Mars Express Bistatic Radar Experiment Operations Plan and Report 31 August 2005 Summary ======= DSN Antenna: 63 Pass: 0822 Orbit: 2091 Orbit Start Time: 2005-08-31T02:27:28 SCET HGA Pointing: Inertial Specular Condition: 2005-08-31T04:28:00 ERT Target: (89.75S, 86.72W; Rp = 3381.5 km) Incidence/Reflection Angle: 76.95 deg Slant Range: 8826 km Slew Angle: 26.03 deg Doppler (carrier, fd): 51100 Hz Doppler (echo, fr): 41388 Hz Doppler Difference (fdd): 9711 Hz Earth-Mars Distance: 9.976E10 m Experiment Set Up ================= This was the first MEX bistatic radar experiment conducted using Madrid's DSS 63. The support team at JPL included Gene Goltz, Danny Kahan, Dick Simpson, Elias Barbinis, and Don Fleischman. The last two were present for RSR/BSR training and may be used as backup in future MEX operations; they will also be participating in Cassini BSR operations, the first (a ring BSR) scheduled for 5 September. In the NOPE area were Jose Valencia (early) and Greg Hewitt (throughout). At DSS 63 were Dwight Holmes, Tommy Thompson, and Crew "Charlie." Holmes and station personnel were able to monitor LCP output from RSR1 using a "benign" command of the form BCONNECT DHOLMES 3-0666 60 rsr1a where the second and third values in the line are not important. They tried, but (for unknown reasons) were not able to connect to RSR2, so missed the stronger pair of signals. Holmes said even the ability to monitor LCP significantly increased station interest in the experiment. Performance Problems ==================== The S-RCP noise diode was enabled at the beginning of the pre-cal, meaning that there was no "ambient load only" pre-cal measurement and the system temperature at zenith could be determined only from the post-cal measurements. The X-LCP configuration appears to have changed in some unknown way when the ambient load was removed at about 05:37:45 during the post-cal. The noise levels become much lower than before, and lower than during corresponding points during the pre-cal. The post-cal estimates of Top and Tndl are then both much lower than expected. The NMC log shows nothing unusual. Assume everything is nominal until 05:37:45, then disregard the later values. The NOPE instructed the station at 00:03 not to use "time stacking" of commands. Holmes was impressed by one of the operators, who converted small sections of the briefing message procedure to macros, which could be triggered by function keys, reducing the possibility of typing errors. The X-RCP channel seems to have an unusually strong noise diode, the S-RCP diode a bit less so. All channels appeared to be very stable throughout the activity, with excellent noise figures. Three ambiguities in the briefing message procedure were identified for future improvement. One was an unnecessary repetition of commands. The other two prompted requests for clarification from the station; these can be improved with addition of a few words to the briefing message. Data Acquisition ================ The set up period began at 23:45 on day 242; these notes are written in terms of day 243, since nothing of consequence occurred during day 242. DSS 63 announced that it was ready to begin the pre-calibrations at about 00:20. RSRs were configured as in Table 1: Table 1 --------------------------------------------- RSR Channel Mode ATT FGAIN Operator dB ----- ------- ---- ---- ----- --------------- RSR1A S-LCP 1-W auto 60 Kahan RSR1B X-LCP 1-W auto 60 Kahan RSR2A S-RCP 1-W auto 65 Goltz RSR2B X-RCP 1-W auto 60 Goltz RSR subchannels (SCHAN) were defined as follows: Table 2 --------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 1 ksps 2 8 ksps 3 25 ksps Primary recording bandwidth 4 100 ksps Backup recording Table 3 lists ADC amplitude levels read from RSR displays during the experiment. Where available, signal-to-noise ratios, frequency offsets, and other measurements are also listed. Times are in UTC read from a wall clock and may not reflect actual times when configurations changed. "Steps" are as defined in the briefing message. Acronyms and abbreviations are explained after Table 3. Table 3 ------------------------------------------------------------------------------ TIME (ERT) RSR1A RSR1B RSR2A RSR2B COMMENTS 2005-08-31 S-LCP X-LCP S-RCP X-RCP ADC ADC ADC ADC (dB) (dB) (dB) (dB) ---------- ------ ------ ------ ------ --------------------------------------- End-to-End Configuration Check 00:29 DSS 63 reports Pre-Cal Step 01 complete Reset all RSR ATTEN using AUTO feature 9.0 19.5 8.5 11.5 ATTEN settings (dB) -10.0 -10.1 -10.3 -10.1 Step 01: ADC amplitudes (all to sky) (dB) 00:35 -10.1 -0.3 -10.4 -0.3 Step 02: X-band to AMB 00:37 -0.9 -0.2 -10.2 -0.2 Step 03: S-LCP to AMB 00:39 -0.9 -0.2 -0.6 -0.2 Step 04: S-RCP to AMB Ambient load temperatures: S1 = 20.56C S2 = 23.50C X1 = 15.69C Weather conditions: T = 25C H = 29% P = 930 mb Weather is dry 00:41 19.5 31.5 19.5 23.5 Reset ATTEN using AUTO; new values (dB) -9.8 -9.9 -9.9 -9.8 Step 05: ADC amplitudes (dB) 00:45 Start SCHAN=3 RSR recordings (25 kHz) 00:49 Ambient load temperatures: S1 = 20.56C S2 = 23.44C X1 = 15.62C Weather conditions: T = 25C H = 31% P = 931 mb Weather is dry 00:50 -9.7 -9.8 -9.6 -8.7 Step 06: XR ND on 00:55 -9.8 -22.2 -9.4 -14.8 Step 07: X-band to sky 01:00 -9.8 -22.1 -9.4 -21.9 Step 08: XR ND off 01:05 -9.9 -18.7 -9.4 -21.9 Step 09: XL ND on; confirm 12.5 diode 01:10 -9.7 -9.6 -9.4 -9.9 Step 10: X-band to AMB Ambient load temperatures: S1 = 20.38C S2 = 23.19C X1 = 15.44C 01:15 -9.7 -10.0 -9.3 -9.8 Step 11: XL ND off 01:20 -9.8 -22.2 -9.4 -22.0 Step 12: X-band to sky 01:25 -9.8 -22.1 -9.3 -21.9 Step 13: SR ND on (weak diode?) 01:30 -9.9 -22.1 -17.3 -21.9 Step 14: SR to sky 01:35 -9.8 -22.3 -21.3 -21.9 Step 15: SR ND off; confirm 12.5 diode 01:40 -9.3 -22.1 -21.4 -21.9 Step 16: SL ND on 01:45 -17.0 -22.0 -21.3 -22.0 Step 17: SL to sky 01:50 -20.7 -22.1 -21.4 -22.0 Step 18: SL ND off Ambient load temperatures: S1 = 20.06C S2 = 22.94C X1 = 15.31C 01:55 Nope and DSS 63 agree to leave antenna at zenith until 02:55 so we can collect noise data. DSS 63 says it will take 3 minutes to move to point. 02:30 -20.6 -22.1 -21.3 -22.0 Continue noise recording 02:52 -20.7 -22.2 -21.1 -21.8 Nearing end of noise recording Spacecraft Calibration (BCAL) 02:55 Going to point 02:57 -2500 -7200 -2500 -7200 Enter FRO's (Hz) 02:59 DSS 63 on point 03:09 -20.5 -21.6 -21.1 -20.0 Egress occultation 1356 5005 1351 4988 Carrier offset (Hz) 32 45 53 68 Carrier to noise ratio C/No (dB/Hz) 03:25 -20.5 -21.6 -21.1 -20.0 TLM off at 03:21 1265 4663 1255 4678 Carrier offsdet (Hz) 32 52 53 75 C/No (dB/Hz) Slew #1 and Mini-Cal #1 03:51 Start slew to BSR attitude 03:52 -20.5 -21.7 -21.2 -14.5 Step 01: XR ND on 03:54 Brief XR echo at -2500 Hz 03:55 -20.5 -21.7 -17.1 -21.4 Step 02: XR ND off, SR ND on Brief SR echo at -1000 Hz 03:58 -20.5 -18.5 -21.2 -21.5 Step 03: SR ND off, XL ND on 04:01 -16.6 -21.8 -21.0 -21.3 Step 04: XL ND off, SL ND on 04:03 XR echo at -3000 Hz 04:04 Step 05: SL ND off Surface Observation (BSR) 04:11 -20.5 -21.7 -21.1 -21.3 Direct signal via sidelobe (ADC, dB) 4093 1107 4092 Carrier offset frequency (Hz) 31 25 30 04:13 Start SCHAN=4 RSR recording (100 kHz) Weak, intermittent XR echoes 04:16 Persistent XR echo at -5000 Hz 04:18 Persistent SR echo 04:23 XR echo has double peak XL echo persistent 04:28 -21.2 -21.3 ADC amplitude (dB) -1589 -5600 -1546 -5610 Echo offset frequency (Hz) 17 31 25 46 Echo peak amplitude (dB/Hz) 04:38 XR echo weak, others mostly gone 04:43 End SCHAN=4 RSR recording (100 kHz) 04:54 -20.6 -21.7 -21.2 -21.2 ADC amplitudes (dB) 04:58 S/C transmitters off (S and X) Mini-Cal #2 04:58 -20.5 -21.6 -21.2 -14.7 Step 01: XR ND on 05:01 -20.5 -21.6 -17.0 -21.4 Step 02: XR ND off, SR ND on 05:04 -20.6 -18.5 -21.2 -21.4 Step 03: SR ND off, XL ND on 05:07 -16.6 -21.7 -21.2 -21.5 Step 04: XL ND off, SL ND on 05:10 -20.5 -21.7 -21.2 -21.3 Step 05: SL ND off Post-Calibration 05:15 DSS 63 starts moving to zenith 05:22 -9.6 -9.8 -9.6 -9.6 Step 01: All receivers to AMB Ambient load temperatures: S1 = 18.56C S2 = 21.69C X1 = 14.50C 05:25 -9.6 -9.9 -9.6 -8.6 Step 02: XR ND on 05:28 -9.7 -9.8 -9.1 -9.6 Step 03: XR ND off, SR ND on 05:31 -9.6 -9.5 -9.5 -9.6 Step 04: SR ND off, XL ND on 05:34 -9.3 -9.9 -9.5 -9.7 Step 05: XL ND off, SL ND on 05:37 -16.5 -23.0 -21.2 -21.8 Step 06: All to sky 05:40 -20.6 -19.7 -21.1 -21.7 Step 07: SL ND off, XL ND on 05:43 -20.5 -22.9 -17.1 -21.9 Step 08: XL ND off, SR ND on 05:46 -20.5 -23.0 -21.2 -14.6 Step 09: SR ND off, XR ND on 05:49 -20.5 -23.0 -21.2 -21.7 Step 10: XR ND off Ambient load temperatures: S1 = 18.46C S2 = 21.44C X1 = 14.25C Weather conditions: T = 20.56C H = 56.55% P = 930.64 mb Weather is partly clear 05:55 End SCHAN=5 RSR recording (25 kHz) Release station AMB = ambient load BOT = Beginning of Track CONSCAN = conical scan tracking CW = continuous wave (carrier only) EOT = End of Track FRO = frequency offset HGA = high-gain antenna LOS = loss of signal ND = noise diode No = noise power Pc = carrier power S1 = ambient load for S-RCP S2 = ambient load for S-LCP SL = S-LCP SR = S-RCP TLM = telemetry X1 = Ambient load for both X-band channels XL = X-LCP XR = X-RCP Dick Simpson original: 2005-08-31 Added Rp: 2005-11-26 Updates re anomalies found during processing: 2006-07-04