Star Metro - Webb telescope reveals clearest infrared image of early universe

The stunning shot, revealed in a White House briefing by President Joe Biden, is overflowing with thousands of galaxies and features the faintest objects ever observed, colorized from infrared to blue, orange and white tones.

"This telescope is one of humanity's great engineering achievements," he said.

Known as Webb's First Deep Field, it shows the galaxy cluster SMACS 0723, which acts as a gravitational lens, magnifying much more distant galaxies behind it.

Webb's primary imager NIRCam -- which operates in the near infrared wavelength spectrum because light from the early universe has been stretched out by the time it reaches us -- has brought these faint background galaxies into sharp focus.

Webb compiled the composite shot in 12.5 hours, achieving well beyond what the Hubble Space Telescope could in weeks.

The next set of images will be released Tuesday.

- First targets -

An international committee decided the first wave of images would include the Carina Nebula, an enormous cloud of dust and gas 7,600 light years away.

Carina Nebula is famous for its towering pillars that include "Mystic Mountain," a three-light-year-tall cosmic pinnacle captured in an iconic image by the Hubble Space Telescope, until now humanity's premier space observatory.

Webb has also carried out a spectroscopy -- an analysis of light that reveals detailed information -- on a faraway gas giant called WASP-96 b, which was discovered in 2014.

Nearly 1,150 light-years from Earth, WASP-96 b is about half the mass of Jupiter and zips around its star in just 3.4 days.

Nestor Espinoza, an STSI astronomer, told AFP that previous exoplanet spectroscopies carried out using existing instruments were very limited compared to what Webb could do.

"It's like being in a room that is very dark and you only have a little pinhole you can look through," he said of the prior technology. Now, with Webb, "You've opened a huge window, you can see all the little details."

- Million miles from Earth -

Launched in December 2021 from French Guiana on an Ariane 5 rocket, Webb is orbiting the Sun at a distance of a million miles (1.6 million kilometers) from Earth, in a region of space called the second Lagrange point.

Here, it remains in a fixed position relative to the Earth and Sun, with minimal fuel required for course corrections.

A wonder of engineering, the total project cost is estimated at $10 billion, making it one of the most expensive scientific platforms ever built, comparable to the Large Hadron Collider at CERN.

Webb's primary mirror is over 21 feet (6.5 meters) wide and is made up of 18 gold-coated mirror segments. Like a camera held in one's hand, the structure must remain as stable as possible to achieve the best shots.

Charlie Atkinson, chief engineer on the James Webb Space Telescope program at lead contractor Northrop Grumman, told AFP that it wobbles no more than 17 millionths of a millimeter.

After the first images, astronomers around the globe will get shares of time on the telescope, with projects selected competitively through a process in which applicants and selectors don't know each other's identities, to minimize bias.

Thanks to an efficient launch, NASA estimates Webb has enough propellant for a 20-year life, as it works in concert with the Hubble and Spitzer space telescopes to answer fundamental questions about the cosmos.

F.Leblanc--SMC