Jun_14_2000_L327.txt Shift L327 Start at 2000:166:11:30:00 GMT = 2000 Jun 14 7:30am EDT End 2000 Jun 14 12:00pm EDT See http://asc.harvard.edu/acis/SOT_reports/sot-shift.html, or /proj/ascwww/AXAF/extra/science/htdocs/acis/SOT_reports/Jun_14_2000_L327.txt SOT Lead Bill Podgorski SOT SC/ACA FOT-SI HRC-SI Jon Chappell ACIS-SI OTHER Plan: - Running JUN1100D observing 3C 273 ACIS-S/LETG (obsid 1711). Discover that LETG is not in and spend rest of day performing diagnostics. ORBITAL EVENTS: 2000:163:15:09:34.298 117 EAPOGEE ORBIT APOGEE 2000:164:22:53:08.029 117 EPERIGEE ORBIT PERIGEE 2000:166:06:37:17.979 118 EAPOGEE ORBIT APOGEE 2000:167:14:20:44.447 118 EPERIGEE ORBIT PERIGEE 2000:168:22:05:11.980 119 EAPOGEE ORBIT APOGEE 2000:170:05:49:27.825 119 EPERIGEE ORBIT PERIGEE EVENTS DONE OBSID -------------- ---- ----- Start Shift LOS 166:1130 AOS DSS-24 (Goldstone) 166:1135 1711 (Status at AOS was not nominal - see below) LOS DSS-24 166:1235 End of shift 166:1900 NOTES/ISSUES/PROBLEMS --------------------- 1) Chandra state at 166:1140 WAS EXPECTED PCAD MODE = NPNT NPNT CONTROL LAW FLAG = NPNT NPNT Stars: = 5 5 FIDS = 0 0 RA = 187.275 deg 187.27387 DEC = 2.100 deg 2.08148 ROLL = 245.659deg 245.69092 Format = 2 2 OBSID = 1711 1711 SIM FA = -467 -468 SIM TSC = 72440 72440 HETGA = 80.2 deg (OUT) OUT HETGB = deg (OUT) OUT LETGA = 78.3 deg (OUT) IN <---ERROR LETGB = deg (OUT) IN EPHIN A-leak = 0.2520 B-leak = 0.0440 ACE Proton Flux = 1600 (2 hr avg in 130-214 keV proton channel) Fluence (130-214KeV) = 1.1E+7 LT 3.6E+8 Radiation Level OK Kp Index (Costello) = 4.00 LT 6 is OK EPHIN Geom = LARG E1300 = 3 LT 1318.52 (RADMON P4GM = 1 LT 3542.40 Triggers) P41GM = 0 LT 100.00 HRC SP PS = ON IM PS = OFF SP Top Step = 43 SP Bot Step = 54 Shield 1 HV = OFF Shield 2 HV = ON - Step 8 Valid Event Rate 1 = - Valid Event Rate 2 = - Shield Event Rates = 3100 ACIS FP Temp = -119.7 Cold Radiator = -127.9 DEA Pwr = 53.5 DPA Pwr = 41.7 Science State = Science Active 2) Notes from 9:00am meeting: Operations (Darrell): - 3 supports last 24 hours, 3 SSR dumps - 1 load segment uplinked, good till 169:2357 - HETG retraction failed at about 166:0338 (RETR LS did not read RETR solidly, bouncing) Spacecraft Engineering (Wallace): - Looking at grating anomaly SOT (Bill Podgorski): - Looking at grating anomaly DSOPS(Joy): - Many quick looks 3) Additional meetings on grating anomaly 9:30am EDT 11:00am EDT 4:00PM EDT 4) DECISIONS/PLANNING: - Analysis shows that HETG insertion at 166:0338 failed to complete properly, a summary by Michael McGuirk follows: The HETG B-side retraction limit switch failed last night. Roger held an anomaly review meeting at 11:00 AM this morning. Harvey, Marty, TRW and EKC participated by phone. All symptoms of the failure are identical to the A-side failure May 8, 2000, i.e. the switch appears to function, but the trigger point has moved to a position after the end of travel bumper spring is compressed. When the switch finally turns off the motor, the spring pushes the grating back, restoring power to the motor. This cycle continues until power times out. The grating rest position leaves the limit switch indicating "not retracted". The two limit switches are actuated by a wide lever arm pivoting on an axis defined by an adjustable bearing on each side. My scenario for the failure is that the bearing on the A-side moved out of adjustment, allowing the A-side limit switch trigger point to change. The B-side trigger point changed also, but not enough so it did not function. Over the subsequent ten actuations, the lever moved enough so the B-side trigger point moved to allow compression of the bumper spring before the motor turns off. TRW and EKC are evaluating this scenario and alternatives. There are about five days of HETG observations scheduled to begin tonight. The plan is to insert HETG tonight using hardware commands in a real time contact. HETG will be left inserted through the radiation belts until the set of observations is completed. That will give us several days to evaluate the situation and formulate plans for the future. There will be another review at 4:00 PM today to sign off the procedures to implement the plan above. Michael McGuirk, Ph.D.