Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2911c Report Date: 09-May-96:17:34 Version: ********** Check-in Date: ********** 1.Proposal Title: EPHEMERIS TABLE LOAD UPLINK ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID OPERATIONS SV/MSC 15 Long Term yrs Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Art Bradley HSTP-G USA ------------------------------------------------------------------------------------ 7. Abstract Periodic S-band single access (SSA) forward link service to the S/C is desired for updating the vehicle ephemeris coordinates. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0.25 par: 0 10. Num targs pri: 0 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2911c PI: Art Bradley Proposal Title: EPHEMERIS TABLE LOAD UPLINK ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Art Bradley STP-G USA ------------------------------------------------------------------------------------ 2. Scientific Justification. The ephemeris clock in the DF-224 flight computer rolls over every 11.5 days. Furthermore the accuracy of the ephemeris fit degrades in time, which will impact the S/C pointing. ------------------------------------------------------------------------------------ 3. Description of proposed observations. S-band single access (SSA) forward link service to the S/C will be scheduled every two days. A contact time of 10 minutes should be sufficient to load and dump the vehicle ephemeris coefficients before enabling their usage in the flight computer. One back-up contact time should also be scheduled in case the primary contact time is unavailable. The required contact time must be after a guide star acquisition termination and before the next guide star acquisition. Loading the ephemeris coefficients during this interval will ensure that the planned guide star reacquisitions and acquisitions will not be distrubed. The update cannot be done while actively guiding using the FGSs or FHSTs. It cannot be done while in gyro mode but waiting for a re-acquisition because it can affect the parallax computations. The update must be made while guiding on gyros with no need to maintain accurate attitude reference. The SMS COMCON request should contain an appropriate text message which indicates the COMCON is for loading vehicle ephemeris coefficients via the PSTOL PROC LOADEPHM. The GSFC Flight Dynamics Facility will provide predicted ephemeris data to PASS which will fit a set of coefficients to the data and establish a PORTS accessible table. The Mission Operations Contractor will execute the PORTS PSTOL LOADEPHM to load the coefficients into the DF-224 flight computer. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. A 10 minute contact time with the S/C should be sufficient to load and dump the coefficients before enabling their usage in the DF-224 flight computer. Loading new ephemeris coefficients at 2-day intervals should keep the in-track and cross- track errors within 60km. If the new ephemeris coefficients result in an error which exceeds 120km, then the vehicle would have to be reconfigured, which would impact science operations. Changes in ephemeris coefficients which result in changes greater than 120km requires HST to be in a flight software "drift mode" which will substantially impact routine operations ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Real time contacts will be required. The communications contact will be defined in the SMS as (U) for uplink and the requested rate is 1kbit. ------------------------------------------------------------------------------------ 11. Address Information Name: ART BRADLEY Category: PI Institution: HSTP-G Address: City: State: Zip Code: Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2911c [ 3] ------------------------------------------------------------------------------------------------------------------------------------ 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 DARK S/C DATA NONE CONTROL=GYRO 1 10M 1 REPEAT 1-2 EVERY 48H +/- 12H FOR 25 MORE TIMES COND IF A / 1-2 REQUIRES UPLINK Comments: EPHEMERIS TABLE LOAD UPLINK. RT ANALYSIS MOC PSTOL "LOADEPHM". CYCLE 0/ 1-6 ------------------------------------------------------------------------------------------------------------------------------------ 2 DARK S/C DATA NONE CONTROL=GYRO 1 10M 1 AFTER 1 BY 4H +/- 3H REQUIRES UPLINK RT ANALYSIS Comments: EPHEMERIS TABLE LOAD UPLINK. MOC PSTOL "LOADEPHM". ------------------------------------------------------------------------------------------------------------------------------------ 3 DARK S/C DATA NONE CONTROL=GYRO 1 10M 1 REPEAT 3-4 EVERY 48H +/- 12H FOR 25 MORE TIMES COND IF B / 3-4 RT ANALYSIS REQUIRES UPLINK Comments: EPHEMERIS TABLE LOAD UPLINK. MOC PSTOL "LOADEPHM". ------------------------------------------------------------------------------------------------------------------------------------ 4 DARK S/C DATA NONE CONTROL=GYRO 1 10M 1 AFTER 3 BY 4H +/- 3H REQUIRES UPLINK RT ANALYSIS Comments: EPHEMERIS TABLE LOAD UPLINK. MOC PSTOL "LOADEPHM". ------------------------------------------------------------------------------------------------------------------------------------ 5 DARK S/C DATA NONE CONTROL=GYRO 1 10M 1 REPEAT 5-6 EVERY 48H +/- 12H FOR 25 MORE TIMES REQUIRES UPLINK RT ANALYSIS Comments: EPHEMERIS TABLE LOAD UPLINK. MOC PSTOL "LOADEPHM". ------------------------------------------------------------------------------------------------------------------------------------ 6 DARK S/C DATA NONE CONTROL=GYRO 1 10M 1 AFTER 5 BY 4H +/- 3H REQUIRES UPLINK RT ANALYSIS Comments: EPHEMERIS TABLE LOAD UPLINK. MOC PSTOL "LOADEPHM". ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2911c [ 4] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations S/C ------------------------------------------------------------------------------------------------------------------------------------ Opmodes DATA ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CONTROL=GYRO ------------------------------------------------------------------------------------------------------------------------------------ Proposal for SV/MSC ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 0.25 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category OPERATIONS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements REPEAT 1-2 EVERY 48H +/- 12H FOR 25 MORE TIMES; COND IF A / 1-2; REQUIRES UPLINK; RT ANALYSIS; CYCLE 0/ 1-6; AFTER 1 BY 4H +/- 3H; REPEAT 3-4 EVERY 48H +/- 12H FOR 25 MORE TIMES; COND IF B / 3-4; AFTER 3 BY 4H +/- 3H; REPEAT 5-6 EVERY 48H +/- 12H FOR 25 MORE TIMES; AFTER 5 BY 4H +/- 3H; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements ------------------------------------------------------------------------------------------------------------------------------------ Target Names ------------------------------------------------------------------------------------------------------------------------------------