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TELECOMM 1.

HOLLOW RF WAVEGUIDES THAT PENETRATE PRESSURIZED STRUCTURE

Constraints/Considerations:

A Ku-Band RF system uses hollow waveguides that penetrate the pressure hull.

Impact:

• The waveguide requires purge air and desiccants to prevent condensation and corrosion. They also require cabin air pressure to prevent corona, and must be leak checked. These are labor intensive efforts.

Design Objectives:

• Use only coax cables or waveguide filled with solid dielectric. No hollow transmission line aperatures (such as waveguides) should penetrate the walls of the pressure vessel. This will reduce critical failure modes and the need for leak tests.

TELECOMM 2.

HAZARDOUS RF SYSTEMS & GROUND ANTENNA COUPLER REQUIREMENTS

Constraints/ Considerations:

RF Systems frequently require extensive GSE Antenna Coupler setups and Radiation hazards impede processing.

Impact:

• Potential radiation hazards from high power RF systems require clear that inhibit vehicle processing in the immediate area. Additionally, antenna coupler setups require precise positioning to ensure repeatable transmission losses needed for testing and troubleshooting.

Design Objectives:

• 1. For hazardous RF systems provide an onboard test load and GSE port to hook up an RF hardline. This will eliminate radiation hazard clears and enable better testing and troubleshooting.
• 2. Implement program policy to direct Radiation Protection Officers and Safety offices to abide by ANSI standards regarding hazardous non-ionizing radiation controls. ALARA (As Low As Reasonably Achievable) principles should not apply to operational non-ionizing radiation programs.

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Edgar Zapata, NASA Kennedy Space Center

Shuttle Process Engineering Directorate, Fluid Systems Division