Systema-Atomox

Systema-Atomox is a 3D geometrical analysis tool for the computation of atomic oxygen (and other species of the residual atmosphere) fluence and resulting material erosion of an orbiting object outer surfaces. This tool accounts for the 3D geometry, the trajectory and attitude, the surface material properties (e.g. absorptivity, diffuse / specular reflection) and computes the species fluence for the mission lifetime. It is particularly adapted to compute the materials erosion of a spacecraft orbiting in Low Earth Orbit.

An advanced Monte-Carlo ray-tracing technique is applied to compute the flux of atomic oxygen. Its principle is to simulate the atomic oxygen / surfaces interactions with enough particles such that the statistics on the simulated results will reproduce satisfactorily the macroscopic behaviour.

The main characteristics of Atomox are the following:

• It is interfaced with standard atmosphere models: NRL MSISE, DTM, IRI and HWM-93.
• The ambient atmosphere temperature can be handled by the tool: this is performed assuming a Maxwellian isotropic distribution of velocity.
• Multiple reflections can be taken into account: this is performed using the ray-tracing method by following the successive histories of the rays after reflection; the surface properties are described by the following parameters: absorption coefficient, specularity ratio, accommodation coefficient.
• Spinning can be modelled: in this case Atomox performs the average of the flux on all the orientations with respects to the ambient atmosphere.

Outputs are:

• Total impacting flux and fluence,
• Absorbed flux and fluence,
• Direct impacting flux and fluence,
• Spacecraft material erosion,
• Mean impact velocity (amplitude and direction),
• Mean particle energy.

Atomox is integrated within the Systema framework.