 5. Miura 1 is designed for sub-orbital flights (where the launcher does not reach to orbit) to enhance scientific research and technology under microgravity conditions. Miura 5 is mainly designed for launching small satellites. There are 100s of companies in the world offering (or promising to offer in the future) launching services: some of them will survive, some others will disappear. There are companies that launch small satellites from airplanes. This is nice but less reliable and expensive. While some companies launch small satellites from platforms in the middle of the sea, but these are not cost effective if we do not launch many satellites per year (maintenance costs). There are also political issues with them. There is also a risk of failure involved in micro launchers. Although constellation system of small satellites shows more resistant to such type of failures than the traditional heavy launchers, but still high failure rate which may be technically acceptable may create safety concerns in populated regions. That is why PLD Space performs its trails from very low populated coastal regions in the south of Spain. In this short discussion, I have briefly discussed the weaknesses and strengths of LEO and GEO. In practical, there are many tradeoffs involved while designing a constellation system. It is far more complex process than the process I discussed here.

Satellites orbits around the earth.

I am pursuing PhD in Electrical Engineering at UPNA, mainly focused to develop techniques to design passive components (filters) aiming for low cost fabrication to be used in small satellites in future. I am a part of European research group called TESLA where UPNA is one of the beneficiaries of the project. This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 811232.

[1] “Planet Labs Imagery: The Entire Earth, Everyday,” GIS Geography, April 21, 2018, https://gisgeography.com/planet-labs-imagery/
[2] “Amid Concerns,OneWeb Gets Vague About Constellation’s Cost,”Space News, September 12, 2018, https://spacenews.com/amid-concerns-oneweb-gets-vague-about-constellationscost/
[3] “Source Reveals Timing of OneWeb Satellites’ Debut Launch on Soyuz,”Space Daily,October12,2018,http://www.spacedaily.com/reports/Source_reveals_timing_of_OneWeb_satellites_debut_launch_on_Soyuz_999.html
[4] “Small Satellite Launch Services Market Quarterly Update Q1 2018, Forecast to 2030,” (Frost and Sullivan, March2018), 6, https://www.politico.com/f/?id=00000163-7043-d9c0-a1f3-74d3df940000.

Movimiento “Maker”: el cambio

La electrónica es un área de conocimiento capaz de generar apasionamiento. Más allá de los proyectos de investigación que se desarrollan en la Universidad, también se intenta dar cabida a esas pasiones acogiendo asociaciones y movimientos como los que nos presentan hoy en el blog

¿Te has dado cuenta del cambio?
Muchas personas no son conscientes, pero las más experimentadas sabrán de qué hablamos. ¿Revolución tecnológica? ¿Automatización? ¿Ciencia ficción?

En un periodo de nuevos procesos, cambio continuo y mejoramiento de la tecnología, las sociedades contemporáneas más avanzadas están evolucionando de una forma tan abrupta que, en algunos casos, hemos llegado a lograr inventos o artefactos propios de las películas de ciencia ficción. Podríamos abrir un extenso debate sobre cómo la tecnología sigue avanzando tan rápidamente en tan poco tiempo, pero hoy nos centraremos en una pequeña parte: la importancia de la tecnología electrónica.

Decíamos que las generaciones más jóvenes no habrán notado el cambio tan repentino que ha sufrido la ciencia y la tecnología las últimas décadas. Sin embargo, todo el mundo puede recordar los primeros televisores u ordenadores con forma de cubo, teléfonos móviles con teclado o una casa donde lo más parecido a la domótica era la desconexión de la red eléctrica cuando saltaban los plomos. ¿Te has dado cuenta del cambio verdad?

No queremos pasar por alto el hecho de que vivimos rodeados de electrónica. Sin quererlo ni beberlo, constantemente mantenemos contacto con lo tecnológico: coches inteligentes, electrodomésticos programables, robots autosuficientes, tarjetas de crédito, móviles, tabletas… Si bien hace medio siglo estos avances formaban parte de visionarios, hoy en día tenemos la enorme ventaja de utilizarlos.

A raíz de esta evolución, ha surgido lo que se conoce como movimiento “Maker”. Se trata de una comunidad de creadores que, mediante su ingenio y habilidad, consiguen hacer prototipos, invenciones o servicios que ayuden a la sociedad utilizando en gran medida la tecnología. Es aquí donde la electrónica toma notoriedad. El desarrollo de ideas de los “makers” está respaldado fuertemente por la electrónica, como, por ejemplo, en proyectos de domótica, impresoras 3D, realidad virtual o automatización de procesos. Todos los años se celebran grandes eventos para exponer o visitar creaciones de este movimiento en las grandes ciudades de todo el mundo: Roma, Bilbao, Barcelona, Berlín, Nueva York, Oaxaca…

Muchos y muchas nos estamos contagiando de esta fiebre de creación e investigación espontánea. Claro ejemplo somos la asociación i²tec de la Universidad Pública de Navarra, donde, gracias a la ayuda de estudiantes, profesores y personas voluntarias, estamos creciendo y fomentando proyectos tecnológicos ligados a la electrónica. Ya hemos ofrecido cursillos de Arduino, diseño de placas electrónicas, talleres de impresión 3D, charlas sobre drones, eventos y todo tipo de conferencias en pos de un futuro creativo y una sociedad innovadora.


Crea tu manera de expandir y desarrollar tus ideas en un ambiente “Maker”.  Como ya mencionábamos al comienzo de este artículo, los avances tecnológicos han favorecido la evolución industrial de las últimas décadas. En el futuro, seguiremos viendo nuevas invenciones y eventos relacionados con la electrónica, pues es una tecnología que está en crecimiento constante y presente en casi todos los ámbitos cotidianos. Si todavía no formas parte del movimiento “Maker”, no esperes más. ¡Participa y colabora!

Desde i2tec creemos que debemos crear una sociedad crítica y con iniciativa propia, independiente y con suficientes recursos como para plasmar sus pensamientos en creaciones y proyectos reales. ¡Por el futuro Maker!

 

Esta entrada ha sido realizada por la Asociación de Estudiantes de Ingeniería para el Impulso de la Tecnología Electrónica-i2tec