Cislunar spacecraft trajectory simulation using digital mission engineering flight dynamics software

By necessity, the laboratory for spacecraft trajectory design exists only as a computational framework. Consequently, the legacy engineering “design-build-test” process has been restricted to simulation for such efforts. This simulation takes the form of software that models the physical environment intrinsic to spacecraft motion as well as the general control mechanisms for that motion. In particular, tools to design a reference path for a spacecraft coupled with a stochastic system for simulating and determining orbital parameters based on measurements present the fundamental building blocks for spacecraft flight dynamics. Together, the Ansys Systems and Orbit Determination Tool Kits (STK and ODTK) present such capabilities. ODTK is generally more specific in its application, while particular aspects of STK, including the Astrogator toolset and other general analysis capabilities, are particularly relevant to the spacecraft trajectory domain.

This discussion examines a simulated mission using STK and ODTK. The associated scenario combines mission planning and simulated orbit determination for one spacecraft in relative configuration to another about the L1 libration point in cislunar space. Applications of dynamical systems theory are employed in analysis of trajectory characteristics to generate favorable relative motion parameters. Given a feasible trajectory state, differential corrections are performed to achieve appropriate orbital reconfigurations based upon updated knowledge of the target spacecraft’s motion. These updated orbital data are achieved through measurements supplied to the orbit determination process. This iterative cycle closely resembles the actual operational processes for spacecraft missions.

Harnessing the power of simulation is required for spacecraft trajectory design, analysis and operations. Through such simulation, incredibly complex and elegant trajectories have been designed and flown to all regions of the solar system. The example offered here represents a concrete illustration of such processes enabled by Ansys technology.