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Last-minute technical problem delays launch of NASA's Parker Solar Probe

Rocket maker United Launch Alliance said it would try again Sunday, provided the issues can be resolved quickly.

CAPE CANAVERAL, Fla. — A last-minute technical problem Saturday delayed NASA's unprecedented flight to the sun.

The early morning launch countdown was halted with just one-minute, 55 seconds remaining, keeping the Delta IV rocket on its pad with the Parker Solar Probe.

Rocket maker United Launch Alliance said it would try again Sunday, provided the helium-pressure issue can be resolved quickly.

You can watch live coverage of the historic liftoff right here.

The $1.5 million mission is already a week late because of rocket issues. Saturday's launch attempt encountered a series of snags; in the end, controllers ran out of time.

As soon as the red pressure alarm for the gaseous helium system went off, a launch controller ordered, "Hold, hold, hold."

Thousands of spectators gathered in the middle of the night to witness the launch, including the University of Chicago astrophysicist for whom the spacecraft is named. Eugene Parker predicted the existence of solar wind 60 years ago. He's now 91 and eager to see the solar probe soar. He plans to stick around at least another few days.

Once on its way, the Parker Solar Probe will get closer to the sun than any other spacecraft in history.

The probe is embarking on a seven-year mission to study the solar corona, the sun's ultra-hot atmosphere where destructive blasts like solar flares and so-called coronal mass ejections originate. These eruptions hurl streams of plasma and charged particles into space that can endanger astronauts in space and interfere with electronics on Earth.

"The solar corona is one of the last places in the solar system where no spacecraft has visited before," Adam Szabo, a mission scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a written statement. "It gives me the sense of excitement of an explorer."