DEBRISK

The DEBRISK software is a tool for analysis of the ablation of debris from a spacecraft after its destruction on re-entry into the atmosphere. It is based on an object-oriented approach, in which the space object is represented by a set of interconnected basic geometries. A structure of the parent-child type is used to define the relations between these different objects. Each object is defined by its shape, its dimensions, its mass and its material.

The user provides the initial kinematic conditions of the entry of the space object, and the software calculates the trajectory of the fragments and the possible ablation along this trajectory. The software gives a list of surviving objects and their characteristics on landing.

DEBRISK allows the creation of one spacecraft at a time, but of as many child fragments as required.

DEBRISK first calculates the trajectory and the kinematic conditions of the vehicle as a whole between the starting altitude specified by the user and the fragmentation altitude (between 70 and 100 km), considering a loss of solar power plant at 95 km. It then calculates the trajectory (between the fragmentation altitude and the ground) and the possible ablation of the fragments from the spacecraft. These fragments are defined by the user and can be matched as parent/child. Finally, DEBRISK calculates the casualty area of the surviving fragments.

To do this, the code solves the fundamental mechanics equation along the descent trajectory. Aerodynamic forces are estimated, for each flight domain, for each object. The heat fluxes encountered by the object for each flight domain are calculated, along with the increase in the temperature of the object. When the temperature of the object has reached the melt temperature, the object is ablated, and the changes in its dimensions and mass are taken into account when calculating the trajectory. The purpose of the DEBRISK tool is to calculate the surviving fragments of a spacecraft during its re-entry into the Earth’s atmosphere. It makes it possible to provide this list of fragments to the ELECTRA tool and to calculate the associated casualty area.

 The main functions of the DEBRISK software are:

•  the calculation of the aerodynamic coefficients of the object,
•  the calculation of the trajectory of an object in free fall towards the Earth,
•  the calculation of the aerothermodynamic fluxes,
•  the calculation of the temperature of the object,
•  the calculation of the ablation of the object.