Contributing to Orbital Sustainability with an Independent Decommissioning Device for Satellite and Launcher Space Implementing Space Debris Mitigation Measures
The increasing population in space of defunct satellites and other man-made debris is an issue that is getting strongly the interest of legislators, agencies and industry. In order to guarantee a safer and sustainable access to orbit is necessary to stop the systematic non operative defunct satellites concentration increase in orbit. This seems to be feasible with an approach based on a preventive debris removal solution, whereby a dedicated and independent de/re-orbiting propulsion system is installed on the satellite prior to launch allowing a safe and quick decommissioning of the spacecraft before it will become a debris. Such an approach will allow Satellite Operators to be compliant with current international and national space debris mitigation regulation, and would help Space Agencies and National Governments to reach that 90% disposal manoeuvre success rate which now looks the target, according to many specialists, to achieve a stable and sustainable orbital debris regime in combination with the Active Debris Removal missions currently under developed. Most Space Agencies (e.g. ESA and NASA) and National Governments (e.g. France) already require performing a controlled disposal manoeuvre. In particular, for satellites and rocket stages in Low Earth the objective is to minimize any potential hazards to other operational satellites in space and to assets or people on Earth. For the Geostationary Orbit and for satellite constellations in Medium Orbits, as well as in Low Orbits, the aim is to preserve the long term sustainability of the orbital slots and therefore the availability of the service. Non-compliant operators can still ask for waivers, however Space Agencies and National Governments have already announced to strongly limit granting those waivers: the French Government has recently stated that no exceptions to space debris mitigation regulations will be allowed beyond 2020. As such, satellite and rocket stages disposal at the end-of-life is becoming expensive in terms of fuel budget and launch mass. Propulsion system components redundancy is required to match a good level of reliability at the end of life. This has and will have an impact on satellite design. To avoid redesign and new qualification, debris mitigation countermeasures would have to take into account future scenarios (orbital debris concentration in 20 years), making the satellite heavier and more expensive and leading to an immediate increase in launch costs. For this reason, D-Orbit has developed an innovative package, designated as D-Orbit Decommissioning Device, or D3, composed by a solid propellant motor and a control / command unit. The device can be completely autonomous, even if the satellite is defunct: this feature will considerably increase the post-mission disposal success rate, which is so far still far below acceptable levels. The D-Orbit Decommissioning Device is designed to be as compact and independent as possible and able of quickly and safely disposing of a satellite at its end-of-life in a controlled manner, freeing up the orbital slot for the replacement satellite even in case of satellite failure. Compared to the satellite’s station keeping propulsion, the D-Orbit Decommissioning Device offers a higher performance-to mass ratio and an optimal disposal maneuver time-to-mass ratio. Moreover, with such a device on-board, a Satellite Operator would be able to exploit the full amount of liquid propellant on-board and delegating to the device the end-of-life: this will ultimately lead to an operational life extension. The D-Orbit Decommissioning Device will allow a reduction in the duration of end-of-life manoeuvres down to less than one hour for LEO satellites and down to a few hours for MEO and GEO Satellites. Such a quick and controlled manoeuvre allows a reduction of the post-mission- disposal and debris monitoring operation costs, especially for large satellite constellations, as well as a reduction of the operator’s liability for in-orbit or on-ground collisions. This paper will present the design and the main technical features of the D-Orbit Decommissioning Device, the operational scenarios, the operational and economic advantages for operators and space stakeholders, the level of compliance with current and possible future space debris mitigation regulations, the safety features and the potential benefits on a long term Space Debris mitigation strategy.