Cryogenic testing completed for NASA's WEBB Telescope mirrors

December 21, 2011

Cryogenic testing is complete for the final six primary mirror segments and a secondary mirror that will fly on NASA's James Webb Space Telescope. The milestone represents the successful culmination of a process that took years and broke new ground in manufacturing and testing large mirrors.

"The mirror completion means we can build a large, deployable telescope for space," said Scott Willoughby, vice president and Webb program manager at Northrop Grumman Aerospace Systems. "We have proven real hardware will perform to the requirements of the mission."

The Webb telescope has 21 mirrors, with 18 mirror segments working together as a large 21.3-foot (6.5-meter) primary mirror. Each individual mirror segment now has been successfully tested to operate at 40 Kelvin (-387 Fahrenheit or -233 Celsius).

"Mirrors need to be cold so their own heat does not drown out the very faint infrared images," said Lee Feinberg, NASA Optical Telescope Element manager for the Webb telescope at the agency's Goddard Space Flight Center in Greenbelt, Md. "With the completion of all mirror cryogenic testing, the toughest challenge since the beginning of the program is now completely behind us."

Completed at the X-ray and Cryogenic Facility (XRCF) at NASA's Marshall Space Flight Center in Huntsville, Ala., a ten-week test series chilled the primary mirror segments to -379 degrees Fahrenheit. During two test cycles, telescope engineers took extremely detailed measurements of how each individual mirror's shape changed as it cooled. Testing verified each mirror changed shape with temperature as expected and each one will be the correct shape upon reaching the extremely cold operating temperature after reaching deep space.

"Achieving the best performance requires conditioning and testing the mirrors in the XRCF at temperatures just as cold as will be encountered in space," said Helen Cole, project manager for Webb Telescope mirror activities at the XRCF. "This testing ensures the mirrors will focus crisply in space, which will allow us to see new wonders in our universe."

Ball Aerospace and Technologies Corp. in Boulder, Colo. successfully completed comparable testing on the secondary mirror. However, because the secondary mirror is convex (i.e., it has a domed surface that bulges outward instead of a concave one that dishes inward like a bowl), it does not converge light to a focus. Testing the mirror presented a unique challenge involving a special process and more complex optical measurements.
-end-
The Webb telescope is the world's next-generation space observatory and successor to the Hubble Space Telescope. It will be most powerful space telescope ever built, provide images of the first galaxies ever formed, and explore planets around distant stars. It is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

For images related to this story, visit:

http://www.nasa.gov/topics/technology/features/webb-mirror-cryo.html

For more information about the Webb telescope, visit:

http://jwst.nasa.gov

NASA/Goddard Space Flight Center

Related Temperature Articles from Brightsurf:

History of temperature changes in the Universe revealed
How hot is the Universe today? How hot was it before?

A drop in temperature
In the nearly two centuries since German physician Carl Wunderlich established 98.6°F as the standard ''normal'' body temperature, it has been used by parents and doctors alike as the measure by which fevers -- and often the severity of illness -- have been assessed.

Kitchen temperature supercurrents from stacked 2D materials
A 'stack' of 2D materials could allow for supercurrents at ground-breakingly warm temperatures, easily achievable in the household kitchen.

Get diamonds, take temperature
Measuring the temperature of objects at a nanometer-scale has been a long challenge, especially in living biological samples, because of the lack of precise and reliable nanothermometers.

Chemical thermometers take temperature to the nanometric scale
Scientists from the Coordination Chemistry Laboratory and Laboratory for Analysis and Architecture of Systems, both of the CNRS, recently developed molecular films that can measure the operating temperature of electronic components on a nanometric scale.

How reliable are the reconstructions and models for past temperature changes?
Understanding of climate changes during the past millennia is crucial for the scientific attribution of the current warming and the accurate prediction of the future climate change.

New method measures temperature within 3D objects
University of Wisconsin-Madison engineers have made it possible to remotely determine the temperature beneath the surface of certain materials using a new technique they call depth thermography.

Who takes the temperature in our cells?
The conditions in the environment are subject to large fluctuations.

Taking the temperature of dark matter
Warm, cold, just right? Physicists at UC Davis are using gravitational lensing to take the temperature of dark matter, the mysterious substance that makes up about a quarter of our universe.

Thermal siphon effect: heat flows from low temperature to high temperature
In this work, researchers study (both thermal and electric) energy transport in physical networks that rewired from 2D regular lattices.

Read More: Temperature News and Temperature Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.