Mars Express Bistatic Radar Experiment Operations Plan and Report 22 August 2009 Summary ======= DSN Antenna: 14 Pass: 2275 Orbit: 7232 Orbit Start Time: 2009-08-22T11:08:03 HGA Pointing: Specular Start Center End -------- ---------- -------- Specular Condition (ERT): 12:58 13:31 14:05 Target Latitude (deg N): 19.63 36.37 52.41 Longitude (deg E): 348.11 343.67 345.93 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 79.23 77.24 73.39 Slant Range (km): 11645. 10140. 7784. Slew Angle (deg): 21.55 25.52 33.21 Doppler (carrier, fd; Hz): 19268. 31891. 47237. Doppler (echo, fr; Hz): 17602. 28620. 42979. Doppler Difference (fdd; Hz): 1666. 3271. 4257. Earth-Mars Distance (m): 2.478E+11 2.811E+11 2.811E+11 Experiment Set Up ================= This experiment was conducted using Goldstone's DSS 14. Danny Kahan and Gene Goltz were in the Radio Science Support Area (RSSA) at JPL. Dick Simpson was available by phone. This report is based on notes provided by Kahan and Goltz. Performance Problems and Notes ============================== The S-LCP data are very noisy, a problem that also affected the experiment on 2009/226. No S-Band signals were detected until MiniCal #2 (approximately 14:07). A review of the NMC log shows that the command to extend the dichroic reflector was rejected during set-up (09:30:59). It was not re-issued until just before MiniCal #2 (14:04:19). DR G109641 was issued to document the configuration error. The fact that the dichroic reflector was retracted during the pre-cal, MiniCal #1, and BSR surface observations and extended during MiniCal #2 and the post-cal means that pre-cal and MiniCal #1 measurements should be used for calibrating the X-Band data. 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 UNK RSR1B X-LCP 1-W auto 60 UNK RSR2A S-RCP 1-W auto 60 UNK RSR2B X-RCP 1-W auto 60 UNK RSR subchannels (SCHAN) were defined as follows: Table 2 ---------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 2 ksps Occultation bandwidth (not recorded for BSR) 2 8 ksps Occultation backup (not recorded for BSR) 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 2009/234 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ FGAIN 08:30 60 60 60 60 PRECAL 09:33 1 1.7 -13.1 -14.0 -13.6 09:34 att auto -7.9 -9.9 -9.8 -10.0 ADC amplitudes (dB) 20.0 12.0 6.0 10.0 Attenuator settings (dB) 09:35 2 -8.1 -0.1 -9.7 0.0 09:42 3 -12.9 -0.2 -9.7 0.1 09:44 4 -12.8 -0.1 -1.2 0.1 09:45 att auto -10.0 -9.7 -10.0 -9.8 ADC amplitudes (dB) 26.5 24.0 16.0 22.5 Attenuator settings (dB) AMB load phys temps: S1=20.50 S2=24.50 X1=16.69" Local weather: T=27.8C H=25.3 percent sky=cloudy 09:47 5 -9.9 -9.6 -10.1 -9.7 09:50 rec 3 e Begin 25 kHz recording 09:55 6 -9.9 -9.7 -10.0 -9.6 10:00 7 -9.9 -22.0 -10.1 -20.0 10:05 8 -9.9 -22.0 -10.0 -22.5 10:10 9 -9.9 -19.7 -10.0 -22.5 Confirm 12.5K ND 10:15 10 -9.9 -9.5 -10.0 -9.7 AMB load phys temps: S1=19.81 S2=24.25 X1=16.62 10:20 11 -9.9 -9.7 -10.0 -9.7 10:25 12 -9.9 -22.0 -10.0 -22.4 10:30 13 -9.9 -22.0 -9.8 -22.5 10:35 14 -9.9 -22.0 -17.1 -22.6 10:40 15 -10.0 -21.9 -18.9 -22.5 Confirm 12.5K ND 10:45 16 -9.7 -21.9 -19.0 -22.5 10:50 17 -4.4 -22.0 -18.2 -22.5 10:55 18 -5.1 -21.9 -19.5 -22.4 AMB load phys temps: S1=19.69 S2=24.12 X1=16.69 11:00 end -3.6 -21.2 -19.4 -22.5 Stop 25 kHz recording BOT 11:05 -3.2 -21.2 -16.9 -21.6 Collecting telemetry until 12:35 12:35 rec 3 e Resume 25 kHz recording No S-band 12:40 -2.3 -21.5 -18.2 -21.6 DSS 14 switch to Mars pointing predicts 12:42 sfro 3/SX +25K +25K +25K +25K Receiver offset (Hz) MINICAL1 12:42 1 -1.4 -21.6 -17.9 -19.5 Confirm 12.5K ND 12:45 2 -1.2 -21.8 -17.0 -21.8 12:48 3 -1.6 -19.7 -18.2 -21.8 12:51 4 -2.0 -21.7 -18.3 -21.9 12:54 5 -0.2 -21.6 -18.2 -22.1 12:57 end -2.1 -21.6 -18.2 -21.9 BSR 12:58 sfro 3/SX 0 0 0 0 Receiver offset (Hz) Begin 100 kHz recording No S-band END BSR 14:05 sfro 3/SX +25K +25K +25K +25K End 100 kHz recording MINICAL2 14:05 1 -13.9 -21.6 -21.0 -19.1 Confirm 12.5K ND 14:08 2 -14.4 -21.6 -19.3 -20.8 S-band signal acquired 14:11 3 -13.5 -19.4 -21.0 -20.7 14:14 4 -10.8 -21.6 -21.0 -20.8 14:17 5 -12.3 -21.5 -21.0 -20.6 14:20 end -12.4 -21.6 -21.0 -20.8 DSS 14 switch to S/C pointing predicts sfro 3/SX 0 0 0 0 Receiver offset (Hz) EOT 14:42 -12.8 -21.6 -21.0 -21.8 POST-CAL 14:44 1 -9.9 -9.7 -10.0 -9.8 AMB load phys temps: S1=18.81 S2=23.25 X1=16.12 14:50 2 -10.0 -9.8 -10.0 -9.5 14:43 3 -10.0 -9.7 -9.7 -9.8 14:56 4 -9.9 -9.4 -9.9 -9.9 14:59 5 -9.7 -9.7 -10.0 -9.7 15:03 6 -16.0 -21.6 -21.1 -22.1 15:06 7 -17.3 -19.5 -21.1 -22.1 15:09 8 -15.9 -21.5 -19.1 -21.8 15:12 9 -17.0 -21.7 -21.1 -19.8 15:15 10 -16.7 -21.8 -21.0 -22.1 AMB load phys temps: S1=18.75 S2=23.12 X1=16.12 Local weather: T=26.7C H=31.8 percent sky=cloudy" EOA 15:20 end -16.1 -21.7 -21.1 -22.2 End 25 kHz recording AMB = ambient load BOT = Beginning of Track CNR = Carrier to noise ratio CONSCAN = conical scan tracking CW = continuous wave (carrier only) EOA = End of activity 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 Post Analysis Summary There is no evidence that the X-Band data were seriously compromised by the dichroic reflector error. There is, however, a large transient at about 14:04:20 in both X-Band channels, which probably occurred when the dichroic reflector moved into place. The X-Band noise powers reached a broad minimum during the middle of the surface observations, perhaps resulting from a brief clearing in the weather (operators reported 'cloudy' during both the pre-cal and post-cal). Estimating Tsys during the BSR observations from the pre- and post- MiniCals may give numbers that are somewhat high on both channels. The pre- and post- Top numbers are very close to those obtained on 2009/226, however; so the 'static' performance of the system was as expected. The S-Band data have not been processed or calibrated. Since the S-Band feed was not looking at the sky during most of the observation (until the dichroic reflector was moved into place), there was little science value in carrying out the work. The X-Band cross-spectrum phase indicates that there is coupling between X- RCP and X-LCP. This is the first such observation since 2006. The X-Band signals were strong at the beginning of the experiment, weakening slowly despite decreasing slant range. The echo width is beam-limited so only qualitative estimates of rms surface slopes are possible. The surface south of 38N has several smooth spots, the most prominent being 33-37N. North of 38N the surface seems to be homogeneous and rougher. The dielectric constant is about 4.5 south of 28N, then decreases approximately linearly with latitude to 3.0 at the end of the track (52N). Dick Simpson Original: 2009-11-03 Added Post-Analysis Summary: 2009-11-30 Added information about DR G109641: 2010-01-20