NASA’s James Webb Space Telescope has completed its nearly 100-day testing series in the cryogenic vacuum chamber, where temperatures dip hundreds of degrees below the freezing point.

The team unsealed the 40-ton door of Chamber A on Saturday, marking the end of a critical test stage ahead of the telescope’s launch.

The vault-like door was closed off on July 10, allowing researchers to assess the telescope’s optics and instruments all together in conditions simulating deep space.

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NASA’s James Webb Space Telescope has completed its nearly 100-day testing series in the cryogenic vacuum chamber, where temperatures dip hundreds of degrees below the freezing point

NASA'S JAMES WEBB SPACE TELESCOPE The James Webb telescope has been described as a 'time machine' that could help unravel the secrets of our universe. The telescope will be used to look back to the first galaxies born in the early universe more than 13.5 billion years ago, and observe the sources of stars, exoplanets, and even the moons and planets of our solar system. When it is launched in 2019, it will be the world's biggest and most powerful telescope, capable of peering back 200 million years after the Big Bang. Advertisement

Inside the chamber, the telescope was cooled with liquid nitrogen and cold gaseous helium.

To detect infrared light from faraway objects, the telescope must be kept very cold, according to NASA.

The James Webb Telescope and most of its instruments have an operating temperature of roughly 40 Kelvin – about minus 387 Fahrenheit (minus 233 Celsius).

But, the mid-infrared instrument (MIRI) must be kept even colder.

This instrument uses a cryocooler to keep it below 7 Kelvin, or minus 447 degrees Fahrenheit (minus 266 degrees Celsius).

This summer’s tests were designed to see how the optical telescope and integrated science instrument module (OTIS) operated in the cold vacuum environment.

The 18 gold primary mirror segments were tested as well, to ensure they act as a single mirror.

The test even managed to continue as Hurricane Harvey battered the Texas coast.

The vault-like door was closed off on July 10, allowing researchers to assess the telescope in conditions simulating deep space

Inside the chamber, the team monitored the telescope using thermal sensors and specialized cameras, to track the temperature and the physical position as each component moved.

‘After 15 years of planning, chamber refurbishment, hundreds of hours of risk-reduction testing, the dedication of more than 100 individuals through more than 90 days of testing, and surviving Hurricane Harvey, the OTIS cryogenic test has been an outstanding success,’ said Bill Ochs, project manager for the James Webb Space Telescope at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

‘The completion of the test is one of the most significant steps in the march to launching Webb.’

The engineers began cooling the chamber on July 20 after removing the air.

The process that took roughly 30 days; then the telescope remained in a cryo-stable state for another 30 days.

The team unsealed the 40-ton door (pictured) of Chamber A on Saturday, marking the end of a critical test stage ahead of the telescope’s launch

The massive golden mirror is made up of 18 hexagonal components which will work together as one structure. Each coffee table-sized mirror segment is made from beryllium and weighs roughly 46 pounds

The team began to warm the chamber back up on September 27, before pumping air back in.

Then, on November 18, they unsealed the door.

‘With an integrated team from all corners of the country, we were able to create deep space in our chamber and confirm that Webb can perform flawlessly as it observes the coldest corners of the universe,’ said Jonathan Homan, project manager for Webb’s cryogenic testing at Johnson.

‘I expect [Webb] to be successful, as it journeys to Lagrange point 2 [after launch] and explores the origins of solar systems, galaxies, and has the chance to change our understanding of our universe.’