NASA’s James Webb Space Telescope (JWST) – the successor to the Hubble Space Telescope – has hit the final assembly phase milestone via the installation of the first of 18 mirrors on the spacecraft’s backbone structure. All 18 segments are expected to be installed by early next year as JWST prepares for launch in 2018 via an Ariane 5 rocket.
The JWST project has NASA, ESA and the CSA as the lead partners, but includes a collaboration of about 17 countries in total.
To be located 1.5 million kilometers from Earth at the Earth-Sun Lagrangian point L2, JWST’s 6.5-meter diameter primary mirror – a gold coated beryllium reflector – and four specialized instruments ensure the spacecraft will provide unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared.
The telescope also has a tennis court sized five-layer sunshield that attenuates heat from the sun more than a million times.
Unlike Hubble’s single monolithic primary mirror, JWST’s primary mirror is made up of 18 individual, adjustable segments that will be aligned in space.
Inside the clean room at NASA’s Goddard Space Flight Center, the engineering team used a robot arm to lift and lower the first hexagonal-shaped segment that measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms).
Followers of the spacecraft’s development can follow the progress via a live webcam provided by NASA.
This week’s milestone begins the process of installing all 18 primary mirror segments that will work together as one large 21.3-foot (6.5-meter) mirror. The full installation is expected to be complete early next year.
“After a tremendous amount of work by an incredibly dedicated team across the country, it is very exciting to start the primary mirror segment installation process,” said Lee Feinberg, James Webb Space Telescope optical telescope element manager at Goddard.
“This starts the final assembly phase of the telescope.”
The JWST is one of NASA;s flagship programs and will be tasked with investigating the birth and evolution of galaxies, and the formation of stars and planets.
The hugely expensive project dodged the prospect of being canceled several years ago when costings showed the original forecast of $1.6 billion was rising by the billions. The program was capped at $8 billion via a decision to continue with the development of the spacecraft.
“The James Webb Space Telescope will be the premier astronomical observatory of the next decade,” noted John Grunsfeld, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington.
“This first-mirror installation milestone symbolizes all the new and specialized technology that was developed to enable the observatory to study the first stars and galaxies, examine the formation stellar systems and planetary formation, provide answers to the evolution of our own solar system, and make the next big steps in the search for life beyond Earth on exoplanets.”
The 18 separate segments are designed to unfold and adjust to shape after launch.
The mirrors are made of ultra-lightweight beryllium chosen for its thermal and mechanical properties at cryogenic temperatures. Each segment also has a thin gold coating chosen for its ability to reflect infrared light.
The mirrors must remain precisely aligned in space in order for JWST to successfully carry out science investigations.
While operating at extraordinarily cold temperatures between minus 406 and minus 343 degrees Fahrenheit, the backplane must not move more than 38 nanometers, approximately one-thousandth the diameter of a human hair.
The mirrors were built by Ball Aerospace & Technologies Corp., Boulder, Colorado. Ball is the principal subcontractor to Northrop Grumman for the optical technology and lightweight mirror system.
“There have many significant achievements for Webb over the past year, but the installation of the first flight mirror is special,” added Bill Ochs, James Webb Space Telescope project manager.
“This installation not only represents another step towards the magnificent discoveries to come from Webb, but also the culmination of many years of effort by an outstanding dedicated team of engineers and scientists.”
(Images via NASA).