PAGE CONTENTS
Objectives
The objectives of this project are the study and development of a new version of the InfraRed Earth Sensor IRES based on the extensive in flight experience of previous IRES NE ones.
The main changes are aimed at an overall cost reduction and, taking advantage of technological innovations, maintaining the same performances of the previous version:
- Replacement of bolometers with pyroelectric sensors with dedicated evaluation tests,
- Redesign of electronics introducing SMD technology,
- Redesign of ASIC, including Pitch and Roll Logic Unit, Motor Scanning and I/F Control Units,
- Improved manufacturing process introducing micro casting technology,
- Removal of USA components with ITAR restrictions,
- Removal of exotic, obsolete and long lead EEE components,
- Increase radiation tolerance.
The contract will have, as starting point, the experience gained from the IRES NE Earth Sensor, which is the current production with more than 80 units produced up to now for several TLC programmes (SATELCOM, SPACEBUS 3000 and SPACEBUS 4000, AMOS, DFH Series).
The sensor main characteristics are:
- Mass: 2.3kg
- Power consumption: < 3.5W
- Optical Wavelength: 14¼m – 16¼m
- Continuous sensor operation altitude: 15350km 140000km
- Field of View: ±5.5º Narrow Scan, ±11º Wide Scan
- Accuracy, at GEO:
- Bias: 0.03º (3Ã)
- NEA: 0.08º (3Ã with three channels)
- Power interface: 24V to 50V unregulated, optional 100V
- Data Interface: DS32, optional DS48 and MIL1553B
Challenges
The new development IRES N2 is mainly addressed at the electronic section: in particular, bolometer detectors are replaced by pyroelectric ones.
An extensive use of SMD components is adopted, maintaining the same electronic architecture of the IRES NE; exotic and obsolete components are removed, as well as USA components subjected to ITAR restrictions.
The opto-mechanical part remains unchanged in its peculiar items, like the indefinite life scanning mechanism and the IR telescope, while an optimisation of the housing is put in place to allocate the new electronic layout and improve production processes.
Plan
The project is divided into four main phases:
- Preliminary design
- Detailed design
- Manufacturing
- Qualification and Pyroelectric evaluation
The first phases of the project were related to the IRES re-design (pyroelectric detectors and electronics upgrade). The subsequent phases of the project were related to the manufacturing of an EQM unit and its full qualification. In parallel the evaluation of the pyroelectric detectors has been carried out.
The following scheduled key milestones have been completed:
- BDR: October, 28th 2004
- MTR: May, 27th 2005
- TRR: December, 15th 2005
- TRB: May, 4th 2006
- Delta TRB (RS EMC) / end of qualification: September 2006
All the activities were concluded in November 2006.
Current Status
The full on ground qualification has been reached and the sensor is ready for the market both for GEO and MEO applications.
The unit has been qualified (DS32, 50VDC power bus) at the following environmental conditions:
- Vibrations: sine (20 g) and random (X-Y 22.19grms; Z 26.35grms)
- Shock: up to 2200 g from 2000Hz to 10000Hz
- Thermal tests: -30C to +65C
- EMC tests: compatible with typical TLC EMC requirements
The evaluation campaign on the pyroelectric detectors has been successfully completed demonstrating the detectors suitability for flight use in long lifetime space applications.
The IRES N2 was chosen as the Earth Sensor unit in the Galileo IOV programme and the FMs will be delivered in 2008.