James Webb telescope sets off on million-mile voyage

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

La fusée transportant James Webb a décollé à 13h30, heure de Paris, le 25 décembre 2021. AFP - -

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.

The telescope is programmed to beam back possible 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.

James Webb was the second ever director of US space agency Nasa. He ran the agency from 1961 to 1968 © Nasa

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.

John Mather, a Nobel laureate in physics and NASA’s chief scientist for the James Webb Space Telescope, says the observatory set for launch this weekend will seek answers to fundamental questions about what happened after the Big Bang.

Our full story: https://t.co/aZPEglD4K3 pic.twitter.com/9qwGDXsxCM

— Spaceflight Now (@SpaceflightNow) December 24, 2021

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.

'Exceptional measures' 

The telescope is unequalled in size and complexity.

Its mirror measures 6.5 metres in diameter, three times the size of the Hubble's mirrorm, and is made of 18 hexagonal sections.

Webb's centerpiece is its giant primary mirror, a concave structure 21.5 feet (6.5 meters) wide and made up of 18 smaller hexagonal mirrors ALEX WONG GETTY IMAGES NORTH AMERICA/AFP/File

It is so large that it had to be folded to fit into the rocket.

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.

Nasa director of operations Jean-Luc Voyer, less than two minutes before the lift-off of the Ariane rocket that carries the James Webb telescope, 25 December 2021. © Nasa TV screengrab

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.

Sun shield

Crew on the ground knew that the 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.

Screen grab of the NasaTV website showing a 3D simulation of the Ariane rocket carrying the James Webb telescope, just over a minute after launch. © Nasa screengrab

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.

(With AFP)