ATS3 is an Atmospheric Trajectory Simulation with 3 degrees of freedom. It generates the ballistic track of a vehicle through a configurable atmosphere composed of one or more free molecular and continuum layers. The simulation can be set up to terminate at a predetermined altitude or when a force-based fragmentation threshold is exceeded. When integrated with the Aerothermal Heating Module, ATS3 will drive the evaluation of vehicle heating and ablation, providing a prediction of vehicle or fragment demise:

  • Aerodynamics - ATS3 is supplied with standard coefficients for free molecular and continuum drag coefficients for standard primitive object shapes and can be configured to accept bespoke aerodynamics for specific objects.
  • Bridging functions - ATS3 contains a configurable bridging function for the transition between free molecular and continuum flow.
  • Atmosphere models - ATS3 is supplied with a set of static (1976 US Standard, CIRA2012 Jacchia-Bowman 2008 profiles) and dynamic (NRLMSISE-00, Jacchia-Roberts, Jacchia-Lafontaine-Hughes) atmosphere models. Other user defined atmospheres can be described using JavaScript.
  • Gravity models - ATS3 can compute JGM3 harmonics up to 70x70, although the standard configuration of zonal harmonics to J4 are sufficient for most re-entry studies.
  • Accurate - At its core ATS3 has a standard 4th order Runge Kutta solver, delivering configurable accuracy and enabling a balance to be struck between simulation fidelity and performance.
  • Modular - The architecture of ATS3 permits the most appropriate components including the solver, atmosphere, gravity and vehicle heating models to be selected from libraries at execution time.
  • Extensible - Interface definitions are provided for all key components, permitting clients to construct implementations optimised for their specific problem domain.
  • Configurable - All aspects of ATS3 can be configured using JavaScript. This enables sequences of simulations and complex conditional scenarios to be scripted and evaluated without resorting to changes in the core engineering simulation.
  • High performance - Simulation scripts can be constructed to execute several ATS3 simulations in parallel, allowing modern multi-core / multi-processor hardware to be fully exploited. ATS3 has been benchmarked at 2 million simulation steps / second on a standard Intel Core i7 processor.
  • Portable - Written in a combination of Java and JavaScript, ATS3 is fully supported on Windows, Unix / Linux and OS X.