SOLAR ORBITER. FDMs subsystem (Feedthroughs, Door & Mechanisms, and electronic unit)

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Solar Orbiter FDM subsystem Solar Orbiter FDM subsystem
Solar Orbiter FDM subsystem
Solar Orbiter FDM subsystem
  • Client: AIRBUS DS LTD (UK)
  • Start date: 2010
  • Ending date: 2017
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This subsystem consists on several through-wall filters (located on the Heat Shield) that provide the satellite with non-hermetic protective covering for its remote detection instruments. Some of these feedthroughs (6) need a door cover to protect the instruments in some operational conditions. The door is the component that prevents sun incidence from going into the feedthrough. It is located at the sun entrance side of the feedthrough. Each door provides identical interface to the mechanism rotating shaft interface.


Feedthroughs (FT)

The generic design consists of a hollow structure, mounted to the Heat Shield (HS) support panel and supporting the top layers of the HS. Inside the hollow structure there are internal vanes that, together with the top and bottom flanges of the feedthrough, define the Unobstructed Field of View (UFOV) for the instruments.
The FTs main functions are:

  • Support the top layer of the heat shield
  • Protect internal part of the heat shield from direct Sun illumination. The FTs close the gap in the heat shield that is needed to provide the instrument an UFOV.

Door & Mechanism

Each door is actuated by a mechanism where its major requirements are:

  • High temperature working conditions till 500° C.
  • High random vibration levels: 73grms (out of plane axis) and 52grms (in plane axes).
  • High emissivity and absortance properties for compatibility with the instruments.


Coating declared as a critical technology process for the instrument needs. An exhaustive coating trade-off  was performed and included different technologies and processes, focused on the thermo-optical, working temperatures, adhesion and electrical conductivity requirements, these requirements are sometimes contradictories in terms to fulfil all of them at the same level.

  • PVD (Astro Black®) technology was selected as the baseline technology for coating:
  • Application: Thermo optical protection
  • Emissivity (ε): 0.72 – 0.76
  • Absortance (α ): 0.88 – 0.90
  • α/ε ratio: 1.18 – 1.20
  • Use Temperature Range (° C): -180 to 500
  • TIS (%): 10 – 14
  • Appearance: Black-violet, homogeneous and even appearance
  • Typical Thickness (μm): 3 – 8
  • Coatable substrates: Titanium, super alloys, steels. Aluminum (restrictions apply)

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