Physical actuation in a simulated mission
ETHILE, the EXTREMA Thruster-In-the-Loop Experiment, is DART's configurable thrust hardware-in-the-loop (HIL) facility for autonomous spacecraft guidance and control. It inserts a physical actuation and measurement chain into a numerical mission simulation, where control commands encounter the response of real hardware.
The experiment commands a representative propulsion setup and measures the resulting actuation with a dedicated thrust-measurement system. Those measurements are fed back to the numerical propagator, which updates the simulated spacecraft state. Guidance and control algorithms then operate on the consequences of measured actuation, including response variation, delays, control discretization, and other effects introduced by the hardware.
Accelerated and configurable testing
Deep-space low-thrust trajectories may span months or years and cannot be reproduced at mission time scale in a laboratory. ETHILE scales and accelerates the simulation so guidance, control, actuation, and orbital dynamics remain coupled over practical experiment durations.
The configuration can be varied to exercise different guidance cases and actuation conditions under repeatable laboratory controls.
Role in the EXTREMA Simulation Hub
Within the EXTREMA Simulation Hub (ESH), ETHILE provides the translational actuation path. It receives commands from the guidance and control software, returns measured thrust to the simulated dynamics, and operates alongside the RETINA optical facility, the STASIS attitude platform, and the ELAPSE FlatSat environment.
Typical applications include closed-loop autonomous-guidance validation, actuator uncertainty studies, control-allocation testing, hardware and software interface checks, and repeatable verification and validation (V&V) campaigns.