James Webb Space Telescope Completes Cryogenic Mirror Test

July 30, 2010, JPL/NASA
During cryogenic testing, the mirrors will be subjected to temperatures dipping to -415 degrees Fahrenheit, permitting engineers to measure in extreme detail how the shape of each mirror changes as it cools. (NASA/MSFC/David Higginbotham/Emmett Given)

Recently, six James Webb Space Telescope beryllium mirror segments completed a series of cryogenic tests at the X-ray & Cryogenic Facility at NASA's Marshall Space Flight Center in Huntsville, Ala.

During testing, the mirrors were subjected to extreme temperatures dipping to -415 degrees Fahrenheit, permitting NASA contractor engineers to measure in extreme detail how the shape of the mirror changes as it cools.

With those measurements, the mirrors will be shipped to Tinsley Corp. in Redmond, Calif., for final surface polishing at room temperature. Using those "surface error" measurements, each mirror will then be polished in the opposite of the surface error values observed, so when the mirror goes through the next round of cryogenic testing, at Marshall, it should "distort" into a perfect shape.

The facility at Marshall is the world’s largest X-ray telescope test facility and a unique site for cryogenic, clean-room optical testing.

The next set of mirrors are due to arrive at NASA Marshall in August.

The Webb telescope has a total of 18 mirrors. Each of the 18 mirror segments will be cryogenically tested twice in the Marshall Center's X-ray & Cryogenic Facility to ensure that the mirror will maintain its shape in a space environment -- once with bare polished and then again after a thin coating of gold is applied.

The cryogenic test gauges how each mirror changes temperature and shape over a range of operational temperatures in space. This helps predict how well the telescope will image infrared sources.

The mirrors are designed to stay cold to allow scientists to observe the infrared light they reflect using a telescope and instruments optimized to detect this light. Warm objects give off infrared light, or heat. If the Webb telescope mirror is too warm, the faint from distant galaxies may be lost in the infrared glow of the itself. Thus, the Webb telescope's mirrors need to operate in a deep cold or cryogenic state, at around -379 degree Fahrenheit.

Northrop Grumman is the prime contractor for the Webb telescope, leading a design and development team under contract to NASA's Goddard Space Flight Center in Greenbelt, Md.

The is NASA's next-generation premier space observatory, exploring deep space phenomena from the formation of distant galaxies to the behavior and interrelationships of nearby planets and stars. The Webb will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth.

Explore further: James Webb Space Telescope first flight mirror completes cryogenic testing

Related Stories

Mirror Testing at NASA Breaks Superstitious Myths

January 7, 2010

(PhysOrg.com) -- In ancient mythological times reflective surfaces like shiny metals and mirrors were thought to be magical and credited with the ability to look into the future. NASA is using mirrors to do just the opposite ...

James Webb space telescope's actual 'spine' now being built

February 9, 2009

Scientists and engineers who have been working on the James Webb Space Telescope mission for years are getting very excited, because some of the actual pieces that will fly aboard the Webb telescope are now being built. One ...

Recommended for you

How massive can neutron stars be?

January 16, 2018

Astrophysicists at Goethe University Frankfurt set a new limit for the maximum mass of neutron stars: They cannot exceed 2.16 solar masses.

Black hole spin cranks-up radio volume

January 12, 2018

Statistical analysis of supermassive black holes suggests that the spin of the black hole may play a role in the generation of powerful high-speed jets blasting radio waves and other radiation across the universe.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.