Friday 24 July 2009 9.00am EDT
|On July 23, we celebrated the 10th anniversary of Chandra's launch and
10 years of successful scientific operations. The spacecraft and
instruments continue to produce superb science and we look forward with
excitement to the coming year of discovery!
During the last week Chandra completed the observing schedule as planned.
On July 19 the pressure reported for the momentum unloading propulsion system (MUPS) tank was anomalously low. As a precaution against a potential leak, a real-time procedure was executed to close a valve to isolate the prime bank of thrusters. Telemetry analysis determined that the readings exhibited a drop of 21 psi over 45 min before changing to a slower rate. All other spacecraft telemetry was nominal. Over subsequent days the reading continued an extremely slow decline and has now leveled. A real-time procedure was executed on July 21 to re-open the valve to the prime bank thrusters as its closure had no effect. A detailed fault-tree of possible causes of the anomaly is being developed which includes the case for false readings from the pressure sensor, internal or external leaks from the MUPS, as well as other causes. Use of the MUPS system had not been scheduled for the week and as a precaution, future weeks will be scheduled without momentum dumps while the anomaly is being analyzed. Note that we expect science to continue without significant impact even in the worst case of a leak and loss of all fuel. In this case we would expect a small decrease in observing efficiency.
A Chandra image release was issued on July 23 in conjunction with the tenth anniversary of Chandra's launch. The image was of the debris of an exploded star, supernova remnant 1E 0102.2-7219, or "E0102" for short. The Chandra image shows the outer blast wave produced by the supernova, and an inner ring of cooler material. This inner ring is probably expanding ejecta from the explosion that is being heated by a shock wave traveling backwards into the ejecta. For further details see: http://chandra.harvard.edu/photo/2009/e0102/
The schedule of targets for the next week is shown below.
Radiation Belts Jul 27 LP400-22 ACIS-S Jul 28 J1718-3718 ACIS-S NGC6440 ACIS-S PSRJ1852+0040 ACIS-S Jul 29 3C268.3 ACIS-S Radiation Belts Jul 30 3C268.3 ACIS-S NGC4051 ACIS-S Jul 31 LS5039 ACIS-S IGRJ17254-3257 HRC-I N49 ACIS-S VelaPWN ACIS-S Aug 1 SDSSJ1539+4203 ACIS-S Radiation Belts RXJ1757.3+6631 ACIS-I Aug 2 LS5039 ACIS-S
All spacecraft subsystems continued to support nominal operations.
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