NASA's James Webb Space Telescope just launched: What happens next

And why this is such a monumental event for the entire field of astronomy.

Monisha Ravisetti Former Science Writer
Monisha Ravisetti was a science writer at CNET. She covered climate change, space rockets, mathematical puzzles, dinosaur bones, black holes, supernovas, and sometimes, the drama of philosophical thought experiments. Previously, she was a science reporter with a startup publication called The Academic Times, and before that, was an immunology researcher at Weill Cornell Medical Center in New York. She graduated from New York University in 2018 with a B.A. in philosophy, physics and chemistry. When she's not at her desk, she's trying (and failing) to raise her online chess rating. Her favorite movies are Dunkirk and Marcel the Shell with Shoes On.
Monisha Ravisetti
4 min read

This false color infrared exposure captures the Christmas morning liftoff from South America of NASA's James Webb Space Telescope.


On Saturday morning, NASA set the stage for the future of astronomy. The James Webb Space Telescope launched, embarking on a journey to recalibrate how we view the universe. Not only will Webb teach us about hidden regions of space, it has the power to prove whether we've correctly documented the events that took place immediately after the Big Bang.

Liftoff went "exactly as expected" at 4:20 a.m. PT (9:20 a.m. local time at the launch pad in French Guiana), according to ground control. The team highlighted the spacecraft's "nominal" trajectory and performance, relieving tensions had been spiking just ahead of the launch from the European Space Agency's base in South America. 

After a seamless deployment of Webb's solar array about 30 minutes later, the telescope began charging up for the rest of its cosmic expedition. The full sequence was a resounding triumph. 

Webb is set to travel 1 million miles (1.6 million km) from Earth over the next six months and begin orbiting the sun at the vital-for-the-mission location known as the second Lagrange point. Once that happens, it will begin sending back images of the universe. But these won't be mere intergalactic photos. Webb will offer us a new story of the cosmos, completely unfiltered. This will be a giant step forward from the Hubble telescope, which launched along with the Discovery space shuttle in 1990.

But before we get into the incredible data that Webb promises to reveal, here's the context of what just blasted into outer space after two decades of work and about $10 billion.

You can also take a deeper dive into the technical aspects of Webb here.

Webb's impressive specs

This is a 3D rendering of how James Webb will look in space once fully deployed.

NASA's Goddard Space Flight Center Conceptual Image Lab

Primary mirror: 21.3 feet (6.5 meters) across, with 18 gold-plated hexagonal segments that collect infrared light. NASA calls it a "light bucket."

Sunshield: A five-layer metal umbrella the size of a tennis court to protect the probe from the heat of the sun, the Earth and the moon.

Near-infrared camera (NIRCam): Webb's primary imager will detect the earliest stars and galaxies that formed.

Near-infrared spectrograph (NIRSpec): This tool can use infrared information to inform scientists on physical properties like chemical composition and temperature of galactic bodies.

Mid-infrared instrument (MIRI): This has both a camera and spectrograph that can detect objects in the mid-infrared electromagnetic region.

Near-infrared imager and slitless spectrograph (NIRISS): This one's thought to be particularly useful in exoplanet detection.

Fine guidance sensor (FGS): Used for navigation.

Why Webb is a very, very big deal

Webb's promise rests on its unprecedented infrared imaging capabilities, especially with NIRCam. In a nutshell, here's what infrared imaging can do. 

A quick physics recap: To get to Webb's promise, we have to talk about the electromagnetic spectrum. On one end of the spectrum, we have blue light, and on the other end, red light. Blue light wavelengths are shorter, so you can think of them as having a ton of narrow, pointy waves on their curvy, wavelength zigzag. Red light has longer, stretched-out wavelengths. 

As the universe expands, wavelengths of blue light slowly stretch out like pulling on a rubber band. As they get longer, they become redder. Once those wavelengths get really far on the red end of the spectrum, they'll enter what's called the infrared light region. 

As cosmic bodies get farther away from Earth, along with the rest of space's fabric, the light illuminating them stretches out simultaneously, resulting in a phenomenon called redshift. Basically, the once-blue light of stars, galaxies, quasars and other luminous cosmic objects will appear as infrared light. 

Unfortunately, humans can't see infrared light, which is why we can't see a ton of things in the universe with our naked eye. And Hubble can see only a portion of it. Webb, by contrast, is designed for the job. Think of it like viewing the stars from a highly lit major city, then traveling to a dark forest before looking up again. The second time around, the sky will appear much, much starrier.

Further, when you take into consideration exactly where that infrared light is coming from, in a sense Webb has a time machine onboard.


Lockheed Martin engineer Alison Nordt works on Webb's NIRCam.

Lockheed Martin

Another physics recap: On Earth, if someone across the room switched on a lightbulb, it would take an infinitesimally short time for its illumination to hit your eye. But if someone were to stand on the moon and switch on a lightbulb, it would take 1.3 seconds for you to see it back on Earth. In essence, every time moonlight reaches your eye, you're looking back in time by 1.3 seconds -- and that's just the moon, some 238,855 miles (nearly 384,400 km) away.

Webb can look much farther into deep space, about 13.7 billion light-years away, which means it can look 13.7 billion years back in time. That's just 100 million years after the universe was born. 

Who knows what we'll find way, way, waaay out there. As per predictions of the experts behind Webb, the telescope could reveal habitable exoplanets, secrets of black holes and perhaps even evidence of life beyond Earth.

After sighing a breath of relief, astronomers will sit tight for the next six months, awaiting Webb's command on how to alter, amend and footnote the entire field of astronomy.


One of the last views we will ever have of the Webb space telescope as it starts a journey of a million miles on Dec. 25.

NASA/Screenshot by CNET