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Objectives
The objective of the project is to establish the Phase A documentation to enable the opportunity to flight an APS Star Tracker as Technology Demonstration Payload (TPD) on AlphaSat.
This requires amongst others the refining of the Payload Technical Specification and the Concept Definition, the agreement with ESA of the interfaces to the spacecraft, the preparation of a TDP development, verification and validation approach, the defining of the Phase B tasks (including necessary technology predevelopments) and the schedule for Phase B and Phase C/D, and the provision of necessary cost estimates.
The high level mission objective of the test flight is to demonstrate in orbit the performance, robustness and lifetime of the APS star tracker and thereby complete the testing of this new type of star tracker and enable its use on other spacecraft.
In particular, the following will be demonstrated:
- Launch survivability,
- Autonomous and aided operation under nominal conditions,
- Acquisition probability and acquisition time,
- Operation with non-stellar objects in the field-of-view,
- Tracking robustness to radiation effects and main engine burn,
- Long term behaviour of several new technologies in the real space environment,
- Lifetime,
- Ability of the STR to change in orbit the software and to modify sensor operation and calibration parameters via the TM/TC interface.
Challenges
The key issues to be addressed in the Alphasat TDP Feasibility Study are:
- To establish the TDP Mission Description Document,
- To complete the Design Definition File (incl. the technical budgets),
- To establish and agree the Interface Control Document,
- To propose the TDP development, verification and validation approach,
- To define the technology predevelopments to be carried out in Phase B,
- To define the Phase B project plan and the schedule for Phase B and C/D,
- To estimate the TDP costs.
Plan
The current Phase A Alphasat TDP Feasibility Study was started in January 2006 and will be completed at the end of July 2006 with a Preliminary Requirement Review.
A payload review and an accommodation review will be performed in March and May 2006, respectively. Afterwards it is planned to start Phase B in September 2006, which will be concluded in December 2007. The Phase C/D will begin in the April 2006 and is expected to finish at the beginning of 2008 with the delivery of the APS Star Tracker Protoflight that will be used as TDP on AlphaSat.
Current Status
In course of the Phase A study the following documentation has been prepared:
- Star Tracker Mission Description Document,
- Star Tracker Design Definition File (that includes documents as Detailed and Top Level Design Reports, IDC, SW ICD, Declared Material and Process Lists, Product Tree),
- Compliance Matrix,
- Payload / AlphaSat Interface Specification,
- Preliminary Schedule for Phase B and C/D,
- Synthesis of Programmatic Aspects.
The work currently in progress concerns the TDP cost estimation, the Engineering Plan for Phase B, and the In-Flight Verification Activities Plan
