SpaceX targeting Dec. 12 launch of ISS supplies from Cape Canaveral

SpaceX's next launch of International Space Station supplies from Cape Canaveral has slipped at least four days and is now targeted for no earlier than next Tuesday, Dec. 12, at 11:46 a.m.

"This new launch date takes into account pad readiness, requirements for science payloads, space station crew availability, and orbital mechanics," NASA said in a statement Tuesday.

The launch had been targeted for as soon as this Friday, Dec. 8.

SpaceX on Wednesday hopes to test-fire the Falcon 9 rocket's nine Merlin main engines on Launch Complex 40 at Cape Canaveral Air Force Station, a test once planned for last weekend.

The engine ignition will be the first at Complex 40 in more than a year. The pad has been undergoing repairs and upgrades since a Falcon 9 blew up on its pad during a fueling test on Sept. 1, 2016.

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SpaceX resumed launching this year from pad 39A at Kennedy Space Center, which is now being readied for the debut launch of the company's heavy-lift Falcon Heavy rocket, possibly next month.

The Falcon 9 booster being prepared for launch next week flew earlier this year, launching cargo on its way to the ISS in June. The mission will be SpaceX's fourth re-flying a used Falcon booster.

The Dragon also has flown in space and visited the station before, in 2015.

If the revised schedule holds up, the Falcon 9 will lift off from Complex 40 next Tuesday with an unmanned Dragon capsule packed with 4,800 pounds of food, equipment and science experiments.

The rocket's first stage will attempt to land for a second time at Cape Canaveral Air Force Station's Landing Zone-1, down the coast from the launch site.

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A backup launch opportunity is available next Wednesday, Dec. 13.

Meanwhile in orbit, a Russian Soyuz spacecraft carrying three astronauts and cosmonauts is expected to depart the space station early Dec. 14.

Three Expedition 54 crew members will remain on board the research complex orbiting 250 miles above Earth. They include NASA astronauts Joe Acaba and Mark Vande Hei, who will be responsible for capturing the Dragon with a  58-foot robotic arm for its month-long stay.

Labeled CRS-13, the mission is SpaceX's 13th under a NASA Commercial Resupply Services contract initially awarded nine years ago.

Contact Dean at 321-242-3668 or jdean@floridatoday.com. And follow on Twitter at @flatoday_jdean and on Facebook at https://www.facebook.com/SpaceTeamGo.