Microshutters Are Key to Webb

Shutters as small as the width of a human hair are a vital component in the James Webb Space Telescope (JWST), giving the spacecraft the ability to see huge distances in the cosmos. The so-called microshutters, which have now arrived at the European Space Agency (ESA), are tiny doorways that focus the attention of the JWST’s infrared camera on specific targets to the exclusion of others. They will focus on objects such as very distant stars and galaxies.

Shown is an array of microshutters – about the size of a postage stamp – to be used aboard the James Webb Space Telescope. (Images: NASA/Chris Gunn)

The microshutters were recently shipped from NASA's Goddard Space Flight Center in Greenbelt, Md., to the ESA for installation into the near-infrared spectrograph (NIRSpec) instrument. This is a big step, because the microshutters are components that will fly on the actual telescope.

Harvey Moseley, a senior astrophysicist at NASA Goddard, who led the microshutter team, said "This delivery is the culmination of nearly a decade of development, in which the device grew from an initial idea to a revolutionary system for vastly increasing the power of Webb telescope as it probes the distant universe. To have completed the development of this device in a space flight program speaks highly of the great team of engineers and technicians who brought this new technology to completion."

The microshutters are being examined with a microscope. A hair is visible in the picture for size comparison.

The 100 × 200-μm shutters are assembled in arrays of more than 62,000 pieces. The telescope will contain four of the arrays. They also have to work at temperatures down to –388 °F (–233 °C).

The microshutters will enable scientists to block unwanted light from objects closer to the camera in space, such as light from stars in our own galaxy, letting the light from faraway objects shine through. To get an idea of how these tiny "hairlike" shutters work, think about how a person raises their hand in front of their eyes to block the sunshine while trying to look at a traffic signal. Microshutters block excess light to see a dim object by obscuring brighter sources of light in the cosmos.

The microshutters were designed, built and tested at the Goddard Space Flight Center specifically for the JWST. They are unique to the Webb telescope. They will work with the NIRSpec, which will allow scientists to determine the kinds of stars and gasses that make up the galaxies and to measure their distances and motions. The microshutters help the NIRSpec separate the light while observing up to 100 objects at the same time, because the microshutter system controls how light enters the NIRSpec.

Engineers at the ESA at EADS/Astrium in Ottobrunn, Germany, will install the microshutters into the NIRSpec instrument. Once installed, ESA will conduct further testing on the entire instrument. Once those tests are complete and the NIRSpec is fully functional and passes all tests, the NIRSpec will return to NASA Goddard to be placed on the main Webb telescope.

The telescope is a joint project of NASA, the ESA and the Canadian Space Agency.

For more information, visit: www.nasa.gov/goddard