SpaceX on Friday confirmed that NASA has greenlighted May 19 as the launch date for the first privately funded cargo mission to the International Space Station following a series of delays.

The launch of a SpaceX Dragon capsule atop a Falcon 9 rocket from Launch Complex 40 at the Cape Canaveral Air Force Station in Florida is scheduled for 4:55 a.m. ET, a SpaceX spokesperson said. NASA Television will start broadcasting the event at 3:30 a.m., she added.

Already months behind schedule, a launch date scheduled for this past Monday was cancelled last week as SpaceX and the U.S. space agency raced to test the Dragon capsule's software systems. If the May 19 launch is again delayed for some reason, a backup plan is to lift off on May 22, a SpaceX spokesperson told PCMag earlier.

"SpaceX and NASA are nearing completion of the software assurance process, and SpaceX is submitting a request to the Cape Canaveral Air Force Station for a May 19 launch target," SpaceX spokeswoman Kirstin Brost Grantham said earlier in the week. "Thus far, no issues have been uncovered during this process, but with a mission of this complexity we want to be extremely diligent."

In what will be the second demonstration launch for SpaceX in NASA's Commercial Orbital Transportation Services (COTS) program. Once in orbit, the automated Dragon capsule, carrying cargo for the orbiting space lab, will berth with the ISS if it passes a systems check.

"The primary objectives for the flight include a flyby of the space station at a distance of approximately 1.5 miles to validate the operation of sensors and flight systems necessary for a safe rendezvous and approach," Brost Grantham said. "The spacecraft also will demonstrate the ability to abort the rendezvous. Once these capabilities are successfully proven, the Dragon will be cleared to berth with the space station."

Fourth Time's the Charm?

The unmanned test flight was originally scheduled for April 30, then pushed back to May 3 before NASA and SpaceX settled on a date a few days later in May. SpaceX, run by PayPal and Tesla Motors co-founder Elon Musk (pictured), plans to conduct manned flights to the ISS by 2015 as part of NASA's Commercial Crew Development (CCDev) program.

After the May 7 date was cancelled, the company's launch plans were constrained because the Russian space agency is scheduled to take three new ISS astronauts to the space station on May 15. Any attempt by SpaceX to send its Dragon capsule to the ISS after this Thursday must wait for the Russian Soyuz spacecraft to safely dock at the space station.

If and when the ISS rendezvous does happen, crew aboard the space station will use the space station's robotic arm to dock the capsule, which will be carrying about 1,150 pounds of cargo for delivery to the orbiting lab. Then the SpaceX Dragon is supposed to take on a 1,455-pound payload to bring back to Earth.

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NASA Greenlights SpaceX ISS Visit for May 19