Interpretations of de-orbit, deactivation, and shutdown guidelines applicable to GEO satellites

As the population of space debris in orbit around the Earth grows, the probability for catastrophic collisions increases. Many agencies such as the IADC, FCC, and UN have proposed space debris mitigation guidelines or recommendations. For example, a minimum increase in perigee altitude of 235km + (1000 Cr A / m) where Cr is the solar radiation pressure coefficient, A/m is the aspect area to dry mass ratio, and 235 km is the sum of the upper altitude of the geostationary orbit (GEO) protected region (200 km) and the maximum descent of a re-orbited spacecraft due to lunar-solar & geopotential perturbations (35 km) with an eccentricity less than or equal to 0.003. While this particular recommendation is reasonably straightforward, the assumptions an operator chooses may change the result by 25 km. Other recommendations are more ambiguous. For example, once the space vehicle has been de-orbited to the required altitude, all on-board stored energy sources must be discharged by venting propellants and pressurants, discharging batteries and disabling the ability to charge them, and performing other appropriate measures. “Vented” is not usually defined. In addition, the broadcasting capability of the spacecraft must be disabled. Boeing and its customers are working together to devise de-orbit and deactivation sequences that meet the spirit of the recommendations. This paper derives and proposes a generic minimum deorbit altitude, appropriate depletion and venting pressures based on tank design, propellant and pressurant type, and an acceptable shutdown procedure and final configuration that avoid interference with those still in the GEO belt well into the future. The goal of this paper is to open a dialogue with the global community to establish reasonable guidelines that are straightforward, safe, and achievable before an absolute requirement is set.