eye in the sky

NASA’s James Webb Space Telescope: Launch date, mission goals, deployment, and the hunt for aliens

The James Webb Space Telescope is scheduled for a December launch from French Guinea.

Originally Published: 
Webb illustration of post-launch faring shedding
ESA / D. Ducros

NASA’s James Webb Space Telescope (JWST) — an ambitious mission in development for more than a decade — has an official targeted launch date of December 18, marking the end of two decades of development and preparing the way for one of NASA’s most ambitious missions.

According to NASA, the Webb telescope will travel farther than any current or planned crewed spacecraft. The telescope will help scientists peer back in cosmic time, with a plan to observe galaxies that are over 13 billion light-years away and study alien worlds with the hopes of finding atmospheres conducive to life.

“Together, we’ve overcome technical obstacles along the way as well as challenges during the coronavirus pandemic,” Gregory L. Robinson, Webb’s program director at NASA, says in a press statement. “I also am grateful for the steadfast support of Congress. Now that we have an observatory and a rocket ready for launch, I am looking forward to the big day and the amazing science to come.”

As JWST gears up for launch, Inverse breaks down its mission, orbital path, and its long and complicated road to space.

By now, space enthusiasts are pretty familiar with the Hubble Space Telescope. Hubble has been running for more than 30 years and is due for a long-awaited retirement. JWST is meant to come in as Hubble’s successor, but 100 times more powerful.

When will the James Webb Space Telescope launch?

The telescope is scheduled for a December 18, 2021 launch date. As of June 2021, JWST was still on schedule. In July, it passed three milestone tests, signaling it’s on track for launch. In August, it began preparations for shipment.

UPDATE: This article was updated on September 9 to reflect a new targeted launch date.

It will launch near Kurou, French Guiana on an Ariane 5 rocket. The European Space Agency is providing the rocket and its launch services: Webb is taking off from the ELA-3 launch complex at the European Spaceport.

First, though, the mission has to make its way safely from Long Beach, California to French Guiana, requiring a trip through the Panama Canal. NASA has been mum on details of its journey — including how long it will take — thanks to a centuries-old problem: piracy on the high seas. No really.

“We've enlisted the services of the US transportation Command to assess the complete route and the likelihood that we would encounter any unsafe individuals (or) situations,” Mark Voyton, NASA’s integrated science instrument module manager for the Webb Telescope, previously told Inverse. However, an ESA press release indicates that the telescope will arrive by the end of September.

In this photograph, testing teams work on the JWST.


JWST has been in the works since 1989 when the idea for it emerged from a NASA co-hosted workshop. But it has suffered from continued delays, which have also contributed to a large cost overrun. The current cost estimate has been $10 billion. Perseverance, the top-of-the-line new Mars rover, cost around $2 billion.

The telescope had an initial launch window scheduled for 2018, which was then pushed back to 2020. Now NASA is aiming for the late-2021 launch.

After the telescope arrives via boat, it will take 55 additional days to prepare it for launch. The first month will involve testing of electrical equipment to make sure its still functioning after its journey.

It’s expected to begin its science operations in 2022. In August 2021, NASA announced its first task, which will be no small feat: mapping the earliest structures in the universe.

What will the James Webb Space Telescope do?

JWST is the biggest and most complex telescope ever built by NASA. By looking in infrared light, the telescope can observe the cosmos in greater detail than ever before.

“This telescope will fundamentally alter our understanding of the universe,” NASA Administrator Bill Nelson announced on August 24, 2021. “For the first time, we’ll see the light from the first galaxies that formed in the early universe. Webb is nearly ready to take flight.”

A poster was made by NASA to celebrate the James Webb Telescope.


The telescope sports a 21-foot-wide, 4-inch-thick tiling of mirrors acting as one large mirror. This will enable it to observe distant objects in the universe better than any other instrument in the world, due to both its size and its location far away from Earth.

A large mirror is needed to reflect light from objects in space. This amplifies the light into the secondary mirror, enabling the telescope's instruments a larger, clearer view of the heavens. This also will enable detailed observations that no telescope on Earth can do, including:

Looking for alien life — Since the discovery of the first confirmed exoplanet in 1992, astronomers have observed more than 4,000 alien worlds orbiting around distant stars.

The explosion in exoplanets is due in large part thanks to NASA’s Kepler mission and the Transiting Exoplanet Survey Satellite (TESS) missions. Kepler stared at a narrow region of space around the constellations Cygnus and Lyra until its demise in 2018, while TESS surveys 200,000 of the brightest stars in the sky.

JWST will study the atmosphere of exoplanets in greater detail than those missions, and probe whether or not they contain the ingredients necessary for life. It will have a high enough resolution to witness planets passing in front of their home star and draw out atmospheric properties when they transit.

Webb should be able to perform spectroscopic measurements of the atmosphere of exoplanets and assess the intensity of light at different wavelengths in order to study the composition of their atmosphere.

Time machine — Due to its powerful observing capabilities, JWST will act as a cosmic time machine as it looks back at objects billions of light-years away.

The telescope will be able to see the composition of some of the first galaxies and determine how they came together and what role they played in an event known as the Epoch of Reionization. This was an era — about 500 million to 1 billion years after the Big Bang — when stars and galaxies began to ionize clouds of neutral hydrogen, making much of the space we see around us transparent instead of opaque.

Using the JWST, scientists will be able to look back at that crucial turning point in the universe’s history, observing the very first stars and galaxies, or sources of light.

OG galaxies — Along with the oddball galaxies that catalyzed reionization, astronomers will be able to look into the process that caused the formation of large galaxies like we see today.

Galaxies, like the Milky Way, formed over billions of years through mergers with smaller galaxies and other processes. But the very first galaxies of the universe looked very different, sometimes rather small and clumpy with stars.

By observing galaxies in the ancient universe, scientists will be able to study how galaxies evolved over time to form the structures that they are in today.

Clear views — Infrared capabilities will help the telescope see beyond what we can in visible ranges — including staring right through otherwise opaque areas of space. As we image nebulae using our current instruments, a lot is hidden from our view with clouds of dust. But an infrared camera picks up heat, so it goes beyond what we can see with visible light.

With JWST, astronomers will be able to see many of the stars tucked behind dust clouds and get a better sense of what the cosmos looks like.

What is the James Webb Space Telescope orbit?

While the Hubble Space Telescope orbits the Earth, the James Webb Space Telescope will orbit the Sun.

JWST will be situated 1 million miles away from Earth at what is called the second Lagrange point or L2. This lets the telescope stay in line with our planet at a stable point as it moves around the Sun.

By doing so, the telescope protects itself against the light and heat of the star.

This video details JWST’s orbit.

It will take the telescope six months to complete one orbit.

JWST’s orbit keeps the telescope out of the shadows of both the Earth and Moon, allowing it to have an unobstructed view of the universe for the entire duration of its orbit. Meanwhile, Hubble goes in and out of Earth’s shadow every 90 minutes.

How will the James Webb Space Telescope be deployed?

After undergoing a series of tests, the telescope will be packaged up and shipped to French Guiana for launch onboard an Ariane-class space rocket. It is expected to make its journey by ship from the Northrop Grumman facility in California to French Guiana in late August 2021. The JWST will travel via the Panama Canal.

The JWST mirror is too large for the rocket ride: In order to fly the telescope into orbit, the mirror must be tucked away during the ride to space. Once in orbit, it will unfold.

The telescope’s mirror was built in 18 separate segments on a structure that folds up. Each of the segments is around 4.3 feet in diameter.

This video shows how the JWST is folded to fit inside the rocket:

JWST is described as the “largest, most complex space observatory ever built.”

Once in space, the telescope will need to unfold in order to go from its compact space launch configuration into the tennis court-sized observatory that will unlock the universe. Deployment will begin shortly after launch, and take around two weeks to complete.

Is JWST better than Hubble?

JWST is intended as a follow-on from Hubble. Webb will primarily look at the Universe in the infrared, while Hubble looks primarily at optical and ultraviolet wavelengths.

Hubble is due for a long awaited retirement, but its successor is more than worth of taking on the task of seeing the vast and expanding universe.


Among the key upgrades:

  • JWST has a massive mirror, much larger than that of Hubble. Hubble’s mirror is 7.8 feet in diameter, while JWST boasts a mirror that is 21 feet in diameter.
  • JWST will be able to peer much further in cosmic time due to it being optimized to infrared light, unlike Hubble which is optimized for visible light.
  • Webb will observe primarily in the infrared and will have four science instruments to capture images and spectra of astronomical objects, providing wavelength coverage from 0.6 to 28 micrometers.
  • The instruments on Hubble can observe a small portion of the infrared spectrum from 0.8 to 2.5 microns, but its primary capabilities are in the ultra-violet and visible parts of the spectrum from 0.1 to 0.8 microns.

Ahead of the JWST launch, Hubble appears ready to hand over the torch.

In March, Hubble entered safe mode after a software error. While the telescope was still able to communicate with NASA, it did not carry out its regular science operations until July when the space agency brought it back online.

This codex article will be updated with more information as we get it.

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