James Webb Space Telescope’s near infrared camera completed
By Darren Quick
April 19, 2012
Assembly has been completed on the Near Infrared Camera (NIRCam) that will be the primary imager on NASA’s James Webb Space Telescope (JWST) and will also act as the telescope’s wavefront sensor to allow for control of its primary mirror. NIRCam covers the infrared wavelength range of 0.6 (the edge of visible) to 5 microns (near infrared) and its focal plane assemblies (FPA) consist of 40 million pixels and are designed to operate at 35 degrees Kelvin (-396°F/-238°C).
The formal successor to the Hubble and Spitzer Space Telescopes, the JWST will be the most powerful space telescope ever constructed. It is designed to study the formation of stars and planets, and the evolution of galaxies and NIRCam is integral to these core goals. It will be used to detect light from the earliest stages of star and galaxy development, reveal the chemical properties of exoplanets and objects within our solar system, and map dark matter via gravitational lensing.
The JWST is a joint project of NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA), with over 100 companies around the world having been involved in its design, planning and construction. NIRCam was assembled by Lockheed Martin, under contract from the University of Arizona, and is scheduled to be delivered to the NASA Goddard Space Flight Center late in the northern 2012 summer.
All 18 of the individual segments that make up the JWST’s primary mirror have now been made, polished and coated and have undergone cryogenic testing. Next, the assembly of the actuators onto the mirror segments and assembling the mirrors onto the support structure for further testing will be carried out.
The full-scale sunshield templates, that will keep unwanted infrared light from the Sun, Moon and Earth from interfering with the telescope’s observations, have also been constructed and are undergoing 3D shape-testing.
Once the telescope’s various components are constructed, they are tested to ensure they function individually and as a group, then finally as a complete telescope. After testing, the mirror assembly and instrument package will be joined, and the system tested as a whole. After this, the sunshield and spacecraft bus, which houses the systems that keep the telescope running, will be added and the telescope tested once again.
At the conclusion of testing, the JWST will be prepared for launch, which is slated for sometime around 2018.
But even before the telescope makes it into space, some of the technology developed in creating it is being adapted and applied to commercial applications in a variety of industries.
Manufacturers of telescopes, microscopes, cameras, medical scopes, and binoculars, have benefited from the development of a machine tool called the aspheric stitching interferometer that resulted from the fabrication and testing of large, high-quality aspheric optics required by the JWST.
The medical industry, and eye doctors in particular, can now get more detailed information about the shape and “topography” of an eye in seconds, rather than hours thanks to new "wavefront" optical measurement devices and techniques created for accurately measuring the JWST primary mirror segments in manufacture.
"The Webb telescope program has enabled a number of improvements in measurement of human eyes, diagnosis of ocular diseases and potentially improved surgery," said Dan Neal, Director of Research and Development Abbott Medical Optics Inc. in Albuquerque, N.M.
The JWST program has also led to improvements in testing the strength of composite materials, while the aerospace and astronomy industries have seen the development of the PhaseCan Interferometer system that can be used to measure the quality of mirror surfaces.
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