Programme Element: ARTES 5.1
Reference nr.: 13.1TT.13
Planned Tender Issue: quarter 3, 2013
The objective of the activity is to determine the maximal angular rate that could be estimated by the new proposed scheme, using only a Star Tracker.
Targeted Improvements:
- Extension of the acceptable kinematic conditions for Star Trackers for target rates in the range of 20 deg/s to compete with gyros in Safe Modes.
- Devise a Single Event Upset-free mode that is relying on different techniques than "traditional" tracking mode for rate estimation.
- Determine the feasibility of full gyroless Safe-Mode based on such a technology
- Cost savings
Description:
For high angular velocity domain, where stars on the detector do not look like single spots anymore, the use of the star trace shape can allow the determination of the absolute value of the angular velocity. Determination of the direction is more complex, and the use of APS detectors in rolling shutter mode is generating distortion in the image. The idea is to take benefit of this distortion.
The contractor shall state whether this determination can be performed by Software or Hardware by specific clocking of the rolling shutter readout (possibly in different directions).
The sensing of the rate shall be performed on one-image-only to increase the robustness to any single event effect.
The need is also to achieve proper software segregation between different functions, just like Normal Mode and Safe Mode on a spacecraft do not rely on the same technologies. It is proposed to completely distinguish the rate estimation method in harsh environment and the one in normal operations.
In terms of work logic, it is proposed to first assess the different possible techniques (in addition to the one proposed in this activity), then to build a simulator to prove the suitability of the technologies. Then, the final task is to determine if the newly achieved kinematic envelope tested on the simulator brings added value to a spacecraft. Consequently, this would allow the use of star-tracker-based design for spacecraft rate damping, down to an angular velocity for which the traditional acquisition mode could succeed.
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