The management of the geostationary environment

The population in the geostationary orbit is increasing at the rate of abou t 25 spacecraft a year and operating lifetimes are increasing. The size of the spacecraft is increasing, as is the power level. The only way to protec t the operational are is to reboost spacecraft at end of life to a burial o rbit. While most operators do some reboost maneuver at end of mission there has been no agreed upon criterion for the maneuver. The ITU-R S, 1003(1) r ecommends reboost of not less than 300 km with the apogee as high as possib le. The Interagency Debris Coordination Working Group (IADC) has recently a chieved a consensus on a recommendation that the minimum maneuver be 235 km + Cr 1000 A/M. The concept is that this accommodates the +/-3 7.5 km varia nce in normal radial positioning and a 167.5 km corridor above the are for repositioning or supersynchronous delivery and establishes a criterion by w hich the dispositioned spacecraft will never enter that zone after its comp letion of the maneuver. It also deals with the fact the area mass ratio of spacecraft has been evolving to higher values. Earlier spacecraft had chara cteristic values of 0.03 but the average now is closer to 0.05 and there ar e some as great as 0.10. Disposition of the upper stage should be the same as the spacecraft if it i s delivered to GSO, It is preferable to have the stage deliver the spacecra ft supersynchronous and then have the spacecraft maneuver down to the GSO, (C) 1999 Elsevier Science Ltd. All rights reserved.