Finally, on 25 December 2021, at 07:20 EST (Eastern Standard Time, the time zone for the east coast of the United States and Canada, which corresponds to 13:20 Italian time), the world’s largest James Webb Space Telescope set off.

Launching information

The James Webb Space Telescope was launched on an Ariane 5 rocket, a European launcher. The Ariane 5 is one of the most reliable launch vehicles in the world, capable of taking Webb into its target orbit.

The launch will take place from French Guiana. James Webb will be launched from Arianespace’s ELA-3 launch complex at the European spaceport located near Kourou, French Guiana. Launch sites near the equator are usually chosen because the Earth’s rotation can help give our launcher an extra boost (the Earth’s surface at the equator moves at 1670 km/h).

In order for the telescope to fit into the rocket housing, it must fold.
After launch, the telescope will unfold on its 30-day, million-kilometre journey to the second Lagrange point (L2).

Some 14 years have passed since scientists in the 1990s hoped that the mission, then known as the Next Generation Space Telescope, would be ready to go on the launch pad. The mission’s launch date has slipped repeatedly and the cost of development has risen to almost €10 billion.

The James Webb Space Telescope is a time machine!

The space telescope will look back more than 13.5 billion years to see the faint infrared light of the first galaxies, revealing a never-before-seen era of cosmic history that shaped today’s universe.

It is practically a cosmic time machine, capable of seeing galaxies and stars as they were just 100 million years after the Big Bang.

This telescope is so powerful that if you were a bumblebee 384,400 kilometres away (which is the distance between the Earth and the moon) we would be able to see you

John Mather, senior project scientist

Everything in the universe to see ranges from the most distant galaxies in the cosmos to the planets, moons, asteroids and comets in our solar system. Webb will be able to observe all those details not seen by any other space observatory.

Webb will be able to see stars and galaxies that are 100 times fainter than previously possible.

Klaus Pontoppidan project scientist

Webb will take the blinders off and show us the formation of the universe: developed over a quarter of a century, the James Webb Space Telescope is the largest astronomical observatory ever launched into space.

How it unfolds after launch

A solar array and a steerable antenna will open, then a sunshade the size of a tennis court will open to begin cooling the scientific instruments and mirrors. These will reach an operating temperature of -233 degrees Celsius, just 40 degrees Kelvin above absolute zero.

Two articulated wings, each with three of the 18 mirror segments, will swing into place, allowing the primary mirror to reach its final shape. The secondary mirror will unfold, aligning to bounce the light collected by the primary mirror directly into Webb’s instrument module, which houses a suite of sophisticated infrared detectors.

What the James Webb looks like

Its primary mirror is composed of 18 hexagonal segments, each made of beryllium, coated with a thin layer of gold and polished to exacting standards of cleanliness.

Buried inside the telescope are four infrared instruments, each tuned for a specific job. Together, the instruments will give astronomers the most powerful telescope in history.

The observatory followed a tortuous journey to launch. The mirrors were fabricated, polished and tested in Ohio, Alabama, California and Colorado at contractor Ball Aerospace, then transported to NASA’s Goddard Space Flight Center in Maryland for assembly.

Webb’s four science instruments were delivered to Goddard from the UK, Germany, California and Canada. Goddard engineers assembled the instruments in Webb’s science module and began putting the telescope together in 2013.

Finally, in October, Webb travelled to French Guiana on a French transport ship to begin final preparations for liftoff. Once there, Webb was fuelled with rocket propellant and hoisted atop his Ariane 5 rocket.

The most powerful telescope ever built

The Space Observatory is named after James Webb, the NASA administrator who helped the space agency for seven years in the 1960s. His tenure was a crucial period for NASA, during which the first Americans launched into space and plans for the Apollo programme matured, culminating in Neil Armstrong’s first steps on the moon in 1969, less than a year after Webb left the job.

Within a month, James Webb Space will arrive in orbit around the Lagrange L2 point, a gravitationally stable position nearly 1.5 million kilometres from Earth. The ground teams operating Webb, using remote control, will spend the next five months perfectly aligning the mirrors, focusing the telescope as it stabilises at its final operating temperature.

In six months’ time, Webb will publish his first scientific images.

The space telescope will peer through clouds of dust to study star-forming regions (opaque to telescopes like Hubble, which see into the visible part of the light spectrum). Webb’s light-gathering power will also allow scientists to measure the chemical composition of atmospheres on planets around other stars, revealing for the first time which extraterrestrial worlds might be suitable for life.

Finally, the James Webb Space Telescope will scan the universe for the first light after the Big Bang, some 13.8 billion years ago.