Tiny shutters for new observatory

With the Hubble Space Telescope’s sharpest camera no longer working and its repair uncertain, the spotlight falls on the orbiting observatory’s successor. Scheduled to fly in 2013, the infrared-sensing James Webb Space Telescope (JWST) is designed to record the first stars and galaxies that flamed into existence.

OPENINGS AVAILABLE. Close-up of a microshutter grid that could let the James Webb Space Telescope be picky about what galaxies it observes. C. Gunn/NASA

NASA engineers now report that they have demonstrated that a set of small but critical electronic devices developed for the new telescope can withstand the rigors of launch and can travel into deep space. With those devices, known as microshutters, the observatory will simultaneously record the spectra of light from 100 galaxies.

Each of the four microshutters to be used on the Webb telescope consists of a grid of 62,415 squares etched into a 0.35-square-centimeter silicon wafer. Each square, only as wide as three to six human hairs, acts as a controllable shutter. It blocks unwanted light from bright foreground objects but permits the faint light from a single remote galaxy to travel to the telescope’s detectors.

In practice, the telescope will apply voltages to keep open only whichever shutters would collect the light from galaxies of interest, notes telescope engineer Murzy Jhabvala of NASA’s Goddard Space Flight Center in Greenbelt, Md.

“The microshutters enable a vast increase in the efficiency of spectral studies from JWST by making it possible to obtain simultaneously spectra of many galaxies or stars that lie close together on the sky,” comments infrared astronomer Michael Werner of NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

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