World's Most Powerful Space Telescope Sets Off On A Million-Mile Voyage

The world's most powerful space telescope on Saturday blasted off into orbit, headed to an outpost 1.5 million kilometres (930,000 miles) from Earth, after several delays caused by technical hitches.

The James Webb Space Telescope, some three decades and billions of dollars in the making, left Earth enclosed in its Ariane 5 rocket from Kourou Space Centre in French Guiana.

"What an amazing day. It's truly Christmas," said Thomas Zurbuchen, head of scientific missions for NASA, which together with the European and Canadian space agencies, ESA and ACS, built the telescope

ESA chief Josef Aschbacher said he was "very happy to say that we've delivered the spacecraft into orbit very precisely... that Ariane 5 performed extremely well".

This was key, since placing the spacecraft in orbit helps economise on the fuel the telescope will need to reach its final destination and perform well after that.

It is expected to take a month to reach its remote destination.

It is set to beam back new clues that will help scientists understand more about the origins of the Universe and Earth-like planets beyond our solar system.

Named after a former NASA director, Webb follows in the footsteps of the legendary Hubble -- but intends to show humans what the Universe looked like even closer to its birth nearly 14 billion years ago.

Speaking on social media, Webb project co-founder John Mather described the telescope's unprecedented sensitivity.