A Physical and Mathematical Model of the Pressure Dynamics of Residue Gas inside a Nonpressurized Instrument Compartment of a High-Orbital Spacecraft

Abstract

This paper presents a physical and mathematical model and the results of evaluation calculations of the process of gas release from structural materials located inside a nonpressurized instrument compartment (NPIC) of a high-orbital spacecraft. Also presented is a model of the dynamics of the pressure drop of the residual gas inside the NPIC, after passing through the active phase of the flight and entering the calculated orbit. It is shown that the main reason for the significant (2–3 week) duration of the process of gas-pressure reduction of an NPIC to a value that allows the inclusion of high-frequency and -voltage equipment is the process of gas evolution from structural and paintwork materials located inside the NPIC. The intensity of outgassing, in turn, depends on the diffusion processes of outgassing substances within the materials themselves. An analysis of the influence of the geometry of the ventilation openings on the duration of the decrease in pressure inside the NPIC to the required level indicated the insignificance of this influence. The physical and mathematical models presented in the paper make it possible to estimate the characteristic time for reducing the pressure inside the NPIC to the required level and, thereby, select the materials inside the NPIC in order to reduce the period of reaching the allowable pressure inside the NPIC.