James Webb space telescope's next moves require mind-boggling precision

The James Webb Space Telescope, the next-generation telescope which will be the successor to Hubble, recently arrived at its new home. It will orbit the sun at a point called L2, or the second sun-Earth Lagrange point, from where it will be able to peer out into space and cover the sky in every direction as it moves around the sun.

Adriana Manrique Gutierrez, NASA Animator

Once it begins science operations, the telescope will be used to study everything from black holes to some of the most distant and ancient galaxies, effectively looking back in time to a period in the early universe when some of the first galaxies formed. But before astronomers can get their hands on this precious data, there are some more steps to get Webb ready for work.

Currently, the Webb team is working on adjusting the telescope's primary and secondary mirrors. The primary mirror is the big, gold-covered set of 18 hexagons which fit together to create a total mirror that's 6.5 meters (21 feet) across. The secondary mirror is a much smaller, convex round mirror that's located on the end of several long booms. The team needs to make sure that both of these mirrors are lined up exactly perfectly and are aligned with extreme precision, in order to allow Webb to pick up very faint signals with great accuracy.

The process of aligning the mirrors is a long and complex one, as it uses a total of 126 actuators which will move each segment of the primary mirror plus six devices to adjust the secondary mirror. Each section of the mirror needs to be tweaked with nanometer-precision, and the adjustment period will take several months (via NASA).


"Getting there is going to take some patience: The computer-controlled mirror actuators are designed for extremely small motions measured in nanometers," Marshall Perrin from the Space Telescope Science Institute explained (via NASA). "Each of the mirrors can be moved with incredibly fine precision, with adjustments as small as 10 nanometers (or about 1/10,000th of the width of a human hair)."

As well as the mirror alignment, the Webb team will also begin activating and then calibrating the telescope's instruments. Webb has four main instruments – Near-Infrared Camera or NIRCam, Near-Infrared Spectrograph or NIRSpec, Mid-Infrared Instrument or MIRI, and Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph or FGS/NIRISS (via NASA). Each of these needs to be turned on and then carefully adjusted so that it can pick up accurate science data. This will take approximately six months, after which the telescope's five-year science mission can begin.

So we'll need to be patient for just a little bit longer while we wait for the first data from this remarkable new tool for understanding the universe. "During the past month, JWST has achieved amazing success and is a tribute to all the folks who spent many years and even decades to ensure mission success," said Bill Ochs, Webb project manager at NASA's Goddard Space Flight Center (via NASA). "We are now on the verge of aligning the mirrors, instrument activation and commissioning, and the start of wondrous and astonishing discoveries."