After traveling nearly one million miles, the James Webb Space Telescope is set to arrive at its new home on Monday. The spacecraft’s arrival at a region in space known as L2 will mark an important milestone as it prepares for its mission of studying distant light from the beginning of time. Here’s what you need to know about this moment.
When does the spacecraft arrive and how can I follow it?
At 2 p.m. Eastern time, the spacecraft is scheduled to reach a location beyond the moon after a final, five-minute firing of the spacecraft’s thrusters. NASA is expected to confirm this event some time after the arrival, and officials will discuss the milestone live on YouTube at 3 p.m., or you can watch it in the video player above.
A news conference will follow at 4 p.m.
But you won’t be able to see the arrival. There are no monitoring cameras on the telescope. Instead, engineers depend on switches, sensors and motors to track the spacecraft’s health and progress.
NASA ditched the idea of including surveillance cameras on Webb because of technical complexities and risk. The telescope’s novel size and shape — with one side of its sunshield deflecting enormous amounts of heat and sunlight and the other instrument-heavy side basking in frigid darkness — would require multiple custom-built cameras, adding weight and risk to an already heavy telescope, the agency explained in a blog post.
What is L2 and why is the spacecraft going there?
L2 is a small pocket of stability where the gravitational forces of the sun and Earth commingle. Also called the second Lagrange Point, the Webb telescope will be dragged around the sun alongside Earth for years.
Stationing the spacecraft at this location, about a million miles from Earth, will help conserve its limited fuel supplies.
“If you try to stay closer, you’ve got to expend fuel to stay there,” said Scott Willoughby, the telescope’s program manager at Northrop Grumman, the primary contractor for the observatory. But less fuel is needed to station the Webb at L2, he said, “meaning the mission life for this vehicle will be the longest.” This month, one mission official suggested that the spacecraft could remain operational for up to 20 years.
Deploying the telescope to the L2 neighborhood also provides enough sunlight for the Webb’s solar panels, which generate electricity.
What has the Webb telescope done so far?
The James Webb Space Telescope, named after a former NASA administrator who oversaw the formative years of the Apollo program, is designed to see further into the past than its celebrated predecessor in order to study the first stars and galaxies that twinkled alive in the dawn of time, 13.7 billion years ago.
The telescope launched to space on Dec. 25, with astronomers all over the world holding their breaths. But the $10 billion telescope still needed to power through the first leg of its setup phase.
The telescope, tightly bundled up to fit inside a European Ariane rocket, unfurled dozens of mechanical limbs and instruments once in space. These included five layers of a thin foil-like plastic that were stretched taut to the size of a tennis court to shield Webb’s instruments from the sun’s heat. Later, the telescope unfolded a 21-foot-wide array of 18 gold-plated mirrors that will help bounce light from the cosmos into its ultrasensitive infrared sensors.