AFRL plug-and-play Spacecraft Avionics Experiment (SAE)

The Air Force Research Laboratory (AFRL) developed an initial plug-and-play capability for spacecraft to better define interfaces, similar to USB on personal computers, in order to simplify spacecraft development and reduce cost and schedule. Much of this improved definition involves standardizing software interfaces between spacecraft components and a spacecraft network. The Spacecraft Avionics Experiment (SAE) was developed and flown as a secondary experiment on the AFRL TacSat-3 spacecraft as the first on-orbit demonstration of the Space Plug-and-Play Architecture (SPA) capability. On numerous occasions during SAE development and test, the modular, reconfigurable SPA interface provided significant cost and schedule savings. SAE consisted of a SPA-USB (SPA-U) network with multiple plug-and-play components with the objective of demonstrating as much core avionics and spacecraft operation as possible in a small secondary payload package. To this end, most elements of a Guidance, Navigation, and Control (GN&C) system were incorporated, to include a sun sensor, rate sensor, temperature sensors, and an AC coupled interconnect experiment. SAE also provided operational backups for TacSat-3 to include a Surrey SGR-05 GPS receiver and a backup high speed SPA-SpaceWire (SPA-S) link between the hyperspectral image processor and the C&DH for payload data transfer. Active GN&C control elements were not included so as not to risk spacecraft stability and control. SAE used built-in self test functions to verify on-orbit performance autonomously. The primary mission of TacSat-3 was to provide hyperspectral imaging data and to receive tasking, collect the data, and downlink to the tactical warfighter in a single flight over theater. TacSat-3 launched on 19 May 2009 and transitioned to the operational user on 12 June 2010. During TacSat-3 on-orbit experimental operations between these dates, SAE performed numerous experiment data collects. Both the SPA-U and SPA-S interfaces operated as designed. One of the SPA-U experiments had a SEU detector on board and no SEUs were observed during experiment operations. SPA-S demonstrated data transfers at 75 Mbps rate with no bit errors observed on orbit. SAE was developed for AFRL by the Space Systems Group at Sierra Nevada Corporation.