Mars Express Bistatic Radar Experiment Operations Plan and Report 24 April 2005 Summary ======= DSN Antenna: 14 Pass: 693 Orbit: 1631 Orbit Start Time: 2005-04-24T07:46:30 HGA Pointing: Inertial Specular Condition (ERT): 11:46 Target Latitude (deg N): 13.84N Longitude (deg E): 99.07W Rp (km): 3399.128 Incidence/Reflection Angle (deg): 67.58 Slant Range (km): 2922 Slew Angle (deg): 44.91 Doppler (carrier, fd; Hz): 27965 Doppler (echo, fr; Hz): -13568 Doppler Difference (fdd; Hz): 41533 Earth-Mars Distance (m): 2.143E11 Data Acquisition ================ This experiment was supported by DSS 14 staff at the Goldstone DSN complex. The support team at JPL included Gene Goltz, Danny Kahan, and Dick Simpson. In the NOPE area was Romy Paredes. Gene Goltz misunderstood the start time for the activities and didn't show up until after the pre-calibration had been completed. Since Danny and I had just returned from the MaRS Team meeeting in Munich and neither of us had received the briefing message, there was some initial scrambling to get basic information into place. Danny set up the voice net with the Comm Chief while I negotiated with Romy to get the briefing message. MEX MOC wanted to know whether DSS 14 would support telemetry after the bistatic radar; this had been the subject of some debate the previous week, and I was hoping that Gene would have the answers. After about 10 minutes MEX MOC withdrew the request, and there was agreement that DSS 14 would support BSR only. The spacecraft did begin to transmit data after the BSR, however. The experiment began with pre-calibration activities starting at 07:50; the pre- cal was completed 45 minutes ahead of schedule. The bistatic surface observations were collected in the interval 11:36-11:49, but echoes were seen during only about two minutes centered on 11:46. At 12:19 the spacecraft returned to Earth point and was one-way with no telemetry modulation for about half an hour. At about 12:50 the S-band transmitter was turned off and X-band telemetry modulation was turned on. The track ended about 10 minutes later, and the post-calibration was completed before 14:00. Jose Valencia had adapted the calibration procedure and briefing message so that it was appropriate for DSS 14 rather than DSS 43, which had been used for the previous three experiments. There were occasional, minor problems relating to our inability to see clearly when the noise diodes were turned on and off. During the post-calibration, it also appeared that the S-LCP channel was unstable; levels fluctuated by a factor of two whether the noise diode was on or off. We attempted to confirm the S-LCP levels by cycling the noise diode one more time after the procedure was completed but without success; the fluctuations continued. There were no companion fluctuations on S-RCP. Neither of these problems requires changes to the procedures. RSRs were configured as follows. Table 1 --------------------------------------------- RSR Channel Mode ATT FGAIN Operator dB ----- ------- ---- ---- ----- --------------- RSR1A S-LCP 1-W auto 50 Kahan RSR1B X-LCP 1-W auto 50 Kahan RSR2A S-RCP 1-W auto 50 Kahan/Goltz RSR2B X-RCP 1-W auto 50 Kahan/Goltz Subchannels were defined as follows: Table 2 --------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 1 ksps Used for seeking weak carrier signals 2 8 ksps 3 25 ksps Primary recording bandwidth 4 100 ksps Backup recording (able to capture both X-band residual carrier and surface echo) Predicts were provided by NSS, but the first time was 10:42, so the RSR's used their default tuning during the pre-calibration period.. Table 3 lists ADC RMS/peak levels read from RSR displays during the pre- calibration. ADC peak values varied too much to be useful in confirming receiver configuration; a different system was employed for the surface observations and post-calibration. Times are in UTC read from a wall clock and may not reflect actual times when configurations changed. Acronyms and abbreviations are explained after Table 4. Table 3 ------------------------------------------------------------------------------ TIME (ERT) RSR1A RSR1B RSR2A RSR2B COMMENTS 2005-04-10 S-LCP X-LCP S-RCP X-RCP RMS/pk RMS/pk RMS/pk RMS/pk ---------- ------ ------ ------ ------ --------------------------------------- 08:00 Voice net established (MEX MOC, MEX NOPE, DSS 14, and RSSG) 08:10 MEX MOCC asks whether DSS 14 will support telemetry; answer, after investigation, is no. 08:37 29 29 29 29 All channels to sky; set RSR attenuators using AUTO feature 08:43 88 91 X-band to AMB 08:45 79 S-LCP to AMB 08:47 86 S-RCP to AMB 08:48 DSS 14 reports ambient load physical temperatures: S1=13.52C, S2=19.75, X1=15.56 Sky overcast, T=10.4C, Humidity = 47.1% 08:49 29/114 28/127 29/118 30/122 Reset attenuators using AUTO feature 08:50 Start RSR recording, subchannel 3 08:56 29/113 28/127 30/118 30/127 All channels to AMB 09:00 30/113 X-RCP ND ON 09:07 29/120 7/28 30/127 9/37 X-band to sky 09:10 29/109 9/36 30/124 7/27 Disable X-RCP ND 09:12 DSS 14 confirms X-RCP ND is OFF 09:15 29/101 9/40 30/110 7/30 Enable X-LCP ND 09:20 29/109 28/109 30/111 29/127 X-band to AMB 09:22 DSS 14 reports ambient load physical temperatures: S1=17.50, S2=19.69, X1=16.56 09:25 29/126 28/101 30/121 29/124 Disable X-LCP ND 09:30 28/120 7/25 29/127 7/27 X-band to sky 09:35 28/108 7/33 31/110 7/30 S-RCP ND ON 09:40 29/114 7/29 10/48 7/28 S-RCP to sky 09:45 29/116 7/26 8/28 7/28 Disable S-RCP ND 09:50 29/107 7/29 8/33 7/28 S-LCP ND ON 09:55 10/44 7/26 8/30 7/29 S-LCP to sky 10:00 8/33 7/27 8/33 7/28 Disable S-LCP ND 10:01 DSS 14 reports ambient load physical temperatures: S1=17.50, S2=19.75, X1=16.44 10:05 Stop RSR recording Table 4 lists ADC RMS and ADC "amplitude" (dB) levels read from RSR displays during the bistatic observations (including the mini-calibrations) and the post- calibration. Times are in UTC and may not reflect actual time when configurations changed. Acronyms and abbreviations are explained below. Table 4 ------------------------------------------------------------------------------ TIME (ERT) RSR1A RSR1B RSR2A RSR2B COMMENTS 2005-04-10 S-LCP X-LCP S-RCP X-RCP RMS/ampl RMS/ampl RMS/ampl RMS/ampl ---------- -------- -------- -------- -------- ------------------------------- 10:58 Enter X-band FRO = -44000 Hz; Enter S-band FRO = -7000 Hz 10:59 10/-18.7 9/-19.6 10/-19.2 10/-19.0 Begin RSR recording subch 3 11:00 Spacecraft enters eclipse 11:00 10/-18.7 9/-19.6 10/-19.2 10/-19.0 Begin mini-calibration #1; Enable X-RCP ND 11:04 10/-19.2 9/-19.7 12/-17.7 10/-19.2 Disable X-RCP ND; Enable S-RCP ND 11:07 10/-19.2 11/-18.5 9/-19.7 10/-19.5 Disable S-RCP ND; Enable X-LCP ND 11:10 12/-17.5 9/-20.0 9/-19.7 9/-19.6 Disable X-LCP ND; Enable S-LCP ND 11:13 10/-19.0 9/-20.1 9/-19.8 9/-19.8 Disable S-LCP ND 11:15 Spacecraft begins Slew #1 11:18 Spacecraft occultation ingress 11:16 Spacecraft S-band TX ON (CW) 11:20 Spacecraft exits eclipse; Spacecraft periapsis 11:24 Spacecraft occultation egress; Spacecraft end Slew #1 11:30 10/-19.0 8/-20.6 9/-20.1 9/-20.1 11:32 Spacecraft X-band TX ON 11:34 Spacecraft X-band TLM ON 11:35 Begin RSR recording, subchannel 4 (100 kHz) 11:36 Spacecraft X-band TLM OFF (CW) 11:46 Echoes peak in X-RCP at approx 28 dB SNR, drifting toward positive frequencies; visible but weaker (20 dB) in X-LCP. Nothing seen in either S-band channel. 11:49 Spacecraft begin Slew #2 11:55 End subchannel 4 recordings 11:59 10/-19.2 8/-21.0 9/-21.0 8/020.6 Setting up for Mini-Cal #2 12:00 9/-20.0 8/-21.0 8/-20.5 10/-18.7 X-RCP ND ON 12:04 9/-20.0 8/-21.2 11/-18.2 8/-20.6 Disable X-RCP ND; Enable S-RCP ND 12:07 10/-19.3 10/-19.4 9/-20.5 8/-20.6 Disable S-RCP ND; Enable X-LCP ND 12:10 11/-18.2 8/-21.2 8/-20.5 8/-20.8 Disable X-LCP ND; Enable S-LCP ND 12:11 9/-19.6 8/-21.2 8/-20.5 8/-20.8 S-RCP carrier briefly visible 12:13 S-LCP ND OFF; end Mini-Cal #2 12:18 Set all FRO = 0; S-LCP SNR=19 dB at -1322 Hz; X-LCP SNR=37 dB at -2856 Hz 12:19 Spacecraft end Slew #2 12:19 X-RCP clipping; set FGAIN=70. 12:21 S-RCP SNR=47 dB at -1325 Hz X-RCP SBR=69 dB at -2860 Hz 12:30 DSS 14 locks to S,X carriers at request of MEX NOPE 12:35 13/-16.9 8/-21.5 8/-20.8 8/-20.8 S-LCP SNR=19 dB at -1334 Hz X-LCP SNR=37 dB at -3000 Hz S-RCP SNR=47 dB at -1335 Hz X-RCP SNR=69 dB at -2898 Hz 12:49 S-band LOS (Tx OFF) 12:51 10/-19.4 7/-21.5 8/-20.7 8/-20.8 X-RCP SNR=69 dB at -2846 Hz 12:53 Spacecraft X-band TLM ON 12:54 10/-19.2 8/-21.6 8/-20.7 8/-20.7 X-RCP SNR=62 dB at -2850 Hz 13:02 DSS 14 moving to zenith; X-band carrier disappears 13:03 X-RCP FGAIN set to 50 13:06 10/-19.5 7/-22.2 8/-21.2 7/-22.1 Prepare for post-calibration 13:13 29/-9.9 27/-10.3 20/-9.7 30/-9.5 All channels to AMB; DSS 14 reports ambient load physical temperatures: S1=16.31, S2=18.50, X1=14.90 13:17 28/-10.0 28/-10.3 29/-9.8 30/-9.5 Enable X-RCP ND 13:20 29/-9.9 27/-10.3 30/-9.5 30/-9.7 Disable X-RCP ND; Enable S-RCP ND 13:23 29/-10.0 28/-10.0 28/-9.7 28/-9.7 Disable S-RCP ND; Enable X-LCP ND 13:26 29/-9.7 28/-10.2 29/-9.8 29/-9.7 Disable X-LCP ND; Enable S-LCP ND 13:29 11/-18.1 7/-22.3 8/-21.1 7/-22.2 All channels to sky 13:32 ??? 9/-20.1 10/-18.7 7/-22.1 Disable S-LCP ND; Enable X-LCP ND; S-LCP unstable (rms varying from 10 to 15) 13:35 12/-17.4 7/-22.3 11/-18.6 7/-22.1 Disable X-LCP ND; Enable S-RCP ND 13:38 11/-18.0 7/-22.3 8/-21.4 9/-19.8 Disable S-RCP ND; Enable X-RCP ND 13:41 ??? 7/-22.3 8/-21.4 7/-22.1 Disable X-RCP ND; S-LCP rms levels range from 9 to 12. DSS 14 reports ambient load physical temperatures: S1=16.12, S2=18.19, X1=14.62. Sky overcast, T=8.3C, humidity=59.3% 13:47 10/-18.7 7/-22.3 8/-21.2 7/-22.2 DC02 reconfigured for S-LCP 13:48 12/-17.2 7/-22.4 8/-21.3 7/-22.1 S-LCP ND ON 13:50 17/-14.4 7/-22.3 8/-20.6 7/-22.1 S-LCP ND OFF 13:52 Stop RSR recordings AMB = ambient load BOT = Beginning of Track CONSCAN = conical scan tracking CW = continuous wave (carrier only) EOT = End of Track FRO = frequency offset HGA = high-gain antenna LOS = loss of signal ND = noise diode No = noise power Pc = carrier power S1 = ambient load for S-RCP S2 = ambient load for S-LCP SL = S-LCP SR = S-RCP TLM = telemetry X1 = Ambient load for both X-band channels XL = X-LCP XR = X-RCP Original: 2005-02-27 Summary section added: 2006-04-12 Summary section updated: 2006-05-19