Launch News Orbital's Antares Maiden Flight & ORB-D "G. David Low" Cygnus Demo updates.

[ky]

Launch viewing area

Viewing resources http://go.nasa.gov/T2NpZd

 

[Kyle]

Countdown underway!

Orbital Sciences ‏@OrbitalSciences (1403Z)
#Antares The count pick up at T-8 hours has started. The team is targeting the
opening of the window at 5 PM local, 2100 UTC.

Orbital Sciences ‏@OrbitalSciences (1518Z)
#Antares T-6 hours: Wx 90% go for launch time. Upper level winds are marginal based on earlier balloon data.

 

[Cosmic Penguin]

No Red Timer today.... because the PR at NASA Wallops provided this: http://www.timeanddate.com/countdown/generic?iso=20130420T17&p0=263&msg=A-One+Launch#

The very big storm system (which flooded Chicago et al. and brought tornadoes across the midwest) finally cleared the East coast right now - it should be bright and sunny at launch time! However this also means the jetstream is very strong right now (especially at 20000-40000 feet), which may be problematic at launch time.

 

[Kyle]

Live stream has started on ustream: http://www.ustream.tv/channel/stennisaj26-1/theater

 

[orb]

T-0 is now set at 22:10 UTC because of wind.

 

[jb860]

Shame its pushed back... now I won't be able to watch it live .

 

[Urwumpe]

Seems to be fully scrubbed now. don't know why.

 

[Cosmic Penguin]

Seems to be fully scrubbed now. don't know why.

Apparently the same thing I reported earlier - high altitude winds. Tomorrow might be tough too with surface winds....

 

[RGClark]

Apparently the same thing I reported earlier - high altitude winds. Tomorrow might be tough too with surface winds....

Is this a more delicate launcher than usual?

Bob Clark

 

[Alfastar]

Is this a more delicate launcher than usual?

Bob Clark

Well, I think there are more careful with this launch because this is the first Antares launch, and that means also that there will a (almost) perfect launch weather.

 

[Kyle]

Is this a more delicate launcher than usual?

Bob Clark

No, it's just we've had an incredibly powerful coldfront for April push through most of the CONUS.

 

[Cosmic Penguin]

Beautiful day for launch today!

http://www.flickr.com/photos/nasahqphoto/sets/72157633278343080/

 

[Kyle]

Weather looking far better than yesterday. Down to a 20% POV.

 

[MattBaker]

At 10 seconds after Stage 1 engine ignition the vehicle will have accelerated to about 40 mph and climbed to 230 feet altitude.

Wait, the Antares is a slower climber than the Saturn V?

 

[Urwumpe]

Wait, the Antares is a slower climber than the Saturn V?

Does the rocket lift-off immediatly with ignition, or does it stay on the ground until thrust is over 95% and stable?

 

[Cosmic Penguin]

Does the rocket lift-off immediatly with ignition, or does it stay on the ground until thrust is over 95% and stable?

Didn't know that the liftoff will be that slow! :blink:

When the engines first ignite, the rocket will not lift off from the pad for two full seconds.

Even though it will consume close to 1ton of prop every second after lift-off, the early acceleration will be surprisingly slow.

 

[Cosmic Penguin]

Wait, the Antares is a slower climber than the Saturn V?

My preliminary calculation puts the Antares thrust-to-weight ratio at ~1.1 (!). That's very, very low: Saturn V is ~1.2 and the Atlas V 401 is ~1.28.....

 

[Urwumpe]

So, in 8 seconds, it accelerates by 40 mph or to 17.78 m/s. This means an acceleration of 2 m/s² after substracting gravity, or 12 m/s². That is pretty low, but not that low.

 

[MattBaker]

And just for clarification: The engine ignition will be at -1.7 seconds with liftoff at T-0.

 

[Cosmic Penguin]

1 hour to go!