Reflector antennas are by far the most used type of antennas for space and often remain the best solution for applications with a single high gain beam or with multiple beams over a narrow field of view. Reflector antennas provide gain from a simple reflecting surface and can operate at multiple frequencies with single or multiple beams and they can also be shaped to provide one or more contoured beams.

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Technologies included in this topic are those listed below.

• Motor: driving line or rotary actuator
• Stepper motors and brushless DC motors (see Actuator Building Blocks for Mechanisms)
• Bearings
• Lubrication
• Electrical transfer unit
• Flex harness, twist capsule, cable wrap technologies (limited rotation angle range)
• Slip ring technologies (not limited rotation angle range)
• Cylindrical or pancake/disk geometry for the slip rings
• Single-wire, braided-wire, flexible blades carrying contact blocks as brush geometries (integral electrical interfaces or “flying lead” for customer interfacing)
• V-grooved or flat tracks
• Brush-track material pairs
• Roll rings
• Contactless power and data transfer units
• Angular position and reference sensors (see the Harmonisation topic “Actuator Building Blocks for Mechanisms”)

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This topic covers the solar generator subsystem, which can be split into 4 design categories and an environmental testing category.

• Solar cells (with and without integral protection diode).
• Solar cell assemblies: solar cells with interconnectors and cover-glass, and discrete solar cell protection diode (when cell integrated diodes are not the preferred choice).
• Photovoltaic assembly: including mainly solar cell string, diodes, resistors, thermistors, harness, connectors and optical surface reflectors representing the integrated electrical part of the solar generator.
• Solar array assembly, enveloping the photovoltaic assembly, structural and mechanical parts of the generator.
• Environmental interaction of the solar generator with other subsystems, such as effects from radiation, atomic oxygen, thruster plume (chemical and electrical) and electrostatic discharge.Most artificial satellites, with a few exceptions, rely on the power generated by photovoltaic solar generators. This topic covers the solar generator subsystem, which can be split into 4 design categories and an environmental testing category.

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This topic is considered a subset of the System Design and Verification domain, which includes technology, methods, and tools to support the System Engineering processes (specification, design, and verification) of space systems during the complete lifecycle of space missions (phases 0 to F). In particular it covers the items below.

- Space system lifecycle and system-level simulation facilities

• System concept simulator
• Mission performance simulator
• Functional engineering simulator
• Software validation facility
• Functional verification bench
• Assembly, integration and verification simulator
• Ground system test simulator
• Training, operations and maintenance simulator (TOMS).
• Digital twin spacecraft

 - System-level modelling and simulation tasks

• Modelling phase (A)
• Software development phase
• Configuration setup phase (B)
• Configuration package setup phase (C)
• Simulation execution phase (D)
• Data processing and archiving phase (E)
• Database and repository function

Virtual system model, reference architecture and standards

- Simulation models and modelling methods: e.g. system dynamics, non-casual, discrete event, agent based, finite state machine, fact based/objects role modelling)

- Tooling

- Virtual reality, augmented reality, and extended reality technologies

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Most spacecraft have appendages (e.g. solar arrays, antenna reflectors, sensors, booms) that are stowed during launch and released once in orbit. To secure and enable these appendages, two types of mechanisms may be used: Hold-Down and Release Mechanism (HDRM) and the Deployment Mechanism (DM). This topic addresses building blocks of such mechanisms:

Hold Down and Release Mechanisms:

- Clamp bands and dispensers

- Non-explosive release actuators

• Magnetic clamp
• Pin puller / pusher
• Shape Memory Alloy
• Fusible wire / split spool
• Thermal cutter
• Bi-metallic actuator

Deployment Mechanisms:

- Dampers (viscous, melting alloy, Eddy current, magneto-rheological fluid)

- Shape Memory Alloy

- Escapement mechanism speed regulator

- Tape spring

- Magnetic bearing

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Mirrors are a small subset of passive optical components, but essential for the success of many space missions. They are involved in every new design or development of space instrumentation. Highly stable and lightweight structures are complimentary to the production of optical and scientific instruments for space missions. Such structures are needed to provide stable support to the components an optical system (e.g. mirrors, lenses, filters, prisms), detector assemblies (e.g. focal plane arrays, photodetectors) and supporting hardware and structures (e.g. mounts, optical benches and telescope structures). This topic covers the areas listed below.

• Deployable mirrors
• Deformable mirrors
• New mirror materials (e.g. ceramics, carbon nanotubes)
• Mirror steering mechanisms
• Metrology and verification methods
• Improvements in ultra-low CTE materials for ultra stable structures (e.g. Zerodur, SiN)
• Improvements in the characterisation of currently qualified materials (e.g. CTE characterisation of structural and optical materials at cryogenic temperatures)
• New manufacturing technologies (e.g. additive manufacturing of ceramics, joining of dissimilar materials or metals with dissimilar CTE like friction welding of Ti and Al)
• Improvements in the characterisation of thermos-elastic stability of additively manufactured structures such as optical benches, and improvements to facilities for verification of stable structures at cryogenic temperatures

Note that from Harmonisation 2024 this topic will combine the two former topics Technologies for Optical Passive Instruments – Stable and Lightweight Structures, and Technologies for Optical Passive Instruments – Mirrors.

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This topic deals with technologies needed for constructing passive instruments operating in a wide frequency range, extending from millimetre waves (30 – 300 GHz) to sub-millimetre waves (300 – 3000 GHz). In particular it covers all building blocks and the corresponding infrastructure needed to design, manufacture, test, evaluate and space qualify submillimetre wave instruments.

• Antenna reflector and reflector technology
• Antenna, receiver and subsystem measurements
• Mechanisms
• Relay optics, frequency selective structures, calibration loads and feeds
• Receivers, including mixers, LO and amplifiers
• Semiconductor devices and device technologies
• Spectrometers

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This topic covers the areas listed below.

• TT&C transponders for Near-Earth (NE) applications operating in S- (2 GHz) or X- (8 GHz) bands and using either standard phase modulation or spread spectrum technology. NE missions requiring higher data rates are increasingly using K-band (26 GHz) frequency band.
• TT&C transmitters, receivers and beacons (with in-orbit frequency selection) for telecommunication satellites
• Operating in C-, Ku- or Ka-band (in Earth Orbit GSO / NGSO), and Payload Control and Configuration transceivers. This covers both conventional (Frequency Modulation / Phase Modulation) and spread-spectrum approaches.
• Operating in X-, Ka- and EHF- (military) bands, using spread spectrum technology.
• TT&C transponders for Deep Space (DS) missions operating in the X- (8 GHz) and Ka- (32 GHz) bands.
• TT&C transponders for CubeSats and nanosats using S-, X- and K-band, and, more recently, lower bands like VHF (between 30MHz to 300MHz) and UHF (between 300MHz and 3GHz).
• Payload Data Transmitters dedicated to the transmission of science payload data.
• Other related areas
• Space-to-Space, Intersatellite or proximity TT&C links: Proximity transceivers (lander and orbiter) in S- and K- Bands in (cis)Lunar orbit and in UHF in DS planetary scenarios, Intersatellite link transceivers in S-Band, K- (NE) or Ka- Bands (DS)
• Launcher telemetry system

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