Engineers from the Richmond, California-based Tinsley Laboratories, Inc. are proud to announce that the first primary mirror segments of the future James Webb Space Telescope (JWST) have passed their flight specifications test at ambient temperature. This achievement marks the successful completion of more than six years of efforts that have led to this day. The American space agency's Goddard Space Flight Center (GSFC), in Greenbelt, Maryland, is in charge of operating the observatory, while the Northrop Grumman Corporation is in charge of the design and development stages of the effort. Tinsely Labs were in charge of polishing the mirrors, and performing the ambient testing, Space Fellowship reports.
JWST's mirrors are very special. They need to be polished using an advanced and complex process known as cryo-null figuring, so as to ensure that they take the correct form they were designed to. The catch is that the mirrors only need to do so upon reaching cryogenic temperatures, and not sooner. The mirror segments that were processed at the Labs were polished according to specifications, down to a precision rating of 20 nanometers, or less than one millionth of an inch. The achievement ensures that, once JWST unfurls in orbit, all its segments will form the necessary angles and setups with each other to promote the most sensitive observations of the Universe ever taken.
“This milestone marks the culmination of an intensive six-year manufacturing effort. To produce these unmatched precision optics, the manufacturing team has worked extremely hard, inventing systems and processes along the way to meet tremendously rigorous specifications,” Northrop Grumman Aerospace Systems sector JWST Program Manager Scott Willoughby says. “This is a tremendously important milestone to the JWST project that bodes well for both our future mirror manufacturing schedule and for the potential performance capabilities of the telescope,” GSFC JWST Optical Telescope Element Manager Lee Feinberg adds.
The infrared orbiting observatory is currently scheduled to be launched no early than June 2014, aboard an Ariane 5 delivery system. The rocket will most likely take off from the European Space Agency's (ESA) Guiana Space Center, in Kourou, the French Guiana. It will operate in the 0.6 to 28 micrometer-wavelength range, in order to be able to peer through large amounts of cosmic dust and gases. Because of its infrared nature, the entire telescope will have to operate in a somewhat cool environment, at roughly 40°Kelvin (−233.15°C or −387.67°F).
In order for that to be possible, the observatory will be placed in an extreme orbit around the Sun, in the second Lagrangian point (L2). Basically, its orbit will be a lot further than the Moon, at a distance of about 1.5 million kilometers away from our planet. Regularly, celestial bodies that orbit the Sun at a distance greater than our planet accomplish a full rotation around the star in less than a year, but James Webb will be able to do so as fast as our planet, mostly because of the complicated characteristics of its orbit, where the gravity pull from the Sun and the Earth makes for a very steady orbit. This would allow for a minimum fuel consumption in thrusters, and for a designated ten-year lifespan.
“It has taken years of intense effort for the Webb Telescope team to begin flight mirror cryotesting and we're gratified that testing was successful. Along the way, we've had to invent entire manufacturing and measurement processes because no one has ever built a telescope this large that has to operate at temperatures this extreme,” Northrop Grumman's Aerospace Systems sector JWST Program Manager Martin Mohan said in an interview last year.
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