NASA has started 'final assembly' on a tennis court-size space telescope

NASA just started assembling a revolutionary telescope that will see farther and deeper into the cosmos than the Hubble Space Telescope.

The James Webb Space Telescope (JWST) will launch into orbit around Earth in 2018. A foldable array of 18 high-tech mirrors will allow it to see farther and clearer than other telescopes that have come before it.

Each of JWST's mirrors are made of beryllium, coated in gold, and will operate at a chilly minus-406 to minus-343 degrees Fahrenheit. A huge, tennis-court sized sun shield will protect it from overheating - and help keep the mirror segments motionless as the whole telescope drifts through space.

But first NASA needs to finish building it.

To that end on Wednesday, Nov. 25, NASA engineers used a giant robotic arm to carefully install the first mirror segment. Each segment spans about 4 feet and weighs 88 pounds.

All 18 segments must fit together precisely so the telescope can capture light from stars and planets and return sharp images to Earth. It's an incredibly complex assembly process scientists have been practicing for years.

NASA has big dreams for JWST:

"The James Webb Space Telescope will be the premier astronomical observatory of the next decade," NASA scientist John Grunsfeld said in a press release.

JWST will give us insight into "every phase in the history of our universe, including the cosmos' first luminous glows, the formation of solar systems capable of supporting life on planets like Earth, and the evolution of our own solar system," according to the NASA release.