In the last decade the space debris issue has been in the spotlight, with more than 13,000 artificial objects currently orbiting around the Earth, including around 1,700 operating satellites, most of which are destined to re-enter the atmosphere and hopefully burn out. NASA estimates that one piece returns to the Earth each day, while around 40 large space debris objects (>800 kg) re-enter the atmosphere each year. Unfortunately, 10-40% of satellite mass survives re-entry and impacts the Earth’s surface, posing serious hazards to people, property, and air traffic.
The atmosphere is dense enough to dissolve most objects owing to air resistance and heat, but 10-40% of mass survives and impacts the Earth’s surface, posing serious hazard to both people and their property.
For instance, out of the 2008 spacecraft ATV-1 mass of 12.3 tons, 3.5 tons in 183 fragments survived re-entry, 28.4% of the mass. Several events like the 2003 Shuttle Columbia disintegration and spreading over a large inhabited area in Texas induced national and international space agencies to adopt Space Debris Mitigation (SDM) policies for minimizing the risk for population. However, the effectiveness of the current SDM plans is hindered by the following limiting factors:
• The impossibility to precisely predict the impact area of surviving fragments. Space debris spread over long, thin ground footprints (e.g. for ATV-1 ~817km by 30km), depending on several factors, such as the flight features of each fragment, local wind, atmospheric condition. Currently, only rough estimations of the fragment impact area can be made. Even few minutes before the impact, these factors determine a positional error in the Earth-impact point of up to 5,000 km.
• The high cost of safety measures in case of dangerous satellite re-entries. Very wide areas potentially concerned have to be closed (with strong direct and indirect economic costs), also due to the inaccurate calculation of the footprint probability area. In 2012 EUROCONTROL (European intergovernmental organization for air traffic management) was notified by Russian authorities to close the whole Europe airspace for 2 hours for the re-entry of the Russian Phobos-Grunt (calculated cost ~€20 Million).
• The increasing risk caused by the large number of satellite re-entries on the earth. Even a falling fragment of 300 grams can be catastrophic for an aircraft (US Federal Aviation Administration data), and over the last decades, more than 1,400 tons of materials have survived re-entry. With the increased number and turnover of satellites, this is pushing higher the risk for casualties, and the worldwide collision risk with space debris for flights has been estimated in 3x10-4 (the generally acceptable risk in aviation is 1x10-7).
While space agencies (NASA, ESA) are adopting increasingly stricter policies for mitigating risks associated to space debris collisions, satellite operators are in search for reliable solutions able to enhance safety measures in the re-entry phase, ensure compliance with regulations, and minimize the impact on spacecraft design performances and costs.
Aviosonic has developed and patented DeCAS, the first high-precision monitoring system for tracking space debris during the re-entry phase, able to precisely determine both the break-up impact point (at an altitude of around 78-84 km) and the area interested by the subsequent fragmentation, and promptly notify safety agencies about potential danger for people and property.
In the framework of the Phase 1 project, both technological and business feasibility study was run.
As a conclusion, the outcomes of the project clearly showed the technological feasibility and that conditions exist for the implementation of the DeCAS technology.
