Description
Priority 2: Priority 2 activities will only be initiated upon a specific request of at least one Delegation.
The objective of this activity is to develop RF power flexible cable assemblies capable to survive extreme environmental conditions when directly exposed to outer space in GEO orbit.
Targeted Improvements: The new cable assembly would allow its use under severe exposed conditions (-100°C to +165°C and above 300 Mrads) where the use of thermal blankets or any kind of radiation protection is not possible such as long booms, unusual payload geometries and distributions or complex antenna farms. The cable assembly will focus on this target while maintaining or even improving the state-of-art in cable electric loss and high power RF handling.
Description: Modern L-/S-Band telecom satellites for mobile applications embark a large number of cable assemblies, which are with no doubts single point failures. Recently, several European space missions have been threated or affected by failure in this type of cable assembly when exposed to. Up to date, one possible solution was to use Silicon Dioxide cables to feed antennas. However, these cables are known for their poor insertion and return losses. In addition, Europe lacks of cable assembly manufacturer capable to design and built this type of product which forced clear dependency from American providers.
The main technical challenges are:
- To improve the radiation capability of its cable to a minimum of 300 Mrads: several ways have to be worked, change of jacket material and/or increase of metal shielding. The best compromise between mass budget and radiation hardness shall be found. Solder limitations are also a serious constrain in existing Silicon Dioxide cables assemblies.
- To increase the temperature range of cable assemblies to, at least -100°C to +165°C instead of -65°C to +150°C. In this sense, the main problems to be solved are shrinkage of the dielectric of cable under temperature cycles and the retention of it by the coaxial connector at interface between cable and connector. If a gap appears between insulator of connector and dielectric of cable, then VSWR will be strongly affected and Multipactor threshold level as well.
The potential ways to solve the problems above-mentioned are:
- Investigate new raw material of cables to replace expanded PTFE ribbon by an exhaustive comparison of the different suppliers available on the market and then audits of supplier processes to understand differences between batches with shrinkage and batches without shrinkage then validation of selected process and material.
- Manufacturing process of coaxial cable itself. Investigate the influence of wrapping process (insulator and copper tape as well).
- Design of coaxial connector: If the shrinkage of cable remains limited it is possible to improve also the behavior of cable assemblies through a design of the connector that retains the cable dielectric inside connector insulator and block the shrinkage of RF cable. Investigate optimum solder materials for high temperature.
Work Logic
1. Identification of materials capable to withstand the temperature ranges and radiation doses.
2. Trade-off of these materials versus low ohmic losses.
3. Design of low loss cable assembly suitable for high power applications while exposed to severe space weather conditions.
4. Manufacture of the cable assembly and testing under extreme conditions.
Procurement Policy: C(1) = Activity restricted to non-prime contractors (incl. SMEs). For additional information please go to EMITS news "Industrial Policy measures for non-primes, SMEs and R&D entities in ESA programmes".