James Webb: It is just the beginning

In the superhot cauldron of the early universe, no light could escape the dense and opaque fog of primordial gas. As the cosmic soup of largely subatomic particles began to cool down, the fog of the lightest elements — hydrogen and helium — condensed to form the first stars. Some early photons — from these newly formed stars — travelled relatively unhindered through the ever-expanding vast and presumably empty open space for over 13 billion years, to reach their final destination: The James Webb Space Telescope (JWST), some 1.6 million km from Earth. 

The first five images from this $10-billion endeavour were published by Nasa earlier this week. Together, these images, featuring the birth of stars and the deepest looks into the far reaches of space, provide the most detailed glimpses into the beginnings of the universe.

Previewed by US President Joe Biden in a press meet, Webb’s first “deep field” image is teeming with galaxies. “Everywhere we look, there are galaxies everywhere,” said Jane Rigby, operations project scientist for the JWST, during the briefing. The most distant galaxies reveal what they looked like more than 13.1 billion years ago, less than a billion years after the Big Bang.

But these stunning images are only a fraction of what the JWST shall provide. Launched on December 25, 2021, Webb is slated to take 6,000 hours of observations in its first year itself. It will target distant galaxies, exoplanets (planets outside our solar system) and even comets with unprecedented infrared imagery and spectroscopy (study of the interaction of light and matter).

“The first year of Webb’s science is going to be very exciting. The programmes that we have been planning for 20 years, most of them will be executed during this first year — to see the first light in the universe, the first galaxies that formed. We will probe the atmospheres of planets around other stars,” Heidi Hammel, interdisciplinary scientist for the JWST, was quoted as saying by Scientific American.

As many as 70 accepted programmes target exoplanets, including hot Jupiters, “super-puffs” (gas giants that are bigger than they ought to be), and hot rocky worlds.

In fact, the JWST in its first images has captured signs of water, along with evidence of clouds and haze, in the atmosphere surrounding a hot, puffy gas giant planet orbiting a distant Sun-like star. WASP-96 b is located roughly 1,150 light-years away in the constellation Phoenix. “With a mass less than half that of Jupiter and a diametre 1.2 times greater, WASP-96 b is much puffier than any planet orbiting our Sun,” according to Nasa. 

“The observation, which reveals the presence of specific gas molecules based on tiny decreases in the brightness of precise colours of light, is the most detailed of its kind to date, demonstrating Webb’s unprecedented ability to analyse atmospheres hundreds of light years away,” it said. Webb’s more detailed observation, according to Nasa, marks a giant leap forward in the quest to characterise potentially habitable planets beyond Earth.

It shall also help humans reach out to distant galaxies, which appear to be frozen in time for us. We’ve heard about the Hubble Deep Fields, a long look into the black space between stars that revealed hundreds of thousands of galaxies. The JWST is set to extend and expand the view.

The plan to carry out the next-generation Deep Extragalactic Exploratory Public (DEEP) survey needs over 120 hours to zero in on the same area of sky covered by Hubble’s deep and ultra-deep fields. The Hubble Ultra Deep Field (observations taken between 2003 and 2004) comprises nearly 10,000 galaxies. The JWST’s first deep field has already revealed far more.

“We have seen galaxies 97 per cent of the way back to the Big Bang,” said Dan Coe of Space Telescope Science Institute (science operations and mission operations centre for the JWST) in a Sky & Telescope report. “I am most excited to finally see objects that existed during that missing first 3 per cent, the first 400 million years of the universe.”

Besides, the giant space observatory will see not only giant galaxies but also the dwarf ones, far smaller than what its predecessor Hubble Space Telescope could capture. Detailed spectroscopy shall help uncover how many and what types of stars formed through cosmic time.

The giant telescope shall also try to identify supermassive black holes that sit at the centre of almost every large galaxy.

It shall observe Mars and the gas giants, dwarf planets like Pluto and Eris, and even smaller bodies in our solar system — asteroids, comets, and Kuiper Belt Objects. It is also slated to study brown dwarfs and other matters of cosmic evolution.

Indeed, James Webb has a lot on its platter, which is highly enticing and scientists are geared up to gorge on its observations exploring the early universe, decoding how galaxies form and evolve, and uncovering the mysteries of exoplanets. What it all needs is a peppering of “surprise” and path-breaking discoveries, which I hope there shall be many.