Gene and Danny: Here is the time line for the MEX BSR on day 218 (local time Thursday 08:50 PM to Friday 2:45 AM) at DSS 43, the first time we have done an experiment at DSS 43 since early May (day 128). This experiment is like many others we have done recently. The surface echo starts well above the carrier and drifts slowly upward for about 30 minutes. Then it reverses direction and ends only about 300 Hz above the carrier. Compared with earlier experiments, the maximum offset between carrier and echo is less, the drift rate is lower, and the need to put in FROs less frantic. There are no occultations on MEX orbits now, but this one comes close. We start (06:50) with an incidence angle about 51 deg, so LCP will be stronger than RCP. The spacecraft is at high altitude (slant range to the target about 8000 km) and the reflecting region is in plains material near a crater named Eddie (14N, 141E). The reflecting region drifts slowly south, crossing the equator and entering cratered terrain near 135E at 07:20. This is when the echo and carrier have greatest separation (about 45 kHz at X-Band). Ten minutes later the incidence angle is 60 deg, so RCP and LCP should be about equal. The reflecting region continues south. By 07:46 the reflecting region is at 25S, the incidence angle is 68 deg (RCP dominating), the echo is moving more quickly to lower frequencies, and the slant range is less than 4000 km (stronger echoes). The reflecting region reaches its most southerly latitude at 08:08 (57S, 190E), where incidence angle is 84 deg (almost all RCP) and slant range is 2000 km. When we end at 08:16 the reflecting region is at (45S, 230E), incidence angle is 87 deg, and slant range is 1500 km. MINICAL #2 should be done with two minute time steps since the spacecraft comes back to Earth point almost immediately; I have thrown in a late FRO to get the carrier out of the 25 kHz passband while we do the second MINICAL. For playback, I recommend the following for the 25 kHz data (no segment longer than 88 minutes): Pre-cal Track until start of 100 kHz data Surface until end of 100 kHz data Remaining track (MINICAL #2) and post-cal For 100 kHz playback two 22-minute segments and two 21-minute segments work. I expect to be in Palo Alto for this experiment. Try my home number (650- 494-9272) if you need to call. Thanks, Dick 2010/218 (UTC) - - - - - - - 03:50 Begin Pre-cal at DSS 43 FGAIN = 60 dB (all channels, except X-RCP) 65 dB X-RCP FRO_X = 0; FRO_S = 0 (all SCHAN) Start 4-channel 25 kHz recordings after Step 5 (new NOP) Stop 25 kHz recording after Step 20 (new NOP) 05:50 Begin track X-Band AOS (with low priority telemetry) 05:53 S-Band AOS 06:09 X-Band telemetry OFF 06:10 Resume 25 kHz recording 06:20 Advise DSS 43 of switch to planetary coordinates at 06:25 Advise DSS 43 of start of MINICAL #1 at 06:31 06:21 Begin SLEW #1 06:25 DSS 43 switch to planetary coordinates 06:28 FRO_X = +37000 Hz (SCHAN 3) FRO_S = +5000 Hz (SCHAN 3) FRO_X = +20000 Hz (SCHAN 4) 06:31 Begin MINICAL #1 06:46 End of MINICAL #1 (end of step 5) 06:50 End SLEW #1 Begin 100 kHz recording (SCHAN 4) 07:20 Maximum upward drift of echoes 07:48 FRO_X = +27000 Hz (SCHAN 3) 07:56 FRO_X = +17000 Hz (SCHAN 3) 08:02 FRO_X = +7000 Hz (SCHAN 3) 08:09 FRO_X = 0 Hz (SCHAN 3) 08:15 Advise DSS 43 that MINICAL #2 begins at 08:20 Advise DSS 43 to return to spacecraft pointing at 08:30 08:16 End 100 kHz recording (SCHAN 4) FRO_X = +37000 Hz (SCHAN 3) FRO_S = +37000 Hz (SCHAN 3) 08:20 Begin MINICAL #2 (two minute steps) 08:30 End MINICAL #2 (end of step 5) 08:31 FRO_X = 0 Hz (SCHAN 3) FRO_S = 0 Hz (SCHAN 3) 08:35 S-Band LOS X-Band telemetry ON (ignore) Early end of track (scheduled for 08:45) Go to zenith Begin post-cal when ready 09:45 End post-cal (or earlier, if post-cal complete) End 25 kHz recordings End of Activity