SpaceX blows up a Falcon 9 rocket as part of crucial safety test

It was the final test flight before the Crew Dragon can fly humans to the ISS.

"We are purposely failing a launch vehicle to make sure that our abort system on the spacecraft that will be flying for our crews works, and so that’s a very, very different way for us to normally conduct a mission,” Kathy Lueders, the manager of the Commercial Crew Program at NASA, said at a news conference Friday. "So, this is a very important test."

The in-flight abort test was designed to try out the spacecraft Crew Dragon's "escape capabilities" for astronauts, according to a statement from NASA.

The Crew Dragon splashed down into the Atlantic Ocean at 10:39 a.m. ET Sunday, which was broadcast by NASA. The launch was canceled on Saturday due to "poor splashdown and recovery weather."

Sunday's SpaceX launch was part of NASA's Commercial Crew program.

It comes just under a month after a separate NASA Commercial Crew launch done in coordination with Boeing did not go as planned.

As part of the test, SpaceX triggered a launch escape of the Crew Dragon spacecraft from the Falcon 9 rocket to see if the spacecraft can safely separate from the rocket.

The Falcon 9 rocket then continued on, following a trajectory meant to mimic a journey to the International Space Station before eventually -- and intentionally -- exploding in the air.

"We expect there to be some sort of ignition and probably a fireball of some kind, whether I would call it an explosion that you would see from the ground I don’t know, we’ll have to see what actually happens," Benji Reed, the director of crew mission management at SpaceX, said at a news conference Friday. "But I wouldn’t be surprised and that wouldn’t be a bad outcome if that’s what we saw. "

If this test is deemed a success, SpaceX could soon send American astronauts to the ISS from American soil for the first time since the U.S. ended NASA's Space Shuttle mission in 2011.

"Critical test launch before flying astronauts is green for Jan 18," SpaceX CEO Elon Musk tweeted a week ahead of the launch.

Musk previously indicated in a tweet that he hopes to send a crew on the Dragon in 2020. NASA's Bob Behnken and Doug Hurley are tapped to be the first SpaceX Commercial Crew astronauts.

Sunday's launch was intended to provide "valuable data toward NASA certifying SpaceX’s crew transportation system for carrying astronauts to and from the International Space Station," the NASA statement added.

ABC News' Julia Jacobo and Gina Sunseri contributed to this report.