Scaling Distributed Spacecraft Autonomy Operations with Simple Temporal Networks: Introducing Splinter

The Absolute Time Sequence (ATS) is a well-established mechanism for high-level spacecraft control, executing commands at specific times. One particular weakness of ATSs is that the cost of making a change to the command sequence grows with the length of the sequence, and the cost paid is a number of repetitive-but-detailed changes to the timing of commands, which is error-prone.

This weakness becomes a liability when scaling up to spacecraft swarms or long ATS durations because any perturbation to the command sequence or schedule incurs significant cost. Fitting that cost within a small team or short sequence development timeline becomes a central challenge for mission operations.

The DSA experiment, on-board Starling 1, addressed these challenges by developing 'Splinter', a tool that utilizes the implicit order of a text file, a custom language for stating temporal constraints, and a Simple Temporal Network (STN) implementation to rapidly develop and update command sequences and coordinate events in time across a small satellite swarm, integrating into the cFS command products workflow. This paper presents the tool and discusses the specific mission challenges that motivated its development as well as the experience of using it.