Webb Telescope Saves Fuel To Run Over 10 Years

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The Webb space telescope would have enough propellant to sustain scientific operations in orbit for more than 10 years—the minimum is 5 years—thanks to the precision of its launch.

Following liftoff on Christmas Day and analysis of the two subsequent trajectory correction maneuvers, the telescope team has determined that less propellant is needed than originally planned to correct Webb’s trajectory toward its final orbit around the second landing point. Lagrange, known as L2, is a gravitational equilibrium point on the far side of the Earth away from the Sun, 1.5 million kilometers away.

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Webb Telescope|Photo via getty images

Consequently, Webb will have much more than the baseline propellant estimate, although many factors could ultimately affect the duration of Webb’s operation, NASA reports.

Webb has rocket propellant on board not only for mid-course correction and insertion into orbit around L2 in the coming weeks, but also for necessary functions during the life of the mission, including “maintenance of latitude” maneuvers (“small thruster burns to adjust Webb’s orbit”), as well as what is known as thrust management, which maintains Webb’s orientation in space.

Precise Maneuvers Webb Telescope

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Webb Telescope|Photo via getty images

 The additional thruster is due in large part to the Arianespace Ariane 5’s launch accuracy, which exceeded the requirements needed to put Webb on the right track, as well as the accuracy of the first halfway correction maneuver, a relatively small engine activation 65 minutes after launch that added approximately 20 meters per second at the speed of the observatory. A second correction maneuver occurred on December 27, adding around 2.8 meters per second at speed.

The precision of the launch trajectory had another result: the timing of the solar array deployment. That deployment ran automatically after the Ariane 5 detached based on a stored command to deploy when Webb reached a certain ideal attitude toward the Sun to capture sunlight to power the observatory, or automatically 33 minutes after launch.

Because Webb was already in the correct attitude after the Ariane 5’s second stage detachment, the solar array was able to unfold approximately one and a half minutes after detachment, approximately 29 minutes after launch.