@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ @ @ MTA Monitoring Report 3/17/00 - 3/23/00 @ @ @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ *************** MTA Problem Tracking. ***************** No new problems are reported this week. Only same problems are keep coming: AOSAILLM, EB2DI, EB3DI, ESAMYI, ESAPYI, AOPSAMUL, EB1DI, EPOVSPR,TSAMYT,TSAPYT, SEHSE400, AWD4TQI, 2DRLSOP,CIUB15V, CUSOB28V, C28VMONB 2RSRFALV, AIOBP5CV,EB3CI, EB1CI,EB2CI,AGWS2V, ASPEB5CV, ES2P5CV, 3S1PSCV,1DPDBBON ******** Trending *********** Most of the trends contine. It is clear up/down ward trends in OBA/HRMA are now flatten. ************ CTI trend ************* No prominant changes are observed. All of them are steady. *********** ACIS Focal Temperature ******** Steady around -120 C. ************* Telemetry *********** No new surprise this week. Much less red warning toward the end of the week. *********** Photon Page ************ --- New --- ACIS ---- Date OBSID DETECTOR GRATING TARGET ANALYSIS? -------------------------------------------------------------------------------- Mar 18 00:27 136 ACIS-I NONE E0102-72.3, CHIP I3 NO SKY Mar 18 00:27 78 ACIS-S NONE 47 TUC OK Mar 18 00:27 954 MISSING INFORMAITON OK Mar 18 00:27 953 MISSING INFORMATION OK Mar 18 00:27 955 MISSING INFORMATION OK Mar 19 00:30 956 MISSING INFORMATION OK Mar 19 00:30 856 ACIS-S NONE B2 0206+35 OK Mar 21 00:31 322 ACIS-I NONE NGC 4472 OK Mar 22 00:30 390 ACIS-S NONE NGC 3031 OK Mar 22 00:30 873 ACIS-S HETG MARKARIAN 3 MISSING Mar 22 00:30 366 ACIS-I NONE PG 1115+080 MISSING Mar 23 00:33 587 ACIS-S NONE BD+303639 OK Mar 23 00:33 816 ACIS-S NONE IRAS07598+6508 OK Mar 23 00:33 841 ACIS-I NONE 3C 371 OK Mar 23 00:33 353 ACIS-S NONE MESSIER 51 OK Mar 23 00:33 798 ACIS-S NONE NGC 5044 OK Mar 23 00:33 493 ACIS-I NONE A1795 OK Mar 23 00:33 387 ACIS-S NONE NGC 1058 OK Mar 24 00:31 822 ACIS-S NONE SBSG1542+541 OK Mar 24 00:31 829 ACIS-S NONE 3C123 OK Mar 24 00:31 544 ACIS-I NONE A2111 OK ************ Some Comments from Exparts ******** ------------------------------------------------------------------- From Wallance (3/10/00 --- bit old): About V trun in several MSIDs. ------------------------------------------------------------------- The solar array is a dynamic beast. There is not one all-encompassing equation which describes or predicts the behavior of the array. There are a number of variables which need to be considered when looking at an array's performance: 1) array temperature 2) S/C load 3) S/C attitude 4) S/C's position in the solar season 5) amount of current being drawn through the harness wires which reside on the back-side of the array 6) glint etc. But with that said though, I am able to reasonably predict the array's output parameters based on a given array temperature and S/C load. Hence my justification to Paul and the ACIS team last year when they brought up this issue. What you're seeing in your trend data is the "self-correcting"nature of the array. As the array warms, it compensates for the resulting loss in total array power by decreasing its voltage and increasing its current output. (remember Power = Voltage X Current) This effect is displayed in the array's IV and PV curves. [Now, the exact opposite occurs when the array cools. i.e. Total array power increases, thus voltage increases and current decreases] Therefore, assuming that over a long period of time, the S/C's changes in attitude are negligible and the average load remains fairly consistent (+/- 50-75 watts), the driving factor for the array's behavior is array wing temperature. Thus, if you plot out your trend data along with array temperature and distance to the Sun data versus day of the year, the sinusoidal nature of the array temperature and resulting array voltage data becomes evident. In other words, as Chandra approaches perihelion, the array wing temperatures increase, resulting in a shift to the left of the array operating point and a subsequent decrease in array voltage. As expected, the opposite is true when Chandra approaches aphelion, which is just now becoming evident in your trending analysis. A good reference to go to first when you have questions concerning Chandra's trends is the FOT quarterly report. The Aug-Oct 1999 version of the quarterly addresses this issue in the EPS section. I think you'll find most of the answers to your questions in these reports. Our second quarterly should be out within the next month. I have provided some charts to go along with the above verbiage. If you have any further questions, please feel free to call or email me. As for the peak in HRMA power, the two are not related. If you look at the long term trends, you'll notice that the average HRMA power has actually decreased. (MLI degradation - discoloring, loss of reflective properties, etc.) What you observed around Jan 1st, was a power spike probably resulting from an attitude orientation which shielded some of the HRMA from direct incident sunlight. (resulting in additional heaters to "kick" on) If you peruse the Thermal section of the FOT quarterly report, Rino addresses these trends/issues. As a matter of fact, his next contribution to the upcoming quarterly will provide even greater detail and analysis towards these issues. You must keep in mind that when it comes to Thermal, it's the long term trends that are most important. (unless something really goes off-kilter) --------------------------------------------------------------- From Katherine Grant (3/17/00) About worse CTI for ccd 5 and 7 --------------------------------------------------------------- Both the BI CCDs (ccd 5 and 7) got worse at -120C. They both have intrinsic CTI problems from manufacturing defects that get worse at lower temperatures. So we knew this would happen and it's nothing to worry about. ----------------------------------------------------- From Scott Wolk (3/21/00) About Radiator Temperature ----------------------------------------------------- Rino Giordano is seeing an increase in the (peak - mean) radiator temperature, from about 2 degrees in ~December to 14 degrees now. This is a seasonal effect due to heating from the Earth near perigee. In the next few months the effect could get worse. Rino is only looking at engineering temps, and suggested the SOT examine temperatures in science data. Perhaps ACIS and MTA are already doing this.