Mars Express Bistatic Radar Experiment Operations Plan and Report 06 June 2010 Summary ======= DSN Antenna: 63 Orbit: 8230 Orbit Start Time: 2010-06-06T13:48:13 HGA Pointing: Specular Start Mid Point End -------- ---------- -------- Specular Condition (ERT): 15:04 15:37 16:11 Target Latitude (deg N): 1.97 -5.50 -16.19 Longitude (deg E): 174.07 167.08 161.16 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 32.71 37.43 44.96 Slant Range (km): 10036. 8891. 7141. Slew Angle (deg): 114.57 105.15 90.08 Doppler (carrier, fd; Hz): -24742. -32215. -39297. Doppler (echo, fr; Hz): 10754. 17125. 22525. Doppler Difference (fdd; Hz): -35496. -49340. -61822. Earth-Mars Distance (m): 2.401E+11 2.401E+11 2.401E+11 Experiment Set Up ================= This experiment was conducted using the Madrid DSS 63. Danny Kahan and Gene Goltz were in the Radio Science Support Area (RSSA) at JPL. This report is largely based on notes provided by Kahan and Goltz. Performance Problems and Notes ============================== There was a 30-minute delay in starting the pre-cal because of minor configuration problems. A microwave switch failure (DR# M-105802) at 16:42 resulted in not being able to complete the post-cal procedure for the S-LCP data; the other three channels were not affected. S-RCP levels were very low throughout. Compared with day 142, the pre-cal levels were about 5 dB low. At about 15:34, the S-RCP levels dropped another 9 dB. This was too low for the remaining activities to be accurately captured in the S-RCP sample stream. It is possible this was related to the microwave switch failure (above), which was noticed over an hour later. X-LCP and S-LCP data were recorded using the WVSR rather than the usual RSR, which was still being repaired after disk problems, which corrupted data on day 142. Data Acquisition ================ RSRs were configured as in Table 1. Table 1 ----------------------------------------------------- RSR Channel Mode ATT FGAIN Operator dB ------ ------- ---- ---- ----- ---------------------- WVSR1A S-LCP 1-W auto 60 UNK WVSR1B X-LCP 1-W auto 60 UNK RSR2A S-RCP 1-W auto 60 UNK RSR2B X-RCP 1-W auto 65 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 2010/157 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ Set-Up 11:04 FGAIN 60 60 60 65 FGAIN settings (dB) Pre-Cal 11:37 1 -4.1 -9.3 11:48 att auto -8.9 -9.4 -9.9 -9.8 ADC amplitudes (dB) 12.0 20.0 15.5 26.5 Set attenuators (dB) 11:49 2 -9.1 -1.1 -9.8 -0.1 11:41 3 -4.2 -1.2 -9.9 -0.1 11:53 "4,5" -4.2 -1.4 -0.4 -0.1 11:55 att auto -10.2 -10.0 -9.9 -3.0 ADC amplitudes (dB) 18.0 30.0 27.0 31.5 Attenuator settings (dB) Ambient load phys temps: S1=19.06 S2=22.44 X1=16.06 Local weather: T=26.1C H=19.9 percent sky=clear 11:57 6 -10.1 -10.1 -9.9 -3.2 Begin 25 kHz recording 12:02 7 -10.0 -10.2 -10.1 -3.0 12:07 8 -10.0 -19.9 -10.0 -12.6 12:12 9 -10.1 -19.7 -10.1 -14.9 12:17 10 -10.0 -18.4 -10.1 -14.8 Confirmed 12.5K ND 12:22 "11,12" -10.0 -9.8 -10.1 -3.2 Ambient load phys temps: S1=19.25 S2=22.62 X1=16.12 12:27 13 -10.1 -10.2 -10.2 -3.2 12:32 14 -10.0 -20.0 -10.1 -14.9 12:37 15 -10.0 -19.8 -10.1 -14.9 12:42 16 -10.1 -19.8 -19.7 -14.9 12:47 17 -10.1 -19.8 -21.5 -14.9 Confirm 12.5K ND 12:52 18 -9.9 -19.7 -21.7 -14.9 12:57 19 -14.4 -19.7 -21.6 -14.9 13:02 20 -14.8 -19.7 -21.7 -14.8 Ambient load phys temps: S1=19.56 S2=23.06 X1=16.19 13:07 21/end -12.8 -19.8 -21.6 -14.9 End 25 kHz recording BOT 13:13 -11.6 -19.3 -20.6 -13.8 Collect TLM until 14:22 14:22 rec 3 e -14.5 -19.3 -21.0 -12.7 Resume 25 kHz recording 14:40 -14.2 -19.5 -20.9 -13.2 DSS 63 switch to Mars pointing predicts 14:41 sfro 3/SX +8K +37K +8K +37K Rcvr tuning offsets (Hz) sfro 4/X +28K +28K MiniCal1 14:45 1 -14.5 -19.5 -20.9 -12.1 Confirm 12.5K ND 14:48 2 -13.7 -19.6 -18.8 -14.3 14:51 3 -13.9 -18.4 -20.9 -14.2 14:54 4 -13.6 -19.6 -20.9 -14.4 14:57 5 -12.9 -19.8 -20.9 -14.3 15:00 end -13.0 -19.7 -21.0 -14.4 BSR 15:04 rec 4 e -13.9 -19.5 -21.1 -14.3 Begin 100 kHz recording 15:25 sfro 3/X +46k +46k Rcvr tuning offsets (Hz) 15:47 sfro 3/X +55k +55k end BSR 16:11 rec 4 d -15.5 -19.9 -18.9 -13.4 End 100 kHz recording MiniCal2 16:14 1 -14.8 -19.6 -18.9 -11.6 Confirm 12.5K ND 16:16 2 -13.9 -19.6 -17.0 -13.5 16:18 3 -14.1 -18.4 -19.0 -13.4 16:20 4 -14.5 -19.8 -18.9 -13.5 16:22 5 -14.8 -19.6 -19.0 -13.5 16:24 end -15.6 -19.6 -18.9 -13.4 16:25 sfro 3/SX 0 0 0 0 Rcvr tuning offsets (Hz) EOT/stow -13.5 -19.6 -19.0 -13.5 Post-Cal 16:28 1 -10.3 -10.1 -8.2 -3.3 Ambient load phys temps: S1=21.12 S2=25.12 X1=16.19" 16:33 2 -10.1 -10.2 -8.6 -3.2 16:36 3 -9.8 -10.1 -8.3 -3.4 16:39 4 -10.0 -9.9 -8.5 -3.4 16:42 5 -9.7 -10.2 -8.5 -3.4 17:12 6 -14.8 -19.6 -19.8 -15.3 Microwave switch #5 failed; unable to complete S-LCP post-cal 17:14 7 -18.4 -19.5 -15.2 17:16 8 -19.8 -17.4 -15.3 17:18 9 -19.9 -19.5 -12.8 17:20 10 -19.8 -19.6 -15.2 Ambient load phys temps: S1=21.00 S2=25.12 X1=16.12 Local weather: T=27.1C H=26.3 percent sky=clear EOA 17:22 11/end -19.8 -19.6 -15.2 End 25 kHz recording AMB = ambient load BOT = Beginning of Track BW = bandwidth 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 NOP = Network Operations Plan occn = occukltation 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 Power: X-Band data were processed to power spectra with 60 second averaging (sums of 1464 individually calculated 1024-point spectra). The 67 minutes of 25 kHz data were divided into 5 time intervals -- two with split echoes (caused by receiver tuning offset changes, FRO) and three during which the echo drifted within the passband at fixed FRO. The directly propagating carrier did not appear in the 25 kHz passband. The carrier tracking window was used to find the frequency bin with maximum echo power. Int Times Spectra Noise Bins Echo Echo Bins Notes Peak --- ----------------- ------- --------------- ------- ---------------- ------ A 15:04-15:25 01-21 104:243,770:916 300:700 245:430->555:765 AB 15:25-15:26 22 104:243,770:916 300:700 245:765 [1] B 15:26-15:47 23-43 104:243,770:916 300:700 245:430->555:765 BC 15:47-15:48 44 104:243,770:916 300:700 245:765 [1] C 15:48-16:11 45-67 104:243,770:916 300:700 245:430->555:765 Notes: [1] Split echo resulting from change in X-Band receiver tuning offset S-Band Power: S-Band data were processed in the same way; but drift was less, so all the spectra could be processed using the same parameters. The echo signals were weak (or non-existent) so two different integrations were used (60 s and 360 s). The directly propagating carrier was in frequency bin 124. No S-RCP echo was detected with either integration; a weak S-LCP echo can be seen in both sets of spectra. Int Times Spectra Noise Bins Carrier Echo Bins Notes (s) Peak --- ----------------- ------- --------------- ------- ---------------- ------ 60 15:04-16:11 01-67 130:430,880:916 122:126 435:600->720:875 360 15:04-16:10 01-11 130:430,880:916 122:126 435:600->720:875 S-RCP performance was unusual during this experiment. Until about 15:33:34 the S-RCP RSR output was about 5 dB lower than normal (compare 2010/142), but Tsys was holding at about 25K. At 15:33:34 the output dropped another 9 dB and Tsys increased to about 163K. In processing, we have modeled this as a linear transition of voltage gain from 5222.978 (at 15:33:34) to 36379.235 (at 15:33:40). The recorded signal levels after 15:33:40 were 46 dB below the ADC saturation level, meaning that there was only 1-2 bit sampling. The S-RCP data after 15:33:34 are not considered to be scientifically valid. S-LCP was also anomalous during this experiment. Tsys was 72-75K throughout the calibration and tracking periods, where 25-30K is normally expected. The S-LCP data may be scientifically valid; but the 3x reduction in S-LCP sensitivity, the generally weak echoes to begin with, and the loss of S-RCP over more than half of the experiment makes the S-Band results of little value overall. Dick Simpson Original: 2010-06-29 Added Post-Analysis Summary: 2010-07-01 Remove PDS unfriendly characters: 2011-05-25