Intuition-1: Integration of Leopard DPU and Optical Instrument with platform bus

In August, the project reached a significant milestone: the integration of KP Labs’ payload with the platform bus to form a complete spacecraft – Intuition-1.  

The payload, while crucial, is just one piece of the puzzle.  Our satellite covers a lot of capabilities. From an on-board computer managing operations and Earth communications to an EPS loaded with batteries and solar panels – the power source for all devices on-board. Add to this mix an ADCS to optimize satellite rotation for precision Earth observations and a robust structure to bind all these elements. All these components, including the pivotal radio system for communication,  integrate to form what experts term a “platform bus”. It’s noteworthy that for Intuition-1, AAC Clyde Space stands as the chosen platform bus provider. Yet, the adaptability of both Leopard DPU and Optical Instrument is commendable – they’re compatible with virtually all platform buses in the industry, courtesy of their adherence to standard protocols and form factors.

It’s intriguing to note that the Platform Bus, Leopard DPU, Optical Instrument, and Software were conceived in different global locales by distinct firms. The developmental phase witnessed a surge in technical documents and ICDs from both teams. However, the real challenge surfaced during the Assembly, Integration, and Test campaign (AIT).

Visualisation of the Intuition-1 satellite

Mechanical Integration

The most obvious aspect of the integration is its physical aspects – all the elements have tobe somehow mounted together. Although, Intuition-1 is a 6U platform, the real magic of observing the Earth and using artificial intelligence to process that requires half of that. Optical Instrument takes 2U of volume,  and Leopard DPU takes 1U.  

The important thing to notice is the fact of the modular design – both subsystems are independent of each other, which has a few important implications:

• Leopard DPU and Optical Instrument can be placed in a different part of the spacecraft as long as it is possible to provide wiring between them,  
• Leopard DPU can work with various optical instruments available on the market,
• Leopard DPU can support missions with goals different than Earth Observation, e.g., SAR  

Leopard can be stacked in a CubeSat platform using standard rod mounting. Optical Instrument, on the other hand, requires panel and central wall mounting.  

Our approach for mechanical integration assumed that the platform’s primary and secondary stack were partially integrated when our KP Labs’ team arrived at the provider’s HQ for payload integration. Since that moment, both teams  have been working together to put everything in the right place.

Thermal Integration

Once the components are properly installed on the platform, the next phase is the thermal side of integration. The Optical Instrument does not require any additional radiators. The Leopard uses two radiators mounted to the satellite shear panels. Both radiators are equipped with extra thermal sensors responsible for constant monitoring of dissipated heat. Combined with Leopard’s internal sensor, the thermal system itself provides an optimalenvironment for heavy computing done in orbit.

Electrical integration

To enable Earth Observation and autonomous data processing our components require power. Leopard draws power from the satellite’s EPS system. Depending on the specific configuration, it can operate on unregulated 6.5 to 14 V. Depending on the task being performed at the moment, the power consumption may differ, reaching an envelope even above 20 W for a single Processing Node. For the Intuition-1 mission, we asses it should not exceed 15 W for most of the real-life scenarios (imaging, data preprocessing to Level-1C, AI processing, high-speed communications on data processing), which would be handled by only one of two Processing Nodes. For more demanding applications, two Processing Nodes can be run in parallel to maximize the processing power, however, for Intuition-1 mission, cold redundancy is a nominal scenario for two Processing Nodes.  

KP Labs team during Leopard Flight Model integration

The Optical Instrument, on the other hand, requires a 7 W peak for its imaging task. Although the Optical Instrument is controlled by the Leopard, the power is also drawn from the EPS as well.  

In terms of the data integration, Optical Instrument is connected to the Leopard only (via 100-pin high speed Samtec LSHM connectors), therefore we can easily say Leopard is the main point of contact between the platform bus and KP Labs hardware. The Optical Instrument during acquisition of the hyperspectral scene generates a massive stream of data – nearly 8 Gbps. All the data need to be transferred from the Optical Instrument to the Leopard DPU over LVDS lines via flat flex cables designed with strict impedance control in mind.

Leopard’s built-in Supervisor module utilizes the CAN bus to interact with the platform’s OBC via M80 connectors. This connection is used to put Leopard in a required mode, gather its telemetry, and upload new data if required. Although, in terms of uploading the large data, it is worth noting that the platform’s OBC only controls UHF radio – for high-speed data transfer between Earth and the spacecraft, an X/S-band radio is used, connected directly to the Leopard via LVDS with nano-D connectors. Thanks to the Leopard’s high-performance System-on-a-Chip with FPGA, Leopard performs well handling high-speed communication requiring real-time coding (for downlink) and decoding (for uplink).

KP Labs team cleaning the lenses during Flight Optical Instrument integration

Challenges during the integration

It’s easy to envision that regardless of the number of ICDs, diagrams, simulations, and procedures created, challenges always arise when integrating different components, particularly those designed and manufactured by distinct companies. Such challenges were evident during our payload integration.

The most challenging part was integrating the Optical Instrument with the rest of the spacecraft. Not only it is the biggest (in terms of volume – more than 2U) but also the heaviest (in terms of mass – more than 2 kg) subsystem. It is also the one that requires the most precision and careful handling which was not an easy task in a very condensed nanosatellite where every millimeter of space is of special significance.

Experienced KP Labs’ team was involved in the integration on-site – overall, our team consisted of System Engineer, Hardware Designer, Mechanical and Thermal Engineer, and Software Engineer, who spent two weeks working together with AAC Clyde Space specialists side by side. Thanks to that, any arising issues could be quickly and confidently resolved.

What’s next?

The Intuition-1 project reached a successful milestone with the integration of KP Labs’ payload with the platform bus. Collaborative efforts with AAC Clyde Space proved instrumental in achieving this accomplishment. A big thank you to our dedicated team for their unwavering support and going above and beyond the call of duty, and to the Clyde group for their contribution to the project.

Stay tuned for our upcoming article, where we will delve into our journey through functional and radio testing, as well as our experience navigating the environmental testing campaign, encompassing both thermal and vibrational aspects.

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