Reaction Control Subsystem (RCS)

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The Reaction Control Subsystem is a hot gas (Hydrazine) propulsion system that provides the propulsion capability for:

Recovery of the Satellite orbital altitude in case of its decay below 450 Km;
Satellite attitude control during orbit recovery.

The Hydrazine (26 kg) is stored in a single bladder type titanium tank at a Maximum Expected Operating Pressure (MEOP) of 2,500,000 Pa.

The tank also contains the pressurant gas (GN2).

The propellant feeds two redundant branches, each of six 10 N thrusters, in blowdown mode under the action of the pressurant gas.

Each thruster assembly consists of a dual-seat, normally closed, solenoid actuated flow control valve and a thrust chamber containing catalyst to decompose the Hydrazine propellant exothermally. Each branch includes:

Four delta velocity thrusters (acting along the Satellite z axis direction);
Two attitude thrusters (providing torque around the Satellite z axis).

A latching type valve provides insulation of each thruster branch and a single fill and drain valve ensures external accessibility for propellant loading/unloading.

During the orbit recovery maneuver, it is the AOCS that manages and controls the RCS operative modes, namely:

Steady state mode with a maximum single burn duration of 1500 s.
Pulse mode with ON time of 100 ms and OFF time 500 ms.
Off modulation mode with ON time of 5 s and OFF time of 500 ms.

Pulse mode and off modulation mode ensure the Satellite attitude control during the orbit maintenance maneuver.

This file was last modified on Wednesday, 02-Sep-1998 17:28:57 CEST by Mauro Orlandini

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