Mars Express Bistatic Radar Experiment Operations Plan and Report 18 October 2009 Summary ======= DSN Antenna: 14 Pass: 2332 Orbit: 7430 Orbit Start Time: 2009-10-18T08:54:34 HGA Pointing: Specular Start Max North End -------- ---------- -------- Specular Condition (ERT): 11:33 12:03 12:25 Target Latitude (deg N): 78.00 87.67 63.74 Longitude (deg E): 101.46 177.39 258.28 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 87.03 75.18 49.00 Slant Range (km): 7329. 3660. 732. Slew Angle (deg): 5.95 29.64 81.99 Doppler (carrier, fd; Hz): 59661. 90519. 85236. Doppler (echo, fr; Hz): 56449. 81693. 89676. Doppler Difference (fdd; Hz): 3212. 8826. -4440. Earth-Mars Distance (m): 1.925E+11 1.925E+11 1.925E+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. No explanation had been offered by mid-December. In the final two minutes (12:23-12:25) the spacecraft may have stopped transmitting (at least at S-Band) and/or the HGA may have stopped tracking the specular point. 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 60 60 60 60 Set FGAIN PreCal 1 -11.2 -9.7 -9.9 -9.8 att auto -10.1 -10.1 -10.1 -9.8 ADC amplitudes (dB) 18.5 11.5 5.0 10.5 Attenuator settings (dB) 09:31 2 -10.1 -0.3 -10.1 +0.2 09:32 3 -3.0 -0.2 -9.9 +0.2 09:36 4 -2.9 -0.3 -0.6 0.1 att auto -9.9 -10.2 -9.9 -9.7 AMB load phys temps: S1=15.88 S2=20.50 X1=13.50 26.0 23.5 16.0 22.5 Local weather: T=19.5C H=22.1 percent sky=clear 09:39 rec 3 e -10.0 -10.1 -9.7 -9.6 Begin 25 kHz recording 09:40 5 -10.0 -10.1 -9.9 -9.7 09:45 6 -10.1 -10.1 -9.8 -9.4 09:50 7 -9.9 -22.3 -9.7 -19.9 09:55 8 -9.9 -22.3 -9.8 -22.3 10:00 9 -9.9 -19.9 -9.7 -22.4 Confirmed 12.5K ND 10:05 10 -10.0 -9.9 -9.8 -9.7 AMB load phys temps: S1=15.81 S2=20.31 X1=13.38 10:10 11 -9.9 -10.2 -9.8 -9.5 10:15 12 -10.0 -22.3 -9.7 -22.2 10:20 13 -10.0 -22.3 -9.6 -22.4 10:29 14 -10.0 -22.3 -19.0 -22.4 10:34 15 -9.9 -22.3 -21.0 -22.3 Confirmed 12.5K ND 10:39 16 -9.8 -22.2 -20.9 -22.3 10:44 17 -18.3 -22.3 -21.0 -22.3 10:49 18 -17.5 -22.2 -21.0 -22.1 AMB load phys temps: S1=15.69 S2=20.06 X1=13.38 10:55 end Stop 25 kHz recording BOT 11:15 -10.0 -21.9 -20.7 -19.6 DSS 14 switch to Mars pointing predicts 11:15 sfro 3/SX +25K +25K +25K +25K Rcvr tuning offset (Hz) 11:16 rec 3 e Resume 25 kHz recording MiniCal1 11:18 1 -12.0 -22.0 -20.8 -18.2 Confirmed 12.5K ND 11:21 2 -10.1 -22.0 -18.9 -19.7 11:24 3 -10.6 -19.7 -18.9 -19.3 Operator reports SR noise diode still ON 11:27 4 -9.6 -22.0 -18.9 -21.4 11:31 5 -10.4 -22.0 -19.0 -21.9 Operator reports SR ND off @ 11:26:29 11:34 end BSR 11:33 sfro 3/SX 0 -5K 0 -5K Rcvr tuning offset (Hz) Begin 100 kHz recording end BSR 12:25 sfro 3/SX +25K +25K +25K +25K End 100 kHz recording MiniCal2 12:25 1 -9.4 -22.1 -18.9 -18.3 Confirmed 12.5K ND 12:28 2 -13.6 -22.1 -19.0 -19.7 12:31 3 -11.8 -19.9 -21.0 -19.9 12:34 4 -9.9 -22.0 -20.9 -19.8 12:37 5 -11.0 -22.1 -20.9 -19.8 12:40 end -11.3 -22.1 -20.9 -19.9 DSS 14 switch to s/c pointing predicts EOT 12:41 sfro 3/SX 0 0 0 0 Rcvr tuning offset (Hz) PostCal 12:59 Zenith -16.3 -22.3 -20.9 -22.3 13:01 1 -10.0 -10.1 -9.7 -9.7 AMB load phys temps: S1=15.19 S2=19.56 X1=13.06 13:04 2 -9.8 -10.0 -9.6 -9.5 13:07 3 -10.0 -10.0 -9.6 -9.7 13:10 4 -9.8 -9.9 -9.7 -9.6 13:13 5 -9.7 -10.1 -9.7 -9.6 13:16 6 -15.6 -22.2 -20.9 -22.3 13:19 7 -16.0 -19.8 -20.8 -22.3 13:22 8 -16.2 -22.2 -18.8 -19.7 13:25 9 -16.2 -22.3 -20.9 -19.7 AMB load phys temps: S1=15.12 S2=19.50 X1=13.00 13:28 10 -16.3 -22.2 -20.8 -22.2 Local weather: T=19.2C H=29.1 percent sky=clear EOA 13:32 end 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 11:33:00-11:53:00 001-120 104:159,614:916 588:605 420:500->161:317 B 11:53:00-12:07:00 121-204 340:570,601:916 580:591 135:335 C 12:07:00-12:15:00 205-252 104:159,601:916 578:584 160:355->320:575 D 12:15:00-12:25:00 253-312 104:320 577:582 320:595->605:920 [1] Notes: [1] Used carrier suppression to estimate echo power, as echo drifted through frequency of directly propagating signal 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 11:33:00-12:15:00 001-252 104:307,464:916 452:460 311:449 B 12:15:00-12:25:00 253-312 104:355,635:916 452:460 358:469->433:629 [1] 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 11:33:00-12:15:00 001-042 104:307,464:916 452:467 311:449 B 12:15:00-12:25:00 043-052 104:355,635:916 452:467 358:469->433:629 [1] Notes: [1] Used carrier suppression to estimate echo power, as echo drifted through frequency of directly propagating signal Very strong echoes. But S-LCP is not detected at the beginning (exiting occultation). All channels lost strength rapidly in the final 2 minutes; it is possible that the S-Band transmitter was turned off early. Also, the weakened X-Band signal stops drifting, suggesting that HGA tracking of the specular point may have ended. Very specular echoes are visible superimposed on the broader background return in X-Band spectra 213-227 and 235-241, suggesting very smooth reflecting surfaces within the HGA footprint. Dick Simpson Original: 2009-12-20 Added post analysis summary: 2010-01-09