High-fidelity telecom analysis techniques for spacecraft dynamic events

Traditional telecom planning is usually limited to single point, worst-case scenario analysis of a static communication link. Communications during spacecraft dynamic events (which are usually critical) such as launch, maneuvers, and orbital insertion are usually not sufficiently characterized a priori. The lack of highfidelity simulation of spacecraft dynamic events results in: 1) Limited ability to timely detect and react to spacecraft anomalies. This might lead to loss of encounter opportunities or even loss of mission. 2) Limited ability to plan and analyze mission communication design and operation strategy during the design phase. This might lead to insufficient information to quantify operation impact and subsystem interaction, resulting in bad onboard design, inefficient telecom resource usage, and reduced science return. In this paper we describe a systematic approach to support telecom planning and analysis for spacecraft dynamic events. This approach involves 1) a standard interface with NAIF SPICE [1] data to incorporate spacecraft trajectory and attitude information, and 2) a set of attitude heuristic models that simulate the spacecraft attitude in normal mode and in safe mode. These techniques are currently implemented in the operational Telecom Forecaster Predictor (TFP) link analysis tool. The TFP tool was used to support Deep Space 1 high-gain antenna pointing activities in the absence of the stellar reference unit. The TFP tool was also used to support Mars Odyssey critical events such as launch, trajectory correction maneuvers, and Mars orbital insertion. This paper will describe in detail how we apply the above approach to support telecom planning and analysis of spacecraft dynamic events.