Mars Express Bistatic Radar Experiment Operations Plan and Report 07 April 2006 Summary ======= DSN Antenna: 63 Pass: 1042 Orbit: 2875 Orbit Start Time: 2006-04-07T13:51:22 HGA Pointing: Inertial Specular Condition (ERT): 19:06 Target Latitude (deg N): -1.26 Longitude (deg E): -127.04 Rp (km): 3400.028 Incidence/Reflection Angle (deg): 33.38 Slant Range (km): 7865 Slew Angle (deg): 113.24 Doppler (carrier, fd; Hz): 16572 Doppler (echo, fr; Hz): -24258 Doppler Difference (fdd; Hz): 40829 Earth-Mars Distance (m): 2.556E+11 Experiment Set Up ================= This experiment was conducted using Madrid's DSS 63. The RSSG support team was Gene Goltz (alone), who operated all four RSR's; Dick Simpson was available by phone at Stanford. The following report is based largely on Gene's notes. Performance Problems and Notes ============================== There were two problems encountered during the pre-cal procedure: 1. when Step #2 was performed, at ~15:48, all of the ADC values went up to just below zero (e.g., -0.n) -- only the two X-band values should have changed in that way -- as if Steps #2, #3, and #4 were all done at the same time; Jesse checked the station's OCIs, and found that a zero had been entered in place of the letter "O" in one of the input directives; we restarted the pre-cal procedure from Step #1 at 15:58 2. there was an unexpected increase in the X-band LCP ADC value at Step #8, but another increase was seen (as expected) when Step #8 was ex- cuted; Jesse found no errors in the station OCIs, and we did not try to repeat any of the earlier steps. [Simpson, later - a check of the NMC log showed that DC01 was configured to control the X-LCP noise diode at 16:25 (Step-08) and it came on at a low level despite the fact that no enabling command was issued. The enable command was issued at 16:30 (Step-09) at which time the noise power rose to its expected level.] Otherwise, everything went well -- but, as expected, any signal was very difficult to discern in the FFTs. Notes added by Simpson after processing: S-RCP: The maser was unstable until about the beginning of MiniCal #1 (18:15); there were reductions in sample power of up to 0.3 dB lasting a few seconds and occurring at intervals of 1-10 minutes. By carefully choosing the time intervals over which calibration data were taken, we seem to have avoided any problems here. There were no maser problems during or after MiniCal #1, so the science should be fine as long as the calibrations hold up. S-LCP: The gain on this channel became unstable after MiniCal #1 (18:30), remaining unstable until completion of the surface observations (19:35). Sample power dropped 2 dB over 18:30-18:40. There was about a 50 percent recovery by 18:44; the remaining recovery was in stages. During the BSR_CAL stage of processing we applied piecewise continuous gain corrections (about 10 segments); the results appear satisfactory with the possible exception of brief periods during 18:30-18:44 when the sample levels were changing most quickly. No echo has been detected in S-LCP; if one is found (probably during 19:01-19:11), the gain adjustments should be reviewed. Also, the assumption that this was only a gain change (and not also a Tsys change) should be reconsidered. 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 Goltz RSR1B X-LCP 1-W auto 60 Goltz RSR2A S-RCP 1-W auto 60 Goltz RSR2B X-RCP 1-W auto 60 Goltz RSR subchannels (SCHAN) were defined as follows: Table 2 ---------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 1 ksps backup (not recorded) 2 8 ksps backup (not recorded) 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 -------- ----- --------- ----- ----- ----- ----- ------------------------ Set-Up channel 1A 1B 2A 2B fgain 60 60 60 60 Pre-Cal 15:45 1 -4.7 -1.7 -8.7 -9.8 15:46 att auto -10.3 -10.0 -9.6 -9.8 15:48 2 -0.3 -0.2 -0.1 -0.1 Configuration problem 15:58 1 -10.3 -10.0 -9.6 -9.8 Restart pre-cal 16:00 2 -10.2 -0.2 -9.6 -0.1 16:02 3 -1.0 -0.3 -9.7 -0.1 16:04 4 -1.0 -0.2 -0.3 -0.1 Ambient load temps: S1=17.88 S2=20.25 X1=15.12" 16:05 att auto 21.5 31.5 20.5 24.5 ATT settings Weather conditions: T=14.89C H=51.06 percent P=926.82 mB" sky=partly cloudy 16:07 rec 3 e -9.9 -9.0 -9.9 -9.6 Begin 25 kHz recording 16:10 5 -10.0 -9.0 -9.7 -9.6 16:15 6 -9.9 -9.1 -10.0 -8.7 16:20 7 -9.9 -21.2 -9.9 -14.6 16:25 8 -9.9 -19.3 -9.8 -21.7 ? No error seen in station OCIs ? 16:30 9 -10.0 -18.0 -10.0 -21.8 Confirmed 12.5K ND 16:35 10 -9.8 -8.7 -10.0 -9.6 Ambient load temps: S1=18.12 S2=20.56 X1=15.12" 16:40 11 -9.8 -9.0 -10.0 -9.6 16:45 12 -9.8 -21.3 -10.1 -21.7 16:50 13 -9.8 -21.2 -9.5 -21.8 16:55 14 -9.8 -21.2 -17.6 -21.7 17:00 15 -9.8 -21.2 -21.7 -21.7 Confirmed 12.5K ND 17:05 16 -9.3 -21.2 -21.4 -21.8 17:10 17 -17.0 -21.3 -21.6 -21.8 17:15 18 -20.8 -21.3 -21.7 -21.8 Ambient load temps: S1=18.10 S2=21.00 X1=15.10" 17:20 end Moved antenna to spacecraft point 17:31 acq. S Occultation egress 17:33 acq. X X TX turned on 17:35 BOT -20.9 -21.1 -21.9 -20.4 17:50 sfro 4/SX -7k -23k -7k" -23k Rcvr offsets (hz) sfro 3/S -7k 0 -7k 0 Rcvr offsets (hz) 18:10 sfro 3/X 0 -44k 0 -44k Rcvr offsets (hz) MiniCal1 18:15 1 -20.7 -21.3 -21.6 -14.2 Confirmed 12.5K ND 18:18 2 -20.8 -21.1 -17.7 -20.1 18:21 3 -20.9 -17.8 -21.5 -20.1 18:24 4 -16.9 -21.2 -21.5 -20.1 18:27 5 -20.8 -20.9 -21.5 -20.2 18:30 end BSR 18:51 rec 4 e -21.6 -20.9 -21.6 -20.0 Begin 100 kHz recording 19:06 max. sig. Peak Px/N0 (X-LCP=25.1) 19:21 rec 4 d -21.0 -21.0 -21.3 -19.7 Stop 100 kHz recording MiniCal2 19:40 1 -20.7 -20.8 -21.4 -14.1 Confirmed 12.5K ND 19:43 2 -20.6 -20.9 -17.4 -19.8 19:46 3 -20.7 -17.7 -21.3 -19.6 19:49 4 -16.8 -20.9 -21.4 -19.6 19:52 5 -20.8 -20.9 -21.3 -19.5 19:55 end Post-Cal 20:00 EOT/stow Ambient load temps: S1=17.62 S2=19.88 X1=14.94 20:06 1 -9.8 -9.0 -9.8 -9.5 20:10 2 -9.8 -9.0 -9.8 -8.6 20:13 3 -9.7 -9.0 -9.2 -9.6 20:16 4 -9.8 -8.8 -9.6 -9.6 20:19 5 -9.3 -9.0 -9.6 -9.6 20:22 6 -16.6 -21.1 -21.2 -21.8 20:25 7 -20.9 -17.9 -21.1 -21.6 20:28 8 -20.7 -21.2 -17.3 -21.7 20:31 9 -20.7 -21.2 -21.1 -14.5 20:34 10 -20.8 -21.2 -21.0 -21.6 Ambient load temps S1=17.25 S2=19.56 X1=14.75 Weather conditions T=11C H=69 percent P=928 mB sky=partly cloudy 20:40 rec 3 d Stop 25 kHz recording end AMB = ambient load BOT = Beginning of Track CNR = Carrier to noise ratio CONSCAN = conical scan tracking CW = continuous wave (carrier only) EOT = End of Track FRO = frequency offset HGA = high-gain antenna LNA = low-noise amplifier 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 SNR = Signal to noise ratio SR = S-RCP TLM = telemetry X1 = Ambient load for both X-band channels XL = X-LCP XR = X-RCP Dick Simpson Original: 2006-04-22 Updated Summary; added LNA to acronym list: 2006-07-05