Speaker
Description
Since the dawn of humanities space age, more and more spacecraft have occupied the Earth’s orbit: Many decades have passed without appropriate concern to preserve the orbital environment. Therefore, the remains of many spacecraft now pose a critical threat to space flight in the form of space debris. This trend has particular relevance for low Earth orbit and polar inclinations and has led credence to the implementation of a regulatory framework for space traffic management. To prevent further cluttering of orbits, this framework demands a mandatory decommissioning of spacecraft within a certain period after end of mission. Reflecting the exponential growth of the space economy, this requirement has recently been tightened from 25 to 5 years.
Operating in this environment, considerations regarding end-of-life and decommissioning are now already considered during the mission design phase. For LEO this decommissioning usually takes shape as controlled entry into Earth’s atmosphere. In cases where the natural orbit decay is not sufficient to guarantee regulatory compliance, a deceleration burn is often conducted, using maneuvering thrusters to lower the orbit sufficiently. The use of propellant for decommissioning further benefits the mitigation of ground risks by offering the possibility of an selectable entry corridor. However, particularly for spacecraft stationed in Low-Earth Orbit the recent decades saw a rise of passive or semi-automatic deorbiting devices such as drag sails or electrodynamic tethers. Particularly in terms of drag sails, the last decade has seen a sharp increase in TRL levels with many COTS solutions now being readily available.
However, the trade space for EoL solutions is complex, since they impact economic as well as ecologic aspects of system design. To offer a quantitative comparison, a review of the current state-of-the-art for different deorbiting technologies is conducted. To offer an empirical comparison for reference cases and outline each technologies implications on the spacecraft during normal operations, simulations and trades have been conducted and a comprehensive comparison in terms of system mass, cost, complexity and overall operational safety has been derived. Taking into account current trends in the space industry, these findings are associated to orbit regions and spacecraft classes to highlight benefits of each technology and current technology gaps in mission planning.
This study has been conducted within DLR’s TEMIS-DEBRIS project to outline potential applications for orbit transfers from end of mission to an entry corridor and derive any potential implications of EoL concepts on future fully demisable spacecraft in agreement with the clean space initiative.