Mars Express Bistatic Radar Experiment Operations Plan and Report 31 October 2005 Summary ======= DSN Antenna: 63 Pass: 883 Orbit: 2308 Orbit Start Time: 2005-10-30T20:18:08 SCET HGA Pointing: Inertial Specular Condition: 2005-10-31T01:14:00 ERT Target: (47.16N, 135.07E; Rp = 3382.050 km) Incidence/Reflection Angle: 62.29 deg Slant Range: 8356 km Slew Angle: 56.16 deg Doppler (carrier, fd): -48154 Hz Doppler (echo, fr): -38552 Hz Doppler Difference (fdd): -9603 Hz Earth-Mars Distance: 6.94277E10 m Experiment Set Up ================= This experiment was conducted using Madrid's DSS 63. The support team at JPL included Danny Kahan and Gene Goltz. Dick Simpson called in occasionally by phone from Stanford. Performance Problems ==================== The only problem worth noting was persistent rain throughout the experiment. See Notes Added During or After Processing, below, for impact. 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 Goltz RSR2B X-RCP 1-W auto 68 Goltz RSR subchannels (SCHAN) were defined as follows: Table 2 --------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 1 ksps 2 8 ksps 3 25 ksps Primary recording bandwidth 4 100 ksps Backup recording Table 3 lists ADC amplitude levels read from RSR displays during the experiment; these were recorded by Kahan and sent by e-mail to Simpson on 2 November. Times are in UTC and should be considered approximate. "Steps" are as defined in the briefing message. Acronyms and abbreviations are explained after Table 3. Table 3 ----------------------------------------------------------------------------- Step/ RSR1A RSR1B RSR2A RSR2B Time Action S-LCP X-LCP S-RCP X-RCP Ancillary Information ----- -------- ----- ----- ----- ----- ---------------------------------- 20:25 fgain 60 60 60 68 **********************************_PRE-CAL_********************************** 20:29 01 -9.8 -9.9 -9.8 -10.1 att auto 20:32 02 -9.9 -1.0 -9.8 -1.2 20:33 03 -0.8 -1.0 -9.7 -1.2 20:34 04 -0.9 -1.0 -0.3 -1.2 S1=15.81, S2=16.88, X1=14.06 att auto 20.0 31.5 20.0 24.0 T=14.0C, H=81.0%, P=925.0, Raining -9.6 -9.5 -9.8 -9.7 begin 25 kHz record 20:40 05 -9.6 -9.6 -9.6 -9.8 20:45 06 -9.7 -9.5 -9.7 -8.6 20:50 07 -9.7 -20.7 -9.6 -14.4 20:55 08 -9.7 -21.1 -9.7 -21.2 21:00 09 -9.7 -18.0 -9.6 -21.3 confirm 12.5 noise diode 21:05 10 -9.5 -9.2 -9.6 -9.7 S1=15.56, S2=16.88, X1=13.50 21:10 11 -9.6 -9.6 -9.7 -9.8 21:15 12 -9.7 -21.0 -9.7 -21.2 21:20 13 -9.6 -21.1 -9.1 -21.2 21:25 14 -9.6 -21.0 -17.2 -21.3 21:30 15 -9.6 -21.0 -21.2 -21.2 confirm 12.5 noise diode 21:35 16 -9.2 -20.2 -21.3 -20.9 (X increasing due to rain) 21:40 17 -16.8 -19.5 -20.9 -19.6 (X increasing due to rain) 21:45 18 -19.7 -18.5 -20.9 -18.6 S1=15.62, S2=16.75, X1=13.25 21:50 ant. to point end 25 kHz record *************************************_BOT_*********************************** 23:10 fro 0 +2000 0 +2000 23:46 begin 25 kHz record *********************************_MINI-CAL #1 ******************************* 00:25 01 -19.7 -13.6 -20.8 -11.5 confirm 12.5 noise diode 00:28 02 -19.6 -13.1 -17.1 -13.3 00:31 03 -19.6 -12.9 -20.7 -14.0 00:36 04 -16.8 -14.3 -20.8 -14.1 00:39 05 -19.8 -13.8 -20.4 -14.0 ************************************_BSR_************************************ 00:59 begin 100 kHz record 01:14 peak echoes seen 01:29 end 100 kHz record *********************************_MINI-CAL #2 ******************************* 01:45 01 -18.5 -13.1 -19.5 -11.2 confirm 12.5 noise diode 01:48 02 -19.3 -13.8 -16.9 -13.1 01:51 03 -19.6 -12.9 -20.7 -13.9 01:54 04 -16.4 -14.2 -20.8 -14.0 01:57 05 -19.6 -14.1 -20.4 -14.0 **********************************_POST-CAL_********************************* 02:10 EOT antenna to zenith 02:18 01 -9.6 -9.6 -10.0 -9.7 S1=15.38, S2=16.12, X1=13.31 02:21 02 -9.6 -9.5 -9.9 -9.7 02:24 03 -9.6 -9.6 -9.4 -9.7 02:27 04 -9.6 -9.2 -10.1 -9.6 02:30 05 -9.2 -9.5 -9.9 -9.6 02:33 06 -16.5 -12.7 -20.5 -13.4 02:36 07 -19.0 -12.3 -20.2 -13.4 02:39 08 -19.1 -12.9 -16.8 -13.1 02:42 09 -18.9 -12.7 -20.1 -11.2 02:45 10 -19.1 -12.8 -20.7 -13.4 S1=15.31, S2=16.06, X1=13.19 T=12.0C, H=82.0%, P=925, Raining 02:50 END end 25 kHz record 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 Notes Added During or After Processing ====================================== Rain: The "rain" turned out to be a major problem. There were three intervals of 10-15 minutes during the track when Tsys increased by about 30 percent at X-Band. The first and second events were smaller at S-band -- but not negligible. The third event was roughly the same at both S- and X- Bands). The increases were centered on approximately 00:27, 00:45, and 01:45. The first coincided with MiniCal #1 and the third coincided with MiniCal #2. These essentially invalidated the mini-cals, since it was impossible to establish a (quiet) noise baseline against which to measure the incremental power added by the noise diodes. There was a fourth increase of about 20% at X-Band (less than 10% at S-Band), centered on 01:14 and coinciding with receipt of maximum surface echo. The background was relatively stable for about 20 minutes on either side, so that a meaningful noise baseline could be established for the surface echo interval. Since the mini-cals were useless, we made the assumption that the gain on all four channels was constant over the full extent of the experiment. We used the values of Tsys derived from the ambient load measurements during the pre-cal as the reference; the relative noise level at quiet times and frequencies during the surface measurement provided scale factors to obtain the effective Tsys during the tracking period. Results are summarized in Table 4. Table 4 --------------------------------------------------------------- X-RCP S-RCP X-LCP S-LCP ------- ------- -------- ------- Top (from tbsr calculation) 21.68 24.44 21.92 28.85 Pre-csl uncalibrated SKY power 12.157 21.188 5.6642 15.602 Uncalibrated quiet BSR window 58.860 23.047 25.452 16.151 Inferred Tsys at 01:14 104.97 26.58 98.50 29.87 Interference: More interfering signals were seen during processing than had been visible in real time. These were common in X-RCP (drifting from high frequencies to low frequencies) during 00:59-01:06, 01:14-01:16, and 01:25- 01:29. The second is the only interval during which signal was present; the interference raises the noise power density, but the echo is strong enough that the results are probably not badly contaminated. Echo: The echo is first visible and finally disappears at the approximate times shown in Table 5. As expected, it is both stronger and more dynamic at X-Band compared with S-Band. Table 5 --------------------------------------------------------- X-RCP S-RCP X-LCP S-LCP ------- ------- ------- ------- Echo first visible 01:07 01:02 01:06 01:03 Echo last visible 01:24 01:26 01:22 01:25 Dick Simpson Added acronyms: 2006-01-12 Added processing notes: 2006-03-11