Failure-reporting devices somewhat similar to the “black box” data recorders on aircraft have been proposed. These devices were conceived for use on spacecraft, but might also be useful on terrestrial autonomous underwater vessels or terrestrial remote exploratory robots. The concept was motivated by the need to learn from mission failures in order to make future missions more failure resistant.
Even more than aircraft “black boxes,” the proposed devices would be extremely rugged to survive re-entry into the atmosphere of the Earth as well as impacts substantially harder than those of airplane crashes. Unlike aircraft “black boxes,” the proposed devices would not be designed to be retrieved: instead, they would be designed to transmit as much pertinent information as possible to enable analysis to identify specific causes of mission failures.
The design of the proposed devices would follow a “spacecraft within a spacecraft” approach. The device would contain data-handling, telecommunication, power-supply, and structural subsystems. The primary interfaces between this system and the spacecraft would be power connections and points of access to the spacecraft data bus and/or the spacecraft telemetry-management system. The links between the failure-reporting device and the spacecraft would be subject to severance at any time. However, even while the spacecraft remained intact and functional with the device connected, the device would transmit subcarrier beacon tones that would convey information on the status of the spacecraft during high-risk maneuvers like entry, descent, and landing.
Upon separation from the spacecraft, the device would stop drawing power from the spacecraft power supply and start drawing power from an internal battery. Once separated from the spacecraft, the device would automatically begin transmitting relevant data back to Earth ground stations and/or nearby orbiting spacecraft. A flight-qualified data processor would run the software necessary to record channelized data, set the beacon state, and execute other functions like those of an aircraft “black box.” The level of data processing would depend on the degree to which the data received by the device were summarized and otherwise preprocessed by the spacecraft data-processing system. The most important data would be stored (most likely in a solid-state memory) aboard the device for transmission.
The telecommunications and software subsystem of the device would generate low-rate telemetry signals to transmit stored engineering data. If possible within the processing constraints, summarization software would transmit the most relevant sensor data recorded around the time of the failure. The subcarrier signals could be programmed to correspond to spacecraft failure modes and would provide some indication of status in the event that acquisition of telemetry was not possible.
This work was done by E. Jay Wyatt and John Szijjarto of Caltech for NASA’s Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Electronic Components and Systems category. NPO-20942