chandra x-ray observatory cxc acis ops team september 27, 2007 1 controlling the acis fp...
Post on 22-Dec-2015
215 views
TRANSCRIPT
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20071
Controlling the ACIS FP Controlling the ACIS FP Temperature: Temperature:
Results from the First Two TestsResults from the First Two Tests
ACIS Ops TeamACIS Ops Team
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20072
ACIS FP TemperatureACIS FP Temperature
DePasquale (SAO)
First ACIS DH Cooling Test: Perigee Passage
Begin
End
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20073
DePasquale (SAO), Vogrin predicts a steady state temperature of -69 to -71 C at the HRC position and pitch angle of ~150
First ACIS DH Cooling Test: Perigee Passage
End
Begin
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20074
DePasquale (SAO), commanded by SOP_61014_DAHTR_B_ON
First ACIS DH Cooling Test: Heating
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20075
DePasquale (SAO)
Second ACIS DH Cooling Test: OBSID 9593 CDF-S
Begin
End
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20076
DePasquale (SAO), Vogrin predicts a steady-state temperature of -68 to -70 C at the ACIS position and a pitch angle of ~120
Second ACIS DH Cooling Test: OBSID 9593 CDF-S
Begin
End
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20077
DePasquale (SAO), commanded in the load
Second ACIS DH Cooling Test: Heating
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20078
What Have We Learned ?What Have We Learned ?
1) The side B heater can be turned off and turned back on
2) The commands/script in SOP_61014_DAHTR_B_ON worked as expected
3) The commands in the load worked as expected
4) The time constant for cooling is shorter than expected (25-30 ks), this means that it is possible that the camera body temperatures (1CB[AB]T) could reach the point at which the survival heaters will turn on (primary -71.1 C, redundant -73.6 C) if the camera body is allowed to cool long enough and the spacecraft orientation permits
5) Asymptotic temperatures determined from the fits are consistent with Vogrin’s predictions
6) The DH heater will draw 55-60 W when turned on for a short amount of time.
7) It takes the DH about 1 hr to get back to the nominal operating temperature of 1CBAT/1CBBT -62.4 C/-59.9 C
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 20079
New Proposed Tests1) Conduct one test per week in upcoming CDF-S observations, there are CDF-S observations
in the OCT1507, OCT2207, OCT2907, NOV0507, and NOV1207 weeks
-- pitch angles vary between 130 and 135
-- model predicts that 1CB[AB]T should not drop below -68/-66 C
-- exposures vary from 28 ks to 160 ks (subject to change of course), we would select observations around 80 ks
-- commanding in the load, with monitoring by ACIS Ops and CC/OC
Possible Future Tests1) Turn off the side B DH heater for perigee passages
-- the HRC position is a colder orientation for the camera body, temperature might drop to the point at which the survival heaters would come on
-- the CTI measurements would benefit from a colder camera body since the FP temperature would be colder
-- we need to be comfortable with relying on the survival heaters to turn on at -71.1 C and then off again at -69.8 C
-- we would like to come back to an FDB meeting in the future after we have thought about this more
Chandra X-Ray Observatory CXC
ACIS Ops team September 27, 200710
ACIS Detector Housing Survival Heater Geometry
•HR7, HR8: 22 W @ 29 V• Prime survival -71.1 °C• Rdnt survival -73.6 °C
•Better than 1.19 °C accuracy (@ -70 °C ) for 1YA94 SSTS that controls survival heater
•Located on +Z face of Detector Housing (side A, 1CBAT)
•Closest telemetry thermistor is 1CBAT (FM07)
Heater description
Pr or Red
Htr Bus
Enable Cmd
Disable Cmd
Heater Flight Telemetry Mnemonic
Heater Power at 29 volts (watts)
Heater Resistance (ohms)
Heater Close Set Point Temp (°C)
Heater Open Set Point Temp (°C)
Primary Heater Monitor Thermistor Mnemonic
Backup Heater Monitor Thermistor Mnemonic
ACIS Det. Hsg. Survival
PR 2 NA NA NA 22 38.2 -71.1 -69.8 1CBAT 1CBBT
ACIS Det. Hsg. Survival
RD 7 NA NA NA 22 38.2 -73.6 -72.5 1CBAT 1CBBT
Trinh(NGST)