This topic addresses various types of On-Board Radio Navigation Receivers and their core technologies, including those listed below.

- High reliability GNSS space receivers for high-end and mid-range performance: platform receivers to determine absolute and/or relative PVT, including on-ground or on-board precise orbit determination (POD).

• High-End Receivers: typically multi frequency receivers with meter level navigation accuracy and sub-decimetre accuracy in case of on-board real-time POD.
• Mid-Range Receivers: typically single frequency receivers with tens of meter level navigation accuracy with standard point positioning, reaching sub-meter accuracy with advanced orbital filter.

- EO/Scientific GNSS space receivers, such as for reflectometry and radio occultation instruments.

- Low Cost GNSS space receivers based on COTS parts and with limited reliability and level of qualification status, including products for CubeSats.

- Supporting GNSS core technologies: Radio Frequency analogue components (including complex MIMIC), Base-Band processing, clock, GNSS antennas, and technologies for detecting and mitigating interference and spoofing.

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The space system on-board software consists of software (SW) applications embedded in space systems. It interfaces with the ground-based SW, which is developed to support daily operations after launch. The topic is organised around the domains listed below.

- Methods and tools for the SW development that are innovative in the commercial world and require analyses for the adoption in the space domain. 

- New functions of the SW systems that are anticipated to be needed but that need pre-development or prototyping before actual space developments (autonomy, FDIR).

- Space Segment SW including:

• Methods and tools for On-Board SW engineering: all aspects of On-Board SW engineering, requirements, automation of the life cycle, testing, model based development, formal methods (programme verification, correctness proof of specific required properties, static schedulability analysis, etc). In particular, it includes SW simulators and emulators of on-board processors interfacing with System and SW engineering and respective tools. 
• Innovative management processes: adaptive engineering, agile life cycle, new planning approaches, cost estimation methods, distributed development. Focus is on system aspects of SW, system SW co-engineering. Covers also SW-HW co-engineering.
• Architectures: Software architectures for space segment software, including TSP approach, communication protocols, Plug and Play technologies.

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Optical communications use light to transmit data between two points. By replacing radio frequency signals with laser light as a means of carrying data, optical communication technologies offer great advantages for links between spacecraft or between spacecraft and the ground. This topic covers optical communication technologies where at least one of two partner terminals in a point-to-point communication link is embarked on a spacecraft.

• Space-borne terminals for inter-satellite links: LEO-LEO, MEO-HAPS, MEO-LEO, MEO-MEO, GEO-HAPS, GEO-LEO, GEO-GEO, Deep Space – Earth Orbit.
• Space-borne terminals for Space Direct-to-Earth (DTE) links: HAPS-DTE, LEO-DTE, MEO-DTE, GEO-DTE, Lunar-DTE, Deep Space – DTE.
• Ground-based terminals for Space Direct-to-Earth links: including steerable optical ground station feeder links to LEO/MEO, non-steerable optical ground station feeder links to GEO, quantum key distribution, and Moon-based optical ground station.

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Detectors form the cornerstone of many space missions as they are used to sense radiation from infrared to X-rays and beyond, and often their performance is the limiting factor for instrumentation on board spacecraft. Within Harmonisation this topic focuses on optical detectors in the range from ultraviolet (UV) to visible and infrared (IR) wavelengths, with a main focus on the latter two.

- Silicon detectors operating in the waveband near UV to near IR (250-1000 nm):

• Charge-Coupled Devices (CCD)
• CMOS Image Sensors (CIS)
• UV to NIR photon-counting detector technologies: mainly Single-Photon Avalanche Diodes / Silicon Photomultiplier (SPAD/SiPM), Avalanche Photodiodes (APDs) and photocathode-based detectors.

- IR detectors operating in the spectral range from 1µm to ~20µm (and up to sub-mm in a few scientific applications): including MCTs, InGaAs, III-V compounds, Type-II super-lattice structures, uncooled thermal detectors, APDs and associated support electronic devices (ASICs).

This topic also looks into supply chain issues related to all applications.

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Photonics is a term for a very broad field which involves the generation, manipulation and detection of light. This topic covers aspects of waveguided optics, in particular fibre optics and integrated optics for space application. 

• Components: lasers for digital and analogue transmission, frequency combs, modulators, photodiodes for digital and analogue communications, opto-couplers, passives (single and multi-mode optical fibres, fibre optic couplers/splitters, multi/demultiplexers, isolators, connectors).
• Sub-systems: modulators, e.g. optical amplifiers.
• End-to-end links: digital and analogue
• Equipment: e.g. Frequency Generator Unit, frequency converter, router, RF filter, beam forming network, optical wireless, fibre sensing (fibre optic gyroscopes, thermal monitoring…), opto-pyrotechnics, micro-photonics, packaging

Note that hybrid devices and equipment used in LIDARs, laser communication terminals, Quantum Key Distribution (QKD) and optical clocks are covered in other Harmonisation topics. See in particular Optical Communications for Space, and Frequency and Time Generation and Distribution.

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Power management and distribution are crucial functions in satellite systems, as they ensure that all subsystems operate reliably. The power management system regulates the power supply, stores excess energy, and distributes it to the various subsystems as required. The distribution system provides the power to each subsystem while ensuring that the overall power usage remains within the limits of the satellite's power budget. The areas covered by this topic are listed below.

• Power subsystems architecture: including power subsystem topologies, sizing, modelling and simulation tools and techniques.
• Power electronics or power conditioning and distribution: including regulation, control and distribution within the spacecraft power subsystem (management of solar array power and battery storage including protection and distribution to the loads), and within any electrical equipment (power converters, distribution, protections).
• Basic materials and processes: including hardware and component technologies used in power conditioning and distribution and analogue domains.
• High voltage power management (>200V) and high voltage and high temperature potting materials for applications like power supplies for Travelling Wave Tubes, Electrical Propulsion electronics.

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This topic covers the main destructive phenomena related to spacecraft RF power, and the technologies available to prevent them or reduce the associated risks.

• Multipactor
• Corona or gas discharge
• Passive intermodulation interference between high-power transmission and low-power receiving antennae

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Printed Circuit Boards and Electronic Assembly Technologies provide the interconnection and packaging technologies for EEE components to operate reliably and in unison within the electronic system. System level packaging by assembly of EEE parts on PCBs constitute the nerves and the veins of the electronic system, interconnecting its brains and senses by distributing power and signal. In addition, system packaging provides the backbone and armour, as the sensitive EEE parts need protection from the harsh environmental conditions of the soldering processes, ground-based testing, launch and prolonged operation in the application environment. The technology domain is strongly driven by reliability, miniaturisation, signal speeds, power integrity, thermal management, environmental legislation and commercial market trends. This Harmonisation topic covers printed circuit board materials, electronic assembly technologies and verification processes of the assemblies as well as harness manufacturing processes.

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Pyrotechnic devices, in the context of release mechanisms, refer to the category of devices that utilise the energy released from a controlled explosion to perform useful work. Pyrotechnic devices are used in many crucial single-use operations in a space mission. This topic includes areas listed below.

• Cords
• Cutters
• Separator nuts
• Detonating transfer lines
• Detonators (including opto-pyro detonators)
• Pyrovalves
• Shock generators
• Microperforators
• Thruster igniters

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Radiation effects on spacecraft are an increasing problem, due to the increasing complexity of spacecraft platforms and payloads as well as the changing nature of missions (longer traverse time in radiation belts, more hazardous locations). Here radiation refers to particle radiation (highly energetic plasma) with a nominal energy range from 30 keV to >10 MeV (electrons) and 0.1 MeV/nucleon to > 1 GeV/nucleon (protons and heavier ions). This topic covers radiation:

• environment measurement techniques,
• environment modelling,
• effects analysis tools,
• hardening and radiation effects mitigation,
• effect mechanisms,
• effects testing methods,
• facilities,
• hardness assurance.

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