Atlas V rocket blasts off with Cygnus spacecraft to ISS

Update: The United Launch Alliance Atlas V rocket successfully launched from Cape Canaveral today. More here.

Update, 2:20 p.m.:

The launch team has given the go-ahead to proceed with cryogenic fueling of United Launch Alliance's Atlas V rocket at Launch Complex 41.

Supercold liquid oxygen will be loaded into both stages, and liquid hydrogen propellant into the Centaur upper stage. The booster is already fueled with Rocket Propellant-1, a rocket-grade kerosene.

All is proceeding toward an on-time launch at 4:44 p.m. today, at the opening of a 30-minute window. There's a 70 percent chance of favorable weather.

Update, 1:35 p.m.:

The latest forecast has improved greatly for today's launch attempt, with a 70 percent chance of favorable conditions now expected during the 30-minute window opening at 4:44 p.m.

United Launch Alliance is on track to begin fueling the 194-foot, two-stage Atlas V rocket with super-cold liquid hydrogen and liquid oxygen around 2:30 p.m. at Launch Complex 41.

An Atlas V rocket is targeting a 4:44 p.m. Sunday launch from Cape Canaveral Air Force Station with a Cygnus cargo spacecraft bound for the International Space Station.

There's a 40 percent chance of weather good enough to permit a liftoff from Launch Complex 41 during a 30-minute window that closes just before sunset.

High winds pushed Saturday's planned launch attempt back one day.

It was the third day in a row that weather had frustrated launch teams, following scrubs Thursday and Friday.

On Saturday, with forecasters predicting only a 20 percent chance of acceptable conditions, managers decided early in the afternoon to halt the countdown before fueling the United Launch Alliance rocket, opting to give crews some rest and wait for better weather to come.

A launch is also possible on Monday, if necessary, when the forecast improves considerably.

Orbital ATK's Cygnus craft is packed with more than 7,000 pounds of food, spare parts and science experiments for the ISS and its six-person crew.

The Cygnus is returning to flight on the Atlas V after its last mission aboard Orbital ATK's own Antares rocket failed seconds after liftoff from Virginia in October 2014.

Contact Dean at 321-242-3668 orjdean@floridatoday.com. And follow on Twitter at@flatoday_jdeanand on Facebook atfacebook.com/jamesdeanspace.

Editor's note: Join Florida Today for live rocket launch coverage beginning at 3:30 p.m. Sunday

At KSC, Cygnus packed for first flight aboard Atlas V

Launch Sunday

Rocket: United Launch Alliance Atlas V (401 configuration)

Mission: Fourth Orbital ATK Cygnus mission under NASA Commercial Resupply Services contract

Launch Time: 4:44 p.m.

Launch Window: 30 minutes, to 5:14 p.m.

Launch Complex: 41 at Cape Canaveral Air Force Station

Weather: 40 percent "go"

Visit floridatoday.com at 3:30 p.m. for countdown updates and chat and live streaming of NASA TV's launch coverage.