A United Launch Alliance Atlas V rocket carrying the OA-4 Cygnus resupply spacecraft to the International Space Station lifted off from Space Launch Complex-41 on Sunday.

High winds in the area forced the launch team to delay liftoff until Sunday. The launch took place at 4:44 p.m. Sunday.

Day three was different for the team. They met and decided to call off the launch early, well before the launch window even opened.

Launch attempts on Thursday and Friday were also scrubbed because of poor weather conditions.

Thursday's steady rains hampered the first try, forcing a scrub. Friday, despite a poor forecast, optimism grew higher as the afternoon wore on. The skies cleared, the winds subsided.

But then they grew stronger as the countdown went on -- and another delay was called.

Weather is already forecast to be slightly better Sunday -- 40 percent go for launch.

Once the mission gets underway, the rocket will send an Orbital ATK Cygnus cargo craft filled with thousands of pounds of supplies to the International Space Station.

  • Launch Window: 4:44 p.m. Sunday, Dec. 6, 2015
  • Mission: OA-4 (Supply mission to the International Space Station)
  • Cargo: Orbital ATK Cygnus spacecraft carrying supplies for the ISS
  • Vehicle: Atlas V 401 Rocket
  • Launch: Space Launch Complex 41, Cape Canaveral Air Force Station
  • View: OA-4 Mission Overview

A mission of firsts

When the rocket does blast off, it will mark the 60th launch of an Atlas V rocket and the 30th launch of the rocket's 401 configuration, but it's the first time this type of rocket will ever launch a cargo ship to the International Space Station.

It's also the United Launch Alliance's first-ever resupply mission to the orbital outpost.

The Atlas V will send Orbital ATK's Cygnus spacecraft into orbit. The cargo craft has been packed with 7,000 pounds of NASA supplies, science equipment and research bound for the ISS.

This launch is also Orbital's return-to-flight mission after a cargo ship was lost last year, when the company's Antares rocket exploded shortly after liftoff at NASA's Wallops Flight Facility in Virginia.

 

Orbital Sciences' Antares rocket explodes 6 seconds after liftoff, Tuesday, Oct. 28, 2014, in Virginia. (NASA TV)
 

Not long after the explosion, Orbital chose the Atlas V as a substitute vehicle until they get back to flying themselves.

The Cygnus spacecraft set to launch is dubbed the S.S. Deke Slayton II, after the original Project Mercury astronaut and pioneer of the first privately funded rocket. The original S.S. Deke Slayton was the cargo craft lost in last year's explosion.

The Deke Slayton II is the first ISS-bound spacecraft that had been previously worked on inside the space station.

The mission also marks Orbital's first launch from Florida, and the first cargo mission to the ISS from American soil since SpaceX's Falcon 9 rocket was lost in June.

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