Last-minute technical problem delays NASA's flight to sun

This photo provided by NASA shows the United Launch Alliance Delta IV Heavy rocket with the Parker Solar Probe onboard shortly after the Mobile Servic

This photo provided by NASA shows the United Launch Alliance Delta IV Heavy rocket with the Parker Solar Probe onboard shortly after the Mobile Servic

This photo provided by NASA shows the United Launch Alliance Delta IV Heavy rocket with the Parker Solar Probe onboard shortly after the Mobile Servic

This photo provided by NASA shows the United Launch Alliance Delta IV Heavy rocket with the Parker Solar Probe onboard shortly after the Mobile Servic

A Delta IV rocket stands ready for launch at complex 37 at the Kennedy Space Center, Friday, Aug. 10, 2018, in Cape Canaveral, Fla. The Parker Solar P

A Delta IV rocket stands ready for launch at complex 37 at the Kennedy Space Center, Friday, Aug. 10, 2018, in Cape Canaveral, Fla. The Parker Solar P

The tower structure for a Delta IV rocket rolls back for launch at complex 37 at the Kennedy Space Center, Friday, Aug. 10, 2018, in Cape Canaveral, F

The tower structure for a Delta IV rocket rolls back for launch at complex 37 at the Kennedy Space Center, Friday, Aug. 10, 2018, in Cape Canaveral, F

The tower structure for a Delta IV rocket rolls back for launch at complex 37 at the Kennedy Space Center, Friday, Aug. 10, 2018, in Cape Canaveral, F

The tower structure for a Delta IV rocket rolls back for launch at complex 37 at the Kennedy Space Center, Friday, Aug. 10, 2018, in Cape Canaveral, F

CORRECTS SPELLING TO TORY, NOT TONY - In this photo provided by NASA, astrophysicist Eugene Parker, center, stands with NASA Associate Administrator f

CORRECTS SPELLING TO TORY, NOT TONY - In this photo provided by NASA, astrophysicist Eugene Parker, center, stands with NASA Associate Administrator f

In this Thursday, Aug. 9, 2018 photo, astrophysicist Eugene Parker sits between Johns Hopkins University project scientist Nicola Fox, left, and NASA’

In this Thursday, Aug. 9, 2018 photo, astrophysicist Eugene Parker sits between Johns Hopkins University project scientist Nicola Fox, left, and NASA’

This July 6, 2018 photo made available by NASA shows the Parker Solar Probe in a clean room at Astrotech Space Operations in Titusville, Fla., after t

This July 6, 2018 photo made available by NASA shows the Parker Solar Probe in a clean room at Astrotech Space Operations in Titusville, Fla., after t

This image made available by NASA shows an artist's rendering of the Parker Solar Probe approaching the Sun. It's designed to take solar punishment li

This image made available by NASA shows an artist's rendering of the Parker Solar Probe approaching the Sun. It's designed to take solar punishment li

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

Saturday's launch countdown was halted with just one-minute, 55 seconds remaining, keeping the Delta IV (four) rocket at Cape Canaveral, Florida, with the Parker Solar Probe. This followed earlier trouble in the countdown.

NASA says it will try again Sunday.

Once on its way, the Parker probe will venture closer to our star than any other spacecraft. The $1.5 million mission is already a week late because of rocket issues.

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.