Today, at around 12.30 am, the James Webb Space Telescope fired its thrusters for 297 seconds and completed the final post-launch course correction. This burn helped insert the world’s most powerful space telescope toward its final orbit – L2 or the second Sun-Earth Lagrange point. The telescope will orbit the Sun and will be about one million miles or 1.5 million kilometres away from Earth.
“Webb, welcome home!” said NASA Administrator Bill Nelson in a release. “We’re one step closer to uncovering the mysteries of the universe. And I can’t wait to see Webb’s first new views of the universe this summer!”
What are Lagrange points and L2?
Named after Italian-French mathematician Josephy-Louis Lagrange, these points are certain positions in space where the gravitational forces of two bodies, for example, the Sun and the Earth, produce a region of great attraction and repulsion and maintain an equilibrium. This region can be used by spacecraft to reduce fuel consumption that is needed to remain in a constant position.
So…you’ve heard that the Webb telescope will be orbiting Lagrange point 2. But what even is that, anyway? And how do you orbit something that isn’t an object?
We’ve got you! Here’s a thread ⬇️#UnfoldTheUniverse pic.twitter.com/7YTUeKh3Me
— NASA Webb Telescope (@NASAWebb) January 21, 2022
L2 is a position directly behind Earth in the line joining the Sun and the Earth. In a series of tweets, NASA explained why L2 was chosen with the number one reason being the shade. “The Sun, Earth (and Moon) are always on one side. At L2, Webb’s sun shield can always face all of these heat and light sources to protect Webb’s optics and instruments, which have to stay super cold to detect faint heat signals in the universe,” NASA Webb tweeted.
It added that the orbit also ensures that Webb will never have the Sun eclipsed by Earth — necessary for Webb’s thermal stability and power generation. L2 is also convenient for maintaining contact with the Mission Operations Center through the Deep Space Network.
The James Webb Space Telescope isn’t the first spacecraft to orbit L2. The Wilkinson Microwave Anisotropy Probe (WMAP) launched in 2001 and the Herschel Space Observatory launched in 2009 use this orbit.
