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.
It is expected to take a month to reach its remote destination.
#NASAWebb is safely in space with its solar array drawing power from the Sun! Its reaction wheels will keep the spacecraft pointed in the right direction so that its sunshield can protect the telescope from radiation and heat: https://t.co/NZJ7sSJ8fX#UnfoldTheUniverse pic.twitter.com/s4nfqvKJZD— NASA Webb Telescope (@NASAWebb) December 25, 2021
It is expected 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.
"#JWST can see the heat signature of a bumblebee at the distance of the Moon," he said.
We have LIFTOFF of the @NASAWebb Space Telescope!— NASA (@NASA) December 25, 2021
At 7:20am ET (12:20 UTC), the beginning of a new, exciting decade of science climbed to the sky. Webb's mission to #UnfoldTheUniverse will change our understanding of space as we know it. pic.twitter.com/Al8Wi5c0K6
All that power is needed to detect the weak glow emitted billions of years ago by the very first galaxies to exist and the first stars being formed.
The telescope is unequalled in size and complexity.
Its mirror measures 6.5 metres (21 feet) in diameter – three times the size of the Hubble's mirror – and is made of 18 hexagonal sections.
It is so large that it had to be folded to fit into the rocket.
#NASAWebb's fairing has been jettisoned, revealing the telescope for the first time in space! Also, we have successfully received telemetry from the observatory. #UnfoldTheUniverse https://t.co/uLUmjnfOO4 pic.twitter.com/MN3xOPounA— NASA Webb Telescope (@NASAWebb) December 25, 2021
That manoeuvre was laser-guided with NASA imposing strict isolation measures to limit any contact with the telescope's mirrors from particles or even human breath.
Once the rockets have carried Webb 120 kilometres, the protective nose of the craft, called a "fairing", is shed to lighten the load.
To protect the delicate instrument from changes in pressure at that stage, rocket-builder Arianespace installed a custom decompression system.
"Exceptional measures for an exceptional client," said a European Space Agency official in Kourou on Thursday.
Crew on the ground found out first stage of the flight was successful about 27 minutes after launch.
Once it reaches its station, the challenge will be to fully deploy the mirror and a tennis-court-sized sun shield.
That intimidatingly complex process will take two weeks and must be flawless if Webb is to function correctly.
Its orbit will be much farther than Hubble, which has been 600 kilometres above the Earth since 1990.
The location of Webb's orbit is called the Lagrange 2 point and was chosen in part because it will keep the Earth, the Sun and the Moon all on the same side of its sun shield.
Webb is expected to officially enter service in June.