The space telescope has saved most of its fuel on the journey, extending the mission

The James Webb Space Telescope (JWST) arrived at its final destination on 24 January at 7:05pm UT.

Webb is an infrared telescope with a 6.5m-wide mirror, making it the largest one ever deployed in space when it launched on 25 December 2021. A month later, it arrived at the gravitationally stable second Lagrange point (L2), located 1.5 million km from Earth. JWST fired its thrusters for five minutes to add around 1.6 metres per second to its speed. Though little more than a walking pace, this was all that was needed to put it into its final ‘halo’ orbit, moving in an ellipse around the L2 point.

This mid-course correction burn occurred a day later than scheduled, as both the launch and previous two course corrections had been so precise that hardly a nudge was needed to achieve its final orbit. Thanks to this accuracy, Webb was able to save a huge amount of fuel that can now be used in its operational phase, potentially extending the mission by decades.

“JWST’s success is a tribute to all the folks who spent many years and even decades to ensure it,” says Bill Ochs, JWST’s project manager, who is now leading the telescope team as they spend the next five months setting it up. They had achieved the first step of establishing the high-speed data connection at the time of going to press. https://webb.nasa.gov/


Comment by Chris Lintott

There are moments in life where you stop, astonished, by what you’ve just managed to do. It could be the tennis shot that sings off the strings, or when you catch all three of the glasses falling from the kitchen cupboard!

A similar feeling of bewildered excitement fills astronomers right now. The incredible JWST team have just played the game of their lives, executing the complex and scary sequence required to unfold the telescope and get it into position. As you read this, starlight is hitting JWST’s mirrors, which are slowly being calibrated.

Because of this brilliance, it’s slowly sinking in that we really are going to get to see the early Universe and the hearts of stellar nurseries. We really are going to get all that data on nearby exoplanets. After years of anxiety, we might just need a few months to grasp that it’s really happened, that’s all.