Unusual risk scenarios - The environmental risk associated with the uncontrolled return to the atmosphere of the Chinese space station Tiangong 1
In 2018, the national system for environmental protection (snpa) is called to provide support on environmental risk provisions from the italian civil protection, in order to collaborate to a technical table. The technical table was established on the occasion of the uncontrolled re-entry into the atmpsphere of the chinese space station Tiangong . The principal aim of the operation is to provide elements in real time for the pre-announcement, the monitoring, the surveillance of the re-entry into the atmosphere of the space station and the associated risk scenarios.
In environmental terms, the main problems are related to the presence of large fragments, capable of crossing the atmosphere and falling with significant release of kinetic energy. Consequently, induced emergency situations can be created: collapse of industrial plants, nuclear plants, dams or the release of monomethyl-hydrazine, a substance that is toxic and harmful to humans and the environment, in propellant tanks.
The space station crosses the national territory four times a day and almost all the national territory is affected by the crossing and, therefore, potentially able to be involved by the fallout of fragments.
The methodological approach followed to manage the crisis is based on a direct environmental risk assessment, through simulation with mathematical and indirect models (fragments able to hit sensitive points on the territory which, if hit, are able to generate potentially more serious induced effects compared to the direct effects), through the preparation of an operating procedure that provides in input, in a geographic information system, the trajectory data of crossing the national territory and the sensitive points. The intersection of the polygon generated by a buffer of 100 km with the sensitive points, previously identified, generated reports containing the representative lists of the sensitive points present within that area.
The evaluations provided a support tool for the decision maker, allowing the DPC to implement the alert strategies suitable for lowering the probability of occurrence of events. The snpa thus provided its technical and scientific contribution for the management of the event.