[sarex] STS-116 LAUNCH BLOG
azrowe80 at verizon.net
Mon Dec 4 17:45:23 PST 2006
SUBMITTED BY ARTHUR N1ORC - AMSAT A/C #31468
NASA's Launch Blog - Mission STS-116
*NASA's launch blog will begin live coverage on Dec. 7, 2006 at 3:30
p.m. EST. *
*Did you know?*
If the countdown clock reads T-26 hours and counting, that doesn't mean
the space shuttle will launch in 26 hours. During every space shuttle
countdown, there are several times when the clock is temporarily
stopped. These periods are called "built-in holds," and they vary in
length from as little as 9 minutes to as long as several hours. For this
reason, hold times must be taken into consideration when watching the
The space shuttle team uses built-in holds to synchronize with other
countdown clocks, monitor weather events, make final adjustments to the
launch time, and check all systems before proceeding.
During the countdown the liquid oxygen vent on the external tank is
opened to allow the super-cold liquid oxygen to boil off, thus
preventing over pressurization while the tank remains near its full level.
Once the space shuttle's on board computers start their terminal launch
sequence, any problem after that point will require calling a "hold" and
the countdown recycled to T minus 20 minutes.
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