The Parker Solar Probe will boldly go where nothing man-made has gone before – the sun.

NASA’s rocket blasted off successfully on Sunday night (Australian time) from Cape Canaveral, Florida on a seven-year mission to “touch the sun”.

Its unprecedented quest will take it straight through the wispy edges of the corona, or outer solar atmosphere, just six million kilometres from the sun’s surface, in order to collect data on the scorching atmosphere.

It is, in NASA’s words, “humanity’s first visit to a star”.

“This mission truly marks humanity’s first visit to a star that will have implications not just here on Earth, but how we better understand our universe,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate.

“We’ve accomplished something that decades ago lived solely in the realm of science fiction.”

Protected by a revolutionary new heat shield, the spacecraft will fly past Venus in October. That will set up the solar encounter in November.

LAUNCH! ULA Delta IV-Heavy launches with Parker Solar Probe! About to become the fastest human-built spacecraft in history! pic.twitter.com/iJhUzxj6bI

— Chris Bergin – NSF (@NASASpaceflight) August 12, 2018

Annnnd liftoff!! The @ulalaunch Delta IV Heavy has lifted off from Cape Canaveral with the Parker Solar Probe!#ParkerSolarProbe pic.twitter.com/kLfVDMDfJy

— Robin Seemangal (@nova_road) August 12, 2018

All together, it will make 24 close approaches over the next seven years.

Scientists hope it will unlock mysteries of the sun, such as why the corona is hotter than the surface of the sun itself.

They also hope to learn more about the sun’s magnetic field and solar wind.

“Exploring the sun’s corona with a spacecraft has been one of the hardest challenges for space exploration,” said Nicola Fox, project scientist at Hopkins University Applied Physics Laboratory.

“The science will be remarkable.”

The second stage's main engine has started (MES1) and the fairing has been jettisoned. #DeltaIVHeavy #parkerSolarProbe pic.twitter.com/f3VeAgv5TE

— NASA's Launch Services Program (@NASA_LSP) August 12, 2018

A last-minute technical problem had delayed NASA’s planned launch on Saturday.

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

Rocket maker United Launch Alliance said as soon as the red pressure alarm for the gaseous helium system went off, a launch controller ordered, “Hold, hold, hold”.

Dr Eugene Parker. Photo: Getty

The $US1.5 billion ($A2.1 billion) mission was 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. He plans to stick around at least another few days.

NASA said the Parker Solar Probe will swoop to within six million kilometres of the sun’s surface, facing heat and radiation like no spacecraft before it.

We're just a few hours away from launching #ParkerSolarProbe to the Sun! It's going to a region where temperatures reach millions of degrees Fahrenheit. So…why won't it melt? https://t.co/4NiJoymEdX

Launch coverage starts at 3am ET on #SunDay, Aug. 12: https://t.co/U8T7pZaI5r pic.twitter.com/OMbQREj3SD

— NASA Sun & Space (@NASASun) August 12, 2018

“Today’s launch was the culmination of six decades of scientific study and millions of hours of effort,” said project manager Andy Driesman, of the Johns Hopkins University Applied Physics Laboratory.

“Now, Parker Solar Probe is operating normally and on its way to begin a seven-year mission of extreme science.”

-with AAP