News by Date
News by Category
Solar System
Stars
White Dwarfs
Supernovas
Neutron Stars
Black Holes
Milky Way Galaxy
Normal Galaxies
Quasars
Galaxy Clusters
Cosmology/Deep Field
Miscellaneous
Press Resources
Status Reports
Press Advisories
Image Releases
Release Guidelines
Image Use Policy
NASA TV
Biographies/Interviews
Web Shortcuts
Chandra Blog
RSS Feed
Chandra Mobile
Chronicle
Email Newsletter
News & Noteworthy
Image Use Policy
Questions & Answers
Glossary of Terms
Download Guide
Get Adobe Reader
Chandra @ NASA
Visit the Chandra pages at the NASA portal
Image Use
Image Use Policy & Request Form
Guidelines for utilizing images, applets, movies, and animations featured in this Web Site.
Getting Hard Copies of Images
Ways to obtain photos, slides, etc of Chandra images.
Operations CXO Status Report

Friday 8 July 2011 12.00pm EDT

During the last week Chandra's observing schedule was interrupted by a spacecraft safemode event that occurred at 8:28am EDT on Jul 6. The safemode transition was identified at the first contact after the event, which started at 5:55pm EDT on Jul 6. The safemode transition was nominal and all systems functioned as expected. Playbacks of the Solid-state Recorder (SSR) to obtain the data containing the safemode transition contained an 80-minute data-gap ending ~12 minutes before safemode entry. Real-time procedures were executed on Jul 6 to perform a diagnostic dump of the Central Processing Electronics (CPE) and to swap to the SSR-B to preserve the data on SSR-A. A real-time procedure was executed on Jul 7 to patch the value of SSR-A playback pointer in the OBC to allow the recovery of the missing data from SSR-A.

The cause for the safemode transition is under investigation. The On-board Computer (OBC) reported cause was that the predicted versus measured change in spacecraft angular momentum was greater than allowed. However, telemetry from the gyroscopes and reaction wheels did not show any anomalous behavior in the time leading up to the safemode event. Analysis of telemetry leading to the safemode event and the contents of the OBC memory (halted at the time of the safemode) are on-going. At this time the leading candidate for the cause of the safemode is an upset or corruption of data within the OBC affecting its processing.







Return to Status Reports