IMPACT OF ASCENT FLIGHT ACOUSTIC ENVIRONMENT ON SPACECRAFT SURFACE CLEANLINESS

摘要

The high intensity acoustic field induced by the rocket motors interacts with spacecraft surfaces. The induced vibration dislodges particles off the payload fairing and the spacecraft surfaces, and the dislodged particles redistribute on the payload surfaces inside the fairing cavity. This paper presents a study of the impact of the ascent flight environment on surface cleanliness and a quantitative approach to analyze the problem of particle redistribution for the sensitive spacecraft surfaces. The beginning-of-life (BOL) surface cleanliness of a critical surface is determined by its initial cleanliness and the amount of particles deposited during ascent flight. The Multiple Panel Particle model was developed to track the redistribution of the surface particles. An application of the model involves the prediction of the BOL surface cleanliness levels of star trackers and the low-emittance thermal control surface of an observatory spacecraft. The star trackers, facing upward during the ascent flight, are especially susceptible to the fallout of dislodged surface particles. The low-emissivity thermal control surface is also vulnerable to additional particle deposit on its surface. Additional particles on the thermal control surface cause the emissivity to increase. The analytical results lead to surface cleanliness requirements of the payload fairing.