Data fusion application for improving orbit determination and re-entry predictions

Re-entry of space objects are common occurrences, which take place every day; however, risks related to these events are marginal for both people and ground infrastructures. Nevertheless, re-entry prediction of uncontrolled objects is a key capability in order to opportunely monitor the decaying of large intact space objects which, in particular cases, could pose a risk for people on the ground, such as the uncontrolled re-entry of the Chinese space station Tiangong-1 in 2018. Surveying and providing early warning of uncontrolled re-entries of spacecraft or space debris is one of the main objectives of the EUSST support framework adopted by the European Commission in 2014. This initiative is implemented by a Consortium initially formed by five European Member States (France, Germany, Italy, Spain, and United Kingdom), and expanded from 2019 with three additional EU Member States (Poland, Portugal, Romania). EUSST service provision is facilitated by EU SatCen and the three SST services, Re-entry, Collision Avoidance and Fragmentation, are provided by different member states. Italy is currently in charge of Reentry and Fragmentation services and the current national architecture of the system is expected to evolve to improve their provision. In this perspective, an added value for the system can be given by the implementation of data fusion between radar and passive optics sensors. This technique could supply additional information about the object's dynamics (i.e. attitude motion, tumbling rate and tumbling axis orientation), which is a critical point for uncontrolled re-entry of massive objects, and it may be helpful for more refined predictions during the final phases of the descent. In addition to that, a network of sensors specifically dedicated to re-entry has the benefit of supporting the orbit determination and propagation accuracy for the whole EUSST Consortium service provision.