Mars Express Bistatic Radar Experiment Operations Plan and Report 25 January 2008 Summary ======= DSN Antenna: 63 Pass: 1700 Orbit: 5219 Orbit Start Time: 2008-01-24T19:47:36 HGA Pointing: Specular Start Center End -------- ---------- -------- Specular Condition (ERT): 01:05:00 01:35:00 02:06:00 Target Latitude (deg N): -44.89 -36.08 -28.02 Longitude (deg E): 357.81 343.01 331.64 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 56.78 57.05 57.35 Slant Range (km): 8985. 10376. 11193. Slew Angle (deg): 66.45 65.90 65.29 Doppler (carrier, fd; Hz): -11064 -8246 -5556 Doppler (echo, fr; Hz): -24926 -16345 -8870 Doppler Difference (fdd; Hz): 13863 8099 3314 Earth-Mars Distance (m): 1.086E+11 1.086E+11 1.086E+11 Experiment Set Up ================= This experiment was conducted using Madrid's DSS 63. Gene Goltz, Danny Kahan, and Dick Simpson were in the Radio Science Support Area at JPL; Kahan operated the RSR's while Goltz handled communications. Greg Hewitt was in the NOPE area until about 01:30. The voice net was not working. Greg Hewitt set up a telephone conference call including MEX MOC, DSS 63, the NOPE, and Radio Science. Starting at 02:05 the call was joined by DSS 15, which was setting up for a MEX telemetry pass. At 02:55 DSS 15 reported a fiber optics system failure; DSS 24 joined the call at 03:22 to substitute. Performance Problems and Notes ============================== This was the first use of DSS 63 for either Mars Express or Venus Express bistatic radar since April 2006. Between BOT and the MiniCal #1, the X-RCP amplitude of the ADC samples rose by about 5 dB; this was not matched by increases on any of the other three channels, nor did it correlate with presence or absence of the X-RCP carrier. During MiniCal #1, the ADC level rose about 1 dB when the noise diode was enabled; it dropped about 5 dB (to the expected level) when the diode was turned off. By 01:38, during the surface observations, the levels had crept up again. They remained higher than expected through MiniCal #2. When the X-Band FRO was reset to zero after the HGA returned to Earth point, the ADC amplitude dropped by about 2 dB. The cause for these changes is not known. X-Band echoes were seen throughout the experiment with LCP being the stronger. The X-Band carrier (direct) signal was intermittent, usually stronger on RCP when present. Echo bandwidth was 1-2 kHz, meaning it was beam-limited. Both the S-Band carrier and surface echo could be seen (after the amount of integration was increased to 10 s), with LCP generally the stronger. 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 Kahan RSR1B X-LCP 1-W auto 60 Kahan RSR2A S-RCP 1-W auto 60 Kahan RSR2B X-RCP 1-W auto 65 Kahan RSR subchannels (SCHAN) were defined as follows: Table 2 ---------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 2 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 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ 2008/024 -------- Pre-Cal 22:20 1 -9.7 -9.9 -10.0 -9.6 All to sky (dB) 29.0 34.0 28.0 30.0 ATT settings 22:24 2 -9.8 -0.3 -10.2 -0.1 X-Band to AMB 22:25 3 -0.5 -0.3 -10.1 -0.1 S-LCP to AMB 22:26 4 -0.6 -0.3 -0.4 0.1 S-RCP to AMB AMB load physical temps: S1=13.81 S2=17.12 X1=14.06 Weather conditions: T=10.1C H=58.8 percent sky = partly cloudy 22:28 -9.6 -9.3 -9.9 -10.2 ADC amp after AUTO reset 30.0 31.5 29.0 28.0 ATT settings 22:30:02 Begin 25 kHz recording 22:32 5 -9.7 -9.2 -9.9 -10.1 Configure DTT's 22:35 6 -9.7 -9.4 -9.9 -9.9 X-RCP ND ON 22:40 7 -9.8 -21.2 -9.9 -20.0 X-Band to sky 22:45 8 -9.7 -21.1 -10.1 -22.1 X-RCP ND OFF 22:50 9 -9.7 -17.9 -10.1 -22.3 XL ND ON 22:51 Confirmed ND = 12.5K 22:55 10 -9.6 -9.0 -9.7 -10.1 X-Band to AMB AMB physical temps: S1=13.88 S2=16.75 X1=14.00 23:00 11 -9.7 -9.4 -9.8 -9.9 X-LCP ND OFF 23:05 12 -9.6 -21.2 -9.7 -22.3 X-Band to sky 23:10 13 -9.6 -21.1 -9.6 -22.3 S-RCP ND ON 23:15 14 -9.7 -21.1 -19.4 -22.2 S-RCP to sky 23:20 15 -9.8 -21.2 -21.8 -22.2 S-RCP ND OFF 23:25 16 -9.2 -21.1 -21.8 -22.2 S-LCP ND ON 23:30 17 -16.7 -21.2 -21.7 -22.3 S-LCP to sky 23:35 18 -20.9 -21.2 -21.8 -22.3 S-LCP ND OFF AMB physical temps: S1=14.25 S2=16.62 X1=14.25 23:40 Stop recording 23:55 AOS S-Band visible 23:58 AOS X-Band appears 23:59 26.9 39.4 52.5 67.6 CNR (dB/Hz) -1240 -2567 -1238 -2557 Carrier offset (Hz) 2008/025 -------- 00:00 Resume 25 kHz recording DSS 62 in lock on S/X 00:06 Ranging modulation OFF 00:26 26.3 47.5 52.5 74.2 CNR (dB/Hz) -3106 Carrier offset (Hz) 00:34 Begin SLEW #1 00:38 26.0 43.5 50.9 54.0 CNR (dB/Hz) -1422 -3223 -1425 -3226 Carrier offset (Hz) 00:40 -20.8 -20.6 -21.7 -17.7 ADC amp (dB) (XR high?) 00:44 -20.7 -20.7 -21.7 -17.8 ADC amp (dB) MiniCal1 00:45 1 -20.6 -20.6 -21.7 -16.7 XR ND ON; conf ND=12.5K 00:48 2 -20.7 -20.7 -19.4 -21.6 XR ND OFF; SR ND ON S-Band carrier gone XR carrier 26 dB/Hz 00:51 3 -20.7 -17.8 -21.7 -21.6 SR ND OFF; XL ND ON 00:54 4 -16.6 -20.5 -21.6 -21.5 XL ND OFF; SL ND ON 00:57 5 -20.7 -21.2 -21.4 -20.6 SL ND OFF 01:02 FRO -12000 -12000 X-Band RX change (Hz) 33.0 25.0 X-Band echo max dB/Hz -4900 -4900 Echo peak offset (Hz) BSR 01:05 Begin 100 kHz recording 01:30 FRO -7000 -7000 X-Band RX change (Hz) 01:38 -20.5 -20.4 -21.6 -17.3 ADC amplitude (dB) 01:58 -20.4 -20.2 -21.4 -17.5 ADC AMPLITUDE (Hz) 01:59 22.0 35.0 34.0 Echo maximum dB/Hz 02:06 Begin SLEW #2 End 100 kHz recordings 02:09 X-Band echoes gone MiniCal2 02:10 1 -20.4 -20.4 -21.4 -16.6 XR ND ON 02:13 2 -20.4 -20.2 -19.4 -17.5 XR ND OFF; SR ND ON 02:16 3 -20.2 -17.4 -21.3 -17.6 SR ND OFF; XL ND ON 02:19 4 -16.6 -20.1 -21.3 -17.5 XL ND OFF; SL ND ON 02:22 5 -20.1 -20.2 -21.3 -17.6 SL ND OFF 02:26 19.4 19.8 22.9 37.3 Carrier to noise (dB/Hz) -1415 3813 -1417 3815 Carrier offset (Hz) 02:36 End SLEW #2 02:37 -20.1 -20.0 -21.2 -16.9 ADC amplitude (dB) 26.5 47.2 51.8 74.2 Carrier to noise (dB/Hz) -1331 4122 -1331 4124 Carrier offset (Hz) 02:40 FRO 0 0 0 0 Receiver offset (Hz) 02:42 26.3 46.4 51.8 74.2 Carrier to noise (dB/Hz) -1328 -2867 -1327 -2867 Carrier offset (Hz) 02:44 -19.9 -21.2 -19.9 ADC amplitude (dB) Post-Cal 02:50 EOT DSS 63 moving to zenith 02:55 -21.0 -21.2 -22.0 -22.2 DSS 63 at zenith 02:58 1 -9.7 -9.2 -10.3 -10.0 All to AMB AMB phys temps: S1=16.19 S2=16.19 X1=15.38 03:00 2 -9.7 -9.1 -10.1 -9.8 XR ND ON 03:03 3 -9.8 -9.1 -10.0 -10.1 XR ND OFF; SR ND ON 03:06 4 -9.8 -8.9 -10.2 -9.9 SR ND OFF; XL ND ON 03:09 5 -9.3 -9.3 -10.0 -10.0 XL ND OFF; SL ND ON 03:12 6 -16.8 -21.1 -21.9 -22.1 All to sky 03:15 7 -21.0 -17.9 -21.9 -22.2 SL ND OFF; XL ND ON 03:18 8 -20.9 -21.1 -19.7 -22.2 XL ND OFF; SR ND ON 03:21 9 -21.1 -21.3 -22.0 -19.8 SR ND OFF; XR ND ON 03:24 10 -21.2 -21.1 -21.9 -22.0 XR ND OFF AMB physical temps: S1=16.12 S2=16.38 X1=15.38 Weather conditions: T=6.9C H=65.1 percent sky=partly cloudy EOA 03:30 Stop 25 kHz recording 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 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 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: 2008-01-25 Added orbit start time: 2008-01-31 Typo corrected: 2008-02-11