A Liftoff Deferred: SpaceX Mission From NASA's Historic Launch Pad Delayed

Updated at 10:25 a.m. ET

Poised on the brink of ushering in a new era, NASA's historic launch pad in Florida will need to wait another day for its milestone. At the last minute, the private space company SpaceX scrubbed its Saturday launch, which would have marked the first time the Kennedy Space Center's Launch Complex 39A was used in over half a decade.

Instead, the launch will wait at least 24 hours while SpaceX takes a "closer look at positioning of the second stage engine nozzle," an anomaly that came to light shortly before liftoff. The company plans to try again on Sunday.

Taken on its face, the launch itself is not particularly notable. Naturally, it's no mean feat to send a rocket to space, but missions like this one happen all the time. The International Space Station needs provisions, after all, and the 5,500 pounds of supplies and materials for scientific experiments would be a common (if still impressive) load for a resupply mission.

Rather, the liftoff now scheduled for Sunday is making history not for its cargo but precisely where it will be taking place: the pad that served as the launch site for the Apollo 11 mission that first sent humans to the moon in 1969.

In fact, Launch Complex 39A served as a pad for many of the most famous missions in NASA's history — from the first missions to space that packed a human crew, to the decades-long space shuttle program that helped construct the orbiting station SpaceX's rocket will be supplying.

As NPR's Rae Ellen Bichell reports for our Newscast unit, the SpaceX mission marks something of a sea change for the historic launch pad:

"According to NASA, this will be the first time the launch pad has been used since the shuttle program ended in 2011 — and it will mark the beginning of a new era for the Kennedy Space Center — as a spaceport open for use by public — and commercial — missions to space."

SpaceX, a privately owned space company, is sending its NASA cargo — and the Dragon spacecraft that bears it — with a Falcon 9 rocket. In a statement, NASA says SpaceX also plans to attempt to land the first stage of the Falcon 9 back on a platform, as it did during its successful launch last month.

NASA also explains some of the experiments this launch will be supporting:

"Science investigations launching on Dragon include commercial and academic research investigations that will enable researchers to advance their knowledge of the medical, psychological and biomedical challenges astronauts face during long-duration spaceflight.

"One experiment will use the microgravity environment to grow stem cells that are of sufficient quality and quantity to use in the treatment of patients who have suffered a stroke. A Merck Research Labs investigation will test growth in microgravity of antibodies important for fighting a wide range of human diseases, including cancer."

According to NASA, the mission will also aid in recording "key climate observations and data records."

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