A thorough discussion of the SPALab project can be found in the Master’s Thesis by Zachary Jacobs titled: Providing a Persistent Space Plug-and-Play Avionics Network on the International Space Station
Overview: SPA, developed by the Air Force Research Lab (AFRL), is a modular technology for spacecraft components based on “plug-and-play” technology. AFRL has been working to achieve Operationally Responsive Space (ORS) by reducing the cost and time to launch a spacecraft. This effort has led to systematic reductions in time for all aspects of developing and launching a spacecraft. This requires standardized systems to be able to assemble a spacecraft and integrate it with a payload rapidly.
Given the complexity of the different systems on a spacecraft, a “plug-and-play” (PnP) standard, called Space Plug-and-play Avionics (SPA), was developed by AFRL to facilitate rapid integration. SPA implements a self-organizing network of modules where components are self-describing and attach to a standardized data and power bus. This allows a satellite to be assembled by connecting the automatically discoverable devices to the SPA network, and focusing the development time on the application that uses the data and services from the SPA modules. This alleviates integration time by ideally eliminating module and bus design, given that SPA-enabled modules that meet the mission requirements are available. SPA networks are self-organizing which means new devices shall automatically be configured and integrated into the existing network. The Satellite Data Model performs the central role of registering SPA devices when they are found in the system
Spa on the International Space Station:
Application of SPA has been limited for CubeSats because implementations of the “discovery and join” mechanics of the SPA network, the Satellite Data Model (SDM), require fairly intensive processing. However, the SPA-1 interface was defined as a low power, low data rate interface for SPA devices, an attractive option for CubeSats. The Space Systems Laboratory (SSL) at the University of Kentucky collaborated with COSMIAC at the University of New Mexico to develop an “SDM-Lite” that runs on low power, low resource microprocessors and provides the necessary SDM functionality required to operate a SPA-1 network of devices. The SSL is adding SDM-Lite support for payloads on the International Space Station using the CubeLab standard and is using SPA-1 derived interfaces for the KySat-2 CubeSat mission. COSMIAC is using SDM-Lite on Trailblazert setup for SDM-lite and SPA-1 devices. An SDM-lite was demonstrated to run on the SSL CubeLab bus development board and 2 SiLabs 8051F120 boards acted as ASIMs.