In a cavernous Los Angeles County cleanroom, Northrop Grumman and NASA engineers have pieced together the space agency's prized next-generation telescope, the James Webb Space Telescope.

It's big.

How big? NASA tweeted a picture of a human standing on a crane beside the behemoth cosmic-sleuthing satellite, for reference.

Tweet may have been deleted

A concept image of the James Webb Telescope unfurled in space.Credit: nasa

The large, gold-tinted hexagons are the space telescope's mirrors. There's a reason they're big.

"A telescope's sensitivity, or how much detail it can see, is directly related to the size of the mirror area that collects light from the objects being observed," wrote NASA. "A larger area collects more light, just like a larger bucket collects more water in a rain shower than a small one."

Mashable Light SpeedWant more out-of-this world tech, space and science stories?Sign up for Mashable's weekly Light Speed newsletter.By signing up you agree to our Terms of Use and Privacy Policy.Thanks for signing up!

Webb's mirrors have a 6.5 meter, or over 21-foot, diameter. That's significantly larger than the nearly 8-foot mirror on NASA's legendary Hubble telescope, the hard-working predecessor to the Webb.

The Webb — designed to peer at distant galaxies, solar nurseries, and exotic exoplanets — will also sit on a light-blocking base, called a sunshield, which is about thesize of a tennis court.

(The Hubble, too, is big. It's the size of a tractor-trailer truck.)

SEE ALSO:The space race forged immortal rock and roll guitars

The James Webb telescope is scheduled to launch into space on March 21, 2021. The $9.66 billion project has been beset with numerous delays, but such is the price of unprecedented outer space endeavors.

"The James Webb Space Telescope is the most ambitious and complex astronomical project ever built, and bringing it to life is a long, meticulous process," European Space Agency director Günther Hasinger said last year. "The wait will be a little longer now but the breakthrough science that it will enable is absolutely worth it."

"From the very first galaxies after the Big Bang, to searching for chemical fingerprints of life on Enceladus, Europa, and exoplanets like TRAPPIST-1e, Webb will be looking at some incredible things in our universe,” said Eric Smith, director of the James Webb Space Telescope, in a statement.