A prototype structure that holds the primary mirrors for the optical element of the James Webb Space Telescope passed a series of cryogenic tests, Webb prime contractor Northrop Grumman Corp. announced.

The tests, conducted at NASA’s Marshall Space Flight Center in Huntsville, Ala., were designed to measure the ability of the Backplane Stability Test Article to perform in the extreme cold of space.

The prototype article is a full-scale subsection of the mirror’s backplane, a structure that holds and supports the mirrors and mirror controls. The test article, developed by ATK, holds up to three of Webb’s 18 primary mirror segments.

The Webb Telescope, scheduled to be launched in 2013, will be able to detect objects 20 times fainter than the Hubble Space Telescope and will be used to observe the earliest formation of galaxy clusters that followed the Big Bang.