Mars Express Bistatic Radar Experiment Operations Plan and Report 27 June 2009 Summary ======= DSN Antenna: 14 Pass: 2219 Orbit: 7037 Orbit Start Time: 2009-06-27T11:09:51 HGA Pointing: Specular Start Center End -------- ---------- -------- Specular Condition (ERT): 14:58 15:32 16:05 Target Latitude (deg N): 49.10 6.35 -70.04 Longitude (deg E): 278.90 321.46 240.03 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 61.42 60.14 58.86 Slant Range (km): 4426. 861. 2577. Slew Angle (deg): 57.15 59.73 62.29 Doppler (carrier, fd; Hz): 29226. 17411. -27092. Doppler (echo, fr; Hz): 48988. 33618. -53256. Doppler Difference (fdd; Hz): -19763. -16207. 26164. Earth-Mars Distance (m): 2.818E+11 2.818E+11 2.818E+11 Experiment Set Up ================= This experiment was conducted using Goldstone's DSS 14. Danny Kahan and Gene Goltz were in the Radio Science Support Area (RSSA) at JPL. Dick Simpson called in for occasional status checks. Performance Problems and Notes ============================== Spacecraft events written into the DSN keyword File (DKF) were mostly wrong (including telemetry transmission after the MEX HGA had been pointed to Mars, and two versions of the HGA slew back to Earth point after the experiments). But the ground antenna needed only to point at Mars, so we built the radio science ground time line around the basic spacecraft events provided by Jim Volp at ESAC and that appears to have been successful. According to Isabelle Dauvin at ESOC, the DKF errors resulted from violations of one or more of the following requirements: (1) BSR end-to-end activities must be completely within the DSN allocation. (2) BSR in the PTR must cover the full BSR sequence from Earth pointing to slew to BSR pointing to slew to Earth pointing (3) The DSN allocation can contain no other slews than the ones for BSR FROs at both S- and X-Band placed the echo at the edge of the passband and the echo powers will be underestimated -- possibly by as much as 25 percent, but probably no more than 10 percent for some of the spectra. Since the processing for both polarizations was carried out using the same parameters, the echo power ratio should still be correct so long as there is enough power to characterize the echo. 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 60 Kahan RSR subchannels (SCHAN) were defined as follows: Table 2 ---------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 2 ksps Recording bandwidth for occultations (RCP only) 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 2009/178 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ Pre-Cal 10:00 1 -1.9 -8.6 -10.4 -10.0 10:07 att auto -10.3 -10.1 -9.9 -10.0 15.0 12.5 4.5 11.0 Attenuator settings (dB) 10:09 2 -9.7 -0.3 -9.8 0.0 10:11 3 -4.0 -0.2 -10.0 -0.0 10:13 4 -4.1 -0.2 -0.6 0.0 10:14 att auto -10.2 -9.9 -10.0 -9.9 Ambient load temps: S1=18.50 S2=22.19 X1=15.94 21.5 24.5 15.5 23.5 Attenuator settings (dB) Weather: T=22.6C H=24.4 percent sky=clear 10:15 rec 3 e -10.1 -10.0 -9.9 -10.0 Begin record 25 kHz 10:20 5 -10.2 -9.9 -9.9 -9.8 10:30 6 -10.3 -10.0 -10.0 -9.7 10:35 7 -10.2 -22.1 -10.0 -20.1 10:40 8 -10.1 -22.1 -9.9 -22.5 10:45 9 -10.1 -19.9 -9.9 -22.5 Confirm 12.5K ND 10:50 10 -10.3 -9.7 -10.0 -9.9 Ambient load temps: S1=19.19 S2=21.81 X1=15.81 10:55 11 -10.2 -9.9 -9.9 -9.8 11:00 12 -10.2 -22.2 -10.0 -22.6 11:05 13 -10.1 -22.1 -9.7 -22.5 11:10 14 -10.2 -22.1 -19.2 -22.6 11:15 15 -10.1 -22.1 -21.0 -22.5 Confirm 12.5K ND 11:20 16 -10.0 -22.0 -21.1 -22.4 11:25 17 -17.4 -22.2 -21.0 -22.6 11:30 18 -18.0 -22.1 -21.1 -22.6 Ambient load temps: S1=17.88 S2=21.56 X1=15.62 11:35 end -18.3 -22.1 -21.1 -22.4 End record 25 kHz BOT 12:00 -13.2 -21.4 -20.5 -21.6 13:40 rec 3 e -14.4 -21.9 -20.9 -22.1 Resume 25 kHz 14:00 -12.1 -21.9 -20.0 -22.1 Switch to Mars planetary predicts 14:05 sfro 3/SX +23k +22k +23k +22k S/X FRO (Hz) MiniCal1 14:06 1 -12.6 -22.0 -21.1 -19.8 Confirm 12.5K ND 14:09 2 -13.3 -21.9 -19.4 -22.2 14:12 3 -14.3 -19.7 -20.9 -22.3 14:15 4 -12.0 -21.9 -20.0 -22.1 14:18 5 -13.3 -22.0 -20.9 -22.3 14:21 end -13.9 -21.9 -20.9 -22.1 BSR 14:22 sfro 3/SX -3k +13k -3k +13k S/X FRO (Hz) rec 4 e Begin 100 kHz -13.9 -21.9 -20.9 -22.1 Alba Patera 14:42 sfro 3/X 0 +7k 0 +7k Receiver offset (Hz) 14:46 sfro 3/X 0 +1k 0 +1k Receiver offset (Hz) Enter Valles Marineris 14:49 sfro 3/X 0 -5k 0 -5k Receiver offset (Hz) Exit Valles Marineris 14:51 sfro 3/SX -8k -9k -8k -9k Receiver offset (Hz) 14:53 sfro 3/X 0 -14k 0 -14k Receiver offset (Hz) 14:55 sfro 3/X 0 -19k 0 -19k Receiver offset (Hz) 14:58 sfro 3/X 0 -25k 0 -25k Receiver offset (Hz) end BSR 15:00 sfro 3/SX +23k +22k +23k +22k Receiver offset (Hz) End 100 kHz recording MiniCal2 15:00 1 -12.5 -22.1 -21.1 -19.4 Confirm 12.5 noise diode 15:03 2 -13.4 -22.0 -19.2 -21.4 15:06 3 -15.8 -19.8 -21.1 -21.4 15:09 4 -12.5 -22.1 -21.0 -21.5 15:12 5 -12.6 -21.9 -21.1 -21.4 15:15 end -10.3 -21.9 -21.1 -21.3 Post-Cal 15:22 1 -10.0 -9.9 -10.1 -10.0 AMB load phys temps: S1=18.12 S2=21.44 X1=15.56 15:25 2 -10.1 -10.1 -10.1 -9.8 15:28 3 -10.1 -10.0 -9.9 -10.0 15:31 4 -10.2 -9.8 -10.0 -10.0 15:34 5 -9.9 -9.9 -10.1 -9.9 15:37 6 -15.2 -22.2 -21.3 -22.6 15:40 7 -15.5 -19.9 -21.3 -22.5 15:43 8 -15.5 -22.2 -19.4 -22.6 15:46 9 -15.2 -22.1 -21.2 -20.1 15:49 10 -14.0 -22.1 -21.3 -22.6 AMB load phys temps: S1=18.44 S2=22.00 X1=15.88 Weather: T=29.4C H=13.9 percent sky=clear EOA 15:52 end -14.3 -22.1 -21.2 -22.5 End 25 kHz recording AMB = ambient load BOT = Beginning of Track 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 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 Post Analysis Summary The table below lists the time intervals over which X-Band data were processed by the MOVIE program. Intervals were chosen primarily on the basis of times and magnitudes of receiver frequency offsets (FRO). See the next page for S-Band processing intervals. 'Split echo' is an interval in which the FRO caused the echo to appear at two distinct frequencies. The echo power estimate is usually correct (or nearly so) if the echo integration bandwidth was chosen large enough. 'Edge Echo' is an echo which landed at the edge of the passband following a FRO. The echo power will be underestimated (by as much as 25 percent, depending on how much of the echo fell into the filter roll-off region). Since the same tuning parameters were chosen for both RCP and LCP, the echo power ratio (RCP to LCP) should be unaffected so long as the echo is strong enough to be measured. 'Carrier Suppression' was used when the residual carrier propagating directly from the spacecraft fell within the bandwidth over which the echo power was calculated. Carrier signals in these data are small relative to the echo powers; the correction process has been validated previously. For these data, carrier suppression is a minor correction. 'MOVIE Run' lists the spectra over which the MOVIE program was run and from which its output was saved. For previous experiments, all spectra were calculated with all processing parameter selections; for 2009 that would have led to a large number of useless results, so only the parameter choices for the intervals over which they were valid were calculated and saved. 'Plots' lists the spectra for which plots were computed and saved as hard copy. Most of these show split echoes when a FRO caused the echo to appear in two places. Interval Spectra Times Split Edge Carrier MOVIE Plots Echo Echo Suppression Run -------- ------- ----------------- ----- ----- ----------- ----- -------- A 001-078 14:22:04-14:34:54 001- 001,078, 079 079 B 079-120 14:35:04-14:41:54 079- 079,120, 121 121 C 121-144 14:42:04-14:45:54 121 121- 121, 144 145 D 145-162 14:46:04-14:48:54 145 145- 145- 145, 162 148 162 E 163-174 14:49:04-14:50:54 163 163- Y 163- 163, 174 166 174 F 175-186 14:51:04-14:52:53 175 175- Y 175- 175, 186 177 186 G 187-198 15:53:03-14:54:53 187 187- 187- 187 191 199-216 14:55:03-14:57:53 199 199- 199 203 217-228 14:58:03-14:59:53 217 217- 228 217, 228 220 For S-Band, the table below should be used: Interval Spectra Times Split Edge Carrier MOVIE Plots Echo Echo Suppression Run -------- ------- ----------------- ----- ----- ----------- ----- -------- A 001-055 14:22:04-14:49:30 001- 001,055, 056 056 B 056-066 14:49:30-14:55:00 Y 056- 056,066, 067 067 C 067-076 14:55:00-15:00:00 067- 067, 076 076 At X-Band, the echoes are modest at the beginning and end. The echo strengths become unusually large as the specular point approaches and departs from the edges of Valles Marineris (but not within the canyon). More surprisingly, the dielectric constant also becomes very large -- typically 6- 9, with the highest value being more than 11. The S-Band echo also peaks on the north and south edges of Valles Marineris, and the data indicate that it is not beam-limited; the inferred rms slopes are on the order of 0.5 deg without a correction for echo drift. 'Steering' should make the S-Band rms slopes smaller. Curiously, the S-Band dielectric constant is much smaller on the edges of Valles Marineris -- typically 3 where the X-Band values are larger than 6. Dick Simpson Original: 2009-08-07 Updated pass number: 2009-08-12