Next launch attempt on the 4th...why not the 3rd?

Neon Knight wrote in news:Xns97F4B6B7D4FF519knightofneon20@
216.196.97.136:

So why don't they try again tomorrow instead of waiting until the 4th?

Two reasons. The weather forecast for the 4th is more favorable than
tomorrow, plus it gives them a chance to top off the H2 cryo reactant tanks
for the fuel cells, to preserve the option of having enough cryo to get a
mission extension day and a third spacewalk.

(It's not necessary to top off the O2 tanks yet because liquid O2 isn't as
cold as liquid H2, so it doesn't boil off as fast. If launch doesn't occur
Tuesday or Wednesday, they'll stand down 72 hours and refill both sets of
tanks.)

--
JRF

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"Jorge R. Frank" wrote in message
...
Neon Knight wrote in
news:Xns97F4B6B7D4FF519knightofneon20@
216.196.97.136:

So why don't they try again tomorrow instead of waiting until the 4th?

Two reasons. The weather forecast for the 4th is more favorable than
tomorrow, plus it gives them a chance to top off the H2 cryo reactant
tanks
for the fuel cells, to preserve the option of having enough cryo to get a
mission extension day and a third spacewalk.

They also mentioned replacing some of the components in some of the on-board
experiments, like fruit-flies.

(also, I think traditionally NASA has generally done the 2 attempts, day
off, routine. If only to give launch crews a rest.

But I could be wrong on that one.)



(It's not necessary to top off the O2 tanks yet because liquid O2 isn't as
cold as liquid H2, so it doesn't boil off as fast. If launch doesn't occur
Tuesday or Wednesday, they'll stand down 72 hours and refill both sets of
tanks.)

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.