Propulsion in the ATV Spacecraft System - Lessons Learnt

Abstract

The Automated Transfer Vehicle (ATV) is an ESA funded unmanned space transport vehicle designed for logistic servicing of the International Space Station (ISS). It was launched by Ariane 5 from Kourou (French Guiana) on March 9 th and successfully docked with the ISS on April 3 rd . The 1 st ISS reboost on April 25 th has been followed by 14 propulsive sequences until undocking and de-orbitation end of September. The main features of its propulsion system are summarised here after : Multiple bi-propellant engines system (4 main engines for the boost phases + 28 attitude control thrusters) taking into account the strong reliability and safety needs Mono Methyl Hydrazine (MMH) and Mixed Oxides of Nitrogen (MON) propellants with helium pressurisation system Large range of operational use from very short pulse (28 ms) to steady state (attitude control system) Moreover, the Propulsion System is one of the onboard Functional Units : a dedicated FU manager is in charge of setting the configuration of the Functional Unit (as also the monitoring and the housekeeping of the FU) according to the commands of the centralized Vehicle Configuration Management. The Propulsion System (named PRO) function provides the propellants and propulsive capabilities to meet the following main objectives : To deliver on command from the GNC : A main thrust along X axis for orbit transfers and rendezvous; Three axes control torque for attitude control, stabilisation after separation and attitude recovery after a loss of attitude Six axes control thrust and torque for rendezvous and departure To deliver a post contact thrust, upon commands from the DRS (Docking & Refuelling System) function at contact with ISS. To deliver individual thrusts as commanded by ISS for station reboost and attitude control. To provide a braking thrust for Collision Avoidance Manoeuvre (CAM) with the ISS upon direct commands from the PFS (Proximity and flight safety), independently from GNC. The first part of this paper describes the Propulsion design and its main functions. The second part of this paper gives the process implementation of the Propulsion FU manager. The last part of this paper gives the lessons learnt from the first ATV Jules Verne flight and presents the link between the mission phases and the Propulsion. 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit 2 5 August 2009, Denver, Colorado AIAA 2009-4900 Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. 1 Recall on the ATV missions objectives and capabilities The Design Reference Mission of the Automated Transfer Vehicle (ATV) is to provide support services to the International Space Station (ISS) during six months following its docking to the Russian Service Module (Zvezda). The main mission objectives are : Propulsive support to ISS including re-boost, attitude control, CMG (Control Moment Gyro) de-saturation and debris avoidance, Delivery of cargo, water and gas, and retrieval of wastes,