Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3247c Report Date: 09-May-96:18:16 Version: ********** Check-in Date: ********** 1.Proposal Title: SA FEATHERING TEST II ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID ENG Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone J Decker CODE 440 USA ------------------------------------------------------------------------------------ 7. Abstract During the initial execution of the Solar Array Feathering test, an unplanned control system gain change resulted in a failure to achieve some of the critical goals of this test. In particular, data required to identify the differences between stick-slip and thermal bending phenomena, and data required to assess the validity of analytical model predictio were suppressed. A partial repeat of this test is necessary t to obtain these data and will consist of reconfiguration of the solar arrays to a series of off-nominal configurations and observing/recording the resulting vehicle disturbances. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3247c PI: J Decker Proposal Title: SA FEATHERING TEST II ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ J. Decker GFSC USA X ------------------------------------------------------------------------------------ 2. Scientific Justification. This test will provide data concerning the behavior of the vehicle throughout the orbit with the arrays in off-nominal configurations. The data will be used to identify differences between stick-slip and thermal bending phenomena and to assess the validity of analytical model predictions of thermally induced vehicle disturbances. This information cannot be obtained by any means other than an on- orbit test involving off-nominal SA config's. The data will be used to determine any modifications to the design of the replacement SAs which are required to minimize the SA induced disturbances. ------------------------------------------------------------------------------------ 3. Description of proposed observations. This test will be conducted with the HST in Normal Mode using gyros for attitude reference. The +V1 will be pointed toward the SEP, and the +V3 axis towards the sun. The battery Rate of Charge (ROC) safemode test must be disabled during the entire test; the SA normal Sun Angle Safemode test will be disabled during specific parts of the test by real time commands and then enabled by Stored Program Commands. All other safemode tests must remain enabled during the test. All critical data e.g format PN data, will be downlinked in realtime when possible, recorded on the ETR as a backup, and dumped to the STOCC to insure that all critical data are available for either real time or near-real time analysis. The nominal orientation of th SAs for this test is an angle of +90 degs. This test consists of series of SA positioning slews that a) place the the -V2 wing 'edge-on' to the sun; b) place the +v2 wing 'edge-on' to the sun. At least one 15 -min forward link contact is required during the time that each wing is in the 'edge-on' configuration to enable the wing to be commanded back to the nominal orientation in the event that the any problems are en- countered; these are designated as critical forward link service. Each SA slew to an edge-on configuration will be accomplished using real-time commands. Two opportunities will be provided for sending the real- time commands to accomplish these slews in order to insure that the edge-on coinfigurations are established and settled prior to a night-day transition. Each edge-on configuration will be maintained for one full orbit of PN data collections. After each test configuration, the SA wings will be slewed back to their nominal positions using stored commands. A recovery period is required between the 2 edge-on configurati to allow the battery test SOC to return to the level that prevailed at the beginning of the test. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Acquisition of the on-orbit data which is necessary both to identify differences between slip-stick and themal bending phenomena contributing to jitter, and to assess the validity of analytical model predictions of thermally induced vehicle disturbances, cannot be accomplished via any other means other than on-orbit testing w/off-nominal SA configurations. The required data are not available during normal operations, and are not acquired from any other planned test. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. HST Rate Gyro Assembly (RGA) data will be anaylzed in both realtime and frequency domains using PSDs. These results will be correlated to the SA configurations wrt to the vehicle, and to the vehicle configuration wrt the sun. This data will be compared to the predicted behavior of each array. ESA, GSFC, MOC, and LMSC-W will process and test the data and issue reports. ------------------------------------------------------------------------------------ 11. Address Information Name: J DECKER Category: PI Institution: CODE 440 Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ Name: J. DECKER Category: PI Institution: GFSC Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3247c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 SEP S.ECLIPTIC POLE RA = 90.0D +/- .1", 1990 DEC = -66.500D +/- .01" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3247c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SEP S/C POINTIN V1 CONTROL=GYRO 1 1S 1 1 SEQ 1- 10 NO GAP G CRIT OBS / 1-10 CYCLE 0 / 1-10 Comments: SLEW TO TARGET SEP WITH +V3 TO SUN, VIA SPC. ------------------------------------------------------------------------------------------------------------------------------------ 2 SEP S/C DATA V1 CONTROL=GYRO 1 30M 1 1 RT ANALYSIS FORMAT=PN REQ UPLINK Comments: DEACTIVATE SAGA. INSTALL, PCS MANEUVER GAINS, AND SA BLANKET TENSION IN "TLMDIAG" DISABLE SA /SUN ANGLE TEST, BATTER ROC TEST, AND PATCH ONNRLM TO 18DEGS VIA RTC ------------------------------------------------------------------------------------------------------------------------------------ 3 SEP S/C DATA V1 CONTROL=GYRO 1 15M 1 1 RT ANALYSIS FORMAT=PN REQ UPLINK Comments: START 25 MINS PRIOR TO EON. SLEW -V2 WING TO 0 DEGS VIA RTC. BEGIN COMCON 25 MINS PRIOR TO SHADOW ENTRY (EON). ------------------------------------------------------------------------------------------------------------------------------------ 4 SEP S/C DATA V1 CONTROL=GYRO 1 15M 1 1 AFTER 3 BY 20M+/- FORMAT=PN 0M RT ANALYSIS REQ UPLINK Comments: LAST OPPORTUNITY TO SLEW -V2 WING TO 0 DEGS. ------------------------------------------------------------------------------------------------------------------------------------ 5 SEP S/C DATA V1 CONTROL=GYRO 1 15M 1 1 RT ANALYSIS FORMAT=PN REQ UPLINK Comments: START ENTER ORBIT DAY. CONTINGENCY FORWARD LINK. ------------------------------------------------------------------------------------------------------------------------------------ 6 SEP S/C DATA V1 CONTROL=GYRO 1 15M 1 1 AFTER 5 BY 105M+/- FORMAT=PN 15M RT ANALYSIS REQ UPLINK Comments: TAPE RECORDER DUMP IN PN FORMAT. ------------------------------------------------------------------------------------------------------------------------------------ 7 SEP S/C DATA V1 CONTROL=GYRO 1 15M 1 1 RT ANALYSIS FORMAT=PN REQ UPLINK Comments: START 25 MINS PRIOR TO ENTER ORBIT NIGHT. COMMAND TO DISABLE SA SUNANGLE TEST AND TO SLEW +V2 WIND TO 0 DEGS. PERFORM DURING NEXT SUNLITE ORBIT ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3247c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 8 SEP S/C DATA V1 CONTROL=GYRO 1 15M 1 1 AFTER 7 BY 20M +/- FORMAT=PN 0M RT ANALYSIS REQ UPLINK Comments: LAST OPPORTUNITY TO SLEW SA +V2 WING TO 0 DEGS. ------------------------------------------------------------------------------------------------------------------------------------ 9 SEP S/C DATA V1 CONTROL=GYRO 1 15M 1 1 RT ANALYSIS FORMAT=PN REQ UPLINK Comments: START AT EOD. CONTACT REQ'D FOR CONTINGENCY. ------------------------------------------------------------------------------------------------------------------------------------ 10 SEP S/C DATA V1 CONTROL=GYRO 1 30M 1 1 AFTER 9 BY 105M +/ FORMAT=PN - 10M RT ANALYSIS REQ UPLINK Comments: COMMANDING TO INSTALL PCS ACQ GAINS, AND TO REACTIVATE SAGA AND PATCH ONNRLM TO 9 DEGS. DUMP TAPE RECORDER. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3247c [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations S/C ------------------------------------------------------------------------------------------------------------------------------------ Opmodes POINTING DATA ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CONTROL=GYRO FORMAT=PN ------------------------------------------------------------------------------------------------------------------------------------ Proposal for ENG ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1- 10 NO GAP; CRIT OBS / 1-10; CYCLE 0 / 1-10; RT ANALYSIS; REQ UPLINK; AFTER 3 BY 20M+/-0M; AFTER 5 BY 105M+/-15M; AFTER 7 BY 20M +/- 0M; AFTER 9 BY 105M +/- 10M; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements ------------------------------------------------------------------------------------------------------------------------------------ Target Names SEP ------------------------------------------------------------------------------------------------------------------------------------