On Saturday, the largest and most advanced telescope to enter space will take off from South America to look deeper into the universe than ever before.
The James Webb Space Telescope, a $10 billion instrument developed by Nasa, the European Space Agency and the Canadian Space Agency, will eventually settle into an orbit over 1.6 million kilometres away — about four times the distance between the Earth and the Moon.
Nasa said the telescope will provide “an unprecedented window into our universe’s deep past”.
It is being billed as the successor to the Hubble Space Telescope, which orbits the Earth about 550 kilometres away.
Named after Nasa's chief during most of the 1960s, the Webb telescope is described by the US space agency as “the most complex space science observatory ever built”.
“Webb will peer more than 13.5 billion years back into cosmic history to a time when the first luminous objects were evolving,” Nasa said.
“It’s the first observatory capable of exploring the very earliest galaxies, and could transform our understanding of the universe.
“Webb will also study the atmospheres of planets orbiting other stars, and observe moons, planets, comets and other objects within our own solar system.
“This data will reveal the molecules and elements that exist on distant planets and could unlock clues to the origins of our planet and life as we know it.”
Webb is about 100 times more sensitive than Hubble and is expected to revolutionise astronomers' understanding of the universe and our place in it.
Its instruments also make it ideal to look for potentially life-supporting atmospheres around numerous newly documented exoplanets — celestial bodies orbiting distant stars — and to observe worlds nearer to home, such as Mars and Saturn's icy moon Titan.
The telescope will mainly view the cosmos on the infrared spectrum, allowing it to gaze through clouds of gas and dust where stars are being born, while Hubble has typically operated on optical and ultraviolet wavelengths.
The Webb had been due to lift off from Europe's Spaceport in French Guiana on December 24, but local weather pushed that date back to at least Christmas Day.
It follows a two-day postponement from an earlier December 22 targeted launch window that was delayed by electronic communications difficulties between the launch vehicle and its payload, Nasa said.
But if all goes to plan, the telescope will be released from its rocket after a 26-minute ride into space before a month-long journey to its destination.