Mars Express Bistatic Radar Experiment Operations Plan and Report 03 July 2008 Summary ======= DSN Antenna: 63 Pass: 1861 Orbit: 5783 Orbit Start Time: 2008-07-03T14:45:28 HGA Pointing: Specular Start Center End -------- ---------- -------- Specular Condition (ERT): 18:24:00 18:33:00 18:40:00 Target Latitude (deg N): 68.16 86.78 67.43 Longitude (deg E): 60.08 139.06 220.40 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 88.01 66.43 44.03 Slant Range (km): 1580. 813. 932. Slew Angle (deg): 3.98 47.13 91.94 Doppler (carrier, fd; Hz): 113211. 117317. 103834. Doppler (echo, fr; Hz): 38109. 88730. 38124. Doppler Difference (fdd; Hz): 110641. 28587 65710. Earth-Mars Distance (m): 3.185E+11 3.185E+11 3.185E+11 Experiment Set Up ================= This experiment was conducted using Madrid's DSS 63. Danny Kahan and Dick Simpson were in the Radio Science Support Area (RSSA) at JPL; Gene Goltz had previously scheduled vacation. Jesse Velasco was in the NOPE area. Performance Problems and Notes ============================== There was a delay in starting the pre-cal because of an unexpected extension of maintenance at DSS 63. Beginning of track was delayed about 15 minutes, but there was no impact on the bistatic radar experiment. Switching to planetary pointing required 15 minutes, more than was expected. But there was no impact. There were X-Band echoes throughout the surface observation period, often in both polarizations. The X-RCP echo peaked at 45 dB/Hz. S-RCP echoes were visible and strong at the beginning, but mostly gone halfway through. Both occultations were recorded, including in the nominal 2 kHz occultation bandwidth for X-RCP and S-RCP. The 2 kHz ingress data appear to be OK, although the X-RCP carrier is 200-250 Hz below the center frequency. The S- RCP levels are very low in both ingress and egress but probably usable. For egress the HGA was slewing to follow the specular point as the spacecraft emerged from occultation, so these data would require special processing if they were to be processed for atmosphere/ionosphere science. The S-Band HGA roll-off is visible in the 2 kHz data immediately after geometric egress. The X-Band transmitter did not come on until a couple minutes after egress (an eclipse power limitation), so only higher order HGA sidelobes appear at the carrier frequency, which is about 700 Hz below the center in the 2 kHz spectra. Near-occultation surface echoes were visible in real time, so these data may be of interest in studying oblique forward scatter at near grazing incidence. Near grazing measurements have been usually been captured as part of occultation observations with the HGA pointed toward Earth; here the HGA followed the specular point even though only S-Band was operational for the first couple minutes. The FRO strategy appeared to work well at 25 kHz. The offset carrier location (about 8.5 kHz above center, but well inside the roll-off) is convenient, and the echoes remained nicely centered in the passband throughout. There was much less FRO activity at 100 kHz, but no problems are expected. 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 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 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ 2008/185 -------- Pre-Cal 14:50 1 -9.7 -9.9 -9.8 -10.0 All to sky (dB) 16.0 20.0 8.5 18.0 ATT settings 14:52 2 -9.7 -0.2 -9.7 -0.1 X-Band to AMB 14:54 3 -0.5 -0.2 -9.8 -0.2 S-LCP to AMB 14:55 4 -0.4 -0.1 -0.3 -0.2 S-RCP to AMB AMB load physical temps: S1=19.50 S2=22.88 X1=18.44 Weather conditions: T=23.5C H=23.9 percent sky = clear, wind 15.4 km/hr 14:57 5 -9.7 -9.4 -9.5 -9.8 ADC amp after AUTO reset 27.0 31.5 20.0 30.0 ATT settings Begin 25 kHz recording 15:05 6 -9.6 -9.3 -9.7 -9.6 X-RCP ND ON 15:10 7 -9.6 -21.7 -9.7 -19.6 X-Band to sky 15:15 8 -9.7 -19.6 -9.7 -22.0 X-RCP ND OFF 15:20 9 -9.7 -18.3 -9.6 -22.0 XL ND ON Confirmed ND = 12.5K 15:25 10 -9.8 -9.0 -9.7 -9.8 X-Band to AMB AMB physical temps: S1=19.88 S2=23.25 X1=18.56 15:30 11 -9.8 -9.4 -9.6 -9.9 X-LCP ND OFF 15:35 12 -9.7 -21.6 -9.6 -22.2 X-Band to sky 15:40 13 -9.7 -21.6 -9.4 -21.9 S-RCP ND ON 15:45 14 -9.7 -20.7 -19.1 -22.1 S-RCP to sky 15:50 15 -9.5 -21.7 -21.2 -22.1 S-RCP ND OFF Confirmed ND = 12.5K 15:55 16 -9.2 -21.7 -21.2 -22.1 S-LCP ND ON 16:00 17 -16.6 -21.7 -21.4 -22.0 S-LCP to sky 16:05 18 -21.0 -21.7 -21.4 -22.1 S-LCP ND OFF AMB physical temps: S1=20.31 S2=23.94 X1=18.81 16:10 Stop recording 25 kHz DSS 63 moving to point BOT 16:18 -21.0 -21.6 -21.3 -20.9 DSS 63 on point 16:20 34.2 59.9 Carrier (dB/Hz) -2044 Carrier offset (Hz) 8420088907 Carrier freq (Hz) 17:21 43.3 59.0 Carrier (dB/Hz) 17:22 -10000 -11000 -10000 -11000 FRO (Hz) 8780 8528 Carrier offset (Hz) 17:25 Resume 25 kHz recording Start 2 kHz recording 17:30 -20.9 -21.6 -21.3 -21.0 ADC amplitude (dB) 21.4 28.5 43.4 59.5 Carrier (dB/Hz) 17:34 -1300 -2500 -1300 -2500 FRO (SCHAN 1) 17:38:55 Occn ingress 17:43 Request planet pointing 17:44 End 2 kHz recording 17:58 DSS 63 pointing to Mars MINICAL1 17:59 1 -20.7 -21.4 -21.1 -19.3 XR ND ON; conf ND=12.5K 18:02 2 -20.8 -21.5 -19.1 -21.1 XR ND OFF; SR ND ON 18:05 3 -20.8 -18.2 -21.1 -21.1 SR ND OFF; XL ND ON 18:08 4 -16.6 -21.5 -21.0 -21.2 XL ND OFF; SL ND ON 18:11 5 -20.7 -21.4 -21.0 -21.2 SL ND OFF BSR: 18:18 Resume 2 kHz recording 18:22 Start 100 kHz recording 18:22:50 S-RCP occn egress 18:25 X Tx ON; strong echoes 18:28:30 2-peak X echoes 18:29 -22000 -22000 FRO_X (SCHAN 3) 18:30 45. X-RCP peak (dB/Hz) 18:31 5-peak X-RCP echo 18:32 -32000 -32000 FRO_X (SCHAN 3) S-RCP echoes mostly gone 18:34 -19000 -42000 -19000 -42000 FRO (SCHAN 3) -80000 -80000 FRO_X (SCHAN 4) 28. 30. Echo peak (dB/Hz) S-RCP echo visible 18:36 -53000 -53000 FRO_X (SCHAN 3) 18:37 End 2 kHz recording 18:38 -64000 -64000 FRO_X (SCHAN 3) 25. Echo peak (dB/Hz) 18:40 End 100 kHz recording MINICAL2 18:40 1 -20.6 -21.3 -20.9 -19.7 XR ND ON 18:43 2 -20.8 -21.2 -18.9 -21.2 XR ND OFF; SR ND ON 18:46 3 -20.7 -18.1 -21.0 -21.0 SR ND OFF; XL ND ON 18:49 4 -16.6 -21.1 -21.0 -21.0 XL ND OFF; SL ND ON 18:52 5 -20.6 -21.1 -20.9 -21.0 SL ND OFF BCAL 2 18:55 -10000 -11000 -10000 -11000 FRO (SCHAN 3) -20.7 -21.1 -21.0 -20.9 ADC amplitude (dB) 20.5 31.4 43.1 65.7 Carrier (dB/Hz) 8541 Carrier offset (Hz) EOT 18:56 DSS 63 going to zenith POSTCAL: 19:05 1 -9.9 -9.9 -9.6 -10.1 All to AMB AMB phys temps: S1=20.75 S2=24.69 X1=20.12 19:07 2 -9.8 -9.5 -9.6 -10.0 XR ND ON 19:09 3 -9.8 -9.4 -9.4 -10.1 XR ND OFF; SR ND ON 19:11 4 -9.8 -9.2 -9.6 -10.1 SR ND OFF; XL ND ON 19:13 5 -9.3 -9.5 -9.6 -10.1 XL ND OFF; SL ND ON 19:15 6 -16.6 -21.8 -21.2 -22.3 All to sky 19:17 7 -21.1 -18.3 -21.4 -22.3 SL ND OFF; XL ND ON 19:19 8 -21.1 -21.8 -19.1 -22.4 XL ND OFF; SR ND ON 19:21 9 -21.1 -21.8 -21.3 -20.0 SR ND OFF; XR ND ON 19:23 10 -17.1 -21.7 -21.1 -22.2 XR ND OFF AMB physical temps: S1=20.62 S2=24.62 X1=20.25 Weather conditions: T=21.1C H=29.1 percent sky=clear EOA 19:25 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: 2008-07-03 Updated orbit number, start time; edits regarding occultations: 2008-07-09