One of the main challenges in space communication has always been attempting to meet the demanding requirement for greater capacity and routing complexity associated with Very High Throughput Satellite (VHTS) missions. Increased amounts of hardware associated with such high capacity mission pushes the payload towards limitation in mass, power consumption, thermal dissipation and accommodation on the spacecraft. This paper describes activities and the final demonstration results of the OPTIMA project. OPTIMA is funded by the EU commission under Horizon 2020, COMPET-2-2016, maturing satellite communication technologies. The objective of the OPTIMA project was to demonstrate and validate the concept of significantly improving the SWaP of VHTS payloads by defining and developing a photonic payload hardware demonstrator based on various photonic equipment building blocks and testing the demonstrator to TRL 6. Since photonic technology is not yet mature for use in the space environment, the OPTIMA project developed and environmentally tested to TRL 6 the necessary photonic devices and hardware payload equipment. Benefits offered from the use of photonic technology in VHTS payload architectures have shown significant mass saving. This comes not only from reduced equipment unit mass but also from a lower number of units required as a consequence of implementing photonic technology. There are also additional benefits, including reduced DC power consumption and improved power dissipation. The OPTIMA demonstrator is based on Ka-band frequency; however, a holistic approach has been taken when deriving equipment specifications by considering VHTS payload requirements as a whole to ensure the demonstrator will lead to technology developments that can easily scale up in terms of frequencies (such as Q/V band) and use in a wide range of VHTS payload architectures. During the early part of the OPTIMA project, the specification of each building block has been established with emphasis on RF and optical performance, mass, footprint, power consumption, power dissipation and cost. The OPTIMA project aims to provide a strong initial impulse to the photonic payloads for telecommunication satellites by focusing the efforts of various industrial and academic actors from the European photonic and space landscape towards the concrete goal of demonstrating the validity of the photonic payload concept.
A laser based soldering technique – Solderjet Bumping – using liquid solder droplets in a flux-free process with localized thermal impact demonstrates the all inorganic, adhesive free attachment of optical components and support structures made of heterogeneous materials for a high-resolution optical filter under harsh environmental conditions. Space applications demand an attachment technology which maintains the precise alignment of bonded components and overcomes challenges of common adhesives such as being more radiation resistant and appropriate for vacuum environments. Besides, stress and strain induced into optical components can deteriorate the wavefront of passing light and therefore reduce the system performance significantly. The presented case study shows the mandatory changes in the design of an optical filter instrument according to the boundary conditions of Solderjet Bumping for different bonding issues. First, a filter window made of N-BK10, covering the optical sensor beneath, is soldered into a frame of DilverP1®. Second, this sub-assembly is aligned w.r.t. to fiducials on a support structure and is attached in this state by soldering as well. The process chain of Solderjet Bumping including cleaning, wettable metallization layer, handling, soldering and inspection is discussed. This multi-material approach requires well-defined reflow energies to melt the spherical shaped solder preforms to create a media-fit joint and to prevent damages on the fragile filter window simultaneously. The findings of process parametrization and environmental testing are presented. The optical performance with respect to stress/strain before and after soldering as well as the alignment state are evaluated using non-contact optical techniques.
Javad Anzalchi, Joyce Wong, Thibaut Verges, Olga Navasquillo, Teresa Mengual, Miguel Piqueras, Eddie Prevost, Karen Ravel, Nick Parsons, Michael Enrico, Johan Bauwelink, Michael Vanhoecke, Antonello Vannucci, Marcello Tienforti
To address the challenges of the Digital Agenda for Europe (DAE) and also to remain in line with the evolution of terrestrial communications in a globally connected world, a major increase in telecoms satellites capacity is required in the near future.
With telecom satellites payloads based on traditional RF equipment, increase in capacity and flexibility has always translated into a more or less linear increase in equipment count, mass, power consumption and power dissipation.
The main challenge of next generation of High Throughput Satellites (HTS) is therefore to provide a ten-fold-increased capacity with enhanced flexibility while maintaining the overall satellite within a “launchable” volume and mass envelope [1], [2], [3]. Photonic is a very promising technology to overcome the above challenges. The ability of Photonic to handle high data rates and high frequencies, as well as enabling reduced size, mass, immunity to EMI and ease of harness routing (by using fibre-optic cables) is critical in this scenario.
Karen Ravel, Charlie Koechlin, Eddie Prevost, Thierry Bomer, Romain Poirier, Laurence Tonck, Guillaume Guinde, Matthieu Beaumel, Nick Parsons, Michael Enrico, Sean Barker
The next generation of telecom satellite makes the industry facing a technological rupture to reach high data throughput up to 1 terabit/s, while making communications links reconfigurable during all mission phases. That is why the introduction of optical communication technologies like laser links or photonic payloads in telecom satellites is foreseen to revolutionize the space telecom market. Hence the groundbreaking photonic payload will enable reaching the increasing demand of debit and flexibility thanks to miniaturization. In such photonic payload, the proposed optical switch will provide both the added value of optical fiber and new flexibility, redundancy and adaptability functions. Sodern, a recognized space equipment provider is presently spatializing the DirectLight® 1,55 μm Optical Switching Technology from HUBER+SUHNER Polatis Ltd (UK), the worldwide leader in optical switch technology for ground telecommunications and datacenter networks.
This paper focuses on the development activities of Sodern and Polatis on their Space Optical Switch development both for GEO 1 terabit/s high reliability and for low cost LEO constellations. An overview of the technology evaluations and design studies as well as of breadboard performance and environmental testing will be presented. Finally Sodern will explain the product development roadmap including the upcoming EQM.
We report the main characteristics and performances of the first – to our knowledge – prototype of an ultra-stable cavity designed and produced by industry with the aim of space missions. The cavity is a 100 mm long cylinder rigidly held at its midplane by an engineered mechanical interface providing an efficient decoupling from thermal and vibration perturbations. The spacer is made from Ultra-Low Expansion (ULE) glass and mirrors substrate from fused silica to reduce the thermal noise limit to 4x10-16. Finite element modeling was performed in order to minimize thermal and vibration sensitivities while getting a high fundamental resonance frequency. The system was designed to be transportable, acceleration tolerant (up to several g) and temperature range compliant [-33°C; +73°C]. The axial vibration sensitivity was evaluated at 4x10-11 /(ms-2), while the transverse one is < 1x10-11 /(ms-2). The fractional frequency instability is < 1x10-15 from 0.1 to few seconds and reaches 5-6x10-16 at 1s.
ATLID (ATmospheric LIDar) is one of the four instruments of EarthCARE satellite, it shall determine vertical profiles of cloud and aerosol physical parameters such as altitude, optical depth, backscatter ratio and depolarisation ratio. The BSA (Beam Steering Assembly), included in emission path, aims at deviating a pulsed high energy UV laser beam to compensate the pointing misalignment between the emission and reception paths of ATLID [1]. It requires a very high stability and high resolution.
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