Shift A July 22nd, 1:30am

Second attempt to launch Columbia with Chandra

** NOTE, shift reports are archived on the ACIS operations Web page,
"http://asc.harvard.edu/acis/ops_reports/shift.html" **


  Sorry Tom and B shift, we screwed up again. Seriously, we will try
again tomorrow.

  We scrubbed tonight due to weather.  There was a small cell off the
coast which produced a few lightning strikes.  Flight rules say that
the Shuttle cannot launch if there is a storm producing lightning within
20 miles.  At its closest, the cell was 8.5 miles from the launch
facility.

  We counted down to T-5m and held at that point due to the weather.
At this point, there was a flurry of discussions about extending the
launch window in order to give more time for the weather to clear.  I
was concerned (as were many others) at the options being discussed
during this period.  There were two major issues which were brought
up.  The first was the impact on our battery margin during earth
eclipses because launching later in the window would increase our
maximum earth eclipse duration. The second was our ability to deploy
on day 1 and/or day 2.  By reducing our 2-battery margin to 0 if we 
deployed on Rev 6, we could extend the window by 6 minutes.  We would 
have more margin on the Rev 7 deployment.  We could extend the launch 
window by 26 minutes if we gave up a day 1 deployment.  This option 
raised a lot of eyebrows.  Fortunately for us, the range shut us down
before the end of this 26 minute window.

  The KSC and JSC folks were clearly frustrated with the confusion
regarding the real constraints on the launch window.  A telecon has
been scheduled for 2am tonight to go over the launch window
requirements and constraints again.  

  ACIS, HRC, and EPHIN are all go for a 24hr recycle.  We shall try
again tomorrow.

stay tuned,
Paul


Addendum @ 2:30 am

   Here is a quick summary of the telecon to flesh out the launch
window issue.  It was agreed that under no circumstances would we give
up a day 1 deployment.
   Anyways, they are considering gaining 30 minutes on the opening of
the launch window by accepting a perigee of 5000 km.  They are also
considering adding the 26 minutes on the closing of the window by
pushing the 2 battery margin for long eclipses.
   There will be a telecon tomorrow at 10 CDT to discuss the issue
further.