NASA's James Webb Space Telescope passes critical milestone

On July 10, the cryogenic testing of the telescope began. 

NASA's James Webb Space Telescope -- the world's premier infrared space observatory of the next decade -- has successfully completed critical testing in a massive thermal vacuum chamber, enabling it to function properly in the extremely cold and airless environment in space in 2019, the agency said.

Webb Space Telescope, developed in coordination among NASA, the European Space Agency, and the Canadian Space Agency, is the most sophisticated -- and expensive -- space observatory ever designed.

It features a 21.3-foot-wide primary mirror made up of 18 adjustable gold-coated segments.

Webb Telescope is a barrier-breaking mission for engineers and astronomers that will help solve mysteries of our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it, NASA said in a statement.

Webb telescope arrived at NASA's Johnson Space Centre in Houston in May 2017, where it underwent critical cryogenic testing for nine months inside Chamber A, a massive thermal vacuum chamber at the center.

On July 10, the cryogenic testing of the telescope began.

During approximately 100 days in the chamber, Webb was put through a series of tests designed to ensure the telescope functioned as expected in an extremely cold, airless environment akin to that of space.

The engineers also checked on the alignment the telescope's 18 primary mirror segments to make sure that all of the gold-plated, hexagonal segments acted like a single, monolithic mirror in a space-like environment.

This test also showed Webb's science instruments were properly aligned with its mirrors and could detect simulated "starlight" within the chamber.

Webb emerged from Chamber A on December 1, the statement said.

Scheduled for launch in the spring of 2019 aboard a European Ariane 5 rocket, the gamut of tests ensured that Webb will safely reach its orbit at Earth's second Lagrange point (L2) and be able to successfully perform its science mission.