Mars Express Bistatic Radar Experiment Operations Plan and Report 26 June 2009 Summary ======= DSN Antenna: 14 Pass: 2218 Orbit: 7033 Orbit Start Time: 2009-06-26T07:35:01 HGA Pointing: Specular Start Center End -------- ---------- -------- Specular Condition (ERT): 10:45 11:17 11:53 Target Latitude (deg N): 43.34 -22.19 -59.25 Longitude (deg E): 291.49 323.47 199.51 Rp (km): 3375. 3375. 3375. Incidence/Reflection Angle (deg): 62.16 62.88 57.84 Slant Range (km): 35.31 635. 3640. Slew Angle (deg): 55.69 54.25 64.32 Doppler (carrier, fd; Hz): 26874. 8859 -21788. Doppler (echo, fr; Hz): 49829. 9598. -49475. Doppler Difference (fdd; Hz): -22955. -739. 27687. Earth-Mars Distance (m): 2.858E+11 2.858E+11 2.858E+11 Experiment Set Up ================= This experiment was conducted using Goldstone's DSS 14. Danny Kahan, Gene Goltz, and Dick Simpson were in the Radio Science Support Area (RSSA) at JPL. Jesse Velasco was in the NOPE area. Kahan handled RSRs, Goltz did communications. Performance Problems and Notes ============================== This was the first MEX bistatic radar experiment conducted using a calibration procedure written into the MEX Network Operations Plan rather than a briefing message sent to the station before the observation. Echoes were visible in both X-Band polarizations before the experiment officially began. They were visible intermittently in S-Band. Echo strength varied during the experiment, seemingly being weaker as the specular point passed the Viking Lander 1 site and peaking as it passed the Eberswalde and Holden MSL sites. There was a brief strong S-Band echo at 11:26, after which all echoes disappeared until about 11:33. The ADC amplitude readings on S-LCP were not stable. This has been seen before without there being a problem with RSR data; so no fixes were attempted in real time. Learned that the antenna continues to 'track' if simply moved to zenith. If 'stowed' the brakes are put on. The S-LCP noise diode was supposed to be turned off in step 7 of the post-cal (12:58). That did not happen, so there is no 'dark sky' measurement at the end of the post-cal. The NMC log shows two 'snt enable' commands at 12:58 instead of a 'disable' followed by an 'enable'; so this was probably an operator error. 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 RSR3A S-RCP 1-W auto 60 Kahan RSR3B 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-RCP X-LCP S-LCP X-RCP Notes / Comments 2008/231 RSR2A RSR2B RSR3A RSR3B -------- ----- --------- ----- ----- ----- ----- ------------------------ Pre-Cal 08:35 1 -15.1 -9.2 -11.5 -9.9 Orig ADC amplitudes (dB) 08:40 17.5 12.5 4.0 11.5 Attens after AUTO reset 08:41 2 -10.5 -0.5 -9.9 0.1 X-Band to ambient load 08:43 3 -6.0 -0.2 -10.0 0.1 SL to ambient load 08:45 4 -6.1 -0.3 -0.6 0.1 SR to ambient load Ambient load phys temps: S1 = 19.19 C S2 = 23.25 C X1 = 16.12 C T = 21.7 C H = 22.3 percent sky clear 08:49 21.5 24.5 15.5 24.5 Attens after AUTO reset 08:50 Begin 25 kHz recording 08:52 5 -10.1 -9.9 -10.5 -10.1 ADC amplitude (dB) 08:55 6 -10.1 -10.1 -10.4 -9.9 XR ND ON 09:00 7 -10.0 -22.1 -10.5 -20.3 X-Band to sky 09:05 8 -10.0 -22.1 -10.4 -22.9 XR ND OFF 09:10 9 -10.0 -19.8 -10.4 -22.8 XL ND ON 12.5 ND confirmed 09:15 10 -10.1 -9.7 -10.4 -10.2 X-Band to AMB load AMB phys temps: S1 = 18.75 C S2 = 22.81 C X1 = 15.69 C 09:20 11 -10.1 -9.8 -10.4 -10.2 XL ND OFF 09:25 12 -10.0 -22.1 -10.5 -22.8 X-Band to sky 09:30 13 -10.0 -22.1 -10.2 -22.7 SR ND ON 09:35 14 -9.9 -22.2 -19.5 -22.8 SR to sky 09:40 15 -9.9 -22.0 -21.5 -22.7 SR ND OFF 09:45 16 -9.9 -22.1 -21.3 -22.9 SL ND ON 09:50 17 -16.2 -22.2 -21.3 -22.8 SL to sky 09:55 18 -16.8 -22.2 -21.3 -22.9 SL ND OFF 12.5 ND confirmed Amb load phys temps: S1 = 18.12 C S2 = 22.19 X1 = 15.12 10:00 -15.3 -22.2 -21.3 -22.7 SL unstable(?) Begin moving to point 10:09 -17.3 -18.7 -19.2 -19.0 On point BOT 10:16 Tracking 10:17 -16.9 -18.7 -19.2 -19.0 ADC amplitude (dB) 18.4 25.4 41.8 53.1 Pc/No (dB/Hz) -1424 -3230 -1428 -3238 fc (carrier offset, Hz) 10:21 telemetry OFF 10:24 19.6 32.8 42.1 60.4 Pc/No (dB/Hz) 10:28 planetary coords loaded 10:29 42.0 56.7 Pc/No, SLEW #1 beginning 10:30 23000 22000 23000 22000 FRO (SCHAN 3) -6000 -6000 FRO (SCHAN 4) MINICAL1 1 -16.0 -19.4 -19.6 -18.2 XR ND ON 10:33 2 -18.2 -19.6 -18.4 -19.6 XR ND OFF, SR ND ON 10:36 3 -16.9 -18.3 -19.8 -19.8 SR ND OFF, XL ND ON 10:39 4 -15.4 -19.1 -19.8 -19.8 XL ND OFF, SL ND ON 10:42 5 -18.1 -19.8 -19.9 -19.8 SL ND OFF BSR 10:44 7500 7500 echo frequency (Hz) 10:45 Begin 100 kHz recordings 10:48 30.0 30.0 echo pwr density (dB/Hz) 11:00 -15.7 -20.4 -20.3 -20.2 ADC amplitude (dB) 25.0 echo pwr density (dB/Hz) 6674 echo peak frequency 11:02 19.2 15.1 echo pwr density (dB/Hz) 6000 6400 echo peak frequency (Hz) 11:08 28.0 echo pwr density (dB/Hz) -548 echo peak frequency 11:09 6000 6000 FRO (SCHAN 3) 11:12 Consistent S/X echoes 11:13 0 0 FRO (SCHAN 3) 11:15 -4000 -4000 FRO (SCHAN 3) 11:17 -11000 -9000 -11000 -9000 FRO (SCHAN 3) -16.5 -20.8 -20.5 -20.5 ADC amplitude 25.0 echo pwr density (dB/Hz) 5036 echo peak frequency (Hz) 11:21 -18000 -18000 FRO (SCHAN 3) 11:24 -25000 -25000 FRO (SCHAN 3) 11:29 -33000 -33000 FRO (SCHAN 3) 11:52 -15.2 -21.1 -20.8 -21.8 ADC amplitude (dB) 21.0 echo pwr density (dB/Hz) 2500 echo peak frequency (Hz) 11:53 23000 22000 23000 22000 FRO (SCHAN 3) End 100 kHz recordings Begin SLEW #2 MINICAL2 11:54 1 -13.2 -21.3 -20.9 -19.7 XR ND ON 11:57 2 -13.3 -21.3 -19.3 -21.8 XR ND OFF, SR ND ON 12:00 3 -12.8 -19.4 -20.9 -21.8 SR ND OFF, XL ND ON 12:03 4 -13.6 -21.3 -20.9 -21.7 XL ND OFF, SL ND ON 372 Weak XR MEX image (Hz) 12:04 End SLEW #2 12:06 5 -14.8 -21.4 -20.9 -21.7 SL ND OFF 12:09 End mini-cal BCAL 12:10 0 0 0 0 FRO (SCHAN 3) 12:11 -17.1 -21.4 -20.9 -21.6 ADC amplitude (dB) 18.6 42.0 42.0 67.3 Pc/No (dB/Hz) -1259 -2618 -1259 -2622 Peak carrier freq (Hz) 12:26 -13.2 -21.5 -21.0 -20.9 S-Band OFF 60.7 X ranging ON EOT 12:30 X-Band OFF PostCal 12:37 -17.6 -22.1 -21.4 -22.9 Antenna at stow 12:40 1 -10.1 -10.0 -10.4 -10.2 All to AMB Ambient load phys temps: S1 = 16.56 C S2 = 20.56 C X1 = 14.25 C 12:43 2 -10.0 -9.9 -10.4 -10.0 XR ND ON 12:46 3 -10.1 -10.0 -10.1 -10.2 XR ND OFF, SR ND ON 12:49 4 -10.0 -9.8 -10.5 -10.2 SR ND OFF, XL ND ON 12:52 5 -9.8 -9.8 -10.5 -10.1 XL ND OFF, SL ND ON 12:55 6 -16.8 -22.2 -21.4 -22.8 All to sky 12:58 7 -16.7 -19.9 -21.3 -22.8 SL ND OFF, XL ND ON 13:01 8 -17.0 -22.1 -19.5 -22.8 XL ND OFF, SR ND ON 13:04 9 -17.0 -22.0 -21.4 -20.3 SR ND OFF, XR ND ON 13:07 10 -16.4 -22.2 -21.5 -22.8 XR ND OFF Ambient load phys temps: S1 = 16.30 C S2 = 20.38 C X1 = 14.12 C Local Weather: T = 20.0 C H = 26.5 percent sky clear 13:10 End 25 kHz recordings End of activity 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 Post-Analysis Summary The specular track began at Tempe Fossae (10:45, 43N, 69W); the illumination ellipse was 79 x 37 km, with the spacecraft 29 degrees east of north viewed from the specular point. The specular point moved southeast across cratered terrain until entering Chryse Planitia (11:00, 26N, 49W). It passed close to the Viking Lander 1 site (11:02, 22N, 47W), then ran parallel to and somewhat west of Simud Vallis. It crossed the eastern ends of Capri Chasma and Eos Chasma (11:13, 10S, 38W), then moved into cratered terrain. It passed about 200 km west of Holden Crater (11:18, 27S, 38W) at periapsis (illumination ellipse 14 x 7 km, oriented 87 degrees east of north) and crossed Nirgal Vallis (11:19, 30S, 38W). It crossed Nereidum Montes (the north rim of Argyre Plantia (11:22, 40S, 40W), the center of Argyre (11:25, 50S, 43W; illumination ellipse 18 x 9 km, oriented 104 degrees east of north), and Charityum Montes (the south rim) (11:27, 57S, 50W). In southern cratered terrain it grazed the northwest rim of Von Karman Crater (11:30, 65S, 60W) and the northwest rim of Schmidt Crater (11:34, 71S, 80W) and passed through the northern half of Stoney Crater (11:44, 69S, 138W) before ending at (11:53, 60S, 161W; illumination ellipse 72 x 38 km, with a spacecraft azimuth of 120 degrees east of north at the specular point). Incidence angle started at 62.2 degrees, peaked at 63.3 degrees (11:12), and ended at 58 degrees. Slant range started at 3531 km, dropped to 629 km (11:18), and ended at 3640 km. There were large fluctuations in X-Band echo power (10 dB) until the specular point entered the southern rim of Argyre (11:27); X-RCP and X-LCP echo powers had very similar variations, and the dielectric constant was 4.0+/-0.5. After 11:27, the powers increased slowly and the dielectric constant was mostly 2.2-2.5. The changes in echo power probably resulted from changes in rms surface slopes (and the evolving observational geometry) since there are apparently only two primary values for dielectric constant. The VL-1 site appears to be in a locally rough area (echo power 300 zW, compared with 1600 zW over 18-20N); the region east of Holden Crater appears to be locally smoother (echo power 2300 zW). Strongest echoes were from an elevated cratered planeau north of Capri Chasma (3600 zW), weakest echoes were from the south rim of Argyre (55 zW). The center of Argyre was surpisingly smooth (2400 zW). S-Band echoes and dielectric constant were also variable, but harder to interpret because of the higher relative noise. Strongest echoes were obtained at 11:12 (elevated cratered platau north of Capri Chasma and 11:26 (center of Argyre). The S- and X-Band dielectric constants are comparable on the plateau (4.0); in Argyre, the S-Band value is 4-5 while the X-Band value is 2.8-4. Dick Simpson Original: 2009-06-26 Filled in summary table at beginning: 2009-06-29 Added note about S-LCP noise diode failure during post-cal: 2009-07-07 Post-analysis summary added: 2009-07-28 Updated pass number: 2009-08-12