Lower NGSO Constellation Orbit Still Safe, Boeing Says

Lowering its planned non-geostationary orbit satellite constellation from a 1,200 kilometer orbital height to 1,030-1,082 kilometer will mean double the number of avoidance maneuvers, to 3.3 per satellite per year, because of increased orbital debris at that altitude, Boeing said in an FCC International Bureau letter posted Wednesday. It responded to a bureau request in April for additional technical details (see 1704120021). Boeing said those additional maneuvers still would be well within each satellite's fuel allocation. It said due to built-in redundancies in the satellites' deorbit subsystems, likelihood of the inability to perform avoidance procedures would be less than 1 percent. Even at a 1 percent failure rate among its planned 2,956 satellites, the probability of impact with any of the failed vehicles is fewer than 0.00268 per year, it said. Boeing earlier this year said it planned to move its constellation, after talks with OneWeb, which has an NGSO constellation planned for roughly the same altitude (see 1703020036).