Will jumper material outgas inside a spacecraft and contaminate instruments?
Yes, materials used in ordinary fiber optic patch cords do indeed release gases that severely contaminate precision instruments inside spacecraft or in ultra-high vacuum (UHV) environments. This physical phenomenon is known as Vacuum Outgassing in spacecraft design and vacuum engineering.
To ensure the absolute safety and long-term stable operation of spacecraft payloads, the vacuum outgassing rate of materials used in electromechanical equipment such as fiber optic patch cords must be strictly controlled.
I. What is “Vacuum Outgassing” of Fiber Optic Patch Cords?
Vacuum outgassing refers to the process where gaseous substances are released from polymer organic materials (such as the jackets, strength members, fiber coatings, and connector adhesives of ordinary fiber optic patch cords) into a vacuum environment. This occurs when the internal adsorbed moisture, residual solvents, additives, and unreacted small molecule monomers overcome intermolecular forces and escape from the material surface in the high vacuum environment of space (or during thermal vacuum cycling).
1. Main Hazards of Outgassed Substances (Molecular Contamination):
The released volatile gases diffuse and condense on cooler surfaces, forming a contamination film that is micrometers or even nanometers thick. This leads to:
- Optical System Failure: Molecular films condensed on lenses, mirrors, or infrared detector windows strongly absorb or scatter light, causing a drastic degradation in optical transmittance and reflectivity.
- Thermal Control Coating Failure: Alters the solar absorptance and infrared emittance of spacecraft thermal control materials, leading to thermal control imbalance.
- Reduced Solar Cell Efficiency: Covers the surface of solar cell arrays, reducing their photoelectric conversion efficiency.
2. International Academic Evaluation Standards:
According to NASA SP-R-0022A and ASTM E595 vacuum outgassing standards, materials used in crewed spacecraft and precision space optical instruments must undergo vacuum thermal gravimetric testing. The following indicators must be met:
- Total Mass Loss (TML): \text{TML} and{ ext{less than}} 1.0\%
- Collected Volatile Condensable Material (CVCM): \text{CVCM} and{ ext{less than}} 0.1\%
II. Why Ordinary Fiber Optic Patch Cords Cannot Be Used Inside Vacuums/Spacecraft?
Ordinary commercial fiber optic patch cords, such as the OFSCN® Standard Fiber Patch Cord, are primarily designed for conventional terrestrial environments (operating temperatures from -20\ ^\circ\text{C} to 50\ ^\circ\text{C} ):
- PVC Jacket: Contains a large amount of plasticizers and volatile organic compounds. In a vacuum environment, PVC outgassing is extremely severe, with TML and CVCM far exceeding space standards.
- Aramid (Kevlar) Strength Member: Highly adsorbs atmospheric water molecules. In a vacuum, it releases water vapor ( \text{H}_2\text{O} ) for extended periods, disrupting the chamber vacuum.
- Acrylate Fiber Coating: Exhibits significant degradation and outgassing phenomena under high temperatures and vacuum conditions.
III. OFSCN® Ultra-Low Outgassing Vacuum Fiber Optic Solution
To meet the non-contaminating requirements of high vacuum, ultra-high vacuum, and space-grade instruments, OFSCN® has developed high-end special fiber optic patch cords and non-destructive sealing technologies based on metal seamless protective tubes and inorganic or low-outgassing polyimide coatings:
1. OFSCN® 300℃ Fiber Optic Patch Cord (Space and Ultra-High Vacuum Grade)
- Core Structure: Utilizes a 0.9\text{mm} stainless steel seamless steel tube as the protective sheath, completely eliminating high-outgassing organic jackets like PVC and aramid. The interior uses high-performance polyimide-coated optical fibers.
- Physical Characteristics: Polyimide possesses excellent molecular thermal stability and extremely low vacuum outgassing rates, meeting the stringent space-grade TML and{ ext{less than}} 1.0\% and CVCM and{ ext{less than}} 0.1\% standards.
- Temperature Range: -270\ ^\circ\text{C} to 300\ ^\circ\text{C} .
- Product Images:
2. OFSCN® 700℃ Fiber Optic Patch Cord (Zero Outgassing Extreme Vacuum Grade)
- Core Structure: Employs a stainless steel seamless steel tube with stainless steel connectors, housing pure inorganic Gold-coated Optical Fibers internally.
- Physical Characteristics: Since the entire patch cord (except for a very small amount of ceramic ferrule in the connector) is made of pure metal, it completely contains no organic polymer substances internally. This physically eliminates the possibility of organic outgassing, making it a fiber optic patch cord with