Chandra Long-Term Trending and Prognostication Tools

The Chandra X-Ray Observatory was launched in July 1999, and is thus in its fifth year on-orbit. The Monitoring and Trends team at the Chandra X-Ray Center (CXC) is charged with tracking observatory performance parameters to optimize the mission's science return. We have built from scratch an IDL-based system, called "dtrend" (derivative trending), for visualizing and quantifying long-term trends. Data are input from our databases of over 600 engineering mnemonics, averaged on 5 minute intervals over the course of the entire mission. Dtrend computes the mean, standard deviation, first derivative and second derivative for each parameter. The derivatives are then used to predict the next 6 month cycle. Output is presented via web pages with statistical summary tables and graphics color-coded to highlight threat level or potential problems. This paper will discuss the algorithms and metrics used to predict future behavior based on previous trends and how the CXC can efficiently identify, track, and possibly curtail problems to extend the length and quality of the Chandra science mission.