New Issue: Orbital Catastrophe Ahead? Read Now

NASA’s James Webb Space Telescope Is Fueled for Late December Launch

After some two decades of development, the orbital observatory is set to at last reach space on December 22

Workers unpack a massive telescope.

Workers unpack the James Webb Space Telescope from its storage container in preparation for its launch from Kourou, French Guiana.

Join Our Community of Science Lovers!

The new James Webb Space Telescope is topped off and one step closer to taking flight. 

Mission team members have finished fueling the 

James Webb Space Telescope at ahead of its planned Dec. 22 launch from the Guiana Space Center in Kourou, French Guiana, the European Space Agency announced Monday (Dec. 6). The fueling for Webb, which is an international collaborative effort between NASA, ESA and the Canadian Space Agency, took 10 days and was completed on Dec. 3, according to the ESA statement. 


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


After a series of delays since the development of the scope first began in 1996, Webb is still on track to finally launch Dec. 22 atop an Arianespace Ariane 5 rocket from the Guiana Space Center in Kourou, French Guiana.

"Webb's propellant tanks were filled separately with [21 gallons] 79.5 l of dinitrogen tetroxide oxidizer and [42 gallons] 159 l hydrazine," the ESA wrote in the announcement, adding that the oxidizer "improves the burn efficiency of the hydrazine fuel."

Now that Webb is fueled, the mission team will begin "combined operations," according to the statement. In this phase, the teams behind the rocket and the telescope will come together to mount Webb on the Ariane 5 rocket and encapsulate it within the rocket's fairing. The newly joined pair will then be moved to the Final Assembly building for final preparations before liftoff.

Once successfully launched and in space, Webb will begin a complicated series of deployment maneuvers to unfurl its solar arrays on its way to its ultimate destination where it will begin making observations. 

Webb is destined for a location in space 930,000 miles (1.5 million kilometers) away known as L2, a Lagrange point or a stable gravitational location in space. Upon arrival, the telescope will spend six months in a "commissioning period" during which the team will ensure that it unfolded correctly and its instruments are working correctly.

Webb was previously set to launch Dec. 18 (after many previous delays, budgetary concerns and more) but, 

as NASA reported, a clamp band that holds Webb to the launch vehicle adapter that will allow it to be integrated into the Arianespace launch vehicle had released unexpectedly. Teams investigated the unexpected event and performed additional testing before setting a new launch date and moving on to run a "consent to fuel" review before beginning fueling. 

Webb, which will observer the universe in infrared light, is set to be the most powerful telescope ever launched into space. Scientists aim to use the instrument to peer farther out into the cosmos than ever before, giving them an unprecedented peek into our universe's past. 

Scientists hope that Webb's powerful observational technology will allow researchers to uncover more information about the early universe, explore mysterious things such as dark matter and dark energy and so much more.

Copyright 2021 Space.com, a Future company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Subscribe to Support Independent Journalism

Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.

When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.

Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber

Thank you,

Jeanna Bryner, Editor in Chief, Scientific American

Subscribe