Orbiter Interface Unit and Early Communication System

This report describes the Orbiter Interface Unit (OIU) and the Early Communication System (ECOMM), which are systems of electronic hardware and software that serve as the primary communication links for the International Space Station (ISS). When a space shuttle is at or near the ISS during assembly and resupply missions, the OIU sends groundor crew-initiated commands from the space shuttle to the ISS and relays telemetry from the ISS to the space shuttle s payload data systems. The shuttle then forwards the telemetry to the ground. In the absence of a space shuttle, the ECOMM handles communications between the ISS and Johnson Space Center via the Tracking and Data Relay Satellite System (TDRSS). Innovative features described in the report include (1) a "smart data-buffering algorithm that helps to preserve synchronization (and thereby minimize loss) of telemetric data between the OIU and the space-shuttle payload data interleaver; (2) an ECOMM antenna-autotracking algorithm that selects whichever of two phased-array antennas gives the best TDRSS signal and electronically steers that antenna to track the TDRSS source; and (3) an ECOMM radiation-latchup controller, which detects an abrupt increase in current indicative of radiation-induced latchup and temporarily turns off power to clear the latchup, restoring power after the charge dissipates

NASA-STD-7012 Leak Test Requirements: Potential Reference for ASNT Nondestructive Testing Handbook for Leak Testing

Developed in 2018-2019, NASA-STD-7012 Leak Test Requirements, has been drafted based mostly on the NASA technical requirement documents applicable to the International Space Station (ISS) hardware and payloads that were developed over the years taking into consideration many known references such as Leakage Testing Handbook prepared by General Electric for the Jet Propulsion Laboratory, the ASTM International standards for leak testing, and last, but not least, the ASNT Nondestructive Testing Handbook for Leak Testing. Thus, NASA-STD-7012 has a reference to the above-mentioned handbook in the leak test method/technique descriptions. However, there are some technical details that are described differently in NASA standard and ASNT Handbook. Those technical details are mostly related to the classification of the leak test methods/techniques, and also to tracer gas to working fluid (gas or liquid) leakage rate conversion methodology, and to some definitions used in the text of both NASA standard and ASNT Handbook. Those differences are going to be briefly described in this paper to let ASNT leak test experts decide if they want to refer to NASA-STD-7012 while working on the next edition of the ASNT Handbook, Volume 2 for Leak Testing

NASA-STD-7012 Leak Test Requirements: Potential Reference for ASNT Nondestructive Testing Handbook for Leak Testing

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