Gene and Danny: Here is the time line for the next MEX BSR on day 142 (local time Saturday 09:20 AM to approximately 3 PM) at DSS 63. This will be almost a perfect copy of the experiment we conducted on day 135; the primarily difference is that the ground track is about 70 degrees farther east. 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. It appears the spacecraft continues to transmit through the occultation and we may be able to see both ingress and egress (at X-Band). I suggest we plan our operations as though this were entirely BSR but that we capture both occultations in case there is something interesting (we got the X-Band egress on day 135). If we do it this way, the surface observations plus occultations will take over 2-1/2 hours (18:31- 21:10); we will only record at 100 kHz for the surface part (19:06-20:32). The FRO schedule is active but should not be stressful; we use the central half of the 25 kHz bandwidth with updates being no more frequent than once every 3 minutes. The DSN Keyword File shows "BEGIN SR FIXED" at 20:15:01. We should ask the station to skip this command, as they did on day 135. The BSR will be better if we do not fix the subreflector. If this is not possible, I can live with the consequences. The reflecting region starts at (17S, 21W), then drifts slowly southwest to (30S, 26W). This surface is not as smooth as what we probed on day 135, so the echoes are likely to be weaker. The reflecting region moves southeast to (56S, 0W) and the occultation occurs at (55S, 33E). Incidence angle on the surface increases from 40 degrees at 19:06 (LCP much stronger than RCP) to 60 degrees at 20:00 (approximately equal RCP and LCP) to 90 degrees at occultation (echoes will be entirely RCP). 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 three 22 minute segments and one 20 minute segment would be best; but I can carve these up at Stanford if you give me an 86 minute file from each RSR. I expect to be at Donner Summit during this experiment. You can phone me at 530-426-3536. If that does not work, try the mobile phone 650-380-0675. Thanks, Dick 2010/142 (UTC) - - - - - - - 16:20 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) 18:20 Begin track S/X-Band AOS X-Band telemetry ON - ignore it 18:31 Resume 25 kHz recording X-Band telemetry OFF 18:35 Advise DSS 63 of switch to planetary coordinates at 18:45 Advise DSS 63 of start of MINICAL #1 at 18:48 18:42 Begin SLEW #1 18:45 DSS 63 switch to planetary coordinates 18:46 FRO_X = +58000 Hz (SCHAN 3) FRO_S = +9000 Hz (SCHAN 3) FRO_X = +35000 Hz (SCHAN 4) 18:48 Begin MINICAL #1 19:03 End of MINICAL #1 (end of step 5) 19:06 End SLEW #1 Begin 100 kHz recording (SCHAN 4) 20:08 FRO_X = +46000 Hz (SCHAN 3) 20:14 Ask station not to execute "BEGIN SR FIXED" command at 20:15:01 20:15 FRO_X = +34000 Hz (SCHAN 3) 20:20 FRO_X = +23000 Hz (SCHAN 3) 20:24 FRO_X = +12000 Hz (SCHAN 3) 20:25 Advise DSS 63 that MINICAL #2 begins at 20:35 Advise DSS 63 of return to spacecraft pointing coordinates at 20:50 20:27 FRO_X = +2000 Hz (SCHAN 3) 20:30 Occultation ingress (S/X-Band LOS) 20:32 End 100 kHz recording (SCHAN 4) 20:33 FRO_X = 0 Hz (SCHAN 3) 20:35 Begin MINICAL #2 20:50 End MINICAL #2 (end of step 5) DSS 63 return to spacecraft pointing predicts 20:55 Occultation egress X-Band AOS (probably no S-Band) 21:05 Early end of track (scheduled EOT 21:30) Go to zenith Begin post-cal when ready 22:20 End post-cal (or earlier, if post-cal complete) End 25 kHz recordings End of Activity