Mars Express Bistatic Radar Experiment Operations Plan and Report 13 September 2009 Summary ======= DSN Antenna: 14 Pass: 2297 Orbit: 7308 Orbit Start Time: 2009-09-13T07:39:22 HGA Pointing: Specular Start Max North End -------- ---------- -------- Specular Condition (ERT): 10:00 10:44 11:07 Target Latitude (deg N): 56.32 72.15 56.03 Longitude (deg E): 237.20 271.61 315.00 Rp (km): 3394. 3394. 3394. Incidence/Reflection Angle (deg): 81.37 68.97 48.59 Slant Range (km): 8589. 4021. 1044. Slew Angle (deg): 17.26 42.06 82.82 Doppler (carrier, fd; Hz): 48303. 77835. 70034. Doppler (echo, fr; Hz): 42799. 72321. 84061. Doppler Difference (fdd; Hz): 5505. 5514. -14026. Earth-Mars Distance (m): 2.287E+11 2.287E+11 2.287E+11 Experiment Set Up ================= This experiment was conducted using the Goldstone DSS 14. Danny Kahan and Gene Goltz were in the Radio Science Support Area (RSSA) at JPL. Dick Simpson was available by phone. This report is based on notes provided by Kahan and Goltz. Performance Problems and Notes ============================== No S-RCP signals were observed using the open-loop equipment. However, S-RCP signals did reach the closed-loop receivers, suggesting that a cable may have been disconnected. DR-G109692 was opened to document the problem. The same error affected the BSR experiment on the previous day (day 255). S-LCP data are very noisy; Top was more than 110K. The problem began with the experiment on 2009/226. In December the problem was traced to a bad board in the RSR; the board was replaced, and tests in January confirmed that Tsys had been restored to normal levels. There is something wrong with Mini-Cal #1 on X-RCP; the noise level with the diode on is only about half what it should be. Telemetry was collected for 37 minutes after BOT and the noise diodes were reset. The NMC log does not show an MFQ=ON command prior to the X-RCP Mini-Cal #1, so it is likely that the noise diode was running at 50 percent duty cycle. An MFQ=ON command was issued at 09:50:18, before the X-LCP Mini-Cal #1. If a 50 percent duty cycle is assumed, Tsys = 24.15K during Mini-Cal #1. There is also a small error in the X-RCP Mini-Cal #2 calculation. A weak interfering signal passed through the X-RCP passband during Mini-Cal#2; its presence increased the presumed noise power by about 1 percent, leading to an underestimate of the Tsys by about 0.5K. Mini-Cal #2 started two minutes early (11:06 rather than the planned 11:08). This affects primarily X-RCP since the other channels were within the nominal Mini-Cal #2 time window. 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 UNK RSR3B X-LCP 1-W auto 60 UNK RSR2A S-RCP 1-W auto 60 UNK RSR2B X-RCP 1-W auto 60 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 2009/256 RSR3A RSR3B RSR2A RSR2B -------- ----- --------- ----- ----- ----- ----- ------------------------ FGAIN 06:30 60 60 60 60 Set FGAIN PreCal 07:27 1 1.8 -12.4 -20.8 -12.6 ADC amplitudes (dB) 07:31 att auto -9.8 -9.8 -20.9 -9.7 Initialize attenuators 22.0 12.0 0.0 10.0 Attenuator Settings (dB) 07:33 2 -9.6 -0.1 -20.9 0.1 07:36 3 -5.3 -0.1 -20.8 0.1 07:36 4 -5.3 -0.1 -20.8 0.1 07:37 att auto -9.9 -9.8 -20.8 -9.8 Reset attenuators 26.5 24.0 0.0 22.5 Attenuator settings (dB) AMB load phys temps: S1=18.19C S2=23.69C X1=15.38C Local weather: T=23.6C H=34.7 percent sky=clear 07:38 rec 3 e Begin 25 kHz recording 07:42 5 -9.7 -9.7 -20.7 -9.8 07:46 6 -9.9 -9.8 -20.8 -9.5 07:50 7 -9.8 -21.8 -20.8 -19.8 07:55 8 -9.8 -21.9 -20.8 -22.2 08:00 9 -9.7 -19.6 -21.0 -22.2 Confirmed 12.5K ND 08:05 10 -9.8 -9.6 -20.8 -9.7 AMB load phys temps: S1=17.88C S2=23.19C X1=13.12C 08:10 11 -9.7 -9.8 -20.7 -9.7 08:15 12 -9.8 -21.9 -20.8 -22.2 08:20 13 -9.8 -21.7 -20.9 -22.3 08:25 14 -9.7 -21.8 -20.8 -22.3 08:30 15 -9.8 -21.8 -20.8 -22.2 Confirmed 12.5K ND 08:35 16 -9.6 -21.4 -20.8 -22.3 08:40 17 -13.3 -21.8 -20.7 -22.3 08:45 18 -13.7 -21.7 -20.8 -22.1 AMB load phys temps: S1=17.44C S2=22.69C X1=14.88C 08:50 end -13.9 -21.8 -20.8 -22.3 Stop 25 kHz recording BOT 09:00 -15.7 -19.6 -20.8 -17.5 Collect TLM until 09:37 09:37 rec 3 e Resume 25 kHz recording 09:43 -14.4 -20.5 -20.9 -19.2 DSS 14 switch to Mars pointing predicts 09:44 sfro 3/SX +25K +25K +25K +25K MiniCal1 09:45 1 -15.5 -20.6 -20.9 -18.6 Confirmed 12.5K ND 09:48 2 -15.6 -20.7 -21.0 -19.4 09:51 3 -16.1 -18.9 -20.9 -19.3 09:54 4 -15.3 -20.7 -20.9 -19.5 09:57 5 -16.3 -20.9 -20.8 -10.7 10:00 end -15.7 -20.9 -20.8 -21.1 BSR 10:00 sfro 3/SX 0 -7K 0 -7K Rcvr tuning offset (Hz) Begin 100 kHz recording 10:54 sfro 3/X -2K -2K Rcvr tuning offset (Hz) 10:59 sfro 3/X +3K +3K 11:03 sfro 3/X +8K +8K 11:07 sfro 3/SX +25K +25K +25K +25K 11:07 end BSR -15.4 -21.3 -20.9 -18.4 End 100 kHz recording MiniCal2 11:08 1 -15.9 -21.4 -20.9 -18.5 Confirmed 12.5K ND 11:11 2 -15.2 -21.2 -20.8 -20.1 11:14 3 -13.5 -19.3 -20.9 -20.1 11:17 4 -17.0 -21.6 -20.9 -20.1 11:20 5 -14.0 -21.5 -20.9 -20.1 11:23 end -16.1 -21.4 -20.8 -20.0 11:24 sfro 3/SX 0 0 0 0 Remove tuning offsets DSS 14 switch to s/c pointing predicts 11:35 EOT/stow -15.1 -21.4 -20.9 -19.9/-22.3 PostCal 11:41 1 -9.9 -9.9 -20.9 -9.6 AMB load phys temps: S1=16.31C S2=21.25C X1=14.25C 11:48 2 -9.8 -9.7 -20.8 -9.5 11:51 3 -9.8 -9.7 -20.9 -9.7 11:54 4 -9.7 -9.6 -20.9 -9.6 11:57 5 -9.6 -9.7 -20.8 -9.7 12:00 6 -13.7 -21.9 -20.8 -22.2 12:03 7 -14.1 -19.6 -20.8 -22.3 12:06 8 -14.2 -21.9 -20.7 -22.3 12:09 9 -14.3 -21.9 -20.8 -19.8 12:12 10 -14.2 -21.9 -20.7 -22.3 AMB load phys temps: S1=16.19C S2=21.06C X1=14.25C Local weather: T=21.3C H=38.1 percent sky=clear EOA 12:15 end -14.2 -21.9 -20.8 -22.3 End 25 kHz recording AMB = ambient load BOT = Beginning of Track 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 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 s/c = spacecraft 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 echo started (10:00) on the low side of the carrier, drifted lower, then reversed direction. It crossed the carrier at about 10:56, and accelerated to higher frequencies. X-Band FROs were used at 10:54, 10:59, and 11:03 to keep the echo within the 25 kHz pass band until the end at 11:07. No FROs were used at S-Band or for the 100 kHz recordings. X-Band 10-s Average Data: The table below summarizes the time division for capturing the echo power as the signal drifted through the 25 kHz X-Band receiving pass band. Int Times Spectra Noise Bins Carrier Echo Bins Notes Bins --- ----------------- ------- --------------- ------- ---------------- ------ A 10:00:00-10:30:00 001-180 104:280,671:916 658:668 357:526->282-431 B 10:30:00-10:40:00 181-240 104:280,671:916 658:668 282:431->302:451 C 10:40:00-10:50:00 241-300 104:300,671:916 658:663 302:451->382:630 D 10:50:00-10:54:00 301-324 104:448,776:916 658:663 450:650->673:770 [1,2] DE 10:54:00-10:54:10 325 104:380,771:916 453:457 382:769 [1,2] E 10:54:10-10:56:00 326-336 104:380,775:916 453:457 382:582->422:628 [1] F 10:56:00-10:59:00 337-354 104:448,775:916 453:457 460:635->565:765 FG 10:59:00-10:59:10 355 104:245,740:916 453:457 390:738 [3,4] G 10:59:10-11:03:00 356-378 104:245,755:916 248:252 390:590->550:750 GH 11:03:00-11:03:10 379 104:245,755:916 045:049 390:750 [5,6] H 11:03:10-11:07:00 380-402 104:375,755:916 045:049 390:590->550:750 [6,7] Notes: [1] Used carrier suppression to estimate echo power, as echo drifted part way through frequency of directly propagating signal [2] X-Band tuning offset at 10:54 [3] X-Band tuning offset at 10:59 [4] Used carrier suppression because receiver offset caused echo to appear at the same frequency as the carrier [5] X-Band tuning offset at 11:03 [6] Carrier at about bin 47, outside the processing window [7] Increased X-RCP noise power because Mini-Cal #2 started prematurely at approximately 11:05:52 (spectrum 396) S-Band 10-s Average Data: The table below summarizes the time division for capturing the echo power as the signal drifted through the 25 kHz S-Band receiving pass band. Int Times Spectra Noise Bins Carrier Echo Bins Notes Bins --- ----------------- ------- --------------- ------- ---------------- ------ A 13:20:00-14:08:00 001-288 104:334,481:916 452:456 338:451 B 14:08:00-14:14:20 289-326 104:376,519:916 452:456 381:451->457:515 [1] C 14:14:20-14:27:00 327-402 104:449,680:916 452:456 457:515->542:676 Notes: [1] Used carrier suppression as the echo drifted through the frequency of the directly propagating signal S-Band 60-s Average Data: The table below summarizes the time division for capturing the echo power as the signal drifted through the 25 kHz S-Band receiving pass band. Int Times Spectra Noise Bins Carrier Echo Bins Notes Bins --- ----------------- ------- --------------- ------- ---------------- ------ A 13:20:00-14:08:00 001-048 104:334,461:916 452:456 338:451 B 14:08:00-14:16:00 049-056 104:376,519:916 452:456 381:451->457:515 [1] C 14:16:00-14:27:00 057-067 104:449,680:916 452:456 457:515->542:676 Notes: [1] Used carrier suppression as the echo drifted through the frequency of the directly propagating signal Dielectric Constant: X-Band dielectric constant is typically 1.6-2.1 throughout the experiment, with slightly higher values in the middle. These are extremely low compared with values measured at other times. There are no S-Band measurements. Dick Simpson Original: 2009-12-03 Added note about MiniCal #1 X-RCP problem: 2009-12-07 Updated S-LCP noise status: 2011-04-27