Reliable health monitoring for man-rated spacecraft having long missions

Abensur T.

Abstract:
In the future, many man-rated spacecraft will have long duration missions (more than one year). We can quote following examples: Crew escape vehicle docked to a space station during many years (dormant phase), and ensuring crew return to earth in case of emergency, Space vehicle going to the moon for a long stay, Space vehicle going to mars. These new missions will raise the following difficulties: The mission, much longer than "classical ones˜ will result in lower intrinsic reliability of health monitoring components (propulsion sensors, associated avionics and communication means with crew and ground stations), Possible interruptions of radio-link between ground stations and the space vehicle push us to re-think the specific roles of crew, ground stations and automatisms. In case of problem detected by the health monitoring during motor firing, means must be given to the crew to make the difference between a real propulsion problem and a false alarm due to a health monitoring failure. More generally, the health monitoring will not be only a very smart system which will announce to the crew that the motor is failed or no. It will also be a toolbox, which will help the crew in terms of diagnosis and prognosis. The crew, being more closely integrated to these processes, will have better information, to estimate risks in case of doubt on an engine health. A very important point must be underlined: the study of these problems must be made very early in the project. Indeed, if the engine is too complex, needing too many monitored parameters, of various types (temperature, pressure, acceleration...), the crew intervention would become infeasible. Key points to ensure the success are the following ones: Simplification of propulsion and heath-monitoring, Parallel design of propulsion and health monitoring, Continuous dialog between propulsion engineers, ergonomy specialists and future crew members, ground station people during the health monitoring design, Good knowledge of propulsion and health monitoring by crew members and ground control people. The health monitoring system must not be a pure "engineering object" having human beings as interfaces. Safety will be improved if design engineers open themselves to cognitive sciences (and, reciprocally, if ergonomy specialists open themselves to engineering); this will shape a reliable and transparent health monitoring system around the crew and the ground station people.

Go Back