Mars Express Bistatic Radar Experiment Operations Plan and Report 08 April 2012 Summary ======= DSN Antenna: 63 Orbit: 10536 Orbit Start Time: 2012-04-08T14:47:58 HGA Pointing: Specular Start Ascend EQX End -------- ---------- -------- Specular Condition (ERT): 17:25 18:33 18:47 Target Latitude (deg N): -2.77 -0.52 36.17 Longitude (deg E): 113.09 222.67 211.87 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 60.24 71.71 55.45 Slant Range (km): 6045. 1226. 2223. Slew Angle (deg): 59.52 36.59 69.11 Doppler (carrier, fd; Hz): -9130. 37849. 31158. Doppler (echo, fr; Hz): 29877. 16513. -22291. Doppler Difference (fdd; Hz): -39007 21336. 53449. Earth-Mars Distance (m): 1.179E+11 1.179E+11 1.179E+11 Experiment Set Up ================= This experiment was conducted using the Madrid DSS 63. Danny Kahan and Gene Goltz were in the Radio Science Support Area (RSSA) at JPL. Dick Simpson monitored by telephone from Stanford. Performance Problems and Notes ============================== The ADC levels were not as expected during the pre-cal; similar problems were noted in the pre-cal for the experiment on 2012/045, but there was no problem with the data. Simpson and Kahan discussed whether to report the problems to maintenance, but no action was taken so far as this BSR was concerned. The X-RCP carrier appeared to be clipping intermittently after X-Band telemetry was turned off. As with the experiment on 2012/045, the XR FGAIN was increased to 70 dB; but the FGAIN was reset to 65 after the slew to the BSR attitude began. The XR FGAIN was set to 70 when the spacecraft came back to Earth-point (19:04-19:12), but was returned to 65 for the post-cal. Echoes, sometimes strong, were seen on all four receiver channels during the course of the observations. 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 UNK RSR1B X-LCP 1-W auto 60 UNK RSR2A S-RCP 1-W auto 60 UNK RSR2B X-RCP 1-W auto 65-70 UNK RSR subchannels (SCHAN) were defined as follows: Table 2 ---------------------------------------------------------------------- Subchannel Sample Rate Comments ---------- ----------- --------------------------------------------- 1 2 ksps Occultation bandwidth (not recorded for BSR) 2 8 ksps Occultation backup (not recorded for BSR) 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 2012/099 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ Set-Up 14:10 FGAIN 60 60 60 65 FGAIN settings (dB) Pre-Cal 14:42 1 -11.2 -19.2 -18.3 -14.4 ADC voltage levels (dB) All to sky 14:49 att auto -9.7 -9.7 -9.7 -9.7 Attenuator auto reset 23.0 17.5 14.5 24.0 Attenuator settings (dB) 14:50 2 -9.7 -0.2 -9.7 -0.1 X-Band to ambient load 14:52 3 -0.9 -0.2 -9.7 -0.1 S-LCP to ambient load 14:53 4 -0.9 -0.2 -0.7 -0.0 S-RCP to ambient load 14:54 att auto -8.0 -9.7 -10.0 -5.2 Attenuator auto reset 31.5 29.5 25.5 31.5 Attenuator settings (dB) Ambient load phys temps: S1=20.24 C S2=22.62 C X1=17.00 C Local weather: T=18.1C H=31.3 percent sky=clear 14:55 rec 3 e Begin 25 kHz recording 14:57 5 -8.0 -10.0 -10.0 -5.3 ADC voltage levels (dB) 15:05 6 -7.9 -10.0 -10.0 -5.0 X-RCP noise diode ON 15:10 7 -8.0 -21.9 -9.9 -15.7 X-Band to sky 15:15 8 -7.9 -21.8 -9.9 -17.3 X-RCP noise diode OFF 15:20 9 -8.0 -19.5 -9.9 -17.4 X-LCP noise diode ON; Confirm 12.5K ND 15:25 10 -8.0 9.7 -10.0 -5.2 X-Band to ambient load; Ambient load phys temps: S1=20.75 C S2=22.88 C X1=16.69 C 15:30 11 -8.0 -9.9 -9.9 -5.3 X-LCP noise diode OFF 15:35 12 -8.0 -21.7 -10.0 -17.5 X-Band to sky 15:40 13 -8.0 -21.7 -9.8 -17.5 S-RCP noise diode ON 15:45 14 -7.9 -21.7 -19.0 -17.4 S-RCP to sky 15:50 15 -8.0 -21.8 -20.8 -17.5 S-RCP noise diode OFF; Confirm 12.5K ND 15:55 16 -7.8 -21.7 -20.8 -17.5 S-LCP noise diode ON 16:00 17 -16.5 -21.7 -20.9 -17.4 S-LCP to sky 16:05 18 -18.3 -21.7 -20.8 -17.3 S-LCP noise diode OFFl Confirm 12.5K Ambient load phys temps: S1=21.00 C S2=23.12 C X1=16.56 C End 16:10 end -18.3 -21.7 -20.8 -17.3 Stop 25 kHz recording 16:14 DSS 63 on point BOT 16:31 -17.7 -20.3 -20.0 -12.0 S/X-Band AOS 16:42 X-Band TLM OFF 16:43 70 X-RCP FGAIN reset (dB) 16:48 rec 3 e Resume 25 kHz recording 17:00 -17.9 -20.7 -20.3 -12.3 DSS 63 to Mars pointing predicts 65 Reset X-RCP FGAIN (dB) 17:03 sfro 3/XS 2k 29k 2k 29k 25 kHz rcvr offset (Hz) sfro 4/X 10k 10k 100 kHz offset (Hz) MiniCal1 17:05 1 -17.9 -20.8 -20.3 -11.6 XR ND ON; Confirm 12.5K ND 17:08 2 -17.9 -20.8 -18.8 -12.3 XR ND OFF; SR ND ON 17:11 3 -17.8 -19.0 -20.3 -12.1 SR ND OFF; XL ND ON 17:14 4 -16.1 -20.9 -20.3 -12.3 XL ND OFF; SL ND ON 17:17 5 -18.0 -20.8 -20.4 -12.2 SL ND OFF 17:20 end -18.0 -21.0 -20.4 -12.4 BSR 17:25 rec 4 e Begin 100 kHz recording 17:49 sfro 3/X 22k 22k 25 kHz rcvr offset (Hz) 17:57 sfro 3/X 15k 15k 25 kHz rcvr offset (Hz) 18:03 sfro 3/X 8k 8k 25 kHz rcvr offset (Hz) 18:05 sfro 3/S -4k -4k 25 kHz rcvr offset (Hz) 18:08 sfro 3/X 1k 1k 25 kHz rcvr offset (Hz) 18:15 sfro 3/X -6k -6k 25 kHz rcvr offset (Hz) 18:20 sfro 4/X -25k -25k 100 kHz rcvr offset (Hz) 18:24 sfro 3/X -13k -13k 25 kHz rcvr offset (Hz) 18:27 sfro 3/S -10k -10k 25 kHz rcvr offset (Hz) 18:29 sfro 3/X -20k -20k 25 kHz rcvr offset (Hz) 18:31 sfro 3/X -27k -27k 25 kHz rcvr offset (Hz) 18:34 sfro 3/X -34k -34k 25 kHz rcvr offset (Hz) 18:35 sfro 3/S -15k -15k 25 kHz rcvr offset (Hz) 18:36 sfro 3/X -41k -41k 25 kHz rcvr offset (Hz) 18:39 sfro 3/X -48k -48k 25 kHz rcvr offset (Hz) 18:41 sfro 3/S -19k -19k 25 kHz rcvr offset (Hz) 18:42 sfro 3/X -55k -55k 25 kHz rcvr offset (Hz) 18:45 sfro 3/X -60k -60k 25 kHz rcvr offset (Hz) end BSR 18:47 sfro 3/S -60k -60k 25 kHz rcvr offset (Hz) rec 4 d -18.3 -21.2 -20.6 -12.1 End 100 kHz recording MiniCal2 18:48 1 -18.2 -21.2 -20.7 -11.5 XR ND ON Confirm 12.5K ND 18:51 2 -18.1 -21.2 -18.9 -12.1 XR ND OFF; SR ND ON 18:54 3 -18.2 -19.3 -20.5 -12.0 SR ND OFF; XL ND ON 18:57 4 -16.2 -21.2 -20.6 -12.1 XL ND OFF; SL ND ON 19:00 5 -18.3 -21.2 -20.7 -11.7 SL ND OFF 19:03 end -18.2 -21.1 -20.7 -11.7 DSS 63 return to s/c pointing predicts 19:04 sfro 3/XS 0 0 0 0 25 kHz rcvr offset (Hz) 70 X-RCP FGAIN reset (dB) EOT 19:12 -18.3 -21.3 -20.8 -11.7 -17.4 DSS 63 to zenith 65 X-RCP FGAIN reset (dB) PostCal 19:17 1 -8.0 -9.9 -10.1 -5.2 All to AMB Ambient load phys temps: S1=21.38 C S2=22.38 C X1=16.88 C 19:22 2 -7.9 -9.8 -10.0 -5.0 XR ND ON 19:25 3 -8.0 -9.8 -9.8 -5.3 XR ND OFF; SR ND ON 19:28 4 -7.9 -9.5 -10.0 -5.2 SR ND OFF; XL ND ON 19:31 5 -7.6 -9.9 -10.0 -5.2 XL ND OFF; SL ND ON 19:34 6 -16.3 -21.7 -20.8 -17.4 All to sky 19:37 7 -18.3 -19.4 -20.9 -17.4 SL ND OFF; XL ND ON 19:40 8 -18.3 -21.7 -19.0 -17.5 XL ND OFF; SR ND ON 19:43 9 -18.4 -21.8 -20.8 -15.7 SR ND OFF; XR ND ON 19:46 10 -18.3 -21.8 -20.8 -17.5 XR ND OFF Ambient load phys temps: S1=21.12 C S2=22.12 C X1=16.88 C Local weather T=13.6C H=49.5 percent sky=clear EOA 19:50 end/rec 3 d End 25 kHz recording AMB = ambient load BOT = Beginning of Track BW = bandwidth C = Celsius 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 k = kilo, thousand K = Kelvin LOS = loss of signal ND = noise diode No = noise power NOP = Network Operations Plan occn = occultation Pc = carrier power rcvr = receiver S1 = ambient load for S-RCP S2 = ambient load for S-LCP s/c = spacecraft SKY = receiver looking a sky 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 There is a range of echo strengths - strong at the beginning near the equator and near the Brewster angle; weaker as the specular point moves south (and incidence angle exceeds 70 deg; strongest at incidence angles 80-85 deg (except S-LCP), and finally very broad (and hard to find) as the specular point crosses the equator heading north after periapsis. Throughout, the echo strength behaves as one might expect; the general trends in all four channels are similar. When one channel goes up or down, the others follow. X-Band echo strengths are larger than S-Band echo strengths. And RCP is usually higher than LCP except during the first 10 minutes (when incidence angle was 60-63 deg) and the last 10 minutes (when incidence angle was 66-55 deg). S-Band dielectric constant is higher than X-Band dielectric constant during the first half of the experiment (until maximum southern latitude (58.7S, 167.4E); they both start in the 3.5-4.0 range, then drop to about 2.0). During the next 15 minutes X-Band dielectric constant rises to almost 7 while S-Band rises to almost 4; then both drop to about 2. Over the final 15 minutes X-Band rises to almost 6 again; S-Band may do the same, but the data are too noisy to draw strong conclusions. In fact, it's hard to see the S-Band echo in either polarization during the final 15 minutes. It would be fair to say that the data are consistent with comparable dielectric constants at S- and X-Band during this time and that they range over 2-6. The X-RCP noise power density estimate (from the fixed noise window) has an increase of 2-3 percent increase over about 18:24-18:32, apparently because the X-RCP echo is spilling into the noise window. S-LCP noise power density wanders more than the others (+/-1 percent); but all seem to be good enough for the processing attempted here. An alarming result is that the S-Band noise is highly polarized. Except over frequencies where the echo is found, the average S-Band cross spectrum phase is about -1 radian with not a lot of variation. The data were processed through FNDLOOK with an unusually large MAXIMUM value (10000.); but reducing the parameter to a value more in line with the actual power per bin (100.) had no effect. The two S-Band channels show very different echo behaviors. Data from other experiments in 2012, including two at DSS 63, do not show this noise correlation. In fact, the noise power densities for S- RCP and S-LCP are very similar on this date -- much closer than they usually are. The cause for this anomaly is not known. Dick Simpson Original: 2012-04-09 Post Analysis Summary added: 2013-06-06 Post Analysis Summary edits: 2013-06-26