SpaceX set to kick off 2015 launch calendar Tuesday

MELBOURNE, Fla. — SpaceX is poised to kick off Cape Canaveral's 2015 launch campaign with a 6:20 a.m. Tuesday attempt to boost another batch of cargo to the International Space Station.

There's a 60% chance of acceptable weather during the instantaneous window at Kennedy Space Center's Launch Complex 40.

An unmanned Dragon capsule packed with more than 5,000 pounds of food, supplies and science experiments will ride atop a Falcon 9 rocket seeking to complete SpaceX's fifth resupply mission under a $1.6 billion NASA contract.

The mission was postponed from late December after a test-firing of the Falcon 9 booster's nine Merlin 1D engines did not go exactly as planned, and because of limited launch opportunities at the end of the year because of heating caused by the sun's angle relative to the space station.

SpaceX successfully repeated the "static fire" engine test, in which the rocket is held down on the pad while the engines fire for a few seconds, a few days later. The second test ran for its full duration, the company reported, after the first ran too short.

If the mission does not launch Tuesday, the next opportunity won't be until Friday morning.

The launch is the first of as many as two dozen from Cape Canaveral this year, according to the Air Force's 45th Space Wing. There were 16 launches last year.

United Launch Alliance's first mission of the New Year is targeted for Jan. 20, with an Atlas V rocket carrying a U.S. Navy communications satellite.