COTS vs RADIATION : MAIN ISSUES

COTS quality level is addressing the Commercial & Automotive markets.

"Class S" quality level is addressing the "Classic Space" High-Reliability market. Taking into account that the quality level has NO impact on the part radiation behavior, this COTS definition is not relevant for radiation hardness assurance.

The main concern, in using COTS for space applications, is the lack of information regarding the traceability of the manufacturing process:

•  Diffusion Lot Number and Diffusion Plant location
•  Exact Technology Description and Mask Number

Considering that:

•    TID testing is valid for the full Diffusion Lot
•    SEE testings are valid for technology and a mask number

Therefore, based on previous published data, we cannot certify the radiation hardness sensitivity for a COTS

As a result, from a radiation effects point of view, our definition is as follow:

The "Class S" RHA is well described in ECSS-Q-ST-60C document.

The NEW SPACE market is mainly using COTS, and now, the "Classic Space" market as well, in order to reduce the overall satellite cost.

"COTS RHA" has to be written but will be different for each domain of application, only one RHA for COTS for any application is not possible.

We can split the actual space applications into the following domains, and we try Main interest  in using COTS, for each domain:

Table 1: Space Domains Identification and Main Interest in Using COTS for Each Space Domain

SATELLITE SIZE: ( F2N ): Femto to NanoSatellite [ 100g - 10Kg ]   |   ( M2S ): Micro to Small satellite  [ 10Kg - 1000Kg ]    |    ( M2B ): Medium to Big Satellite  [ > 1000Kg ]

ORBITS: ( LEO ) : Low Earth Orbit   |   ( LEO  Low Rad ) : LEO @ Low Radiation    |      ( MEO ): Medium Earth Orbit     |     XEO: Exotic Earth Orbit   |     ( GEO ): GEOstationary

ESA RHA for COTS: Commercial Off The Shelf (COTS) Components in Space Programs – Challenges for Radiation Hardness Assurance      Microelectronics Workshop MEWS - 2019

CNES RHA for COTS: Presentation to ESSCON 2021,

For each Space Domain, and for each Radiation Engineering activity, we  provide the cost impact on "radiation activities", relative to the "normal cost" on Class S missions :

HIGH: Huge Savings are done

MEDIUM: Significant Savings, but may be very important for a full constellation

IDEM: No Savings are expected

NO: EXTRA COST is expected

Radiation Engineering activities are summarized as follow:

Radiation Analysis: This is the 3D modeling and calculation at the satellite and unit level, for TID, TNID, and SEE. Writing of a radiation analysis document, at each level. These activities are at Prime and Sub-Contractor levels

Radiation Qualification: All activities to perform TID, TNID, Heavy Ions, and High Energy testings. Cost is mainly at the Radiation Testing level, with an important cost for SEE testings. In addition, the cost of Hirel Parts to be tested has to be added.   

Radiation Engineering: All activities implemented in the frame of the program: Radiation Control Board at each Sub-Contractor levels, Radiation Audits on tools and methods, Radiation testing list to implement and follow-on, Progress meetings, Preliminary Design Revue, Critical Design Review, As Design and As-Built meetings, reporting to the customer     

CONCLUSION

As a result, we have to develop RHA philosophy only for Space Domain C1, C2, C3 & S3

For Space Domain C1, C2 & C3, so far, each Prime contractor has its own RHA, but the space community needs to converge on a RHA document for each different domain. Key point is that for COTS procurement, we need to buy all the needed quantities at once, in order to minimize as much as possible the number of different Diffusion Lot numbers inside the "procured" lot. Then, a "Procured lot" TID qualification has to be performed. A New Procured lot will induce a new TID qualification. The same thing for SEE testings, if we cannot get the evidence of the technology and mask number in the procured lot.

For Space Domain S3, it could be more difficult, and it is not sure that they need an RHA: we will see.