Mars Express Bistatic Radar Experiment Operations Plan and Report 11 October 2009 Summary ======= DSN Antenna: 14 Pass: 2325 Orbit: 7406 Orbit Start Time: 2009-10-11T11:24:29 HGA Pointing: Specular Start Mid-Time End -------- ---------- -------- Specular Condition (ERT): 15:56 16:30 17:03 Target Latitude (deg N): -40.65 -50.50 -56.94 Longitude (deg E): 150.54 142.11 133.50 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 54.58 64.39 70.79 Slant Range (km): 5287. 8288. 10366. Slew Angle (deg): 70.84 51.22 38.42 Doppler (carrier, fd; Hz): -56226. -51019. -41731. Doppler (echo, fr; Hz): -56887. -40405. -28925. Doppler Difference (fdd; Hz): 661. -10615. -12806. Earth-Mars Distance (m): 2.001E+11 2.001E+11 2.001E+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 more than 100K. The problem began with the experiment on 2009/226. In December the problem was isolated to a bad board in the RSR. The board was replaced, and tests in January confirmed that Tsys had returned to normal levels. The S-LCP Mini-Cal #2 is compromised by a drop-out about two thirds of the way through the measurement. The post-cal transition from AMB+ND to SKY+ND may not be worth much because of noise diode drop-outs AND ambient load switching problems. 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 13:00 60 60 60 60 Set FGAIN PreCal 13:38 1 -10.8 -9.9 -24.1 -10.0 13:39 att auto -9.8 -9.9 -9.7 -10.0 Attenuator auto set 19.0 11.5 5.5 10.5 Attenuator settings (dB) 13:40 2 -9.7 -0.2 -9.6 +0.1 ADC amplitudes (dB) 13:42 3 -3.1 -0.2 -9.6 -0.0 13:44 4 -3.0 -0.1 -0.5 -0.0 13:45 att auto -10.1 -9.8 -10.1 -9.9 Attenuator reset 26.5 23.5 17.0 23.0 Attenuator settings (dB) AMB load phys temps: S1=12.00 S2=15.88 X1=10.88 Local weather: T=12.6C H=39.3 percent sky=clear 13:47 rec 3 e Begin 25 kHz recording 13:50 5 -10.2 -9.0 -10.0 -9.9 13:55 6 -10.2 -9.8 -10.0 -9.6 14:00 7 -10.2 -21.9 -10.0 -20.0 14:05 8 -10.1 -22.0 -10.0 -22.5 14:10 9 -10.1 -19.7 -10.1 -22.5 Confirmed 12.5K ND 14:15 10 -10.2 -9.6 -10.0 -9.9 AMB load phys temps: S1=11.94 S2=15.69 X1=11.00 14:20 11 -10.2 -9.8 -10.1 -9.8 14:25 12 -10.1 -22.0 -10.0 -22.5 14:30 13 -10.2 -21.9 -9.9 -22.5 14:35 14 -10.2 -22.0 -19.1 -22.4 14:40 15 -10.2 -22.0 -21.2 -22.5 Confirmed 12.5K ND 14:45 16 -9.9 -22.0 -21.3 -22.5 14:50 17 -16.3 -21.9 -21.1 -22.5 14:55 18 -17.4 -22.0 -21.2 -22.5 AMB load phys temps: S1=11.94 S2=15.69 X1=11.00 15:00 end -17.5 -22.1 -21.2 -22.4 Stop 25 kHz recording BOT 15:10 -13.4 -21.9 -21.1 -22.3 15:16 rec 3 e -13.6 -21.9 -21.2 -22.2 Resume 25 kHz recording 15:38 -15.6 -21.7 -21.3 -19.8 DSS 14 switch to Mars pointing predicts 15:40 sfro 3/SX +25K +25K +25K +25K Rcvr tuning offset MiniCal1 15:41 1 -14.1 -22.0 -21.3 -18.2 Confirmed 12.5K ND 15:44 2 -14.6 -21.9 -19.1 -20.3 15:47 3 -13.5 -19.5 -21.2 -20.3 15:50 4 -15.0 -21.8 -21.4 -20.1 15:53 5 -16.4 -21.8 -21.3 -20.3 15:56 end -17.1 -21.9 -21.3 -20.2 BSR 15:56 sfro 3/SX 0 0 0 0 Rcvr tuning offset (Hz) Begin 100 kHz recording 16:20 sfro 3/X +5K +5K X-Band rcvr offset (Hz) end BSR 17:03 sfro 3/SX +25K +25K +25K +25K End 100 kHz recording MiniCal2 17:05 1 -17.8 -21.7 -21.5 -19.8 Confirmed 12.5K ND 17:08 2 -17.8 -21.8 -19.3 -22.2 17:11 3 -17.6 -19.6 -21.2 -21.6 17:14 4 -17.2 -21.8 -21.3 -21.6 17:17 5 -18.3 -21.8 -21.3 -21.6 17:20 end -17.9 -21.7 -21.3 -21.6 17:20 sfro 3/SX 0 0 0 0 Rcvr tuning offset (Hz) DSS 14 switch to s/c pointing predicts EOT 17:25 stow -16.2 -21.7 -21.3 -21.7 PostCal 17:30 1 -10.3 -9.9 -10.3 -10.0 AMB load phys temps: S1=12.94 S2=17.50 X1=11.44 17:37 2 -10.2 -9.9 -10.3 -9.8 17:40 3 -10.3 -9.9 -9.0 -9.9 17:43 4 -10.3 -9.6 -10.3 -9.8 17:46 5 -10.1 -9.8 -10.3 -9.8 17:49 6 -18.4 -21.9 -20.6 -22.5 17:52 7 -15.0 -19.7 -21.5 -22.6 17:55 8 -15.9 -21.9 -19.4 -22.5 17:58 9 -16.5 -22.0 -21.6 -20.0 18:01 10 -14.6 -22.0 -21.5 -22.5 AMB load phys temps: S1=13.31 S2=18.00 X1=11.69 Local weather: T=19.7C H=27.8 percent sky=clear EOA 18:05 end -15.0 -22.0 -21.5 -22.5 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 X-Band 10-s Average Data: The table below summarizes the time division for capturing the echo power as the signal drifted through the 25 kHz X-Band receiving pass band. Int Times Spectra Noise Bins Carrier Echo Bins Notes Bins --- ----------------- ------- --------------- ------- ---------------- ------ A 15:56:00-16:01:00 001-030 104:270,525:916 377:382 273:389->389:521 [1] B 16:01:00-16:20:00 031-144 104:370,795:916 372:380 389:561->614:788 BC 16:20:00-16:20:10 145 172:368,795:916 165:169 431:788 [2] C 16:20:10-17:03:00 146-402 172:448,780:916 165:169 452:646->621:755 Notes: [1] Used carrier suppression to estimate echo power, as echo drifted through frequency of directly propagating signal [2] X-Band tuning offset at 16:20 S-Band 10-s Average Data: The table below summarizes the time division for capturing the echo power as the signal drifted through the 25 kHz S-Band receiving pass band. Int Times Spectra Noise Bins Carrier Echo Bins Notes Bins --- ----------------- ------- --------------- ------- ---------------- ------ A 15:56:00-16:04:00 001-048 104:412,527:916 449:454 417:480->460:523 [1] B 16:04:00-17:03:00 049-402 104:445,655:916 449:454 460:573->561:650 Notes: [1] Used carrier suppression to estimate echo power, as echo drifted through frequency of directly propagating signal S-Band 60-s Average Data: The table below summarizes the time division for capturing the echo power as the signal drifted through the 25 kHz S-Band receiving pass band. Int Times Spectra Noise Bins Carrier Echo Bins Notes Bins --- ----------------- ------- --------------- ------- ---------------- ------ A 15:56:00-16:04:00 001-008 104:412,527:916 449:454 417:480->460:525 [1] B 16:04:00-17:03:00 009-067 104:445,655:916 449:454 460:573->561:650 Notes: [1] Used carrier suppression to estimate echo power, as echo drifted through frequency of directly propagating signal Incidence angle increases from 54 to 71 deg over surface observations; slant range increases from 5287 to 10366 km. S- and X-Band echo power curves have some similarities, but X-Band Brewster angle is 60 deg and S-Band Brewster angle is more like 65 deg (but difficult to pin down since RCP and LCP have similar average values over 62-67 deg and S-LCP is very noisy, even with 60 s averaging). Inferred X-Band dielectric constant is 4 at beginning, dropping linearly to about 2.7 after 20 minutes and then staying there for the remaining 47 minutes. Mean S-Band dielectric constant starts at about 7 and drops to about 4 at the end, but with much scatter. Noise power density is very stable throughout; this might be a good example of normal surface except that S-Band dielectric constant seems high. Dick Simpson Original: 2009-12-19 Added Post Analysis Summary: 2010-01-08 Updated status of noisy S-LCP: 2011-04-29