Mission studies and technology preparation for the ATHENA (Advanced Telescope for High ENergy Astrophysics) [1- 5] mission are continuing to progress. The X-ray optics of this future space observatory are based on the Silicon Pore Optics (SPO) technology [6-58], and is being evolved in a joint effort by industry, research institutions and ESA. The SPO technology benefits from substantial investments made by the semiconductor industry, and spins-in materials, processes and equipment into the development of novel X-ray optics. A comprehensive Technology Development Plan (TDP) is being implemented, funded by ESA and involving a large number of experts in key areas ranging from micro machining of Silicon, over sophisticated automation and robotic systems, to hybrid manufacturing. The performance, environmental compatibility and serial automated production and testing are being addressed in parallel, aiming at the demonstration of the required technology readiness for the ATHENA Mission Adoption Review (MAR) expected by the end of 2021. A formal Technology Readiness Assessment is in place and is being currently exercised in preparation of the ATHENA Mission Formulation review (MFR). The programmatics for the flight model implementation is being defined in detail, and preparations are starting for the design and implementation of the necessary facilities. An overview of the ATHENA optics technology preparation, the technology readiness assessment and the related activities is provided.
Advanced Manufacturing (AM) has the potential to improve existing technologies and applications in terms of performance, light-weighting and costs. In the context of the SME4ALM initiative, launched by DLR and ESA, the company Kampf Telescope Optics GmbH (KTO) in cooperation with the Fraunhofer Institute for Material and Beam Technology (IWS) have assessed the feasibility of AM to build a high-performance optical mirror for space applications.
For the assessment of the AM potentials, a mirror design concept for cryogenic instruments for observations in the IR and NIR range was baselined. In a second step, Nickel-Phosphorus (NiP) was selected as optical coating. The combination of coating and mirror material is a primary design driver for optical performance. Both materials must have a very similar CTE as well as be compliant to modern optical manufacturing (diamond turning, polishing). As a promising candidate for NiP coating the AlSi40 was selected for the mirror structure.
The potential advantages of AM for optical mirrors in terms of mechanical performance, cost, and manufacturing time were exploited. The achievement of those objectives was / will be demonstrated by:
1. verifying AM material properties and manufacturability of AM mirrors by material sample tests and subcomponent tests
2. designing AM mirror demonstrator by structural, thermal, and optical performance analysis
3. applying and elaborating AM specific design methods (topology optimization, sandwich structures with internal microstructures, monolithic design, etc.)
4. manufacturing, assembling, and testing AM mirror demonstrator to verify manufacturability and optical performance
5. comparing optical and mechanical performance of the AM mirror demonstrator to a conventional mirror by numerical analysis to exploit potential advantages of AM
Additive Manufacturing (AM) processes as Laser Metal Deposition (LMD) addresses various benefits such as the build-up of complex shaped parts, the possibility of functional integration, reduced lead times or the use of difficult machinable materials compared to conventional manufacturing possibilities. Beside mentioned advantages, the use of more than one material in a component strongly increases the field of applications. Similar to structures in nature, multi-material arrangements can be realized by (I) sharp intersections from one material to the other (e. g. in the case of a thin corrosion protection), (II) graded structures enabling smoother material transitions (e. g. dissimilar materials joined together without defects), (III) composite structures with enclosed particles in a matrix material as well as by (IV) in-situ alloying of different material compositions. Due to varying material properties (e.g. thermo-physical, mechanical, optical), the combination of materials often requires a detailed investigation of occurring process phenomena and well-chosen modifications of the process regimes. Within this paper, (a) the right material feeding as well as powder interaction between various materials in Laser Metal Deposition, (b) the suitable selection of laser wavelengths for different materials, (c) process window adjustments by means of additional sensor equipment, (d) limitations of material combinations as well as (e) results and material characterization of multi-material parts are discussed. Phenomena are discussed by means of exemplary industrial applications, e.g. from the jet engine or medical business.
The development of the X-ray optics for ATHENA (Advanced Telescope for High ENergy Astrophysics)[1-4], the selected second large class mission in the ESA Science Programme, is progressing further, in parallel with the payload preparation and the system level studies. The optics technology is based on the Silicon Pore Optics (SPO) [5-48], which utilises the excellent material properties of Silicon and benefits from the extensive investments made in the semiconductor industry. With its pore geometry the SPO is intrinsically very robust and permits the use of very thin mirrors while achieving good angular resolution. In consequence, the specific mass of the resultant ATHENA optics is very low compared to other technologies, and suitable to cope with the imposed environmental requirements. Further technology developments preparing the ATHENA optics are ongoing, addressing additive manufacturing of the telescope structure, the integration and alignment of the mirror assembly, numerical simulators, coating optimisations, metrology, test facilities, studies of proton reflections and meteorite impacts, etc. A detailed Technology Development Plan was elaborated and is regularly being updated, reflecting the progress and the mission evolution. The required series production and integration of the many hundred mirror modules constituting the ATHENA telescope optics is an important consideration and a leading element in the technology development. The developments are guided by ESA, implemented in industry and supported by research institutions. The many ongoing SPO technology development activities aim at demonstrating the readiness of the optics technology at the review deciding the adoption of ATHENA onto the ESA Science flight programme, currently expected for 2021. Technology readiness levels of 5/6 have to be demonstrated for all critical elements, but also the compliance to cost and schedule constraints for the mission.
The work on the definition and technological preparation of the ATHENA (Advanced Telescope for High ENergy Astrophysics) mission continues to progress. In parallel to the study of the accommodation of the telescope, many aspects of the X-ray optics are being evolved further. The optics technology chosen for ATHENA is the Silicon Pore Optics (SPO), which hinges on technology spin-in from the semiconductor industry, and uses a modular approach to produce large effective area lightweight telescope optics with a good angular resolution. Both system studies and the technology developments are guided by ESA and implemented in industry, with participation of institutional partners. In this paper an overview of the current status of the telescope optics accommodation and technology development activities is provided.