4th Ld Writethru: SpaceX successfully launches ISS resupply mission, rocket lands on ground.

U.S. space firm SpaceX launched its 10th cargo mission to the International Space Station on Sunday morning from U.S. space agency NASA's historic moon pad for the first time.

A Falcon 9 lifted off on time at about 09:39 a.m. EST (1439 GMT) from U.S. space agency NASA's historic Launch Complex 39A (LC-39A) at NASA's Kennedy Space Center in Florida for the first time, NASA TV showed.

"...3, 2, 1, Ignition! And Liftoff of the Falcon 9 to the space station, on the first commercial launch from Kennedy Space Center's historic 39A," said NASA launch commentator George Diller.

Video from the scene showed hundreds of space program enthusiasts turned out in force to witness the first launch off LC-39A since the space shuttle Atlantis blasted off in July 2011 on the program's final flight.

The launch pad was best known as the launch site for the Apollo 11 mission, which sent the first humans to the surface of the moon, as well as numerous space shuttle missions.

The launch went smoothly on Sunday.

The Falcon 9's first and second stage separated about 2.5 minutes into Sunday's launch. As the first stage flew back for its touchdown, the second stage continued to power Dragon to orbit.

Approximately 8 minutes after the initial lift-off, the California-based company successfully landed the first stage of its Falcon 9 rocket on ground.

"Baby, came back," SpaceX founder and CEO Elon Musk posted on Instagram, along with a photo of the rocket landing on ground at LZ-1 on the Florida coast.

Right on schedule, the Dragon spacecraft, which is carrying about 5,500 pounds of research equipment, cargo and supplies equipment to the International Space Station, then separated from Falcon 9's second stage about 10 minutes after liftoff and achieved its preliminary orbit. The spacecraft's two solar arrays then completed deployment.

"Dragon is on its way to the International Space Station. Capture by @Space_Station crew set for early Wednesday morning," SpaceX then posted on Twitter.

According to NASA, major experiments that will look into a range of scientific disciplines from human health to atmospheric conditions on Earth are on their way to the International Space Station. The supplies and payloads, including critical materials to directly support dozens of more than 250 science and research investigations that will occur during Expeditions 50 and 51.

The research and hardware sent to the station represents the work of about 800 scientists around the world, according to NASA officials. Among the investigations are experiments with potential to help fight human disease, monitor climate data, and improve autonomous spacecraft docking with the orbiting laboratory.

"It was really awesome to see 39A roar back to life for the first time since the shuttle era, and it was extremely special that this first launch off 39A was a Dragon mission for NASA headed to the space station," Jessica Jensen, Dragon mission manager for SpaceX, said in a post-launch news conference.

This is the beginning of what SpaceX hopes will be a busy period for the historic launch pad. The company is hoping to launch from Pad 39A again in about "two weeks", Jensen said.

The pad has been configured to accommodate the flight of the the company's Falcon Heavy launches, as well as the first reflight of a previously used first-stage booster, which is scheduled for March.

The liftoff was originally scheduled for Saturday, but SpaceX called that attempt off in a last minite to investigate an issue with the upper stage of its Falcon 9 rocket.

According to NASA, the launch attempt has been scrubbed because of the "thrust vector control system issue" that developed late in Saturday's countdown.

SpaceX determined that the potential issue was with one of two thrust vector control actuators, which help steer the second-stage engine nozzle through flight, and replaced the actuator Saturday night and then ran tests on the pad before launch, according to Jensen.

This is the first SpaceX launch from Florida since a Falcon 9 exploded on the launch pad at Cape Canaveral Air Force Station on September 1, 2016. The accident during prelaunch testing heavily damaged that pad. SpaceX turned to the LC-39A.

SpaceX did launch a rocket from Vandenberg Air Force Base in California on January 14, 2017, but this will the first from the Cape since the blast. Endit