Satellite and space debris photometric phase functions used for astronomical images contamination prediction

Abstract The increasing amount of space debris and the number of mega-constellations are creating a serious problems for terrestrial astronomy. Light trails caused by these objects contaminate astronomical images, rendering them ultimately worthless. Knowing where in the sky these objects will be and how bright they will be are essential to optimising observation planning and avoiding such contamination. Photometric phase functions are a powerful tool for understanding asteroids and resident space objects (RSOs) such as satellites, upper stages, and space debris. However, they also provide a means of predicting how these objects will reflect sunlight toward the observer. We consider a model that assumes a spherical object with diffuse and specular components. We defined the phase functions of more than 600 rotating RSOs using more than one million photometric measurements of more than 10 000 objects from the Mini-MegaTORTORA (MMT) light curve catalogue. We discuss in detail the photometric properties of space debris and satellites extracted from the MMT photometric catalogue using the model. We introduce our freely available online service that predicts the brightness of RSOs, including space debris and mega-constellations, for the purpose of supporting astronomers’ decision-making.