PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2001-01-25 NOTE = "MGS RST Instrument Health Report HEA1025A.TXT" END_OBJECT = TEXT END Miscellaneous ============= Note new clock conversion file under Ancillary Data (data type SCK). The following item on MGS reaction wheels was compiled from contributions received from Jesse Glance and Tom Thorpe. See Figure HEA1025A.PS1 for an apparently correlated change in USO temperature. On DOY-018, MGS redundancy management software (REDMAN) detected the X-Reaction Wheel being (unexpectedly) off and the S-Reaction Wheel and associated controls being switched on. In addition, there are indications of an event on the S/C power bus. On 2001-018 between 15:35 and 15:37 SCET, the MGS Payload Bus Current dropped to at least 0.225 Amps below expected. During this time, the PDS appears to have experienced a Warm POR (due to a postulated undervoltage threshold trip). Payload Bus Voltage (sampled at only 1/16 sec., vs. bus current sampled at 1/4 sec.) telemetry contains no samples during the timeframe for which two low-current samples were collected (beginning at 15:35:45 SCET). Spacecraft operation continues in a stable configuration using the Skew (S) reaction wheel while returning nominal science data. Wednesday morning (2001-01-24) a command was sent to the spacecraft to go to XYZ wheel configuration followed by return to SYZ after 20 seconds to keep Redman software from accummulating 20 counts (40sec) of non-nominal speeds should the X-wheel not spin up. The X-wheel did not respond. Verification of command execution was obtained and the effect of XYZ control without X-wheel spin up was obvious in the AACS measurements. No power, rpm, or temperature change occured in the subsystem engineering data. As mentioned in the last report, it is likely the X-wheel fuse is permanently open. Over the next few weeks the Project intends to proceed as follows: 1. Continue efforts to determine the source and character of the incident. 2. Review fault response to another wheel failure: revise Redman fault protection software for YZS control review thruster (RCS) control operation/wheel combination revise priorities for such instance with MER EDL support topmost, e.g fuel budgeting with occasional nadir science measurements 3. Proceed with Extended Mission Objectives using YZS-wheel spacecraft control: update constraints, software patches, fuel use/budgets and do ROTO demonstration (mid-February) 4. Consider operations approaches to minimize risk, e.g. wheel stress, fuse fatigue, current transients We have every expectation of accommplishing the Extended Mission/MER objectives and will proceed to do so as long as a viable fault response configuration exists. Dave Eckart (LMCO) reports the spacecraft fuel and mass status as follows: 29.09 Kg Hydrazine remaining 0.2146 Kg used over last 6 days. Average daily use over the last 6 days = 35.70 g/day Spacecraft Mass = 674.52 Kg (dry mass) + 5.289 Kg (Ox) + 29.09 Kg (Fuel) = 708.90 Kg (Total Mass) The change to Yaw axis unloads (high limit set to 6 Nms) has resulted in a nominal unload frequency of once every 21 hours (approximate.) Spin axis unloads are still occuring once every 7.5 hours (approximate), but they have seen an increase in number of pulses required to complete the unload. The increase can be attributed to the cross coupling of momentum between the skew and Y wheels. The increase in pulse numbers is evident in the daily fuel consumption change (approx. 20 % increase.) Engineering Data ================ Engineering Data Statistical Summary from CSV2STAT: First SCET: 2001-01-23T00:00:01.761 Last SCET: 2001-01-23T23:59:57.761 CHANNL CHANNEL TITLE DN-LO DN-HI EU-LO EU-HI EU-AVG/STDEV RECDS ------ ------------- ----- ----- --------- --------- ---------/-------- ----- F-0190 HGA_AZ_ANG 6424 13005 1.57E+00 3.18E+00 2.98E+00/1.06E-02 2113 F-0195 HGA_EL_ANG -11232 11089 -2.74E+00 2.71E+00 -8.34E-01/3.80E-02 2113 L-0034 MOT1_RANGING 0 0 4246 L-0036 MOT1_TLM_MOD 0 0 4235 L-0037 MOT1_USO_ENA 0 0 4246 L-0044 MOT2_RANGING 1 1 4246 L-0046 MOT2_TLM_MOD 0 1 4235 L-0047 MOT2_USO_ENA 1 1 4246 L-0053 RF_SW_OSC 2 2 4235 L-0060 TWTA1_FILMNT 0 0 4246 L-0061 TWTA1_HV 0 0 4240 L-0070 TWTA2_FILMNT 0 1 4240 L-0071 TWTA2_HV 0 1 4246 L-0080 USO_PWR 0 0 4246 L-0090 KaBLE_STAT 0 0 4246 L-0091 KaBLE_ENABLE 1 1 4240 L-0111 MOT1_RCV_AGC 255 255 -1.53E+02 -1.53E+02 -1.53E+02/3.94E-07 4246 L-0121 MOT2_RCV_AGC 149 255 -1.53E+02 -1.22E+02 -1.46E+02/1.78E-01 4246 L-0131 TWTA1_HLX_I 0 1 -3.84E-02 -1.85E-02 -3.83E-02/2.14E-05 4246 L-0132 TWTA1_ANOD_V 0 1 -1.00E+03 -1.00E+03 -1.00E+03/1.53E-02 529 L-0141 TWTA2_HLX_I 17 42 2.86E-01 7.85E-01 4.74E-01/2.92E-03 4246 L-0142 TWTA2_ANOD_V 61 229 -8.66E+02 -5.30E+02 -6.42E+02/6.73E+00 529 L-0200 USO_REG_V 203 205 4.06E+00 4.10E+00 4.08E+00/2.47E-04 530 L-0201 USO_OVEN_V 128 131 2.56E+00 2.62E+00 2.59E+00/4.23E-04 530 T-0302 EPC1_T 189 197 -4.65E+00 -1.15E+00 -3.09E+00/3.99E-02 529 T-0303 EPC2_T 181 192 -2.43E+00 2.11E+00 -7.61E-01/5.25E-02 529 T-0310 RF_ISOLTR1_T 229 233 -6.05E+00 -1.15E+00 -3.34E+00/9.73E-03 4235 T-0311 RF_ISOLTR2_T 225 233 -6.05E+00 3.13E+00 -1.66E+00/3.11E-02 4235 T-0312 TWT1_T 228 233 -6.05E+00 -2.48E-02 -2.83E+00/4.17E-02 533 T-0313 TWT2_T 218 234 -7.39E+00 9.37E+00 -7.89E-01/2.02E-01 533 T-0315 USO_T 140 143 2.09E+01 2.17E+01 2.11E+01/8.28E-03 529 T-0316 KA_AMP_T 215 220 7.73E+00 1.16E+01 9.83E+00/2.73E-02 531 L-0200 and L-0201 are nominal. T-0315 is still above values being seen a week ago. Open Loop Data ============== Data Collection --------------- We have transferred the following open loop data to Stanford: YYYY/DDD DSS DSP SAMP BW DSP BIT REC RECS RECS MAX START STOP RATE MODE RESN LEN MSSG SNR -------- --- -------- -------- ---- ---- ---- ---- ---- ----- ---- ----- 2001/024 45 15:40:00 15:47:00 5000 2000 2 12 1666 2101 0 48.8 2001/024 45 17:38:00 17:44:00 5000 2000 2 12 1666 1801 0 50.8 2001/024 45 19:35:00 19:42:00 5000 2000 2 12 1666 2101 0 51.0 2001/025 65 03:26:00 03:33:00 5000 2000 2 12 1666 2101 0 48.4 2001/025 65 05:24:00 05:31:00 5000 2000 2 12 1666 2101 0 49.3 2001/025 65 07:21:00 07:28:00 5000 2000 2 12 1666 2101 0 46.5 2001/025 65 09:19:00 09:26:00 5000 2000 2 12 1666 2101 0 50.0 2001/025 25 11:17:00 11:24:00 5000 2000 2 12 1666 2101 0 49.8 2001/025 25 13:15:00 13:21:00 5000 2000 2 12 1666 1801 0 50.5 2001/025 25 15:12:00 15:19:00 5000 2000 2 12 1666 2101 0 49.9 2001/025 25 17:10:00 17:17:00 5000 2000 2 12 1666 2101 0 49.9 Anomalies --------- Data from DSS 25 suffer from occasional +/-0.5 dB jumps in signal level. Only one occultation was problem-free; the last occultation had two changes, one almost on top of ingress. Occultation Start Date/Time Description ----------- ----------------- ------------------------------ 8425i 2001/025-11:17:00 -0.5 dB carrier about 75s before ING 8427i 2001/025-15:12:00 +0.5 dB carrier about 75s before ING 8428i 2001/025-17:10:00 -0.5 dB carrier about 5s before ING +0.5 dB noise about 60s after ING Analysis -------- See Figure HEA1025A.PS3 for Allan Deviation calculations surrounding solar conjunction last summer. Joe Twicken prepared the figure to assist Dave hinson in evaluating data quality during that period. Closed Loop Data ================ Data Collection --------------- We have obtained the following files from OSCAR and EPIC: Original File Name Name on SOPC -------------------------------- ------------ ODF: 01023O024_10S.SJO;1 1023024A.ODF ODF: 01024O025_10S.SJO;1 1024025A.ODF Analysis -------- Alex Konopliv has examined Doppler residuals in X-band radio tracking data acquired last summer (2000-07-14T03:16:30 to 2000-07-24T16:59:30) using the NEAR spacecraft. These are not directly applicable to MGS, but can be used to estimate relative tracking errors attributable to ground station equipment. The observations were nearly continuous over the 10 days, and all data were acquired with 34-m antennas. Results are summarized in the table below and in Figure HEA1025A.PS2. Data from SPC 60 have somewhat lower quality, but there is no obvious difference between HEF and BMG antennas. PLOT SYMBOL ANTENNA RMS(RESID) MAX(RESID) NUMPTS ------------------------------------------------------ 1 DSS 54 0.2597E-01 0.8304E-01 1784 2 DSS 34 0.1824E-01 0.7057E-01 3448 3 DSS 25 0.2034E-01 0.9955E-01 3068 4 DSS 15 0.2283E-01 0.7890E-01 795 5 DSS 45 0.2086E-01 0.8820E-01 1964 6 DSS 65 0.3275E-01 1.1230E-01 1698 Ancillary Data ============== Data Collection --------------- We have obtained the following files from the FIS: Original File Name Name on SOPC -------------------------------- ------------ AMD: amdgen.01-025.out 1023024A.AMD OPT: optg_m_010125_OD8425-8427_8682_V1 1025046A.OPT SAK: mgs_solar_array_2001-023.ck 1023023A.SAK SCK: MGS_SCLKSCET.00035.tsc TSC00035.SCK SOE: mm111b.01.tsoe 1035039B.SOE SPK: spk_m_010125_OD8425-8427_8682_V1 1025046A.SPK TCK: mgs_spice_c_kernel_2001-023.ck 1023023A.TCK We have obtained the following file from NAIF: Original File Name Name on SOPC -------------------------------- ------------ AGK: mgs_hga_ck_2001-01-15.bc 1015015A.AGK Figure Captions =============== HEA1025.PS1: MGS USO temperature (S/C engineering channel T-0315) during the time preceding and following the reaction wheel swap from X to S. USO temperature oscillates about +/-0.3 C during each orbit; the approximately +1 C change near 2.6E05 seconds past 2001-01-16T00:00:00 correlates with the reaction wheel swap, but its precise cause is unknown. HEA1025.PS2: Doppler residuals from radio tracking of NEAR during July 2000. Symbols denote DSN antenna number: 4 = DSS 15, 3 = DSS 25, 2 = DSS 34, 5 = DSS 45, 1 = DSS 54, and 6 = DSS 65. RMS residual values are about 0.033 mm/s for DSS 65, 0.026 mm/s for DSS 54, and 0.02 mm/s for the other four antennas. HEA1025A.PS3: MGS Allan Deviation calculated at 3.2 s integration times around solar conjunction in mid-2000. High Allan Deviation limits our ability to extract atmospheric profiles from occultation data." Figures ======= Plot(s) illustrate some of the points made in the text. Each plot is a PostScript file, created and printable on our SOPC. For report text file HEAydddC.TXT Figure N will be labeled HEAydddC.PSN and sent as the N+1st e-mail message of a set. We assume that you can strip off the e-mail headers and either display or print copies of the figures on a machine in your area. People who have indicated that they cannot handle these files by e-mail are not included in the e-mail distribution of figures.