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Aqua DPREP Ephemeris and Attitude Data Interruption


Early this past Sunday (December 2, 2007; Day 336), circumstances both onboard the spacecraft and at the EOS Operations Center led to corruption of the memory partition that holds the ground-based attitude determination (GBAD) data in the Aqua spacecraft's solid state recorder (SSR). GBAD data is the primary input used in producing PM1ATTNR. About 19 hours of GBAD data were permanently lost because nothing was written to that partition for most of Sunday.

Since late Sunday, GBAD data have been being recorded on the SSR and downlinked as usual, but the data has format problems which have prevented it from being processed at EDOS, and hence GES DISC
has been unable to process PM1ATTNR.

The Earth Science Mission Operations (ESMO) Project at GSFC is working with Northrop-Grumman (the builders of the spacecraft) to correct the problem. Possible solutions are being discussed. Unfortunately, all options involve new procedures which will have to be developed and thoroughly tested. In the meantime, EDOS is working on a way to process the GBAD data that is coming down now, so that normal science data processing can resume while the SSR problem is being worked.

We recently received a set of GBAD data produced with one of those solutions; however, it's validity has yet to be established.

The ESMO Project is also investigating the possibility of reconstructing the lost GBAD data using other spacecraft telemetry and help from the Flight Dynamics Facility.

GES DISC continues AIRS NRT processing (Level-1B only) without the GBAD data.

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Last updated: Sep 09, 2009 02:25 PM ET