SpaceX F9 - Comm Crew DM-2 - LC-39A

[mongo]

Why don't they do this in the morning before the weather comes in for the day!?!

The launch window shifts ~20 minutes per day, thus the reason today's window is 3:22 vs 4:33 three days ago. To get to 9am ish will require a delay of 18 days or so.

From the Shuttle days: How Things Work: Shuttle Launch Windows | Flight Today | Air & Space Magazine

 

[Nikxice]

Currently launch is a no go, but by 2:30 local time the weather is expected to clear. Just before fueling should begin.

 

[SMAlset]

Just noticed this from Wednesday’s screen grabs. plates read ISSBND...ISS Bound! Both cars had the same plate.

 

[Ben W]

They must launch at the moment the ISS orbital path passes over KSC, that is only once a day (heading the correct direction)

Launching at a different time would require an "orbital phase maneuver" to synchronize the orbits once in space, which would add complexity, time, and risk. I'm not sure Dragon is designed to stay attached to the second stage after launch, but for a significant orbital shift they would have to launch into an elliptical orbit with a different period from the ISS, wait until they are synchronized with the plane of the ISS, then fire the second stage again to match the ISS' circular orbit. Dragon has limited life support capability (only a day or two?), and its own thrusters, even Super Dracos, are only capable of a very slight phase shift over that amount of time. (Anyone want to calculate how much?)

Edit: just realized that an orbital phase maneuver is not enough; it only changes phase within a given plane, but here we would need to change the plane altogether, which is even more expensive. The explanation above more describes why they can only launch on certain days, even though the launch site passes through the orbital plane every day.

 

[mongo]

Launching at a different time would require an "orbital phase maneuver" to synchronize the orbits once in space, which would add complexity, time, and risk. I'm not sure Dragon is designed to stay attached to the second stage after launch, but for a significant orbital shift they would have to launch into an elliptical orbit with a different period from the ISS, wait until they are synchronized with the plane of the ISS, then fire the second stage again to match the ISS' circular orbit. Dragon has limited life support capability (only a day or two?), and its own thrusters, even Super Dracos, are only capable of a very slight phase shift over that amount of time. (Anyone want to calculate how much?)

And fuel, lots of fuel...

 

[swaltner]

Launching at a different time would require an "orbital phase maneuver" to synchronize the orbits once in space, which would add complexity, time, and risk. I'm not sure Dragon is designed to stay attached to the second stage after launch, but for a significant orbital shift they would have to launch into an elliptical orbit with a different period from the ISS, wait until they are synchronized with the plane of the ISS, then fire the second stage again to match the ISS' circular orbit. Dragon has limited life support capability (only a day or two?), and its own thrusters, even Super Dracos, are only capable of a very slight phase shift over that amount of time. (Anyone want to calculate how much?)

AVWeb posted an interview with Paul Dye on this exact topic. Basically, the Falcon 9 doesn’t have the fuel reserve to do an orbital plane change, so it has the instantaneous launch window requirement when meeting up with the ISS.

 

[SMAlset]

Weather go

 

[SMAlset]

Getting exciting with the possibility of launch this time. Visors down! Launch escape armed. Looks like blue skies, fingers crossed.

 

[SMAlset]

Propellent loading

 

[ecarfan]

I think Bob and Doug are taking a nap...

 

[swaltner]

1.4 million folks watching the SoaceX stream on YouTube. Nice!

 

[SMAlset]

Guys are probably trying to keep their calm in case it gets halted, and not thinking about it. I know I’m nervous and excited for them. Just started raining here. Hope east coast stays favorable.

 

[adiggs]

I'm on the edge of my seat

 

[SMAlset]

 

[Nikxice]

It's clear to the east. The closest cell is 10 miles west over Titusville, but it isn't going anywhere!

 

[SMAlset]

Gwen is talking now.

T-0:11:30

 

[SMAlset]

OMG about T-:05

now down to T-:02:30

 

[ohmman]

For a dude just sitting on his couch, I’m outrageously nervous.

 

[Kamixus]

Watching this in my Tesla with great anticipation!!!!

 

[SMAlset]

I’m in tears! Go guys. Thru Max Q. MECO