Distributed Automation Suite for Heuristic Execution and Response (DASHER) Executive cFS Component
Our latest flight software innovation is the development of a cFS App suite, called the Distributed Automation Suite for Heuristic Execution and Response (DASHER), which extends the current state of the art in onboard automation for spacecraft flight software. We focus on improving the coordination between the executive agents on each spacecraft and on improving their ability to operate autonomously. The main component of the DASHER software suite is an execution agent that builds on the existing cFS services to create an Executive on steroids that can execute both mission and science analysis plans intelligently. DASHER uses the PLEXIL planning language to encode and intelligently execute plans and communicates plan execution status across the message bus, so other components of the system can make use of that information.
Keck Institute L5SWS Mission Concept. Fractionated satellites enhance the space science capabilities.
Distributed Spacecraft Missions (DSM) have become increasingly important in the effort to extend the capabilities of instruments to gather science data. DSMs, which include constellations, formations, and clusters, have been demonstrated in the Magnetospheric Multiscale (MMS) and Space Technology 5 (ST-5) missions, but these have relied on ground-based automation to help reduce the mission cost. Future DSMs, such as the proposed Keck Institute Fractionated L5 Space Weather Sentinels (L5SWS), seek to exploit emerging “smallsat” technology to reduce spacecraft development costs. L5SWS will use a cluster of smallsats at the distant L5 libration point make critical heliophysics measurements. Smallsats in the 6U/12U cubesat class have now reached the technological maturity for such missions to be feasible. The challenge that remains is to reduce their operations costs while not increasing the mission risk. As a result, a key enabling technology for future DSMs will be the on-board automation and autonomy software needed to support the mission operations capabilities associated with an MMS-type ground system at a fraction of the cost. This is done routinely in the commercial communication satellite industry, but the complexities of even a small constellation of science spacecraft far exceed those of a fleet of communication satellites.
In DASHER we address some of the inherent uncertainties present in plan execution by incorporating temporal and vehicle health constraints into the executive’s task execution plan. Vehicle autonomy for cars is one thing, but spacecraft have additional concerns including much more limited processing capabilities. We address this by designing algorithms that are streamlined and light-weight enough to run on the processors expected to equip upcoming small to medium satellites and testing them early and often on those processors.
DASHER Architecture. DASHER implemented as a distributed executive communicating via the cFS Software Bus Network (SBN).
We build upon the cFS Executive Services and integrate with our existing CFA application [BMOC1] to enable a DSM with extensive autonomy. We incorporate heuristics to allow the Executive to adapt to changing conditions during execution. We adapt and extend an existing planning language so that it incorporates temporal and vehicle health constraints and develop a streamlined execution engine designed for application on a distributed network of embedded platforms.
Our team consists of both experienced developers of on-board automation software, Emergent, and experts in the development of embedded spacecraft processing systems and algorithms that run efficiently on them, the NSF Center for High-performance Reconfigurable Computing (CHREC). Both teams have experience with the cFS. Together we will create a practical system for robustly implementing autonomy capable of enhancing a DSM.