Study of the risk of impact between a spacecraft and space debris

Abstract

This work lies in the field of Space Situational Awareness (SSA). Nowadays there is a clear interest within Europe to know in detail the real time distribution of space debris objects orbiting around the Earth. One of the main problems from that population is the collision risk between operational satellites and the space debris. For this reason, it is necessary to characterize the probability of collision between the objects in near Earth altitudes whose orbits are known with certain level of uncertainty. First of all, as part of this work, a review of the existing methods to compute the probability will be done. Some of them are based on the hypothesis of statistical distribution of the object trajectory uncertainties, while others are based on Monte Carlo methods. It is necessary to compare those methods and select one for its operational implementation. Moreover, nowadays the most accurate available information for space operators to compute the conjunction probability is the Conjunction Summary Message (CSM) provided by the US Strategic Command to all commercial operators. These messages characterize geometrically the conjunction but do not provide information related to the collision probability. The central objective of the project will be to develop a tool able to handle the information contained in the CSM and calculate the probability related to the specific conjunction described in the CSM. In addition, in order to better understand the conjunction and produce some graphical representations, additional information will be also extracted from the CSM. Open Source Java libraries will be used for the code implementation. Those libraries implement the necessary algorithms to propagate orbits or transform coordinate systems particularly between inertial and Earth fixed frames. However, those libraries do not contain any algorithm to compute the collision risk. For the tool validation, some published examples in the literature will be analyzed and compared with the tool developed in the project. Furthermore, a Monte Carlo method will be also used as an independent validation. A methodology similar to that proposed by the ECSS standards from the European Space Agency will be used for the development of the tool. This implies defining the following clear phases for the project: requirements engineering, design, implementation, validation and acceptance