4 Final Report - Emits - ESA

4 Final
Report
(Spacecraft Computer Unit) and instrument and high-speed interface for the instrument data to be
transferred to the PDH. Cross-coupling is achieved by redundant Milbuses and cross-coupled
interface to the PDH. Since G-Link is now obsolete, newer technology such as Aeroflex UT54 series
may be more appropriate.
The proposed electrical architecture is given in the following figure. The payload subsystem contains
an Instrument Control Unit (ICU) for self-standing instrument mode control and to facilitate instrument
testability.
Figure 4.5-4 Geo-Oculus Electrical Architecture (Overview)
4.5.3 Power Subsystem
The Electrical Power System (EPS) shall serve the satellite in sun and eclipse with the required power
as derived from the power budget. The following essential EPS sizing requirements apply:
• Life time: 10 years
• Orbit: Geostationary
• Maximum eclipse duration: 72min
• Unit margin: between 5% to 30% pending maturity
• System margin: 10% at EOL plus 10% time margin on energy recharge
The main functions of the electrical power systems are
• generation of electrical power with a photo-voltaic solar array
• storage of excess energy during sun phases into the battery
• safe distribution of the electrical power to the on-board users
• protection of the battery against overcharging and deep discharging
• fully autonomous operation.
The EPS consists of solar array, battery, Power Shunt Regulator (PSR), battery charge and discharge
regulators as well as bus distribution and protection. Two one axis drive mechanism provide optimum
Page 4-52 Doc. No: GOC-ASG-RP-002
Issue: 2
Astrium GmbH Date: 13.05.2009