IAC 2024: Hitting a moving target - ADRAS-J launch targeting to rendezvous with a derelict resident space object

Active debris removal (ADR) spacecraft need to rendezvous with objects that are derelict and do not maintain their orbit, and that can only be tracked with ground-based sensors, which are less accurate than e.g. on-board GPS receivers. This makes the Client orbit forecasting challenging, especially for objects at low altitudes that interact with the atmosphere. The feasibility of ADR rests on its cost-effectiveness, which requires minimizing the spacecraft mass that is driven partially by the ΔV. To reduce the amount of needed fuel, passive right-ascension (RAAN) drift needs to be employed to avoid performing large orbital plane changes with satellite’s own propulsion. This imposes a constraint on the entire launch trajectory but also the insertion state, which needs to be separated in RAAN from the Client by exactly the planned amount. This reduces the daily launch window to only a few minutes per day. What complicates the injection orbit selection further is the fact that launch delays can move the feasible launch window at short notice, thus requiring the injection orbit to be re-targeted to reflect the latest Client orbit. This makes selecting the launch parameters for ADR missions notably different than for others that perform rendezvous, which typically approach the International Space Station. This paper reviews how the launch of ADRAS-J was targeted to achieve rendezvous with a derelict RSO. The concept of operations involving ADRAS-J and the launcher, Rocket Lab’s Electron, is outlined. Further, Client orbit forecasting and corresponding launch targeting algorithms are described, and the results of the final orbit targeting are compared to the performance demonstrated during the launch in February 2024.