Category: James Webb Space Telescope

At 7:50 pm EST, Webb’s first mid-course correction burn began. It lasted 65 minutes and is now complete. This burn is one of two milestones that are time critical — the first was the solar array deployment, which happened shortly after launch. 

This burn adjusts Webb’s trajectory toward the second Lagrange point, commonly known as L2. After launch, Webb needs to make its own mid-course thrust correction maneuvers to get to its orbit. This is by design: Webb received an intentional slight under-burn from the Ariane-5 that launched it into space, because it’s not possible to correct for overthrust. If Webb gets too much thrust, it can’t turn around to move back toward Earth because that would directly expose its telescope optics and structure to the Sun, overheating them and aborting the science mission before it can even begin.  

Therefore, we ease up to the correct velocity in three stages, being careful never to deliver too much thrust — there will be three mid-course correction maneuvers in total. 

After this burn, no key milestones are time critical, so the order, location, timing, and duration of deployments may change.

You can track where Webb is in the process and read about upcoming deployments.  NASA has a detailed plan to deploy the Webb Space Telescope over a roughly two-week period.The deployment process is not an automatic hands-off sequence; it is human-controlled. The team monitors Webb in real-time and may pause the nominal deployment at any time. This means that the deployments may not occur exactly in the order or at the times originally planned.

The James Webb Space Telescope is on its way!  The mission launched on an Ariane 5 rocket at 7:20 a.m. EST  on Saturday, Dec. 25.

Jane Rigby, the operations project scientist for Webb at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, told us what it was like to be supporting the launch from the Mission Operations Center at the Space Telescope Science Institute in Baltimore:

Launch day. It’s 7:00am, and I’m at the Mission Operations Center, “the MOC” — mission control to regular folks, for the launch of JWST. I’m wearing a mission patch polo and a headset. We launch in twenty minutes. The mood here is nervous, excited, and ready. I hear laughter in the hallways and see grim eyes over KN95 masks. We know that the future of NASA science is at stake. We know how audaciously hard the task will be. We know how many times we rehearsed. Now we do it for real.

Here was my Thanksgiving script:
Family: “Where will you be for launch?”
Me: “Baltimore!”
Friends: “It’s launching from Baltimore?”
Me: “No, we’re launching from French Guiana. Mission Control is in Baltimore.”

So much must go right the first day. JWST must deploy its solar array to get power. No solar array, no mission.

LAUNCH. I can hear some shrieking from the VIPs downstairs, but it’s quiet here. We’re waiting to take control of JWST when it separates from the rocket about 30 minutes after launch.

The second stage shuts down and the launch vehicle separates. The call comes out that the attitude control system is working. The solar array should be deploying automatically…. There’s a tense wait… and then the call “Sun is on the array, current is on the array!” Suddenly it’s DEAFENINGLY loud on the voice loops, with clapping and shouts of happiness echoing through the MOC. I look up to see the video feed from the launch vehicle and THERE IT IS, our beautiful observatory with its solar panel all the way out, shining in the sun.

Things keep getting better. We acquire our first ground station, Malindi in Kenya, and the MOC sends our first command to JWST, accompanied by shouts and cheering. The reaction wheels are powered up and take over. We hear “Wheel Sun!” and I write it in all caps in my log. The call comes over the voice loop: “JWST is flying on its own.”

I glance down at the photos I brought for luck: my wife and my kid in front of JWST under construction; and my hero Frank Kameny in his youth, peering through a telescope. I close my eyes and give silent thanks for the entire team. Every piece of this huge, gorgeous observatory was ingeniously designed, custom made, mostly by hand, and torture-chamber tested and re-tested. So many hands cradled this bird. So many brains dreamed up science observations. So many worked so hard —  now we see if it works.

—Jane Rigby, operations project scientist for Webb at NASA’s Goddard Space Flight Center

The James Webb Space Telescope is safely in space, powered on and communicating with ground controllers.

Webb continues in coast phase, and is now oriented correctly with respect to the Sun. The six reaction wheels of the spacecraft’s attitude control system have been powered on, and they are now responsible for keeping the spacecraft pointing in the right direction – so that its massive sunshield, which is the size of a tennis court and which will deploy over the course of the next week – will be able to keep the telescope protected from solar radiation and heat.

Webb is on its way to L2. Our next big milestone is this evening, when we conduct the first Mid-Course Correction burn.

Follow all of Webb’s upcoming milestones here.

At approximately 30 minutes after launch, Webb’s solar array began to open up.  It is now fully deployed and we have confirmed that the spacecraft is power positive.

The Ariane 5 upper stage brought the James Webb Space Telescope up to a speed of approximately 22 thousand miles per hour – headed for its final orbit around the second Lagrange point, commonly known as L2.

The upper stage engine has now cut off and the spacecraft has separated. An extra battery on the upper stage provided power for a boost after release of the telescope, distancing it from Webb.

Webb is now flying on its own in coast phase.

Webb has completed internal checks. All ground stations and the spacecraft are go for launch. Spacecraft and launch engineers at the Jupiter Control Center at Europe’s Spaceport in French Guiana and at the Mission Operations Center at the Space Telescope Science Institute in Baltimore, Maryland, have confirmed that Webb is on internal battery and is in its final launch configuration.

At seven minutes before launch, computers will initiate all Ariane 5 automatic countdown activities. The Ariane 5 will launch unless computers detect an issue, ground controllers initiate a stop, or the Webb team requests a hold due to a concern.

During liftoff the two solid propellant boosters — known as EAPs, from the French Etage d’Acceleration à Poudre – ignite and, along with the main stage engine, power the Ariane 5 up and away from the pad. The EAP boosters are the largest solid rocket boosters ever produced by European industry, providing roughly 92% of the total thrust at liftoff.

Fueling for both the main and upper stages of the Ariane 5 rocket is now complete.

In preparation for launch scheduled for no earlier than 7:20 am EST (9:20 am GFT). The cryogenic arms attached to the Ariane 5 are now supplying top-up fuel until liftoff. All systems are being continually measured to monitor the readiness of Ariane 5 to launch and the condition of its precious cargo.

Webb has been confirmed as being go for launch, and the countdown clock was started!  With weather reports looking favorable, the team authorized fueling of the Ariane 5, which began at 3 am EST.

Arianespace will measure winds at high altitude with the help of balloons to ensure absolute safety for the launch. Meanwhile the team continues to monitor Webb which is kept in a stable condition in the fairing. The team is monitoring temperatures, relative humidity, and cleanliness of the air entering the fairing – critical parameters to keep Webb cool, dry, and clean before liftoff.

Our broadcast of launch will begin at 6 am and can be watched on nasa.gov/live.  You can also follow along on the NASA app, and on social with the hashtag #unfoldtheuniverse.

Both immediately after launch and over the following weeks, the James Webb Space telescope will pass through numerous milestones on its journey of approximately 1 million miles to its final orbit around the second Lagrange point, commonly known as L2.

NASA has a detailed plan to deploy the Webb Space Telescope over a roughly two-week period. For details on any particular milestone – or to get updates on how far along Webb is in the process – please read about the deployments here. You may also watch a visualization.

The process involves hundreds of individual deployments. It is not an automatic, hands-off sequence; it is human-controlled. This means that the order, location, timing, and duration of deployments may change. However, the default order and approximate timing is as follows:

First hour:
Liftoff
~9 minutes: main stage separation
~27 minutes: upper stage separation
~33 minutes: solar array deployed

First Day
~12.5 hours: Midcourse correction burn (MCC1a)
~1 day: Release and motion test of the gimbaled antenna assembly

.  . . and on
2 days: Midcourse correction burn (MCC1 b)
3 days: Forward sunshield pallet deployment
3 days: Aft sunshield pallet deployment
4 days: Deployable tower assembly
5 days: Aft momentum flap
5 days: Sunshield covers release
6 days: Sunshield port mid-boom and sunshield starboard mid-boom
7 days: Sunshield layer tensioning begins
8 days: Sunshield layer tensioning complete
10 days: Secondary mirror deployment begins and is completed
11 days: Aft Deployed Instrument Radiator
12 days: Port primary mirror wing deployment begins and is completed
13 days: Starboard primary mirror wing deployment begins and is completed
13 days: Webb is fully deployed
15-24 days: Individual mirror segment movements
29 days: Midcourse correction burn (MCC2)/L2 insertion burn
29.5 days: Orbit insertion complete