Mars Express Bistatic Radar Experiment Operations Plan and Report 17 September 2009 Summary ======= DSN Antenna: 14 Pass: 2301 Orbit: 7322 Orbit Start Time: 2009-09-17T08:11:21 HGA Pointing: Specular Start Max North End -------- ---------- -------- Specular Condition (ERT): 13:06 13:26 13:46 Target Latitude (deg N): -57.80 -61.52 -63.44 Longitude (deg E): 313.67 299.41 284.95 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 66.67 70.98 74.18 Slant Range (km): 7581. 9181. 10354. Slew Angle (deg): 46.66 38.04 31.64 Doppler (carrier, fd; Hz): -54072. -46795. -40069. Doppler (echo, fr; Hz): -45473. -36692. -30072. Doppler Difference (fdd; Hz): -8598. -10103. -9997. Earth-Mars Distance (m): 2.248E+11 2.248E+11 2.248E+11 Experiment Set Up ================= This experiment was conducted using the Goldstone 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 ============================== S-LCP data are very noisy; Top was 112K. The problem began with the experiment on 2009/226. In December the problem was traced to a bad board in the RSR. It was replaced, and tests in January confirmed that Tsys had returned to normal values. Observations ended at 13:46 when the spacecraft transmitter was turned off. The spacecraft sequence was tight and ESA planners decided not to give the normal 65 minutes to bistatic radar. The DSN Keyword File was ambiguous, and it was only after the experiment had been completed that the reasoning was reconstructed. Data Acquisition ================ RSRs were configured as in Table 1. Table 1 ---------------------------------------------------- RSR Channel Mode ATT FGAIN Operator dB ----- ------- ---- ---- ----- ---------------------- RSR3A S-LCP 1-W auto 60 UNK RSR3B 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 2009/260 RSR3A RSR3B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ FGAIN 10:00 60 60 60 60 Set FGAIN PreCal 10:45 1 -0.9 -10.9 -14.6 -9.0 10:46 att auto -10.0 -9.8 -10.0 -10.3 Initialize attenuators 20.5 12.0 5.0 13.0 Attenuator settings (dB) 10:47 2 -9.9 -0.1 -10.0 -1.3 ADC amplitudes (dB) 10:49 3 -4.0 -0.1 -10.0 -1.3 10:50 4 -4.0 -0.1 -0.7 -1.3 10:51 att auto -9.8 -9.7 -9.8 -10.0 Reset attenuators 26.5 24.0 16.0 23.0 Attenuator levels (dB) AMB load phys temps: S1=16.62 S2=21.94 X1=14.81 Local weather: T=20.5C H=28.0 percent sky=clear 10:54 rec 3 e Begin 25 kHz recording 10:54 5 -9.8 -9.6 -9.9 -10.2 11:00 6 -9.8 -9.7 -9.8 -10.0 11:05 7 -9.9 -21.8 -9.9 -20.3 11:10 8 -9.9 -21.8 -9.8 -22.8 11:15 9 -9.9 -19.6 -9.9 -22.8 Confirmed 12.5K ND 11:20 10 -9.9 -9.5 -9.8 -10.3 AMB load phys temps: S1=16.44 S2=21.81 X1=14.75 11:25 11 -9.8 -9.6 -9.8 -10.2 11:30 12 -9.7 -21.8 -9.8 -22.8 11:35 13 -9.9 -21.8 -9.7 -22.8 11:40 14 -9.8 -21.8 -19.0 -22.8 11:45 15 -9.8 -21.8 -20.9 -22.8 Confirmed 12.5K ND 11:50 16 -9.7 -21.9 -20.9 -22.8 11:55 17 -16.5/-15.3 -21.7 -20.9 -22.8 12:00 18 -16.1 -21.8 -20.8 -22.6 AMB load phys temps: S1=16.38 S2=21.38 X1=14.56 12:05 end -16.3 -21.8 -20.8 -22.6 End 25 kHz recording BOT 12:20 -10.9 -21.7 -20.8 -20.7 Collecting TLM to 12:46 12:46 rec 3 e Resume 25 kHz recording 12:48 -21.8 -20.8 -20.7 DSS 14 switch to Mars pointing predicts 12:50 sfro 3/SX +25K +25K +25K +25K Rcvr tuning offset (Hz) MiniCal1 12:51 1 -9.6 -21.6 -20.9 -19.0 Confirmed 12.5K ND 12:54 2 -12.1 -21.7 -18.9 -20.8 12:57 3 -11.1 -19.5 -20.9 -20.9 13:00 4 -11.7 -21.6 -21.0 -20.8 13:03 5 -11.7 -21.6 -21.0 -20.8 13:06 end -13.3 -21.7 -21.0 -20.7 BSR 13:06 sfro 3/SX 0 +7K 0 +7K Rcvr tuning offset (Hz) Begin 100 kHz recording end BSR 14:10 sfro 3/SX 0 0 0 0 Rcvr tuning offset (Hz) End 100 kHz recording 14:15 EOT/stow -11.8 -21.8 -21.0 -21.0 PostCal 14:16 1 -9.8 -9.7 -9.7 -10.2 AMB load phys temps: S1=15.81 S2=20.56 X1=13.56 14:20 2 -9.9 -9.7 -9.8 -10.0 14:23 3 -9.8 -9.7 -9.5 -10.2 14:26 4 -9.8 -9.5 -9.8 -10.3 14:29 5 -9.6 -9.7 -9.8 -10.3 14:32 6 -12.1 -21.8 -20.9 -22.8 14:35 7 -15.9 -19.6 -21.0 -22.7 14:38 8 -16.9 -21.8 -18.9 -22.7 14:41 9 -16.8 -21.8 -20.9 -20.4 14:44 10 -16.8 -21.8 -20.9 -22.9 AMB load phys temps: S1=15.88 S2=20.56 X1=13.56 Local weather: T=20.2C H=32.0 percent sky=clear EOA 14:47 end -16.8 -21.8 -20.9 -22.8 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 s/c = spacecraft 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 No FROs were required and the X-Band echo drifted leisurely from about 11 kHz to 13 kHz above the direct signal over the 40 minutes of surface observations. Incidence angles increased from 67 to 74 deg. X-Band dielectric constant was well-confined to the 2.3-2.7 range. S-Band echoes were weak, but S-RCP was unambiguous; S-LCP was very noisy. Inferred S-Band dielectric constants were 2-8 over the first half, then became generally unreliable because S-LCP was near zero. Dick Simpson Original: 2009-12-06 Added Post Analysis Summary: 2010-01-08 Updated S-LCP noise status: 2011-04-28