Monitoring the Health and Safety of the ACIS Instrument On-Board the Chandra X-ray Observatory

Kavli Affiliate: Peter G. Ford

| First 5 Authors: Shanil N. Virani, Peter G. Ford, Joseph M. DePasquale, Paul P. Plucinsky,

| Summary:

The Chandra X-ray Observatory (CXO), NASA’s latest “Great Observatory”, was
launched on July 23, 1999 and reached its final orbit on August 7, 1999. The
CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and
has a period of approximately 63.5 hours (~2.65 days). Communication with the
CXO nominally consists of 1-hour contacts spaced 8-hours apart. Thus, once a
communication link has been established, it is very important that the health
and safety status of the scientific instruments as well as the Observatory
itself be determined as quickly as possible.
In this paper, we focus exclusively on the automated health and safety
monitoring scripts developed for the Advanced CCD Imaging Spectrometer (ACIS)
to use during those 1-hour contacts. ACIS is one of the two focal plane
instruments on-board the CXO. We present an overview of the real-time ACIS
Engineering Data Web Page and the alert schemes developed for monitoring the
instrument status during each communication contact. A suite of HTML and PERL
scripts monitors the instrument hardware house-keeping electronics (i.e.,
voltages and currents) and temperatures during each contact. If a particular
instrument component is performing either above or below pre-established
operating parameters, a sequence of email and alert pages are spawned to the
Science Operations Team of the Chandra X-ray Observatory Center so that the
anomaly can be quickly investigated and corrective actions taken if necessary.
We also briefly discuss the tools used to monitor the real-time science
telemetry reported by the ACIS flight software.
The authors acknowledge support for this research from NASA contract
NAS8-39073.

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