PAGE CONTENTS
Objectives
The objective of the activity was to derive an optimized star tracker design for Telecommunication satellites based on the Faint Star detector. Main development focused on optimizing the use of the Faint Star sensor and the Star Tracker software in order to host the Star Tracker Software in the avionics on-board computer.
Challenges
The main challenges of the project were the following:
- Development of a low-impact star tracker software architecture (including associated implementation guidelines), that eases integration of the star tracker run-time library (STRLib) in on-board computers, thus providing an attractive option for the telecom primes.
- Meetings with the major European telecom primes revealed the need for a redundant star tracker interface, covering both power and communication. The actual implementation of the redundant interface into the current compact Faint Star camera head unit design turned out to be challenging.
System Architecture
The overall system architecture consists of the following entities:
- Customer furnished on-board computer (OBC) (part of the spacecraft bus) with modest amount of spare resources, a SpaceWire interface, and software SpaceWire interface drivers
- Terma star tracker optical head
- Terma star tracker library (STRLib)
- Small supervisor application (developed by customer or Terma) equivalent to the Terma STRLib example supervisor
This architecture eliminates the need for a dedicated computer for processing of the image stream from the optical head, thus reducing total mass and power consumption.
As a proof-of-concept, the STRLib was integrated standalone on a customer-furnished spacecraft computer for interfacing to the optical head. The customer subsequently integrated STRLib in a space and time partitioned safety-critical real-time operating system, thereby demonstrating the ease with which the combination of flight-proven STRLib and high accuracy optical head may be integrated with the avionics platform.
Plan
The project has been executed according to the following schedule:
- Kick-Off: September 2017
- Baseline Design Review: May 2018
- Mid-Term Review/Test Readiness Review: December 2019
- Test Review Board/Final Review: March 2021
Current Status
Completed