Spoke 3 develops advanced technologies for next-generation Earth Observation (EO) systems, with a particular focus on distributed synthetic aperture radar (DSAR) architectures, digital radar technologies, spectroscopy on chip, and optical payloads designed for nanosatellite and cubesat platforms. The Spoke integrates mission analysis, hardware development, algorithmic innovation, and extensive laboratory testing, aiming to push the limits of imaging capability, miniaturization, and system autonomy for future spaceborne sensing missions.

A core component concerns distributed SAR technologies. Activities encompass the design of miniaturized antennas suitable for cubesats, taking advantage of additive manufacturing to reduce mass and envelope while supporting high-power operations and multi-polarization capabilities. Research investigates MIMO DSAR formations for tomographic applications, atmosphere sounding, surveillance, and passive sensing using transmitters of opportunity. In parallel, the Spoke develops cooperative, coherent DSAR mission concepts, explores multi-satellite architectures, and assesses synchronization, metrology, and calibration strategies using both inter-satellite links and GNSS-based solutions. These developments are complemented by work on signal processing and image formation, including multi-static 2D/3D reconstruction, atmospheric compensation, phase synchronization, and high-resolution wide-swath imaging. Simulation environments and UAV-based demonstrators are created to validate algorithms under controlled yet realistic acquisition conditions.

The Spoke also advances digital radar technologies for EO. Research includes the study of flexible SAR functions, digital beamforming, and reconfigurable payload architectures tailored for small satellite classes. Emphasis is placed on shifting digital–analog interfaces toward the antenna and defining architectures for distributed payloads operating across multiple spacecraft. Key enabling technologies required for onboard digitalization are identified and validated through breadboards and laboratory experiments, supporting TRL growth and readiness for next-generation responsive SAR missions.

In parallel, Spoke 3 develops on-chip spectrometers for sub-millimetre remote sensing, focusing on environmental and atmospheric monitoring. The work includes the definition of science requirements, conversion into instrument specifications, and the design of optical, mechanical, and thermal layouts. Breadboards of critical subcomponents are produced and tested in cryogenic conditions to validate feasibility and consolidate the final instrument configuration.

Another major line concerns optical imaging payloads for nano/cubesats. Activities include information content analysis across multisensor datasets to identify optimal spectral bands and resolutions, the development of free-form optical configurations to maximize performance within compact volumes, and the design of CMOS-based optical technologies and single-photon detection modules. Complementary research investigates AI-based data fusion techniques to enhance image resolution and quality by merging multisource or multitemporal datasets, enabling richer information retrieval despite the constraints of small payloads.

These research efforts are closely coupled with a substantial experimental programme organized under a dedicated work package. This includes UAV formations for DSAR proof-of-concept campaigns, breadboarding and testing of RF components produced via additive manufacturing, experiments on spatially modulated optical architectures, and field acquisitions for MIMO DSAR tomographic imaging. Additional activities validate passive DSAR configurations using illuminators of opportunity, develop digital SAR breadboards for small satellites, and test emerging optical technologies for cubesat applications. Breadboards for the on-chip spectrometer are designed, produced, and evaluated through iterative laboratory testing.