The Time Series Analysis Resource (TSAR) program was developed at Aerospace and is used routinely to analyze flight data. As this picture illustrates, time series data can be looked at in many different ways.
Aerospace plays a significant role in analyzing flight data for each national security space launch. During liftoff and ascent, sensors mounted on the launch vehicle continuously measure critical parameters such as acceleration, external pressure, internal engine performance, propellant tank pressure, temperature, thrust-chamber pressure, and guidance and navigation performance. These parameters vary with flight time—some of them quite rapidly. Acceleration, for example, can oscillate up to several thousand times each second.
Launch vehicle organizations, as well as Aerospace, have developed specialized time-series data analysis techniques to process and analyze the data. An onboard sampling process converts the analog measurements to digital time histories. These digital time histories are transmitted to ground stations which forward them to the appropriate organizations for postflight analysis.
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The Time Series Analysis Resource (TSAR) program was developed at Aerospace and is used routinely to analyze flight data. As this picture illustrates, time series data can be looked at in many different ways. |
To establish cause and effect among observed parameters, the launch team must resolve time differences to fractions of a millisecond—a task made difficult by errors inherent in telemetry acquisition and processing. Further complicating the analysis is the nonlinear and nonstationary nature of the underlying physics, which limits the applicability of standard time-series analysis techniques. Consequently, Aerospace continues to develop new data-analysis methods that address these issues.
Flight data analyses help support postflight data assessments, anomaly investigations, and research geared toward improving launch vehicles and their payloads, and the analysis methodologies used to predict loads and other performance parameters. On the day of launch, telemetry data are transmitted from the launch site, either Cape Canaveral or Vandenberg Air Force Base, over dedicated lines to the Spacelift Telemetry Acquisition and Reporting System (STARS) facility at Aerospace. Nearly instantaneous telemetry data are acquired, processed, and stored in the telemetry database and made available for cursory analyses and more involved postflight data assessments. The assessments include comparing the measured quantities to historical data and to preflight and postflight analytical predictions.
—B. H. Sako