Nasa's powerful next-generation telescope has blasted off into space from its launchpad in Florida, with a mission to explore dark energy, black holes and other mysteries of the Universe.

The Nancy Grace Roman telescopewill capture vast panoramic views of space, with a field of vision 100 times larger than both the Hubble and James Webb space telescopes, Nasa says.

The mission begins with a 100-day journey to a vantage point roughly one million miles from Earth, where the telescope will then start charting planets outside our solar system, known as exoplanets.

"Roman is going to change the way we look at the Universe," said Nicky Fox, a Nasa administrator.

"It is going to discover tens of thousands, maybe even 100,000 new exoplanets."

US President Donald Trump dialled in to Nasa's news conference on Sunday morning to congratulate the scientists working on the project.

"You're the hottest in space, and we have the hottest country anywhere in the world. So let's keep it all going. You're a big part of it," Trump said.

The successful launch of the telescope took place on Sunday morning local time from the Kennedy Space Center in Florida.

"What a glorious dawn launch," Jackie Townsend, a project manager on Nasa's Roman telescope, said at the news conference after liftoff. "The ride was magnificent. It put us right where we wanted to be."

About 30 minutes after launch, Roman separated from its SpaceX rocket and is now heading towards its orbiting point around a million miles away.

The telescope is named after physicist Nancy Grace Roman, who was Nasa's first chief astronomer in the 1960s and its first female executive.

During her career, she was instrumental in getting the Hubble Space Telescope approved by US Congress and later said its most interesting discovery was dark energy.

The new telescope is similarly expected to revolutionise our understanding of the Universe, including through investigating dark energy. It has a five-year primary lifespan with a goal to operate for 10 years.

Nasa says its "crisp, sweeping surveys will help scientists investigate dark energy and dark matter, discover and characterise exoplanets, map billions of galaxies, study black holes, and explore objects from our own solar system to the edge of the observable Universe."

The origins of dark matter and dark energy remain unknown, but they are believed to make up about 95% of the Universe.

Dark matter, which is invisible, acts as a kind of gravitational glue, while dark energy is believed to be a repulsive force driving the Universe's expansion.

"One of our main goals at Nasa is answering the question: are we alone in the Universe?" Fox said at a Sunday morning news conference.

"With Roman, we are going to make this giant leap forward... that is going to allow us to look at these distant, distant worlds and start to really resolve the atmosphere around them to let us know: could they be habitable?"

Nasa's James Webb Space Telescope, launched in 2021, also orbits the Sun around one million miles from Earth, but its field of vision is not as expansive. Nasa's Hubble Space Telescope, launched in 1990, orbits at about 300 miles above Earth's surface.