Mars Express Bistatic Radar Experiment Operations Plan and Report 14-15 February 2012 Summary ======= DSN Antenna: 63 Orbit: 10352 Orbit Start Time: 2012-02-14T23:49:05 HGA Pointing: Specular Start Descend EQX End -------- ---------- -------- Specular Condition (ERT): 00:54 01:25 02:23 Target Latitude (deg N): 9.75 -0.03 -27.91 Longitude (deg E): 242.68 236.85 234.97 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 61.10 63.34 68.92 Slant Range (km): 11141. 10111. 6671. Slew Angle (deg): 57/80 53.33 42.15 Doppler (carrier, fd; Hz): -5668. -704. 15778. Doppler (echo, fr; Hz): 10195. 17458. 34125. Doppler Difference (fdd; Hz): -15863 -18162. -18347. Earth-Mars Distance (m): 1.072E+11 1.072E+11 1.072E+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. Jesse Velasco was in the JPL NOPE area. Dick Simpson monitored by telephone from Stanford. Performance Problems and Notes ============================== There were some problems with signal levels at the beginning of track. Expected ADC levels were not obtained with the nominal FGAIN and automatic attenuator settings on two channels. It appeared that the X-RCP levels were clipping intermittently. After some experimentation it was decided to change X-RCP FGAIN to 70 dB and not to make changes on other channels. Echoes were visible in all four channels; they became stronger as the experiment progressed. 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 2012/045 RSR1A RSR1B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ Set-Up 21:30 FGAIN 60 60 60 65 FGAIN settings (dB) 0 0 0 0 RSR tuning offset (Hz) Pre-Cal 22:14 1 -7.8 -18.4 -15.8 -11.9 All rcvrs to SKY 22:15 att auto -10.0 -9.9 -9.7 -9.9 Autoset attenuators 23.0 17.5 13.5 24.5 Attenuator settings (dB) 22:16 2 -10.0 -0.4 -9.6 -0.1 22:18 3 -0.8 -0.3 -9.6 -0.1 22:19 4 -0.7 -0.3 -0.4 -0.1 22:23 att auto -7.8 -9.8 -9.8 -4.8 Ambient load phys temps: S1=14.75 S2=14.56 X1=14.56 31.5 29.0 25.0 31.5 Attenuator settings (dB) Local weather: T=3.4C H=55.4 percent sky=clear 22:25 rec 3 e Begin 25 kHz recording 22:30 5 -7.6 -9.6 -9.7 -4.7 22:35 6 -7.6 -9.7 -9.8 -4.5 22:40 7 -7.5 -21.5 -9.7 -14.6 22:45 8 -7.7 -21.4 -9.7 -17.1 22:50 9 -7.6 -19.5 -9.9 -16.9 Confirm 12.5 K ND 22:55 10 -7.7 -9.6 -9.7 -4.7 Ambient load phys temps: S1=14.38 S2=14.25 X1=14.12 23:00 11 -7.7 -9.8 -9.8 -4.8 23:05 12 -7.7 -21.4 -9.8 -17.0 23:10 13 -7.7 -21.5 -9.8 -17.0 23:15 14 -7.7 -21.4 -19.3 -17.0 23:20 15 -7.7 -21.4 -21.3 -17.0 Confirm 12.5 K ND 23:25 16 -7.4 -21.4 -21.3 -17.1 23:30 17 -16.3 -21.4 -21.2 -17.0 23:35 18 -18.6 -21.5 -21.3 -17.1 Confirm 12.5 K ND Ambient load phys temps: S1=14.25 S2=13.88 X1=13.31 23:40 end -18.6 -21.5 -21.3 -17.1 Stop 25 kHz recording; antenna to point 2012/046 -------- BOT 00:10 -18.6 -21.2 -21.1 -13.0 X-Band AOS, TLM on 00:16 S-Band AOS 00:31 rec 3 e Resume 25 kHz recording 70 Revised FGAIN X-Band TLM OFF 00:33 -18.6 -21.2 -21.1 -12.2 Switch to planetary pointing predicts 00:34 fro 3/X +10k +10k RSR tuning offset (Hz) MiniCal1 00:37 1 -18.3 -21.1 -21.2 -10.8 Confirm 12.5 K ND 00:40 2 -18.4 -21.2 -19.2 -11.8 00:43 3 -18.5 -19.3 -21.1 -11.6 00:46 4 -16.3 -21.2 -21.1 -12.3 00:49 5 -18.4 -21.3 -21.1 -12.2 00:52 end -18.4 -21.1 -21.1 -12.1 BSR 00:54 rec 4 e -18.4 -21.2 -21.2 -12.5 Begin 100 kHz recording end BSR 02:15 rec 4 d -18.5 -21.3 -21.3 -16.3 End 100 kHz recording MiniCal2 02:24 1 -18.4 -21.3 -21.2 -14.0 Confirm 12.5 K ND 02:27 2 -18.4 -21.3 -19.4 -16.3 02:30 3 -18.4 -19.4 -21.1 -15.6 02:33 4 -16.2 -21.3 -21.2 -14.7 02:36 5 -18.3 -21.2 -21.2 -14.6 02:39 end -18.4 -21.2 -21.2 -14.7 02:40 sfro 3/X 0 0 RSR tuning offset (Hz) Return to spacecraft pointing predicts EOT 02:48 -18.4 -21.6 -21.1 -14.6 Move antenna to zenith (do not stow) Post-Cal 02:51 1 -7.6 -9.8 -9.7 -4.6 AMB load phys temps: S1=14.00 S2=12.81 X1=13.25 02:54 2 -7.7 -9.8 -9.7 -4.3 02:57 3 -7.6 -9.9 -9.5 -4.6 03:00 4 -7.6 -9.6 -9.8 -4.6 03:03 5 -7.4 -9.8 -9.7 -4.7 03:06 6 -16.1 -21.4 -21.0 -16.8 03:09 7 -18.4 -19.4 -21.1 -16.8 03:12 8 -18.5 -21.5 -19.2 -16.8 03:15 9 -18.5 -21.5 -21.0 -14.2 03:18 10 -18.5 -21.4 -21.1 -16.8 AMB load phys temps: S1=14.06 S2=12.81 X1=13.56 Local weather: T=1.2C H=54.7 percent sky=clear EOA 03:22 rec 3 d -18.4 -21.5 -21.1 -16.9 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 at 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 Strong echoes at end, modest at the beginning, and weak in the middle (but very visible at X-Band). Only over the final 20 minutes is the S-LCP echo strength above 20 zW, which means earlier is probably not good for estimating S-Band dielectric constant. Over the final 20 minutes (south of 15 deg S latitude), X-Band dielectric constant is 3-4 while S-Band dielectric constant is 2-2.5 (wavelength inversion). Dick Simpson Original: 2012-02-19 Post Analysis Summary added: 2013-05-08