Mars Express Bistatic Radar Experiment Operations Plan and Report 06 July 2005 Summary ======= DSN Antenna: 43 Pass: 767 Orbit: 1894 Orbit Start Time: 2005-07-06T22:46:47 (ERT) HGA Pointing: Inertial Specular Condition: 2005-07-06T23:18:00 (ERT) Target: 60.85S, 74.92E (S of Hellas) Incidence/Reflection Angle: 64.92 deg Slant Range: 11550 km Slew Angle: 50.7 deg Doppler (carrier, fd): 27755 Hz Doppler (echo, fr): 11744 Doppler Difference (fdd): 16011 Earth-Mars Distance: 1.451E11 m Data Acquisition ================ This experiment was supported by DSS 43 staff at the Canberra DSN complex. The support team at JPL included Gene Goltz, Danny Kahan, and Dick Simpson. In the NOPE area were Jose Valencia and Jesse Velasco. There were some early problems establishing the voice network; Gene Goltz had these resolved by 18:55, only 10 minutes after the beginning of the setup period. The DSS 43 receiver configuration seemed somewhat unstable throughout the experiment. According to operators at DSS 43, the X-band microwave configuration, which is usually automatic, was not correctly set initially; when commands were issued to the X-band noise diode controller, they were not executed. By using "lower level" UWV commands the operators were able to force the proper configuration; but these UWV commands had to be issued repeatedly throughout the activity. In fact, the pre-cal was restarted after the first hour so that a more continuous set of measurements could be obtained. The problems were documented in DR C104458. The set up period began at 18:45. DSS 43 announced that it was ready to begin the pre-calibrations at 19:25. Because of the UWV configuration problems, the pre-calibrations were restarted at about 20:15; they then moved more-or-less smoothly to completion at 21:35. The antenna was tracking the spacecraft by 21:45 and operators reported both S- and X-band closed loop receivers in lock at 21:52. The spacecraft transmitted an unmodulated carrier toward Earth at both S- and X-band until about 22:37 (ERT), when it slewed to the BSR inertial pointing attitude. For the BSR observation an X-band frequency offset of -13 kHz moved the carrier to about +10 kHz in the ±12.5 kHz RSR bandwidth; an S-band offset of -3.5 kHz moved that carrier to about +2.5 kHz. Good X-RCP and X-LCP echoes were seen in real time displays for about 15 minutes centered on 23:18. The X-band echoes were at about -6.5 kHz and reached a maximum 30 dB/Hz in RCP and 27 dB/Hz in LCP. Convincing S-RCP echoes were seen at about -2.5 kHz, but no reliable estimates of strength were obtained in real time. No S-LCP echoes were observed in real time, but they have been identified in quick-look output at Stanford. Mini-calibrations were performed during the HGA slew periods using the noise diode sources; both mini-calibrations appear to have been successful. There was no spacecraft bistatic radar calibration (BCAL) after the experiment because of time constraints. The ground system post-calibration began at about 00:10 and was completed at 00:42. Except that the X-band noise level appeared to be significantly higher (both polarizations) than during the pre-cal, these measurements appeared to be nominal. Light rain had been reported during the pre-cal; although the sky was described only as "overcast" for the post-cal, the humidity had increased and the difference is consistent with a weather change. A better picture of the X-band noise question may emerge from the more detailed data processing which will be carried out at Stanford. Jose Valencia adapted the calibration procedure and briefing message from the version that was used at DSS 43 in April. He is planning to include more specific UWV configuration instructions in future messages. He will also change "US" commands to "UG" commands; the former do not work at DSS 43. DSS 43 also reported that the operator directive to turn CONSCAN off does not work as written in the procedure. 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 60 Goltz RSR2B X-RCP 1-W auto 65 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 2005-07-06 S-LCP X-LCP S-RCP X-RCP ADC ADC ADC ADC (dB) (dB) (dB) (dB) ---------- ------ ------ ------ ------ --------------------------------------- 18:30 Goltz seeking to establish voice net 18:55 Voice net operational Pre-Calibration 19:25 -10.0 -10.2 -10.4 -10.0 Step 1: all receivers to sky 19:27 -9.9 -0.3 -10.3 -0.2 Step 2: X-band to AMB 19:28 -0.5 -0.3 -10.4 -0.2 Step 3: S-LCP to AMB 19:29 -0.4 -0.4 -1.5 -0.2 Step 4: S-RCP to AMB 19:30 Ambient Load physical temperatures: DC01 S1=19.22C S2=20.00C X1=19.75C DC02 S1=19.19C S2=20.00C X1=19.75C 19:31 Begin RSR SCHAN=3 (25 kHz) recording -10.0 -9.6 -10.0 -9.7 Use RSR auto feature to set attenuators 19:32 Meteorological conditions: T = 8.3C H = 70.9% Sky: overcast; light rain in area 19:35 -9.9 -9.6 -10.0 -9.7 Step 5: Reconfigure closed loop receivers 19:40 DSS 43 unable to link 12.5K noise diode to X-band closed loop receiver 19:45 DSS 43 will reboot X-band receiver 19:52 DSS 43 working through some options in attempt to clear controller problem. 19:53 Problem resolved by issuing "low level" UWV command to assign ND controller to receiver; usually this happens automatically during initialization. Will resume with Pre-Cal Step 5. 19:54 -10.0 -9.6 -10.1 -9.0 Step 5: Configure closed loop receivers 19:55 -9.8 -9.7 -9.9 -8.9 Step 6: X-RCP ND on 20:01 DSS 43 reports continuing problems; X-RCP did not go back to the ambient load 20:05 DSS 43 will enter a "more permanent" correction for the low level command problem, then return to Pre-Cal Step 1 20:12 Valencia requests that operators use full commands (per briefing message) rather than short forms. DSS 43 reports that "US" commands in message must be replaced by "UG" commands in Canberra and that the CONSCAN OFF command in the briefing message does not work at all. 20:17 DSS 43 reports it is ready at Step 1. RSR operators reset attenuators using RSR "auto" feature. 20:18 -9.8 -10.2 -10.4 -10.0 Step 1: All receivers to sky 20:19 -9.9 -0.3 -10.4 -0.2 Step 2: X-band to AMB 20:20 -0.5 -0.4 -10.4 -0.2 Step 3: S-LCP to AMB 20:21 -0.4 -0.3 -0.5 -0.3 Step 4: S-RCP to AMB 20:22 DSS 43 ambient load physical temperatures DC01: S1=18.56C S2=19.56C X1=18.56C DC02: S1=18.56C S2=19.56C X1=18.56C Weather: T=8.1C H=71.7% Sky: overcast, light rain in area 20:23 RSR operators reset attenuators using "auto" feature 20:23 -10.0 -9.6 -10.2 -9.8 20:28 -10.0 -9.6 -10.2 -9.8 Step 5 successfully completed 20:30 -10.1 -9.6 -10.0 -9.0 Step 6: X-RCP ND on 20:35 -10.0 -21.2 -10.0 -15.5 Step 7: X-band to sky 20:40 -10.0 -21.1 -9.9 -21.4 Step 8: X-RCP ND off 20:41 DSS 43 unable to reset ND; attempting low level command again 20:48 -10.0 -16.4 -9.9 -21.5 Step 9: X-LCP ND on 20:50 -10.0 -9.1 -10.0 -9.9 Step 10: X-band to AMB DSS ambient load physical temperatures DC01: S1=18.25 S2=19.31 X1=18.19 DC02: S1=18.31 S2=19.31 X1=18.12 20:55 -9.9 -9.7 -9.9 -9.7 DSS 43 reports that the ND controller has been lost again; there is a crew change, and the new crew will have to re-enter the low level UWV command from time to time. 21:01 -9.9 -19.2 -10.0 -20.7 Step 12: X-band to sky 21:06 -10.1 -19.1 -9.8 -20.8 Step 13: S-RCP ND on 21:10 -9.9 -19.0 -19.3 -20.7 Step 14: S-RCP to sky 21:16 -9.9 -19.0 -21.7 -20.8 Step 15: S-RCP ND off 21:21 -9.7 -19.0 -21.5 -20.8 Step 16: S-LCP ND on 21:25 -18.5 -19.1 -21.6 -20.7 Step 17: S-LCP to sky 21:30 -21.1 -19.2 -21.7 -20.8 Step 18: S-LCP ND off DSS 43 ambient load physical temperatures s1=17.94C S2=18.81C X1=17.75C 21:35 End of Pre-Calibration Begin Tracking 21:42 -21.1 -18.8 -21.6 -19.9 ADC Amplitudes (dB) 50.24 64.28 Carrier to Noise ratio (dB/Hz) -1130 -2147 Carrier offset from spectrum center (Hz) 21:52 FRO_x = -12300 puts carrier at ~10 kHz DSS 43 reports both receivers in lock 21:53 -1190 -2364 Carrier offset from spectrum center (Hz) after resetting FRO_x=0 22:21 -1325 -2862 Carrier offset from spectrum center (Hz) 22:29 24.38 36.37 49.88 68.45 Carrier to Noise ratio (dB/Hz) -1355 -2971 -1350 -2950 Carrier offset from spectrum center (Hz) 22:30 Entered FRO_x = -12300, FRO_s = -3500 22:31 Reset FRO_x = -13000 22:32 26.18 37.22 50.13 67.75 Carrier to Noise ratio (dB/Hz) +2319 +10007 +2137 +9998 Carrier offset from spectrum center (Hz) -20.9 -16.9 -21.5 -17.2 ADC Amplitude (dB) 22:38 22.41 36.23 50.02 66.03 Carrier to Noise ratio (dB/Hz) -5164 9960 2127 9964 Carrier offset from spectrum center (Hz) -20.9 -16.6 -21.2 -17.0 ADC Amplitudes (dB) Begin Mini-Cal #1 (simultaneous with HGA SLEW #1) 22:40 -20.9 -16.5 -21.2 -14.0 Step 1: X-RCP ND on 22:43 -20.7 -16.6 -19.0 -17.3 Step 2: X-RCP ND off, S-RCP ND on 22:46 18.48 Carrier to Noise ratio (dB/Hz) +9920 Carrier offset from spectrum center (Hz) -20.7 -14.3 -21.1 -17.2 Step 3: S-RCP ND off, X-LCP ND on 22:48 Begin RSR SCHAN=4 (100 kHz) recording 22:49 21.52 Carrier to Noise ratio (dB) +9911 Carrier offset from spectrum center (Hz) -18.3 -16.5 -21.2 -17.3 Step 4: X-LCP ND off, S-LCP ND on 22:52 16.05 21.45 Carrier to Noise ratio (dB/Hz) +9902 +9900 Carrier offset from spectrum center (Hz) -20.9 -16.5 -21.1 -17.2 Step 5: S-LCP ND off 22:53 DSS 43 confirms use of 12.5K ND, MFQ=ON 23:13 Hint of X-RCP echo at offset -6 kHz 23:16 25 20 Surface echo peak SNR (dB/Hz) -6000 -6000 Surface echo frequency offset (Hz) 23:18 28 20 30 Surface echo peak SNR (dB/Hz) -6000 -2200 -6000 Surface echo frequency offset (Hz) 23:20 27 19 30 Surface echo peak SNR (dB/Hz) -5900 -2225 -5920 Surface echo frequency offset (Hz) 23:22 25 29 Surface echo peak SNR (dB/Hz) -5705 -5776 Surface echo frequency offset (Hz) 23:26 Echo no longer visible 23:47 -20.5 -16.3 -20.7 -16.6 ADC Amplitudes (dB) 23:48 End RSR SCHAN=4 (100 kHz) recording Begin Mini-Cal #2 (simultaneous with HGA SLEW #2) 23:48 -20.5 -16.4 -20.7 -13.8 Step 1: X-RCP ND on 23:51 17.0 Carrier to Noise ratio (dB/Hz) +9912 Carrier offset from spectrum center (Hz) -20.5 -16.4 -18.5 -16.8 Step 2: X-RCP ND off, S-RCP NS on 23:54 -20.4 -14.2 -20.6 -16.8 Step 3: S-RCP ND off, X-LCP ND on 23:57 -18.3 -16.2 -20.8 -16.6 Step 4: X-LCP ND off, S-LCP ND on 00:01 -20.4 -16.3 -20.6 -16.3 Step 5: S-LCP ND off Begin Post-Calibration 00:07 DSS 43 confirms EOT; will advise when ready to begin post-cal measurements 00:08 Set FRO_x = 0, FRO_s = 0. 00:12 DSS 43 ambient load physical temperatures; antenna to zenith S1=16.69C S2=17.19C X1=16.94C -10.3 -9.8 -10.1 -9.8 Step 1: All receivers to AMB 00:15 -10.2 -9.8 -9.9 -9.0 Step 2: X-RCP ND on 00:18 -10.2 -9.8 -9.8 -9.8 Step 3: X-RCP ND off, S-RCP ND on 00:21 -10.3 -9.1 -10.0 -9.8 Step 4: S-RCP ND off, X-LCP ND on 00:24 -10.0 -9.7 -10.0 -9.7 Step 5: X-LCP ND off, S-LCP ND on 00:27 -18.8 -15.5 -21.4 -15.6 Step 6: All receivers to sky 00:30 -21.3 -13.8 -21.4 -15.7 Step 7: S-LCP ND off, X-LCP ND on 00:33 -21.3 -15.6 -19.1 -15.7 Step 8: X-LCP ND off, S-RCP ND on 00:36 -21.4 -15.7 -21.5 -13.3 Step 9: S-RCP ND off, X-RCP ND on 00:39 -21.4 -15.5 -21.5 -15.9 Step 10: X-RCP ND off DSS 43 ambient load physical temps S1=16.62C S2=17.19C X1=16.88C Weather conditions: T = 9C H = 80% Sky: overcast 00:42 End RSR SCHAN=3 (25 kHz) recording 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