Gene and Danny: Here is the time line for the next MEX BSR on day 135 (local time Saturday 09:25 AM to approximately 3 PM) at DSS 63. This will be very similar to the experiment we tried to conduct on day 128. The surface echo starts well above the carrier, drifts slowly upward for about 40 minutes, changes direction, and then races back toward the carrier, which it joins at occultation. In this case, it appears the spacecraft continues to transmit at X-Band through the occultation and we may be able to see both ingress and egress. I suggest we plan our operations as though this were entirely BSR but that we capture both occultations in case there is something interesting. If we do it this way, the surface observations plus occultations will take over 2-1/2 hours (18:37-21:15); we will only record at 100 kHz for the surface part (19:12-20:40). I have relaxed the FRO schedule so that we use more of the 25 kHz bandwidth and the updates are no more frequent than once every 3 minutes. The DSN Keyword File shows "BEGIN SR FIXED" at 20:22:18. If we can override that command, the BSR will be better; if not, I can live with the consequences. That is a useful configuration adjustment for two-way occultations; we have occultations, but ours will not benefit much from having the subreflector fixed in one-way mode. Having the station do something like "END SR FIXED" at 20:22:20 would probably do the job. The reflecting region starts in Sinai Planum, then drifts slowly southwest to Solis Planum. Both regions are very smooth in Earth-based radar data from the 1970s, and you should see stronger echoes at both S- and X- Band than you are used to at the beginning of recent experiments. The specular point then drifts south through cratered terrain, crosses Thaumasia Fossae, and ends by crossing the southern edge of Argyre Planitia very quickly just before occultation. Incidence angle on the surface increases from 40 degrees at 19:12 (LCP much stronger than RCP) to 60 degrees at 20:06 (approximately equal RCP and LCP) to 90 degrees at occultation (echoes will be entirely RCP). The SCHAN 3 X-Band FRO assignments below are intended to keep the echo +/-6 kHz from the center of the 25 kHz window. The S-Band carrier will be at the far left edge of its 25 kHz window; the surface echo will roam over most of the remaining frequency space. The SCHAN 4 settings keep the X-Band action within +/- 35 kHz of the center of the 100 kHz window. The S-Band carrier will be near the center of its 100 kHz window, and the echo will roam 0-20 kHz higher. 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 observations until end of 100 kHz data Remaining track (ingress, MINICAL #2, egress) Post-cal For 100 kHz playback four 22 minute segments would be best; but I can carve these up at Stanford if you give me an 88 minute file from each RSR. I expect to be at home during this experiment. You can phone me at 650-494- 9272. If that does not work, try the mobile phone 650-380-0675. Thanks, Dick 2010/135 (UTC) - - - - - - - 16:25 Begin Pre-cal at DSS 63 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) 18:25 Begin track S/X-Band AOS; X-Band telemetry ON - ignore it 18:37 Resume 25 kHz recording X-Band telemetry OFF 18:45 Advise DSS 63 of switch to planetary coordinates at 18:50 Advise DSS 63 of start of MINICAL #1 at 18:55 18:48 Begin SLEW #1 18:50 DSS 63 switch to planetary coordinates 18:51 FRO_X = +58000 Hz (SCHAN 3) FRO_S = +9000 Hz (SCHAN 3) FRO_X = +35000 Hz (SCHAN 4) 18:55 Begin MINICAL #1 19:10 End of MINICAL #1 (end of step 5) 19:12 End SLEW #1 Begin 100 kHz recording (SCHAN 4) 20:15 FRO_X = +46000 Hz (SCHAN 3) 20:22 FRO_X = +34000 Hz (SCHAN 3) 20:22:20 Ask station to override "BEGIN SR FIXED", which is in DSN Keyword File at 20:22:18 20:27 FRO_X = +22000 Hz (SCHAN 3) 20:30 Advise DSS 63 of return to spacecraft pointing coordinates at 20:40 Advise DSS 63 that MINICAL #2 begins at 20:45 20:31 FRO_X = +10000 Hz (SCHAN 3) 20:34 FRO_X = 0 Hz (SCHAN 3) 20:38 Occultation ingress S/X-Band LOS 20:40 End 100 kHz recording (SCHAN 4) DSS 63 return to spacecraft pointing coordinates 20:45 Begin MINICAL #2 21:00 End MINICAL #2 (end of step 5) FRO_S = 0 Hz (SCHAN 3) 21:04 Occultation egress X-Band AOS (probably no S-Band) 21:15 Early end of track (scheduled EOT 21:35) Go to zenith Begin post-cal when ready 22:35 End post-cal (or earlier, if post-cal complete) End 25 kHz recordings End of Activity