Mars Express Bistatic Radar Experiment Operations Plan and Report 19 June 2010 Summary ======= DSN Antenna: 63 Orbit: 8275 Orbit Start Time: 2010-06-19T16:31:49 HGA Pointing: Specular Start Mid Point End -------- ---------- -------- Specular Condition (ERT): 18:28 19:05 19:39 Target Latitude (deg N): -1.74 -15.06 -38.74 Longitude (deg E): 245.79 239.52 243.63 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 39.52 47.91 64.83 Slant Range (km): 8626. 6539. 4064. Slew Angle (deg): 100.97 84.17 50.34 Doppler (carrier, fd; Hz): -29870. -36803. -36660. Doppler (echo, fr; Hz): 18934 24435. 15902. Doppler Difference (fdd; Hz): -48803. -61237. -52562. Earth-Mars Distance (m): 2.557E+11 2.557E+11 2.557E+11 Experiment Set Up ================= This experiment was conducted using the Madrid DSS 63. Gene Goltz and Danny Kahan were in the Radio Science Support Area (RSSA) at JPL. This report is largely based on notes provided by Goltz and Kahan. Performance Problems and Notes ============================== Because of ongoing repairs to RSR1, the X-LCP and S-LCP channels were recorded using WVSR1. Because of confusion over real-time monitoring, the LCP data were mistakenly recorded at 8 kHz (instead of 25 kHz) during the pre-cal. This adds slightly to the uncertainty in the LCP pre-cal power measurements but should otherwise have no effect on science. The original DSN Keyword File (DKF) was not clear about when the experiment would end on the spacecraft. Ground activities were planned so that the surface echo would be captured until ingress occultation. In fact, the slew to Earth point began at about 19:38 and all surface echoes were gone within two minutes. An updated DKF received after the experiment confirmed this sequence. The X-Band ingress occultation may have been captured at about 20:02:43; it appears the S-Band transmitter was turned off about two minutes earlier. There was no attempt to observe the egress occultation. As has been true for other recent experiments, S-RCP LNA output was unstable at the 0.2 dB level throughout the experiment. S-LCP was stable except for a 0.2 dB increase over 19:14-19:15 and a 2.5 dB dropout over 19:26-19:33. Similar dropouts have been seen during experiments on days 106, 135, and 142. Data Acquisition ================ Receivers 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/WVSR 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/WVSR 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 2010/170 WVSR1A WVSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ Set-Up 15:09 FGAIN 60 60 60 65 FGAIN settings (dB) Pre-Cal 15:20 1 -4.0 -9.6 -8.5 -10.1 15:23 att auto -9.7 -9.7 -9.7 -10.1 17.0 18.5 13.0 27.0 Attenuator settings (dB) 15:24 2 -9.8 -0.3 -9.9 -0.2 15:25 3 -0.5 -0.4 -9.8 -0.3 15:26 4,5 -0.6 -0.3 -0.4 -0.2 15:28 att auto -10.0 -10.1 -9.8 -2.9 Attenuator reset 28.5 30.5 24.5 31.5 Attenuator settings (dB) Ambient load phys temps: S1=19.75 S2=22.81 X1=15.69 Local weather: T=23.5C H=29.5 percent sky=partly cloudy 15:30 rec 3 e Begin 25 kHz recording 15:30 6 -10.1 -10.0 -9.7 -2.8 ADC amplitude (dB) 15:35 7 -10.1 -10.0 -9.7 -3.0 15:40 8 -10.1 -21.8 -9.5 -13.3 14:45 9 -10.0 -21.8 -9.5 -14.8 15:50 10 -10.0 -19.9 -9.5 -14.7 Confirm 12.5K ND 15:55 11,12 -10.1 -10.0 -9.3 -3.0 Ambient load phys temps: S1=20.00 S2=23.06 X1=16.06 16:00 13 -10.1 -10.0 -9.4 -2.9 16:05 14 -10.1 -21.8 -9.5 -14.7 16:10 15 -10.1 -21.8 -9.5 -14.8 16:15 16 -10.0 -21.8 -19.3 -14.7 16:20 17 -10.1 -21.8 -21.2 -14.9 Confirm 12.5K ND 16:25 18 -9.9 -21.8 -21.2 -14.6 16:30 19 -19.4 -21.8 -21.2 -14.8 16:35 20 -21.4 -21.7 -21.3 -14.7 Ambient load phys temps: S1=20.25 S2=23.38 X1=16.31 16:40 21/end -21.4 -21.7 -21.2 -14.6 Stop 25 kHz recording BOT 17:10 -21.5 -21.6 -21.2 -14.6 AOS 17:36 -21.5 -21.6 -21.3 -13.1 Collect TLM to 18:51 17:51 rec 3 e -21.4 -21.7 -21.2 -13.1 Resume 25 kHz recording 18:05 -21.2 -21.6 -21.1 -13.4 DSS 63 switch to Mars pointing predicts 18:06 sfro 3/SX +8K +45K +8K +45K Rcvr tuning offset (Hz) sfro 4/X +28K +28K Rcvr tuning offset (Hz) MiniCal1 18:10 1 -21.3 -21.6 -21.1 -11.5 Confirm 12.5K 18:13 2 -21.3 -21.6 -19.1 -13.2 18:16 3 -21.3 -19.8 -20.9 -13.3 18:19 4 -19.3 -21.6 -20.9 -13.3 18:22 5 -21.3 -21.6 -21.0 -13.4 18:25 end -21.2 -21.6 -20.8 -13.3 BSR 18:28 rec 4 e -21.2 -21.6 -20.8 -13.3 Begin 100 kHz recording 18:38 sfro 3/X +55K +55K Rcvr tuning offset (Hz) 19:39 sfro 3/X +45K +45K Rcvr tuning offset (Hz) 19:45 sfro 3/X +36K +36K Rcvr tuning offset (Hz) 19:49 sfro 3/X +28K +28K Rcvr tuning offset (Hz) 19:53 sfro 3/SX 0 +18K 0 +18K Rcvr tuning offset (Hz) 19:56 sfro 3/X +9K +9K Rcvr tuning offset (Hz) 19:59 sfro 3/X 0 0 Rcvr tuning offset (Hz) ING 20:02 -20.8 -21.3 -20.7 -13.0 Occultation ingress end BSR 20:04 rec 4 d -20.7 -21.4 -20.8 -13.2 End 100 kHz recording MiniCal2 20:07 1 -20.7 -21.2 -20.9 -11.3 Confirm 12.5K ND 20:09 2 -20.7 -21.3 -19.0 -13.1 20:11 3 -20.7 -19.6 -20.7 -13.3 20:13 4 -19.1 -21.3 -20.8 -13.1 20:15 5 -20.7 -21.2 -20.8 -13.1 20:17 end -20.7 -21.2 -20.8 -13.0 EOT 20:19 stow -21.1 -21.7 -21.0 -14.8 PostCal 20:27 1 -10.3 -10.2 -9.6 -3.0 Ambient load phys tems: S1=18.50 S2=22.19 X1=15.12 20:32 2 -10.1 -10.2 -9.9 -2.9 20:35 3 -10.1 -10.1 -9.7 -3.0 20:38 4 -10.2 -10.1 -9.9 -3.0 20:41 5 -9.9 -10.2 -10.0 -3.0 20:44 6 -19.5 -21.9 -21.3 -14.7 20:47 7 -21.5 -19.8 -21.3 -14.7 20:50 8 -21.5 -22.0 -19.4 -14.7 20:53 9 -21.4 -22.0 -21.4 -12.3 20:56 10 -21.4 -21.9 -21.3 -14.7 Ambient load phys temps: S1=18.19 S2=21.88 X1=14.81 Local weather: T=20.6C H=32.7 percent sky=clear EOA 21:00 11/end -21.5 -21.9 -21.5 -14.7 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 71 minutes of 25 kHz data were divided into 6 time intervals -- one with split echoes (caused by receiver tuning offset changes, FRO) and five 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 18:28-18:38 01-10 104:430,765:916 435:760 435:629->605:760 [1] AB 18:38-18:39 11 104:205,765:916 210:760 210:760 [2] B 18:39-18:57 12-29 104:203,650:916 435:645 210:410->445:644 C 18:57-19:15 30-47 104:440,765:916 425:760 445:644->580:760 D 19:15-19:32 48-64 104:400,805:916 425:760 580:800->405:684 E 19:32-19:39 65-71 104:130,620:916 134:615 397:615->134:417 [1] Notes: [1] The first and last spectra may include data for which the HGA was not pointed at the specular point; according to the DKF, the first slew ended at 18:28:40 and the second slew began at 19:38:00 [2] 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 spectra could be processed using only two time intervals (corresponding to the two physical files). The echo signals were weak (or non-existent), so 360 s integrations were used; this leaves an unprocessed gap of five minutes between the files. The directly propagating carrier was in frequency bin 124. Int Times Spectra Noise Bins Carrier Echo Bins Notes Peak --- ----------------- ------- --------------- ------- ---------------- ------ A 18:28-19:10 01-07 139:635,850:916 122:125 641:845 B 19:15-20:03 08-15 139:635,850:916 122:125 641:845 S-RCP performance was unstable during this experiment, fluctuating 0.1-0.2 dB for no apparent reason. Before the experiment on day 184, the S- RCP maser was warmed and then cooled. Engineers said this could remove contaminants in the system, and performance on day 184 was noticeably better. S-LCP was also unstable during this experiment. Over 19:14-19:15, output from the S-LCP LNA rose 0.2 dB without explanation. Starting at about 19:24 output began to decrease, accelerating until the total loss was about 2.5 dB at 19:31:30, after which it recovered quickly to its original level a minute later. These S-LCP changes were modeled in the S-LCP GNC file. Dick Simpson Original: 2010-07-14 Removed PDS unfriendly characters: 2011-05-26