Mars Express Bistatic Radar Experiment Operations Plan and Report 23 March 2008 Summary ======= DSN Antenna: 14 Pass: 1758 Orbit: 5423 Orbit Start Time: 2008-03-22T23:33:46 HGA Pointing: Specular Start Center End -------- ---------- -------- Specular Condition (ERT): 02:10:00 02:40:00 03:10:00 Target Latitude (deg N): 7.72 41.99 49.27 Longitude (deg E): 133.10 128.44 -124.81 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 70.55 71.24 59.55 Slant Range (km): 6461. 3487. 594. Slew Angle (deg): 38.93 37.57 60.97 Doppler (carrier, fd; Hz): 25944. 44467. 38256. Doppler (echo, fr; Hz): 38109. 54357. 30811. Doppler Difference (fdd; Hz): -12166. -9891. 7445. Earth-Mars Distance (m): 1.870E+11 1.870E+11 1.870E+11 Experiment Set Up ================= This experiment was conducted using Goldstone's DSS 14. Gene Goltz, Danny Kahan, and Dick Simpson were in the Radio Science Support Area (RSSA) at JPL; Kahan operated the RSR's while Goltz handled communications. Jesse Velasco was in the NOPE area. Performance Problems and Notes ============================== During the initial configuration check, the S-LCP noise power rose only 5.3 dB when the ambient load was connected (pre-cal Step-03); an increase of about 10 dB is expected. DSS 14 confirmed that the front end was LNA-2. Jesse Velasco checked maintenance status and reported nothing. The poor performance of LNA-2 was confirmed as the pre-cal progressed. Velasco planned to notify maintenance personnel. Kahan noticed a signal at exactly 8.42 GHz in the X-Band 100 kHz spectra at about 00:30 during the pre-cal. After discussions within the group in the RSSA, Danny reported the tone to Velasco at 01:10, who reported it to DSS 14 at 01:11. The DSS 14 operator said there had been GSSR activity earlier. At 01:12 the spur disappeared. At 01:15 DSS 14 reported that no GSSR tones were on but that an ENABLE switch had been set incorrectly. He had changed the switch setting, which explains our observation that the tone disappeared at 01:12. There were no further problems with spurious signals. DSS 14 switched to planetary pointing before MINICAL-1 and returned to spacecraft pointing after completion of MINICAL-2. Echoes were visible in all four channels before SLEW 1 had been completed. They decreased in amplitude as the experiment progressed (and the spacecraft approached periapsis); but they were visible in all four channels throughout the hour. The DSS 14 azimuth brake engaged at 02:10:13 and the antenna was off point until 02:12:24. During that time all echoes were lost. DR G108446 was opened. The azimuth brake engaged again at 02:57:56 and was released, causing loss of about a minute of data. The brake engaged a third time at 03:09:58, at the end of the surface observations. The DSS 14 operator said there were about 10 more incidents until Radio Science requested at about 03:18 that the brake be ignored so that MINICAL-2 could be completed. Normal pointing resumed at 03:30:30. The azimuth brake problem has apparently occurred during other supports recently; the DSS 14 operator indicated that it is most common at certain azimuth-elevation angles. Data Acquisition ================ 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 Kahan RSR2B X-RCP 1-W auto 65 Kahan RSR subchannels (SCHAN) were defined as follows: Table 2 ---------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 2 ksps backup (not recorded) 2 8 ksps backup (not recorded) 3 25 ksps Primary recording bandwidth 4 100 ksps Backup recording Table 3 lists ADC amplitude levels read from RSR displays during the experiment. Times are in UTC and should be considered approximate. "Steps" are as defined in the briefing message. RSR ATT settings are in units proportional to dB. Acronyms and abbreviations are explained after Table 3. Table 3 ----------------------------------------------------------------------------- Activity Time Step # S-LCP X-LCP S-RCP X-RCP Notes / Comments RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ 2008/083 -------- Pre-Cal 00:07 1 -10.0 -10.0 -10.3 -10.0 All to sky (dB) 13.5 13.0 3.0 11.0 ATT settings 00:09 2 -10.0 -0.5 -10.3 -0.4 X-Band to AMB 00:10 3 -4.7 -0.7 -10.2 -0.4 S-LCP to AMB 00:15 4 -4.8 -0.6 -0.6 -0.4 S-RCP to AMB AMB load physical temps: S1=15.94 S2=21.38 X1=13.81 Weather conditions: T=67F H=12 percent sky = clear, calm 00:18 -10.2 -9.7 -9.8 -9.8 ADC amp after AUTO reset 19.0 24.0 14.0 22.5 ATT settings 00:19:59 5 Begin 25 kHz recording 00:23 6 -10.1 -9.8 -9.7 -9.6 X-RCP ND ON 00:26 7 -10.3 -20.6 -9.7 -19.4 X-Band to sky 00:29 8 -10.2 -20.7 -9.8 -21.3 X-RCP ND OFF 00:32 9 -10.2 -18.8 -9.8 -21.2 XL ND ON Confirmed ND = 12.5K 47.3 47.3 Spur at 8.42 GHz (dB/Hz) 00:35 10 -10.2 -9.5 -9.5 -9.9 X-Band to AMB AMB physical temps: S1=15.88 S2=21.31 X1=13.81 X-Band spur gone 00:38 11 -10.2 -9.6 -9.8 -9.8 X-LCP ND OFF 00:41 12 -10.2 -20.8 -9.7 -21.2 X-Band to sky X-Band spur returns 00:44 13 -10.1 -20.6 -9.5 -21.2 S-RCP ND ON 00:47 14 -10.3 -20.7 -19.3 -21.3 S-RCP to sky 00:50 15 -10.2 -20.6 -21.2 -21.1 S-RCP ND OFF 00:53 16 -10.0 -20.7 -21.1 -21.2 S-LCP ND ON 00:56 17 -15.4 -20.7 -21.1 -21.2 S-LCP to sky 00:59 18 -15.0 -20.7 -21.1 -21.2 S-LCP ND OFF AMB physical temps: S1=15.81 S2=21.12 X1=13.81 01:05 Stop recording DSS 14 moving to point BOT 01:10 -13.0 -21.7 -21.2 -19.5 DSS 14 on point 01:12 Spur gone 01:21 -14.1 -21.6 -21.3 -19.5 ADC amplitude (dB) 21.0 40.5 48.6 71.0 Carrier (dB/Hz) -1387 -3086 -1387 -3092 Carrier offset (Hz) BCAL 1 01:22:59 Resume 25 kHz recording SLEW 1 01:39 Begin slew 01:44 12.5 35.3 39.8 46.9 Carrier (dB/Hz) 01:46 DSS planetary pointing 01:49 -15.3 -21.7 -21.2 -20.0 ADC amplitude (ADC) MINICAL1 01:50 1 -13.0 -21.8 -21.3 -18.3 XR ND ON; conf ND=12.5K 01:52 19.5 34.1 17.3 34.2 Carrier (dB/Hz) 01:53 2 -16.1 -21.7 -19.3 -20.0 XR ND OFF; SR ND ON 01:56 3 -16.8 -19.6 -21.2 -20.0 SR ND OFF; XL ND ON 01:59 4 -14.9 -21.5 -21.2 -20.0 XL ND OFF; SL ND ON 02:02 5 -16.4 -21.8 -21.3 -20.0 SL ND OFF BSR: 02:05 36.0 38.0 Echo visible (dB/Hz) 02:06 3000 3000 FRO_X (SCHAN 3) 02:08 Begin 100 kHz recording End SLEW 1 02:09 22.0 33.9 24.1 39.1 Echo (dB/Hz) 1790 5698 1845 5906 Echo offset (Hz) 02:10:13 DSS 14 AZ brake engaged 02:12:24 On point (DR G108446) 02:34 21.8 23.7 Carrier (dB/Hz) -6435 -6429 Carrier offset (Hz) 3500 Echo offset (Hz) 02:39 -15.2 -21.8 -21.2 -19.7 ADC amplitude (dB) 02:50 2500 Echo offset (Hz) 02:57:36 AZ brake set; sigs lost 02:58:14 DSS 14 back on point 03:04 -2500 Echo offset (Hz) 03:04 -6400 Carrier offset (Hz) 03:06 -7000 Echo offset (Hz) 03:07 -5000 -5000 FRO_X (SCHAN 3) 03:09 -2500 -2500 -2500 -2500 Echo offset (Hz) 03:09:58 AZ brake set again; released, but repeated until about 03:18 when it was left braked SLEW 2 03:10 End 100 kHz recording Begin Slew back to Earth 03:12 50000 50000 50000 50000 FRO_X = FRO_S (SCHAN 3) 03:14 -15.2 -21.7 -21.2 -22.3 ADC amplitude (dB) MINICAL2 03:15 1 -18.8 -21.7 -21.2 -19.6 XR ND ON 03:18 2 -13.6 -21.6 -19.3 -22.1 XR ND OFF; SR ND ON 03:20 End SLEW 2 03:21 3 -13.9 -19.5 -21.3 -22.2 SR ND OFF; XL ND ON 03:24 4 -15.0 -21.7 -21.2 -22.2 XL ND OFF; SL ND ON 03:27 5 -14.8 -21.7 -21.2 -22.1 SL ND OFF BCAL 2 03:30 Returning to spacecraft pointing; AZ brake off 0 0 0 0 FRO_X = FRO_S = 0 03:30:30 Back on point 03:32 16.3 39.5 48.6 71.1 Carrier (dB/Hz) -1408 -3169 -1409 -3167 Carrier offset (Hz) 03:50 Early EOT POSTCAL: 04:01 1 -10.0 -9.4 -9.6 -9.5 All to AMB AMB phys temps: S1=14.31 S2=19.00 X1=12.31 04:02 2 -10.1 -9.5 -9.6 -9.3 XR ND ON 04:05 3 -10.1 -9.5 -9.4 -9.5 XR ND OFF; SR ND ON 04:08 4 -10.2 -9.4 -9.6 -9.6 SR ND OFF; XL ND ON 04:11 5 -10.0 -9.4 -9.6 -9.5 XL ND OFF; SL ND ON 04:14 6 -16.4 -21.7 -21.2 -22.3 All to sky 04:17 7 -18.2 -19.5 -21.2 -22.2 SL ND OFF; XL ND ON 04:20 8 -17.2 -21.7 -19.1 -22.1 XL ND OFF; SR ND ON 04:23 9 -16.5 -21.7 -21.1 -19.6 SR ND OFF; XR ND ON 04:26 10 -17.1 -21.7 -21.1 -22.2 XR ND OFF AMB physical temps: S1=14.12 S2=18.56 X1=12.19 Weather conditions: T=60F H=13 percent sky=clear, calm EOA 04:30 Stop 25 kHz recording AMB = ambient load BOT = Beginning of Track CNR = Carrier to noise ratio 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 rcvr = receiver S1 = ambient load for S-RCP S2 = ambient load for S-LCP SL = S-LCP SNR = Signal to noise ratio SR = S-RCP TLM = telemetry X1 = Ambient load for both X-band channels XL = X-LCP XR = X-RCP Dick Simpson Original: 2008-03-23