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ESA Document - Emits - ESA

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s<br />

3.3.5.6 Electrical architecture<br />

Figure 3-52 shows the following electrical architecture which applies to all stages:<br />

EMAs PDU - ECU<br />

EMAs<br />

TVC8 EMAs<br />

TVC…<br />

TVC1<br />

PDU - ECU<br />

Battery<br />

PDU - ECU<br />

Battery<br />

Battery<br />

IMU<br />

CSS<br />

“ Stage” ECU<br />

ACS<br />

Figure 3-52: Electrical architecture<br />

RCS<br />

CMG<br />

IMU<br />

OBC<br />

STR<br />

HMM<br />

Assessment Study<br />

Report: CDF-20(A)<br />

February 2004<br />

page 196 of 422<br />

The main intelligence shall reside in the habitation module, where the principal attitude sensors<br />

(Inertial Measurement Unit, IMU and Star Tracker, STR) shall be mounted as well.<br />

This main intelligence shall control directly the actuators mounted on the habitation module: i.e.<br />

Thrusters (RCS) and Control Moment Gyros (CMG). OBC will control the other actuators via<br />

several remote units, the "stage" ECU (Electronic Control Units). During the propelled phase the<br />

OBC shall control (via the ECU) also the Thrust Vector Control system (TVC). The inner<br />

control of the actuators of each TVC shall be realized through an additional box (PDU-ECU)<br />

mounted on the individual motor.<br />

The stage ECUs shall be in charge of the control of the stage when not mounted on the main<br />

vehicle (before assembly or after separation, for de-orbiting), and shall work as routers when<br />

connected with the main OBC.<br />

To accomplish the secondary function of controlling the stand alone stages, the ECU shall make<br />

use of local sensors: IMU and Coarse Sun Sensor (CSS). The IMU can be used (if needed) also<br />

during the control of the main vehicle to control the structural flexibility, which has not been<br />

considered in this study, but which might be a design issue in the future.<br />

3.3.6 Data handling<br />

3.3.6.1 General consideration<br />

This section summarizes the requirements applicable to avionic systems that will fly on a long<br />

lasting human mission with target launch date 2033.<br />

Several assumptions shall be made to generate a consequent design.<br />

From the DHSs point of view a human mission to Mars is extremely challenging considering<br />

presently available space technologies.<br />

Major issues that require attention are:<br />

3.3.6.1.1 Computing power

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