Author: Steven Siceloff

Launch managers have set a new liftoff time for today at 6:03 p.m. EST. Weather remains the only concern.

 

The chances of rain clearing out of the Cape Canaveral area before today’s launch window closes are not encouraging, Clay Finn, launch weather officer of the Air Force’s 45th Weather Squadron, told the launch team during a briefing that just concluded. The Atlas booster stage and Centaur upper stage are fully fueled. The countdown is proceeding towards a 5:55 p.m. EST liftoff and the launch window runs until 6:25 p.m.

The cryogenic propellant loading for the Atlas V is complete, with the liquid oxygen tank of the first stage loaded and the Centaur upper stage’s liquid oxygen and hydrogen tanks in topping off mode.

The weather forecast has been downgraded to a 10 percent chance of acceptable conditions for this evening’s launch opportunity.

Orbital ATK’s enhanced Cygnus spacecraft carries the name S.S. Deke Slayton II as a tribute to the Mercury astronaut who became a pioneer of commercial spaceflight endeavors after retiring from NASA. Slayton, a decorated Air Force test pilot before being chosen as one of the original astronauts, flew on the Apollo-Soyuz Test Project in 1975.

Here’s a look at today’s countdown events leading up to an on-time liftoff at 5:55:45 p.m. EST.

EST                        Event
4:45 p.m.                Start flight open loop Flight Termination System test
5:09 p.m.                Initiate fuel fill sequence
5:21 p.m.                Begin 30 minute hold at T-4 Minutes
5:25 p.m.                Weather Briefing
5:48 p.m.                Status check to continue countdown
5:51:45 p.m.           T-4 Minutes and counting
5:55:42 p.m.           RD-180 engine ignition
5:55:45 p.m.           Launch
5:56:03 p.m.           Begin pitch/yaw/roll maneuver
5:57:07 p.m.           Mach 1
5:57:18 p.m.           Maximum Dynamic Pressure
6:00:00 p.m.           Atlas booster engine cutoff (BECO)
6:00:06 p.m.           Atlas booster/Centaur separation
6:00:16 p.m.           Centaur first main engine start (MES1)
6:00:24 p.m.           Payload Fairing jettison
6:14:01 p.m.           Centaur first main engine cutoff (MECO1)
6:16:50 p.m.           Cygnus spacecraft separation
~7 p.m.                   Cygnus solar array deploy
~8 p.m.                   Post-Launch News Conference on NASA Television

Current weather conditions violate rules for thick clouds and disturbed weather at Space Launch Complex 41. Forecasters expect both conditions to remain red for the next hour. Today’s launch window will be open for 30 minutes beginning at 5:55 p.m. Fueling procedures are continuing normally for the United Launch Alliance Atlas V booster that will carry Orbital ATK’s enhanced Cygnus spacecraft into orbit.

We’re less than an hour-and-a-half from the launch of Orbital ATK’s Cygnus cargo spacecraft on a United Launch Alliance Atlas V rocket.

All eyes are on the weather right now, with the forecast changed to a 30 percent chance of acceptable conditions at launch time. Air Force meteorologists are watching for thick clouds and disturbed weather. The launch team has a 30-minute window today to send the Atlas V and Cygnus on their way to deliver more than 7,300 pounds of supplies and experiments to the International Space Station.

Countdown is on schedule for 5:55 p.m. EST from here at Cape Canaveral Air Force Station in Florida adjacent to NASA’s Kennedy Space Center. The rocket is being loaded with super-cold propellants right now.

We will give you up-to-the-moment updates throughout this afternoon’s countdown and show you some of the details of the research that this mission will enable as station residents continue their work off the Earth for Earth and help find answers for future crews who will make an eventual journey to Mars. You can also watch launch coverage live on NASA TV either on your television or streaming at www.nasa.gov/ntv.

Weather forecasters downgraded the prediction for today’s launch opportunity to 30 percent chance of acceptable conditions. The countdown continues to move toward a liftoff at 5:55 p.m. EST at the beginning of a 30-minute window.

Pending real-time updates during today’s countdown, the 45^th Weather Squadron forecast remains 60 percent favorable for the liftoff of Orbital ATK’s S.S. Deke Slayton II Cygnus spacecraft atop a United Launch Alliance Atlas V rocket at 5:55:45 p.m. EST. NASA Television launch coverage begins at 4:30 p.m. This is the company’s fourth scheduled cargo delivery mission to the International Space Station under the agency’s Commercial Resupply Services contract.

A launch today will result in the Cygnus spacecraft arriving at the space station on Sunday, Dec. 6. NASA crew members Kjell Lindgren and Scott Kelly will use the station’s Canadarm2 robotic arm to reach out and capture Cygnus at approximately 5:30 a.m. NASA TV coverage of rendezvous and grapple of Cygnus will begin at 4 a.m. Cygnus will be the first cargo ship to be berthed to the Earth-facing port on the Unity module. Coverage of Cygnus’ installation will begin at 7:15 a.m.

If the launch does not occur on today, the next launch opportunity would be at 5:33 p.m. tomorrow, resulting in a grapple and berthing on Dec. 7. Photo credit: NASA/Kim Shiflett