Space debris (satellites no longer in use, fragments of various sizes and from various stages of launchers) is a serious safety issue for Earth’s citizens. A recent example is an alarm triggered in early May 2021 by the uncontrolled re-entry of the second stage of the CZ-5B (Long March 5B) rocket that put the first module of China’s Tiangong-3 space station into orbit. The debris re-entered Earth’s atmosphere over the Indian Ocean at 4:15 am CET on 9 May 2021, near the Maldives, after the entire world anxiously awaited its return.
According to the Space Debris Office of the ESOC ESA in Darmstadt, Germany, there are at least 34,000 pieces of debris larger than 10 cm, 900,000 pieces between 1 and 10 cm and 128 million pieces between 1 mm and 1 cm for an estimated total of approximately 9,300 tons of debris in Earth’s orbit. While the objects may vary in nature, they are all potentially dangerous for Earth’s population if they were to fall uncontrolled into an inhabited area of the planet.
In order to monitor these objects and their trajectories, Italy—as part of an agreement between the Italian Space Agency, the Ministry of Defence and the National Institute of Astrophysics—participates in the European Consortium for Space Surveillance & Tracking, which observes space debris to provide early warning and prevent collision with satellites, managing any returns safely. There are currently 28,160 potentially hazardous objects under constant monitoring.
For several years, Leonardo, through its subsidiary Vitrociset, has provided support to the Italian Air Force to implement Space Surveillance & Tracking and Space Situation Awareness systems, both in the field of radar technologies and data processing software.
The trajectory of Long March 5B was continuously monitored by various space centres to determine where it would re-enter Earth’s atmosphere. Vitrociset collaborated in the orbital determination of Long March 5B with its ISOC 1.0 system, developed by the company’s engineers and software experts alongside the Aerospace Engineering Group of the Experimental Flight Department of the Italian Air Force in Pratica di Mare (Rome). Working with the newly formed Space Situational Awareness Center of the Aerospace Operations Command in Poggio Renatico (Ferrara), the group generated reports and supported analysis that was essential to the monitoring and tracking of the incoming rocket.
The ISOC 1.0 system is used daily by the EU-SST to monitor the re-entry of space objects, fragments, possible collisions between satellites, and sensor tasking to coordinate various observation systems and orbital determinations.
Vitrociset also participated in European efforts to monitor the falling stage with its Radio Frequency Transmitter—a radar surveillance sensor whose transmitter was entirely designed and manufactured by the Leonardo-owned company—from the Salto di Quirra weapons testing range and rocket launching site near Nuoro in Sardinia. The radar operates in the bistatic configuration in collaboration with the Croce del Nord INAF receiver in Medicina (Bologna) to perform surveillance (BIRALES) and with the INAF and ASI Sardinia Radio Telescope in San Basilio (Cagliari) for tracking (BIRALET). Throughout the tracking and monitoring chain, the Italian Air Force, through the Sardinian rocket launching site, uses MFDR-LR and CTM (Compact Tracking Mount) radars. The former is a monostatic tracking sensor, while the latter is a high-precision, high-accuracy optical apparatus. Both systems are managed by highly specialized Vitrociset personnel.
Through the combined use of different radar sensors and data acquisition and processing algorithms, it was possible to monitor the trajectory of the falling objects with great precision—starting from an altitude of about 150 km— and to predict exactly where the debris would impact Earth's atmosphere. This example adds to previous monitoring successes, such as the re-entry of China’s Tiangong-1 air station, which disintegrated in Earth’s atmosphere on 2 April 2018 in the South Pacific Ocean. The Italian Air Force is thus able to offer a high added value to the country in collaboration with the Civil Protection, whose data is also made available at the European level and combined with data from other countries such as France, Germany and Spain, which also participate in the Consortium.
As space activity increases, scenarios like the aforementioned will occur with greater frequency and intelligence will become just as important as monitoring activities. Telespazio is working to offer both institutions and business an increasingly complete suite of Space Domain Awareness services. Thanks to satellite operations skills acquired over the years, Telespazio offers an integrated approach based on Space Traffic Management and Space Intelligence: the former aims to optimize traffic management to reduce the risk of collision while the latter pieces together the most advanced information to identify non-collaborative manoeuvres and characterize space debris. Lastly, through investment in the start-up Northstar, Telespazio can also rely on information from space-based sensors, improving their performance in terms of reactivity and precision.