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Objectives
The objective is to develop and qualify for GEO applications a new type of Optical Solar Reflector (from now on FF-OSR) that combines the high performance and durability of quartz OSRs with the easy handling and flexibility of Ag-FEP Second Surface Mirrors. The solution is based on patented “Interferential CERMET” (IC) coating technology designed and qualified for the extreme environments of the Bepi Colombo mission and now flying on the High Gain Antenna of the Mercury Planet Orbiter. With First-Flex, the IC coating is transferred from small rigid metal parts to large sheets of polyimide tape.
Challenges
The main challenge is to ensure good adhesion and reduced mechanical stress between a fully inorganic coating and a thin polymer substrate.
System Architecture
The base product is built on a polyimide sheet of Kapton HN or FPC, 2÷3 MIL thick. The front side of the sheet is coated with Interferential CERMET, a multi-layer coating topped by a thin layer of Indium Tin Oxide (ITO). The back side is glued to a commercial non-conductive acrylic transfer tape (3M 966 or 3M 9460). After applying the sheet to the radiator panel, grounding is established by a conductive strip glued to the IC coated surface.
FF-OSRs can also be offered with perforated interconnects. In this case the transfer tape is conductive (3M 9703), and the Kapton sheet has a regular pattern of small perforations and a metal layer on the second surface. The two sides of the sheet are in electrical contact and grounding is established automatically when the product is applied to the radiator panel.
Plan
The project consists of two phases, the first aiming at the development of the technology up to TRL 6, the second at the qualification of the technology for GEO missions.
Current Status
The project was successfully completed and FF-OSRs are now qualified for application on 15-years GEO missions. Thermo-optical properties at the end of the qualification tests show negligible degradation, with αEoT < 0.12 and εEoT ≥ 0.79. Complementary tests indicate that FF-OSRs are also very resistant to Atomic Oxygen and to Xenon ions and fit for use in a much wider range of missions and environments, from LEO to cislunar. Results confirm that FF-OSRs combine the performance and durability of quartz OSRs with the easy handling of SSMs, at fair costs. Delta qualification for specific missions is currently underway and the product is expected to fly by 2026.
