Mars Express Bistatic Radar Experiment Operations Plan and Report 15 May 2010 Summary ======= DSN Antenna: 63 Orbit: 8155 Orbit Start Time: 2010-05-15T17:15:42 HGA Pointing: Specular Start Mid Point End -------- ---------- -------- Specular Condition (ERT): 19:12 20:05 20:36 Target Latitude (deg N): -16.83 -39.05 -56.58 Longitude (deg E): 272.14 268.67 321.63 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 39.88 59.47 89.44 Slant Range (km): 8457. 5289. 3326. Slew Angle (deg): 100.24 61.07 1.12 Doppler (carrier, fd; Hz): -39468. -45128. -19063. Doppler (echo, fr; Hz): 17967. 18083. -17625. Doppler Difference (fdd; Hz): -57435. -63211. -1438. Earth-Mars Distance (m): 2.123E+11 2.123E+11 2.123E+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 ============================== The pre-calibration was initiated with X-RCP and S-RCP noise diodes on. A subsequent command turned the X-RCP diode off, and the zenith system temperature was obtained. There was no redundancy built into the S-RCP pre- calibration; so the zenith system temperature can be obtained only from the post-cal. The S-RCP ambient load showed signs of instability during the pre-cal (noise power varied by +/-0.2 dB with the ambient load connected). During the post- cal, noise power increased by 0.5 dB while the ambient load was connected. Cause for these variations is not known. S-LCP noise power varied by +/-0.3 dB before, during, and after MINICAL #1 (approximately 18:48-19:12). The variations are severe enough that the MINICAL will not be usable. Six minutes after MINICAL #2, S-LCP noise power dropped -2.5 dB. The decrease was gradual, beginning immediately after the MINICAL; it then recovered quickly. Similar behavior was seen in the S-LCP data from 2010/106. One-way ingress and egress occultations were captured at X-Band; the ingress occultation was captured at S-Band. 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 2010/121 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ Set-Up 15:30 FGAIN 60 60 60 65 Set RSR FGAIN (dB) Pre-Cal 16:31 1 -10.4 -16.0 -14.1 -9.5 ADC amplitudes (dB) 16:37 att auto -10.0 -10.1 -10.0 -10.1 Reset attenuators 17.5 18.0 15.5 27.0 Attenuator settings (dB) 16:38 2 -10.0 -0.5 -10.1 -0.3 16:40 3 -0.6 -0.5 -10.2 -0.2 16:41 "4,5" -0.6 -0.5 -0.6 -0.3 16:43 att auto -9.8 -10.1 -10.1 -2.9 Reset attenuators 28.5 29.5 27.0 31.5 Attenuator settings (dB) Ambient load phys temps: S1=16.44 S2=20.00 X1=14.50 Local weather: T=15.6C H=33.6 percent sky=partly cloudy 16:44 6 -9.7 -10.1 -10.0 -3.0 16:45 rec 3 e Begin 25 kHz recording 16:50 7 -9.8 -10.0 -10.0 -2.8 16:55 8 -9.7 -21.7 -10.0 -13.3 17:00 9 -9.8 -21.7 -10.1 -14.7 17:05 10 -9.9 -19.7 -9.9 -14.8 Confirm 12.5K ND 17:10 "11,12" -9.7 -9.9 -9.9 -3.1 Ambient load phys temps: S1=16.72 S2=20.12 X1=14.56 17:15 13 -9.8 -10.1 -10.0 -2.9 17:20 14 -9.8 -21.7 -10.0 -14.8 17:25 15 -9.7 -21.8 -9.9 -14.7 17:30 16 -9.7 -21.8 -19.6 -14.7 17:35 17 -9.7 -21.8 -21.5 -14.7 Confirm 12.5K ND 17:40 18 -9.6 -21.6 -21.7 -14.7 17:45 19 -19.1 -21.7 -21.7 -14.7 17:50 20 -21.1 -21.8 -21.7 -14.7 Ambient load phys temps: S1=16.62 S2=20.12 X1=14.56 17:55 21/end -21.0 -21.8 -21.6 -14.8 Stop 25 kHz recording BOT 18:25 -20.3 -21.6 -22.6 -12.7 Collecting telemetry until 18:37 18:37 rec 3 e -20.1 -21.7 -22.8 -12.4 Resume 25 kHz recording 18:50 -20.1 -21.7 -22.7 -12.8 DSS 63 switch to Mars pointing predicts 18:51 sfro 3/SX +9k +58k +9k +58k Rcvr tuning offsets (Hz) sfro 4/X +35k +35k Rcvr tuning offsets (Hz) MiniCal1 18:55 1 -20.4 -21.6 -22.6 -10.9 Confirm 12.5K ND 18:58 2 -20.3 -21.6 -20.4 -12.8 19:01 3 -20.2 -19.8 -22.7 -12.7 19:04 4 -18.8 -21.5 -22.6 -12.8 19:07 5 -20.1 -21.6 -22.7 -12.8 19:10 end -20.0 -21.5 -22.7 -14.4 BSR 19:12 rec 4 e -20.4 -21.6 -22.8 -14.3 Begin 100 kHz recording 20:15 sfro 3/X +46k +46k Rcvr tuning offset (Hz) 20:22 sfro 3/X +34k +34k Rcvr tuning offset (Hz) Override "subreflector fixed" command 20:27 sfro 3/X +22k +22k Rcvr tuning offset (Hz) 20:31 sfro 3/X +10k +10k Rcvr tuning offset (Hz) 20:34 sfro 3/X 0 0 Rcvr tuning offset (Hz) 20:38 -19.9 -21.4 -22.2 -12.7 Begin ingress occn 20:40 DSS 63 return to s/c pointing predicts end BSR 20:40 rec 4 d -20.1 -21.4 -21.9 -12.7 End 100 kHz recording MiniCal2 20:45 1 -20.1 -21.3 -21.9 -10.8 Confirm 12.5K ND 20:48 2 -20.1 -21.4 -19.7 -12.6 20:51 3 -20.0 -19.5 -22.1 -12.7 20:54 4 -18.5 -21.3 -22.0 -12.6 20:57 5 -20.1 -21.4 -22.0 -12.6 21:00 end -20.5 -21.3 -21.9 -12.6 sfro 3/S 0 0 Rcvr tuning offset (Hz) EOT 21:15 stow -20.0 -21.7 -21.9 -14.7 PostCal 21:22 1 -9.8 -10.0 -9.3 -2.8 Ambient load phys temps: S1=16.62 S2=18.50 X1=13.88 21:25 2 -9.8 -10.0 -9.3 -2.7 21:28 3 -9.8 -10.0 -8.8 -2.8 21:31 4 -9.7 -9.8 -9.1 -2.9 21:34 5 -9.5 -10.1 -9.1 -2.9 21:37 6 -19.0 -21.7 -20.4 -14.7 21:42 7 -21.0 -19.7 -20.4 -14.6 21:45 8 -20.9 -21.6 -18.4 -14.6 21:48 9 -21.0 -21.7 -20.6 -12.1 21:51 10 -21.0 -21.7 -20.5 -14.5 Ambient load phys temps: S1=16.94 S2=18.31 X1=14.81 Local weather: T=9.8C H=55.6 percent sky=partly cloudy EOA 21:55 11 -21.0 -21.6 -20.5 -14.6 ADC amplitude (dB) 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 S-Band Amplitude: The S-RCP and S-LCP amplitude calibrations do not appear to be reliable. Higher level processing was carried out with best guess values; but neither echo power nor dielectric constant should be considered sound on S-Band. The only S-RCP pre-cal ambient load measurement was with the noise diode turned; the noise diode had been turned on during the setup and its modulation state (i.e., duty cycle) is not known. So there is no way to determine either the pre-cal system temperature or noise diode value. The power measurements during the post-cal were internally consistent; system temperature was 22.24K, and the noise diode was 12.23K. These compare to 22.77K and 11.66K from the pre-cal on the previous experiment (2010/121). However, the post-cal power levels for all measurements are about 30 percent higher than the pre-cal levels, suggesting a gain change in the S-RCP LNA of that magnitude. More troubling, the system temperatures during MINICALS #1 and #2 were 18.73K and 19.40K, respectively - much lower than the pre-cal and post-cal values. It is not easy to make system temperature change with LNA gain variations. On S-LCP, the pre- and post-cal determinations of mean system temperature and noise diode value were 24.08K and 12.88K, respectively. These compare favorably with 24.93K and 12.43K from the previous experiment (2010/121). The system temperature appears to be about 15 percent higher during tracking, compared with the zenith value - a reasonable difference. However, the S-LCP LNA appears to have been unstable for about 30 minutes centered on MINICAL #1, making that measurement useless. The final half hour, ending with a 2.5 dB drop in background noise power only 5 minutes after MINICAL #2, also appears questionable. MOVIE Processing: For X-Band 9 distinct processing windows plus 5 averaged spectra with split echoes were used; this was because of the many FROs, especially during the second half of the experiment. Details are in the table below: Int Times Spectra Noise Bins Echo Echo Bins Notes Peak --- ----------------- ------- --------------- ------- ---------------- ------ A 19:12-19:36 01-24 104:245,740:916 300:630 250:415->538:734 B 19:26-20:07 25-51 104:533,785:916 620:710 538:780 C 20:07-20:15 52-63 104:166,734:916 200:630 513:734->171:465 CD 20:15-20:16 64 104:166,859:916 600:800 171:855 [1] D 20:16-20:22 65-70 104:196,825:916 300:700 513:820->200:500 DE 20:22-20:23 71 104:196,450:580 200:900 200:900 [1] E 20:23-20:27 72-75 104:196,855:916 200:900 513:850->200:580 EF 20:27-20:28 76 104:196,520:600 200:916 200:916 [1] F 20:28-20:31 77-79 104:245,855:916 250:850 450:850->250:650 FG 20:31-20:32 80 104:245,520:620 250:916 250:916 [1] G 20:32-20:34 81-82 104:360,855:916 375:855 450:850->365:700 GH 20:34-20:35 83 104:320 375:916 390:916 [1] H 20:35-20:38 84-86 104:320,800:916 375:795 540:795->420:475 [2] I 20:38-20:40 87-88 104:320,800:916 375:795 325:795 [3] Notes: [1] Because of FRO, spectrum has split echo [2] Occultation ingress during spectrum 86 [3] Occultation; no carrier or echo For S-Band 3 distinct processing windows were used; there were no FROs. Int Times Spectra Noise Bins Carrier Echo Bins Notes Peak --- ----------------- ------- --------------- ------- ---------------- ------ A 19:12-20:11 01-59 104:670,885:916 82:87 675:880 B 20:11-20:27 60-75 104:395,825:916 82:87 655:870->400:580 [1] C 20:27-20:40 76-88 555:916 82:87 400:550->160:200 [2] Notes: [1] Occultation ingress during spectrum 86 [2] Occultation; no carrier or echo Dick Simpson Original: 2010-05-27 Post-Analysis Summary: 2010-06-03 Removed PDS-unfriendly characters: 2011-05-19