Mars Express Bistatic Radar Experiment Operations Plan and Report 21 January 2006 Summary ======= DSN Antenna: 14 Pass: 965 Orbit: 2602 Orbit Start Time: 2006-01-21T03:12:06 SCET HGA Pointing: Inertial Specular Condition: 2006-01-21T06:54:00 ERT Target: (46.93S,60.37E, 3380.166 km - predicted) Incidence/Reflection Angle: 32.71 deg Slant Range: 850 km Slew Angle: 114.63 deg Doppler (carrier, fd): 85475 Hz Doppler (echo, fr): 14285 Hz Doppler Difference (fdd): 71191 Hz Earth-Mars Distance: 1.434E+11 m Experiment Set Up ================= This experiment was conducted using Goldstone's DSS 14. The support team at JPL included Danny Kahan, Gene Goltz, Dwight Holmes, and Dick Simpson. Jesse Velasco (NOPE) was on call. Essam Marouf had planned to participate, but had to cancel because of illness. The spacecraft used fixed HGA inertial pointing. Periapsis was about 12 minutes before the BSR specular condition. Doppler separation between the direct signal and surface echo was predicted to be about 75 kHz; Doppler spreading was predicted to be 32260 Hz (before beam-limiting). So we chose higher sampling rates (up to 250 ksps) for the RSR subchannels than have been used previously. Then the carrier and surface echo could be seen together in the 250 kHz spectra, though these samples were not recorded. In fact, only the X-LCP carrier was seen in real time; but its presence was reassuring. FRO's were entered 1 minute after the 100 kHz recordings started so as to place the surface echoes in the middle of the passband. The FRO's were removed 1 minute before 100 kHz recording was stopped. This provides a brief frequency reference at each end of the BSR interval. Performance Problems and Notes ============================== There was interference from MGS throughout the tracking pass, except around Mini-Cal#1 when MGS was in occultation. It's hard to tell what effect this had on the MEX data, but modulation splatter was visible in the X-RCP spectrum frequently. Without the 250 kHz channel, however, we would not have known MGS was nearby for most of the time. Danny Kahan watched the MGS SOE to identify key events. At BOT there was no MEX signal. The spacecraft transmitters were turned on and the slew to the BSR inertial attitude were completed while the spacecraft was in occultation. So the first (and only) real-time signal from MEX was a weak X-LCP carrier more than 90 minutes after actual BOT. The post-BSR BCAL was only 8 minutes at S-Band and 10 minutes at X-Band. The S-RCP signal path failed three times. The first was between the pre-cal and BSR (approximately 05:49 to 06:14). Gene Goltz brought up RSR1B, which showed the same thing as RSR2A (that is, no input to the RSR), indicating that the problem was upstream of the RSR's. When the signal came back at about 06:14 it seemed the same as before the failure. The problem was assigned DR G106457. S-RCP was lost a second time before the beginning of the post-cal (08:01-08:10) and a third time at the end of the post-cal (08:39-08:50). John Klose investigated the next day; he reported that station personnel had concluded that there was something fishy with the maser but were not able to characterize the problem further. By the time of the next experiment 24 hrs later, the S-RCP maser was "red." The echo was first visible in X-LCP at about 06:51 and had disappeared by about 06:55. It moved from left to right (rather than from right to left, as predicted for the specular point in BSRPREDICT), was off the edge of the 25 kHz passband by shortly after 06:54, and had a width of about 5 kHz throughout. Quantitative study may be best performed using the 100 kHz data. During the Post-Cal there was no X-RCP noise diode plus ambient load measurement. Reason for this error is not known. Data Acquisition ================ RSRs were configured as in Table 1: Table 1 --------------------------------------------- RSR Channel Mode ATT FGAIN Operator dB ----- ------- ---- ---- ----- --------------- RSR3A S-LCP 1-W auto 60 Kahan RSR3B 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 25 ksps Primary recording bandwidth 2 100 ksps Backup recording 3 250 ksps Real-time monitoring 4 not available 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 ----------------------------------------------------------------------------- Step/ RSR3A RSR3B RSR2A RSR2B Time Action S-LCP X-LCP S-RCP X-RCP Ancillary Information ----- -------- ----- ----- ----- ----- ---------------------------------- FRO 0 0 0 0 RSR frequency offset (Hz) ********************************** PRE-CAL ********************************** 03:30 01 12.5 11.0 5.0 10.5 RSR ATT after AUTO reset -9.7 -10.0 -10.1 -10.0 ADC amplitude (dB) All channels to sky 03:32 02 -10.2 -0.3 -10.1 -0.0 X-Band to AMB 03:33 03 -1.8 -0.2 -10.0 -0.1 S-LCP to AMB 03:34 04 -1.8 -0.2 -0.4 -0.0 S-RCP to AMB 03:37 Ambient load physical temperatures S1 = 16.19C S2 = 19.00C X1 = 15.12C Weather at station T = 5C H = 26 percent P = 906 mB W = 3 mph from ESE sky = clear 05 22.0 23.0 16.5 23.0 RSR ATT after auto reset -10.3 -10.0 -9.8 -9.8 ADC amplitude (dB) 03:38 Begin SCHAN=1 (25 kHz) recording 03:39 -10.2 -9.9 -9.7 -9.9 Begin SR, SL 100 kHz recording 03:45 06 -10.2 -10.0 -9.3 -9.7 XR ND ON (why did SR change?) 03:50 07 -10.4 -22.1 -9.5 -20.1 X-Band to sky 03:55 08 -10.5 -20.9 -9.7 -22.6 XR ND OFF (did XL ND come on?) 04:00 09 -10.4 -19.8 -9.6 -22.5 XL ND ON 04:05 10 -10.2 -9.8 -9.6 -9.8 X-Band to AMB Physical AMB temperature S1 = 15.81C S2 = 18.44C X1 = 14.81C 04:10 11 -10.3 -9.9 -9.7 -9.8 XL ND OFF Stop SR, SL 100 kHz recording 04:15 12 -10.2 -22.1 -9.4 -22.5 X-Band to sky 04:15 Start XR, XL 100 kHz recording 04:20 13 -10.3 -22.1 -9.8 -22.5 SR ND ON (SR wrong direction) 04:25 14 -10.2 -22.1 -18.9 -22.6 S-RCP to sky 04:30 15 -10.3 -22.0 -22.3 -22.5 SR ND OFF Confirmed 12.5 ND, MFQ=ON 04:35 16 -10.0 -22.1 -21.7 -22.5 SL ND ON 04:40 17 -18.9 -22.1 -22.3 -22.6 S-LCP to sky 04:45 18 SL ND OFF Ambient load physical temperatures S1 = 15.31C S2 = 17.88C X1 = 14.38C 04:47 End XR, XL 100 kHz recordings 04:50 End all 25 kHz recordings ************************************ BOT ************************************ 04:55 DSS 14 on point (actual BOT) Interfering carrier visible at -75 kHz in XR SCHAN=3 spectrum. Modulation splatter visible for most of the pass. 05:20 BOT (scheduled) 05:49 -42.4 Lost S-RCP input to RSR2A 06:00 Goltz tries RSR1B on S-RCP; no signal there either. DSS14 suspects maser; tech is investigating. 06:11 Strong XR interference at +70 kHz 06:13 Interference gone (MGS TWNC ON) ********************************_MINI-CAL #1 ******************************** 06:14 Start 25 kHz recording (SCHAN=1) 06:15 01 -20.9 -21.6 -20.7 -21.8 S-RCP is back; XR ND ON 06:18 -20.4 -21.6 -18.9 -19.6 XR ND may have been delayed 06:19 02 -20.4 -21.6 -18.0 -21.7 XR ND OFF; SR ND ON 06:21 03 -20.8 -19.5 -20.6 -21.7 SR ND OFF; XL ND ON 06:24 04 -19.2 -21.5 -20.8 -21.8 XL ND OFF; SL ND ON 06:27 05 -20.9 -21.6 -21.2 -21.6 SL ND OFF 06:32 -20.8 -21.6 -21.5 -21.6 ADC amplitude (dB) 26 Carrier to noise (dB/Hz) -1843 Carrier offset (Hz) ************************************ BSR ************************************ 06:39 Start 100 kHz recordings 06:40 -20.9 -21.3 -20.6 -21.3 ADC amplitude (dB) FRO -21000 -74000 -21000 -74000 Used FRO (Hz) to center echo +71884 Carrier offset (Hz) MGS egress (no visible effect on MEX channels) 06:47 XR interference appears at 25 and 120 kHz (SCHAN=3) 06:52 5000 Echo width (Hz) 5 Echo peak amplitude (dB) 06:54 25 35 Echo SNR (dB/Hz) 3000 6000 Echo offset (Hz) 06:55 XL echo leaving 25 kHz passband (high side) 06:56 MGS interference at -100 kHz 07:05 -20.8 -21.4 -20.5 -21.3 ADC amplitude (dB)( 07:08 FRO 0 0 0 0 FRO (Hz) to center direct signal 07:09 Stop 100 kHz recordings *********************** MINICAL #2, SLEW #2, AND BCAL *********************** 07:10 01 -20.7 -21.3 -20.4 -19.3 XR ND ON 07:13 02 -20.6 -21.2 -20.4 -21.2 XR ND OFF 07:15 -20.8 -21.2 -17.8 -21.3 SR ND ON (late; typo) 07:16 03 -20.5 -19.2 -20.4 -21.1 SR ND OFF; XL ND ON 07:19 04 -18.9 -21.2 -20.3 -21.2 XL ND OFF; SL ND ON 07:22 05 -20.8 -21.3 -20.2 -21.1 SL ND OFF 07:24 Begin Slew #2 07:30 16 28 Carrier to noise (dB/Hz) -1341 -2910 Carrier offset (Hz) 07:33 22 Carrier to noise (dB/Hz) -2900 Carrier offset (Hz) 07:40 23 15 31 Carrier to noise (dB/Hz); DSS 14 reports XR in lock 07:43 15 30 CNR (dB/Hz); SR in lock 07:50 46 50 72 CNR (dB/Hz); Slew #2 ends ********************************* POST-CAL ********************************* 08:00 EOT Going to zenith; operator indicates he will stow 08:01 -42.4 S-RCP input to RSR2A gone 08:10 Antenna at zenith; Begin post-cal Step-01 S-RCP seems to be back 08:13 01 -10.2 -10.0 -20.8 -9.9 All to AMB 08:18 -9.9 -9.1 -9.9 Re-entered S-RCP configuration OD Ambient load physical temperatures S1 = 12.69C S2 = 15.19C X1 = 11.94C 08:20 02 -10.2 -9.9 -9.1 -9.9 XR ND ON (?) 08:23 03 -10.0 -9.9 -9.0 -9.9 XR ND OFF; SR ND ON 08:26 04 -10.2 -9.7 -9.1 -9.8 SR ND OFF; XL ND ON 08:29 05 -10.0 -10.0 -9.1 -9.8 XL ND OFF; SL ND ON 08:32 06 -18.4 -22.3 -20.9 -22.5 All to sky 08:35 07 -19.7 -19.9 -21.2 -22.4 SL ND OFF; XL ND ON 08:38 08 -20.3 -22.1 -42.4 -22.7 XL ND OFF; SR ND ON S-RCP input to RSR2A gone 08:41 09 -20.5 -22.1 -42.4 -20.0 SR ND OFF; XR ND ON 08:44 10 -20.1 -22.2 -42.4 -22.6 XR ND OFF Ambient load physical temperatures S1 = 12.50C S2 = 14.94C X1 = 11.94C Weather at DSS 14: T = 32F H = 33 percent P = 906 mb W = 2 MPH from S sky = partly cloudy 08:50 End of activity 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 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: 2006-01-21 Minor edits: 2006-07-04