The successor to the Hubble Space Telescope is one step closer to completion. NASA has announced that they’ve just placed the 18th and final mirror segment into the array of the James Webb Space Telescope (JWST). The completion of the mirror array is a major milestone in the construction of the JWST, says NASA.
"Scientists and engineers have been working tirelessly to install these incredible, nearly perfect mirrors that will focus light from previously hidden realms of planetary atmospheres, star forming regions and the very beginnings of the Universe," said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. "With the mirrors finally complete, we are one step closer to the audacious observations that will unravel the mysteries of the Universe."
Each of the 18 individual hexagonal mirror segments that make up the primary JWST mirror array are 4.2 feet (1.3 meters) across and weigh 88 lbs. They were lowered onto the array just millimeters from each other by a highly specialized robotic arm. Their modular design allows the mirror to be folded compactly to facilitate liftoff from the planet and travel in space. Once fully deployed in space, the 18 primary mirror segments will work in unison as a single large 21.3-foot diameter (6.5-meter) mirror.
Work on the JWST began 20 years ago in 1996 when it was then called the Next Generation Space Telescope (NGST). It was renamed the James Webb Space Telescope in 2002 in honor of James E. Webb, the administrator of NASA since his appointment by John F. Kennedy in 1961 up until 1968. The JWST combines the work of 17 countries around the world, and when completed it will be the most powerful telescope ever built, allowing scientists and astronomers to peer into the farthest reaches of the universe. NASA says that the telescope will "study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System."
With the mirror array completed, work now moves on to completing the aft optics assembly and the secondary mirror, which will make the telescope whole. Everything will then be combined with other components of the JWST and then it will be transported to French Guiana, where it will launch on board an Ariane 5 rocket in 2018.