Simplifying On-Board Control Procedure Development: A Generic Tool Based on ESOC Experience

Abstract

Spacecraft on-board autonomy is becoming more and more prevalent, in particular for deep space missions with long propagation delays and low telemetry bandwidths. One method by which the Spacecraft is able to maintain this autonomy is through the use of On-Board Control Procedures (OBCPs) which are similar to Flight Control Procedures (sending of telecommands, reception of telemetry and the processing of information) without the need to have the ground based Flight control system in the loop.OBCPs, which are executed by spacecraft on-board software and capable of interacting with on-board subsystems and payload instruments through sending telecommands and receiving telemetry, have significant advantages over the traditional way of spacecraft operations. However, only few Flight Control Team engineers are currently specialised in managing OBCP as writing OBCP code requires expert knowledge of various OBCP languages.The MOIS-Toolset, providing the framework for ground based flight control operational procedure preparation at ESOC and throughout the European Space Industry, was selected for developing a common and integrated framework that allows an easier and more intuitive OBCP development, taking advantage of the large engineering community which is already familiar with the tool in developing Flight Control Procedures. The goal was firstly to develop a prototype taking into account the lessons learnt by the engineers experienced in developing hand-coded OBCPs.This paper briefly describes the OBCP concept and the usual practice used for developing OBCPs with the Rosetta mission as study-case. It introduces a new way for simplifying the development of OBCPs with the integrated development tool at ESOC and presents a solution for a common OBCP language across different spacecraft. Finally, an analysis of advantages, disadvantages and reusability of the proposed solution is provided. I. Background I.A. On-board Control Procedure concept and capabilitiesSpacecraft operations are traditionally executed with Flight Control Procedures (FCPs) and the Mission Time Line (MTL). FCPs are executed in a stepwise manner by a ground operator, and involve sending Telecommands (TC) to the spacecraft and checking Telemetry (TM) downlinked to ground. Missions with limited ground station coverage might also use the MTL, which is a sequence of time-tagged TC loaded from ground and executed by the on-board software (OBS) when their time tag expires. While the MTL allows for autonomous on-board TC execution, the concept is limited as it consists in success-oriented commanding without immediate reaction to unexpected behaviour such as failed TC.On-board Control Procedures (OBCPs), which are small stand-alone computer programs executed onboard, allow for a more capable on-board automation of spacecraft operations. An OBCP can be seen as an FCP executed on-board the spacecraft, as if it was a ground operator controlling the spacecraft. While OBCP execution is initiated and partially monitored by the ground, interaction with spacecraft on-...