Pressure measurement inside non-sealed equipment bay of the geostationary spacecraft

The equipment of the non-sealed spacecraft is functioning during the operation phase in the environment that includes the equipment bay inherent atmosphere. JSC “ISS” together with MAI have developed and implemented in software a mathematical model for the pressure dynamics estimation of the equipment bay inherent atmosphere and for the design parameters selection and construction of the ventilation openings of the non-hermetic equipment bay. The pressure drop dynamics estimation of the equipment bay inherent atmosphere was also carried out according to the developed model. A block of the pressure sensors (joint development of ISS and Novosibirsk State University) was integrated into the geostationary spacecraft for the in-situ pressure measurement inside the nonhermetic equipment bay during the operation. This block consists of two sensors: a semiconductor sensor based on MEMStechnology (micro-electromechanical system) and an inverse magnetron sensor with the cold cathode. The pressure sensor unit provides the pressure measurement from 790 up to 1·108 mm Hg. The authors present the results of pressure measurements inside the non-hermetic equipment bay during the first six months of the spacecraft operation on the geostationary orbit. This article also compares the in-situ pressure measurement results and the calculated pressure drop obtained using the mathematical model for the non-hermetic equipment bay spacecraft.