“It’s shiny.” That’s how one woman described the new telescope unveiled by NASA on Wednesday that they hope will someday replace the Hubble. The reason it’s shiny is that its main mirror, which is a collapsible honeycomb, is made up of 18 gold-covered hexagons. The mirror is portable, collapsing so it can fit onto a rocket to be carried into orbit.
The James Webb Space Telescope is big as well. As tall as a three-story building, it is as wide as a tennis court, weighs 14,300 pounds and cost $8.8 billion. It took more than 20 years to build. Some have called it a giant waste, others have termed it revolutionary. But NASA hopes that it will soon give astronomers a glimpse of the edge of space that will be unprecedented.
The telescope has a projected launch date of October 2018. Engineers just finished assembling the gigantic mirror earlier this year, and this week they removed the protective coverings for the first time, showing the primary mirror: more than 250 square feet of shiny gold, designed to catch and focus some of the faintest light in the universe.
JWST is bigger by far than any other NASA telescope previously launched. The primary mirror on the Hubble Space Telescope is less than one-fifth the size of the collecting area of the new equipment. JWST will also orbit at a much more distant, and much colder, point in space. That required some new engineering methods by NASA builders.
Lightweight beryllium makes up each hexagon in the mirror, a material that can withstand the temperatures of minus 388 degrees that it will have to endure in deepest space. The brilliant covering is gold because that is the best reflector of infrared light, which marks most distant objects in the universe. Expect views of light from stars that formed 13.5 billion years ago.
The golden telescope will carry four scientific instruments at launch, two provided by NASA, one from the Canadian space agency and one from the European space agency. Each of the instruments is designed to pick up differing wavelengths of light, which will allow the telescope to perform feats such as peering through clouds of gas and dust to watch new stars form, or look back in time and space to see the light of the most distant galaxies.
There are four scientific missions of JWST: finding the earliest galaxies and stars, figuring out how those galaxies evolved, observing the birth of new stars and solar systems, and scanning the planets around Earth for signs of life.
JWST currently resides at the Goddard Space Flight Center in Greenbelt, Mary., in a sterile “cleanroom.” Lynn Chandler, JWST program spokeswoman, describes the assembly of the telescope as “the ultimate game of Operation.”
“You’ve got to get it all in there, and you can’t touch anything.” This is because even the tiniest smudge on the telescope could have catastrophic consequences. One group of scientists joked about identifying a new galaxy and then discovering it was actually a fingerprint.
Image credit: Chris Gunn, NASA