The first six of  18 segments that will form NASA's James Webb Space Telescope’s primary  mirror for space observations completed final cryogenic testing this  week. The ten week test series included two tests cycles where the  mirrors were chilled down to -379 degrees Fahrenheit, then back to  ambient temperature to ensure the mirrors respond as expected to the  extreme temperatures of space. 

A  second set of six mirror assemblies will arrive at Marshall in late  July to begin testing, and the final set of six will arrive in the fall.  

The X-ray  and Cryogenic Facility at NASA's Marshall Space Flight Center in  Huntsville, Ala. provides the space-like environment to help engineers  measure how well the telescope will image infrared sources once in  orbit.

Each mirror  segment measures approximately 4.3 feet (1.3 meters) in diameter to form  the 21.3 foot (6.5 meters), hexagonal telescope mirror assembly  critical for infrared observations. Each of the 18 hexagonal-shaped  mirror assemblies weighs approximately 88 pounds (40 kilograms). The  mirrors are made of a light and strong metal called beryllium, and  coated with a microscopically thin coat of gold to enabling the mirror  to efficiently collect infrared light.

The telescope  is a combined project of NASA, the European Space Agency and the  Canadian Space Agency. Northrop Grumman is the prime contractor under  NASA's Goddard Space Flight Center in Greenbelt, Md. Ball Aerospace  & Technologies Corp. in Boulder, Colo., is responsible for mirror  development. L-3- Tinsley Laboratories Inc. in Richmond, Calif. is  responsible for mirror grinding and polishing.

 Engineers and technicians guide six  James Webb Space Telescope’s mirror segments off the rails after  completing final cryogenic testing this week at Marshall. (NASA/Emmett  Given) 

Engineers ready the crane to lift one  James Webb Space Telescope’s mirror segment off the stand after  completing final cryogenic testing this week at Marshall. (NASA/Emmett  Given)

 See the webside for more details.http://www.nasa.gov/centers/marshall/news/jwst/first_round.html (SY)