Gene, Danny:

Here is the time line for the MEX BSR on Monday.  I'm going to stay at
Stanford for this one to save on body wear and tear and to save money so I
can afford to go to the MEX/VEX meetings in Brussels next month.  This should
look very much like the MEX BSR we did on 2008/185 except that there's no
time squeeze.  I'll be in touch via phone; you can call me at 650-723-0296.

We have 29 minutes of tracking before X-Band even comes on, then there's
another 80 minutes before S-Band comes on.  There is an ingress occultation,
which we can collect.  The switch to planetary coordinates, Minical #1, and a
pretend SLEW #1 (none is needed) should fit comfortably within the 28-minute
occultation.

You might consider asking the station to prepare for the switch to planetary
coordinates during the approximately two hours before we start recording.
They could even practice.  If it's just a matter of swapping one table for
another, I imagine it could be done in seconds if they have all the pieces
ready to go; then we won't run into conflicts between planetary pointing and
MiniCal #1 while the spacecraft is occulted.  If there is a problem, do the
MiniCal and skip the planetary pointing.

The DSN Keyword File shows the subreflector being fixed at 22:37:43 and being
released at 23:31:52.  I suspect this is a carryover from standard operating
procedure when stations do occultations.  But the occultation is secondary to
the BSR in this pass, and I would prefer NOT to have the subreflector fixed
at any time.  If changing this is going to cause a mess, don't bother; but if
you can work something with Jesse, it would make the BSR incrementally
better.

The BSR begins at exit occultation with the carriers on the high edges of
each filter.  After 5 minutes (23:26) we start updating the 25 kHz X-Band FRO
every two minutes (except the last two are spaced by 3 minutes).  There's
also an update to the 25 kHz S-Band FRO at 23:31 and at 23:39.  There's a
single update to the 100 kHz X-Band FRO at 23:31.

The BSR ends at 23:43.  We do Minical #2 between 23:45 and 00:00, return the
ground antenna to spacecraft pointing at 00:05, set the 25 kHz FROs to their
original values at 00:06, and watch the spacecraft return to Earth point at
00:13.

So far as I'm concerned you can end the track early at 00:25, do the post-
cal, and call it a day well before the nominal EOA at 01:50.

The last experiment (2008/185) produced some very nice data; although Mars is
a bit farther away now, this one should be similar.

Thanks,
Dick









2008/231 (UTC)
- - - - - - -

18:25  Begin Pre-cal at DSS 14
       FGAIN = 60 dB (all channels, including X-RCP)
       FRO_X = 0; FRO_S = 0
       Start 4-channel 25 kHz recordings after Step 4
       Stop 25 kHz recording after Step 18


20:20  Begin track (spacecraft transmitters should be OFF)

20:49  AOS (X-Band only; telemetry ON, 1-way)

       Ask station to prepare for switching to planetary coordinates (?)

22:09  AOS (S-Band; carrier only, 1-way)

22:24  X-Band telemetry OFF (expect 6 dB carrier-to-noise increase)

22:25  FRO_X = -11000 Hz (SCHAN 3)
       FRO_S = -10000 Hz (SCHAN 3)
       FRO_X = -40000 Hz (SCHAN 4)
       FRO_S = -40000 Hz (SCHAN 4)

22:30  Resume 25 kHz recording (SCHAN 3)

22:53  Occultation ingress

22:55  Ask station to switch to "planetary pointing" (center of Mars)

23:00  Begin MiniCal #1

23:15  End MiniCal #1 (end of Step 5)

23:20  Begin 4-channel 100 kHz recordings (SCHAN 4)

23:21  Occultation egress

       Expect X-RCP echo to build as it quickly drifts lower;
       others will be weaker; S-LCP may not be visible

23:26  FRO_X = -22000 Hz (SCHAN 3)

23:28  FRO_X = -32000 Hz (SCHAN 3)

23:30  FRO_X = -42000 Hz (SCHAN 3)

23:31  FRO_S = -20000 Hz (SCHAN 3)
       FRO_X = -80000 Hz (SCHAN 4)

23:32  FRO_X = -52000 Hz (SCHAN 3)

23:34  FRO_X = -62000 Hz (SCHAN 3)

23:36  FRO_X = -72000 Hz (SCHAN 3)

       If visible, the X-LCP echo should be stronger than X-RCP

23:39  FRO_X = -82000 Hz (SCHAN 3)
       FRO_S = -30000 Hz (SCHAN 3)

23:42  FRO_X = -92000 Hz (SCHAN 3)

23:43  Begin SLEW #2

       End 100 kHz recording (SCHAN 4)

23:45  Begin Minical #2


2008/232
--------

00:00  End MiniCal #2

00:05  Return to spacecraft pointing coordinates

00:06  FRO_X = -11000 (SCHAN 3)
       FRO_S = -10000 (SCHAN 3)

00:13  End SLEW #2

00:25  EOT (25 minutes early)

       Begin Post-Cal

01:50  End Post-cal (if not before)

       End 25 kHz recordings

       End of Activity