The mechanism is the most advanced of its kind ever produced

Sep 19, 2011 20:31 GMT  ·  By
Northrop Grumman lead venting analyst Dan McGregor with a sunshield test article as it is placed in the vacuum chamber at Aerospace Systems' test facility in Redondo Beach, California
   Northrop Grumman lead venting analyst Dan McGregor with a sunshield test article as it is placed in the vacuum chamber at Aerospace Systems' test facility in Redondo Beach, California

Engineers working for the James Webb Space Telescope (JWST) development program at major contractor Northrop Grumman have recently began the first rounds of tests on the massive observatory's solar shield material.

The JWST is the largest, most advanced space telescope ever built, and as such sports its own challenges and technical difficulties. Technicians have recently achieved a major milestone when they finished polishing the mirrors that will act as its eyes, but many milestone await completion ahead.

Northrop experts are currently working on the first, full-scale model of the large sunshield. For many years, scientists have been looking for the most efficient material mixture to create the protective device from. Its efficiency will determine how far the telescope sees in the distant Universe.

The JWST will have sensitive infrared detectors onboard, which need to be shielded by any stray light radiation. The telescope will be placed in the L2 Lagrangian point, about 1.5 million kilometers (930,000 miles) away from lunar orbit.

This will ensure that the machine always retains the same relative position from the Earth-Sun-Moon system. But this is also where the sunshield comes into place. Its role is to protect the observatory's sensitive eyes from obtrusive light emitted by these objects.

The device is made up of five distinct layers of material, each of which is as large as a tennis court. This will pose unique engineering challenges when the telescope has to unfurl its protective blanket in space. In fact, the entire JWST deployment process will be stomach-churning.

Experts explain that – without the sunshield in position – the telescope will not be able to cool to its standard operating temperature of 40 degrees Kelvin (-233ºCelsius, -387.4ºFahrenheit). This is required in order for it to be able to observe the most distant galaxies in the Universe.

Northrop is constructing the telescope as a prime contractor, following an agreement the corporation made with the NASA Goddard Space Flight Center (GSFC), in Greenbelt, Maryland. The latter manages Hubble's replacement for the NASA Science Mission Directorate, in Washington, DC.

“Testing the full-size sunshield in a fully simulated flight configuration and comparing test results to our computer models is a very significant step forward in validating the sunshield's predicted performance,” expert Jim Flynn explains.

“The size of the sunshield mandates the use of computer models to verify performance, and this test represents the next level of analysis on a full-size membrane,” adds the researcher, who is the Northrop Grumman Aerospace Systems JWST sunshield manager.