Tuesday, August 25, 2009

Weather slightly better for 2nd launch try

Rain and lightning forced postponement of the space shuttle launch this morning and could do the same to the 2nd attempt overnight.

NASA aims to try again at 1:10 a.m. Wednesday to launch the space shuttle Discovery and seven astronauts on a supply run and crew delivery mission to the International Space Station.

Throughout the countdown today and tonight, look for the latest updates and breaking news in the box just above this post. If the box is not displaying the latest headlines, click the arrow and it will launch.

The weather forecast calls for a 70 percent chance of acceptable conditions. Yesterday's forecast was for an 80 percent of good launch weather, but conditions deteriorated fast late last night. Lightning and rain storms persisted late into the night and NASA could get Discovery and the crew off the ground.

Today's attempt is already under way. The loading of fuel and oxidizer into the big external tank is set to begin just before 4 p.m.

The image above shows the space shuttle sitting on the launch pad this morning. Photographer Michael R. Brown snapped it while out checking on his remote-controlled cameras this morning in preparation for the overnight liftoff.

4 comments:

Mark said...

I've always meant to ask this question and didn't want to clog the live box with this. Between the time the sound suppresion water system and the hydrogen burn ingitors start, I seem to hear a high-pitched noise. I would guess it's around the t-13 second mark. What is this? I know those two are armed around the one minute mark. Perhaps it's the ignitors getting ready to fire at t-10 seconds. The first couple of times I heard it, I figured it was something with the TV feed, but I think I hear it every time.

Thanks!

Todd Halvorson said...

Mark:

I wonder whether you might be hearing the APUs? They start chugging like a railroad train at T-Minus five and make a hitch-pitched whine closer to launch, so I suspect that's what you are hearing..

Todd

Anonymous said...

The SRB APUs are the more likly source. They are called HPUs (Hydraulis Power Units) they start just after T-18 sec.

Mark said...

Maybe that's it, Anon. I know I hear the noise before the hydrogen burn ignitors fire. I thought it was around t-13 but maybe it's a few seconds before. Is that something the audio would be able to pick up? I wish I had the last launch still on my TiVo to check.