The countdown finally came out of a built-in hold at the T-minus four-minute mark, ticking toward a launch attempt at 4:28 a.m. when an engineer called out "hold, hold, hold" at the T-minus one-minute 55-second mark.
The Parker Solar Probe will fly to the sun to collect data from inside the solar atmosphere.
The launch was pushed back because a technical glitch on the rocket carrying the probe, United Launch Alliance's Delta IV Heavy rocket, caused NASA to run out the clock on its 65-minute launch window Saturday.
Thousands of spectators gathered in the middle of the night on Friday to witness the launch, including the University of Chicago astrophysicist for whom the spacecraft is named.
The probe's seven-year journey will bring it to within 6.16 million kilometers (3.83 million miles) of the sun's surface.
By better understanding the basic science of solar wind - how the sun's atmospheric particles accelerate and interact - scientists hope to more accurately model larger, more complex solar phenomena, and improve space weather prediction models.
"Today, this is finally possible with cutting-edge thermal engineering advances that can protect the mission on its risky journey". The agency is now targeting Sunday for the launch of the spacecraft which is created to go all the way to the Sun's atmosphere, or corona - closer to the Sun than any spacecraft in history.
An illustration of Parker Solar Probe approaching the Sun
The goal for the Parker Solar Probe is to make 24 passes through the corona during its seven-year mission.
NASA stated: "Parker Solar Probe will provide unprecedented information about our sun, where changing conditions can spread out into the solar system to affect Earth and other worlds".
"And it needs to be, because it takes an enormous amount of energy to get to our final orbit around the Sun", Driesman added.
Not only is the corona about 300 times hotter than the Sun's surface, it also hurls powerful plasma and energetic particles that can unleash geomagnetic space storms and disrupt Earth's power grid.
Image: An illustration of the probe leaving Earth.
"The sun is full of mysteries", said Nicky Fox, project scientist at the Johns Hopkins University Applied Physics Lab.More news: Hands-on with the Samsung Galaxy Note 9