GREENBELT, United States - As the Hubble Space Telescope celebrates 25 years in space this week, NASA and its international partners are building an even more powerful tool to look deeper into the universe than ever before.
The James Webb Space Telescope will be 100 times more potent than Hubble, and will launch in 2018 on a mission to give astronomers an unprecedented glimpse at the first galaxies that formed in the early universe.
"JWST will be able to see back to about 200 million years after the Big Bang," NASA said on its website.
It described the telescope as a "powerful time machine with infrared vision that will peer back over 13.5 billion years to see the first stars and galaxies forming out of the darkness of the early universe."
The project has drawn scrutiny from lawmakers for its ballooning costs -- now at about $8.8 billion, far higher than the initial estimate of $3.5 billion.
But NASA has promised to keep the next-generation telescope on track for its October 2018 launch.
"What the Webb will really be doing is looking at the first galaxies of the universe," Webb telescope observatory project scientist Mark Clampin told AFP at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
"We will also be able, with these capabilities, to look in very dark parts of the universe where stars are being born."
Inside a massive room that is partially closed off from view, in clean room where no dust can harm the telescope, a team of engineers dressed in white, resembling surgeons, work on building the JWST.
The space telescope will weigh 6.4 tons. JWST's main mirror will be 6.5 meters (yards) in diameter, three times as large as Hubble's.
A joint project of NASA, the European and canadian space agencies, JWST will carry four instruments, including cameras and spectrometers that can capture extremely faint signals.
Infra-red capability will help it observe distant celestial bodies, and its camera shutter will be able to remain open for long periods, explained Matt Greenhouse, JWST project scientist for the science instrument payload.
"The Webb will have 70 times the light-gathering capacity of Hubble. So the combination of the large size and the infra-red capabilities will allow us to observe this epic of the universe past," he said in an interview.