In general, the use of commercial components is envisaged where existing requirements can not be fulfilled with conventional space qualified components. Typical examples are fast processors for payload data processing and high-speed high capacity memories. However, the lower reliability and the greater sensitivity to the space environment (vacuum, temperature, and particularly radiation) require great care in the selection of components and designs. A COTS based Computer must include HW and SW techniques that mitigate or nullify the intrinsic weakness of COTS parts. An extensive test and validation campaign is therefore necessary to assess the performances of the developed products in the relatively harsh environment of space.
In term of pure processing power capabilities the majority of the mission needs can be served by space qualified products but a small percentage of applications asks for more performances. This was the case of the processing power needed for the Video Processing Unit of the GAIA mission: no space qualified solutions were (and still today they are not) available to fulfil the mission requirements and consequently a solution based on an U.S. ITAR restricted COTS based Single Board Computer (the Maxwell SCS750 board) has been developed. Similar situation can again occur in the next future. The fully space qualified products have several advantages as being ITAR free, providing full visibility and traceability of the design and development process and having the possibility to include IP-cores previously developed under ESA contracts but in case that specific high performances are needed there is no other way than investigating the use of commercial parts. However, as also presented at ESCCON 2011, the usage of commercial components typically does not bring with it a cost reduction with respect to a solution that makes exclusively use of fully space qualified products: analyses, specific test (e.g. tolerance against radiation effects) and extra logic to be implemented in order to mitigate the intrinsic weakness of commercial parts can be culprits of costs increase.
Possible applications of COTS based solution are Visual Navigation, Science Missions, Exploration, High Available systems for new launchers and vehicles.The COTS based computer Programme announced in the 2006 edition of the Harmonisation dossier on Data Systems and On-Board Computers has concluded the design phase in spring 2010. The implementation phase of this programme aiming to develop an architectural framework based on COTS parts and to build breadboards of the key modules for the selected architectures has started in 2012.
The Programme is composed by five (5) contracts:
- COTS System Contract – TAS-F with support from TAS-I and RUAG-A – TEC-EDD
- COTS Software contract – DTSO-F – TEC-SWE
- Highly reliable COTS computer (HI-R computer ) – TAS-I with support from INAF and Sanitas EG – TEC-EDD
- Highly available COTS computer (HI-V computer ) – AST-D- TEC-EDD
- High performance COTS computer (HI-P computer) – AST-F with support from CGS-I – TEC-EDP
